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Biomedical subjects

H K Hellerstein

Publications and source records attributed to H K Hellerstein.

At least 19 recordsLinked to original sources
PubMed1990

Comparison of scales used to quantitate the sense of effort to breathe in patients with chronic obstructive pulmonary disease.

Several different scaling techniques, i.e., Borg category (BC) and visual analogue (VA) scales have been used to quantitate the intensity of the respiratory sensations elicited during exercise, but their relationship is unclear. Six subjects with stable chronic obstructive lung disease (FEV1 = 1.2 +/- 0.1 SE L) simultaneously rated the sense of effort to breathe with both BC and VA scales during progressive, maximal exercise tests performed three to five times on a cycle ergometer. The VA scores correlated linearly with minute ventilation in all subjects in all trials (r = 0.98 +/- 0.01), and when converted to common units (i.e., Z scores) correlated closely with simultaneous scores obtained using the Borg scale (r = 0.99 +/- 0.01). Furthermore, VA scores varied minimally over several trials. Coefficient of variation for the maximal VA scores was 6 +/- 1%, which was similar to the variation in maximal Borg score (i.e., 3 +/- 1%). We conclude that the visual analogue scale is reproducible and correlates closely with the Borg score when scaling the sense of effort to breathe during exercise in subjects with stable chronic obstructive pulmonary disease.

Aged↗
PubMed1989

Umbilical artery waveform during bicycle exercise in normal pregnancy.

Eighteen healthy pregnant women in the last half of gestation exercised to 85% of their predicted maximum heart rate on a bicycle ergometer. Pulsed Doppler flow studies before the exercise and during the recovery period were taken close to the umbilical artery's placental insertion site. The systolic-to-diastolic ratio (S/D) of the umbilical artery waveform did not change significantly during the period of observation. In three women, however, a significant increase in the S/D ratio occurred in the first few minutes post-exercise; this was due to a transient fetal bradycardia. In one woman, the S/D ratio remained high despite return of a normal fetal heart rate.

Adult↗
PubMed1987

Augmented Hageman factor and prolactin titers, enhanced cold activation of factor VII, and spontaneous shortening of prothrombin time in survivors of myocardial infarction.

Hyperestrogenemia has been implicated in the pathophysiology of myocardial infarction. Because marked augmentation of the titer of Hageman factor is brought about by the administration of estrogens in humans and by prolactin or estrogen infusion in hypophysectomized rats, we measured the plasma concentrations of estradiol, prolactin, and clotting factors participating in surface-mediated reactions of coagulation in survivors of myocardial infarction. We observed higher titers of Hageman factor, prolactin, and high molecular weight kininogen but no significant change in estradiol or prekallikrein in survivors of myocardial infarction compared with controls. The titer of Hageman factor tended to be directly associated with the prolactin titer. We also report an increase in factor VII activity and spontaneous shortening of prothrombin time in the cold-stored plasma of survivors of myocardial infarction. In such individuals as well as in the control group, the titer of Hageman factor appeared to be responsible for half of the observed increase in factor VII activity and two thirds of the observed shortening of prothrombin time. These data indicate that although the titer of Hageman factor strongly influences the cold activation of factor VII, other factors may affect these phenomena.

Aged↗
PubMed1985

Distance running in the 1980s: cardiovascular benefits and risks.

Although within the capacity of perhaps one to two percent of highly motivated patients after myocardial infarction, long-distance and marathon running do not confer on normal subjects immunity from coronary atherosclerosis or freedom from high grades of ventricular ectopy during running and nonrunning activities. The presence of significant coronary heart disease does not preclude participation in long-distance and marathon running, provided appropriate safety precautions are taken. There is no conclusive proof that the long-term prognosis is improved by long-distance or marathon running or by increasing the intensity of training above the generally accepted level of 60 to 80 percent of VO2 max. Marathon running for coronary patients and for coronary-prone persons remains experimental and awaits further scientific evaluation employing a prospective randomized study of subjects with angiographic proof of significant coronary artery disease.

Adaptation, Physiological↗
PubMed1978

A comparison of continuous and intermittent progressive multistage exercise testing.

Twelve male subjects were compared on continuous and intermittent treadmill test of identical exercise stages. Each stage was three minutes in duration. Oxygen uptake during minutes one and two was significantly lower in the intermittent test. Heart rate VE and R were lower and oxygen pulse greater during all three minutes at moderate and strenuous workloads and throughout recovery of the intermittent protocol. There were no significant differences in exercise minute three or recovery VO2 and blood pressure. Regression equations for the relationship between VO2 oxygen pulse heart rate, VE systolic blood pressure and workload during the third minute of exercise included curvilinear functions whereas the regression equations between VO2 and heart rate, and between R and workload were linear. Slopes of percent maximal heart rate vs. percent percent maximal VO2 of the third minute were not different. Heart rate responded more rapidly to onset and cessation of exercise than did VO2. A near steady state was obtained during low and moderate workloads prior to minute three supporting the feasibility of reducing test time. Result suggest a slight advantage in intermittent testing compared to continuous testing for evaluating cardiovascular function and for exercise prescription.

Adult↗
PubMed1977

Limitations of marathon running in the rehabilitation of coronary patients: anