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Biomedical subjects

E Ben-Ari

Publications and source records attributed to E Ben-Ari.

26 records · Page 2Linked to original sources
PubMed1987

Effects of prolonged intensive versus moderate leg training on the untrained arm exercise response in angina pectoris.

To compare the effects of 2 different leg training intensities on the cardiocirculatory exercise response of the untrained arm, 58 patients with angina pectoris were randomized to either an intensive (at least 85% of symptom-limited exercise, n = 28) or a moderate (70 to 85% of symptom-limited exercise, n = 30) training group. Patients trained for 6 months, 2 times per week for 30 minutes each. Results of the 2 groups after training showed similar significant (p less than or equal to 0.001) decreases in heart rate (HR), systolic blood pressure (BP) and HR X BP product for trained legs and untrained arms at matched subanginal workloads and significant (p less than 0.01 to 0.001) increase in anginal threshold HR and HR X BP for the onset of 1 mm or more ST horizontal depression during testing of trained legs as well as of untrained arms. The improvement in exercise capacity at subanginal workloads results from decreased HR X BP product. In contrast, the significant increase in HR X BP product for the onset of ST-segment displacement and precipitation of anginal pain for both the trained and untrained limbs may imply an increase in myocardial blood flow. Thus, prolonged intensive or moderate training may significantly improve coronary blood flow in selected patients with angina pectoris. Patients with the highest anginal threshold HR and HR X BP product before training showed the most improvement at 6 months after training.

Adult↗
PubMed1987

Exercise testing in juvenile borderline hypertension.

Exercise testing has emerged as an important method for improved evaluation of the cardiovascular system. However, juvenile patients presenting resting borderline hypertension have not been extensively studied. Therefore, this study evaluated the response to exercise in this group of patients. Nine hundred men aged 16 to 29 years performed a multistage near-maximal exercise test. The control group consisted of 338 age- and weight-matched, asymptomatic, healthy, normotensive individuals. Mean physical working capacity (+/- SD) was 129 +/- 28 W (82 +/- 18% of the normal according to our standardization) in the hypertension group, and 153 +/- 29 W (102 +/- 18%) in the control group (P less than 0.001). Mean systolic blood pressures at termination of exercise were 181 +/- 25 and 164 +/- 25 mm Hg in the hypertensive and the control groups, respectively; the mean diastolic values at termination of exercise were 49 +/- 32 and 32 +/- 29 mm Hg, respectively. The magnitude of the changes in blood pressure from rest to near-maximal values was smaller in the borderline-hypertensive individuals demonstrate a clear hypertensive pattern of reaction to physical activity, thus emphasizing the importance of exercise testing as part of the routine workup of such patients. The relationship between borderline hypertension and the risk of myocardial events has been established, and early hygienic or even pharmacological measures are necessary.

Adolescent↗
PubMed1986

Pressure/volume ratio and pressure/volume ratio exercise quotient: an echocardiographic comparative study of left ventricular function indicators.

Noninvasive evaluation of left ventricular function (LVF) has been performed with two-dimensional echocardiography (TDE). Ejection fraction (EF), end systolic volume index (ESVI) and systolic blood pressure/end systolic volume index ratio (PVR)--an indicator which is independent of preload and afterload changes in a wide physiologic range--were assessed at rest and after exercise. Twenty-seven postmyocardial infarction (MI) patients were compared to 27 normal controls in an attempt to examine the above parameters of LVF in each group, measured by TDE. Correlation of TDE EF with radionuclide angiography EF proved the reliability of TDE. Rest and postexercise values of EF and PVR showed highly significant differences between the two groups. Using ESVI, a relatively lesser significant difference was found. PVR values at rest were 4.86 mm Hg/ml/m2 in the study group and 9.51 in the control group. These values increased to 5.34 and 15.15, respectively, after exercise. The ratio of PVR after exercise to PVR at rest, expressed as percentage change (PVREQ), seemed to be an additional tool in separating between both groups. This indicator merges pressure, volume, and the influence of exercise on both; a PVREQ of at least 145% correlated well with absence of MI in most of our patients.

Adolescent↗
PubMed1986

Left-ventricular exercise echocardiographic abnormalities in patients with sarcoidosis without ischemic heart disease.

We performed postexercise two-dimensional echocardiography in 21 patients with sarcoidosis but no signs of ischemic heart disease and in 24 normal control subjects. This was done to assess global and regional left-ventricular (LV) function and to try to identify the presence of occult myocardial involvement among sarcoidosis patients. All 21 sarcoidosis patients had a normal resting left-ventricular ejection fraction (LVEF) and echocardiogram. An abnormal LV response to exercise was detected in 10 sarcoidosis patients in the form of a significant decrease in mean LVEF with exercise without concomitant clinical and ECG evidence of myocardial ischemia. Seven of these 10 patients were found to have a pathological increase in LV and systolic volume with exercise, although it did not achieve statistical significance. In addition, markedly abnormal regional septal wall motion was noted in two of these patients. In the remaining 11 sarcoidosis patients, mean LVEF increased significantly with exercise. This is the normal ejection fraction response to stress. These 11 patients also showed that LV end-systolic volume decreased with exercise; the decrease was from 40.8 to 27.9 ml (P = 0.0004). In the control group, the mean LVEF increased from 69.5 +/- 7.2 at rest to 78.5 +/- 7.6 with exercise (P less than 10(-6)). We conclude that postexercise echocardiography is a noninvasive, simple, and safe method to detect and to follow the course of possible occult myocardial sarcoidosis.

Adult↗
PubMedDate not supplied

Doppler-derived aortic flow measurements during and after heavy isometric exercise in healthy men versus men with myocardial infarction.

Doppler echocardiography is a useful noninvasive determination of left ventricular function during dynamic exercise. Scarce data are available for the use of this technique during heavy isometric exercise. Therefore, Doppler-derived aortic flow indexes were assessed during and after 50% maximal upper-body isometric exercise in 25 healthy men (aged 47 +/- 6 years) and compared with those of 22 men (aged 48 +/- 9 years) who had suffered myocardial infarction. The heart rate increased (p = 0.01) in each of the groups from a mean of 68 +/- 12 at rest to 84 +/- 11 during isometric exercise. At rest, systolic blood pressure was higher (p = 0.05) in the patients with coronary artery disease. During exercise, the patients with cardiac disease, compared with the healthy volunteers, demonstrated a lesser reduction in flow velocity integral, stroke volume, and cardiac indexes (p = 0.001). Immediately on recovery, the patients with cardiac disease, compared with the healthy group, showed significantly greater (p = 0.001) increase in stroke volume and cardiac indexes. At 3 minute's recovery, the stroke volume index continued to increase in the patients with cardiac disease, while the healthy group showed a decrease to below its resting value. Although 50% of maximal upper-body isometric exercise caused similar heart rate and systolic blood pressure responses in healthy patients and patients with cardiac disease, there were significant group differences in Doppler-derived left ventricular systolic function indexes, which were greatest on immediate and 3 minute's recovery. The results suggest that this novel isometric test may be useful in clinical testing.

Aorta↗
PubMedDate not supplied

[GABA--the basic mediator of excitation in the early stages of hippocampal development].

GABA is the principal neurotransmitter of inhibition in the adult mammalian brain. However, at early stages of development, including embryonic period and first week of postnatal life, GABA plays the role of main neurotransmitter of excitation. The paradoxical excitatory effect of GABA is due to an inversed chloride gradient and therefore a depolarizing direction of GABA-A receptor mediated responses. In addition, another type of GABAergic inhibition mediated by postsynaptic GABA-B receptors is not functional at early stage of life. In the neonatal rat hippocampus, GABA, acting via GABA-A receptors, activates voltage gated sodium and calcium channels and potentiates the activity of NMDA receptors by reducing their voltage dependent Mg2+ block. The temporal window when GABA exerts excitatory actions coincides with a particular pattern of activity of hippocampal neuronal network that is characterized by periodical giant depolarizing potentials (GDPs) reminiscent of interictal-like epileptiform discharges. Recent studies have shown that GDPs result from the synchronous discharge of GABAergic interneurons and principal glutamatergic pyramidal cells and are mediated by the synergistic excitatory actions of GABA-A and glutamate receptors. GDPs provide synchronous intracellular Ca2+ oscillations and may therefore be implicated in hebbian modulation of developing synapses and activity-dependent formation of the hippocampal network.

Aging↗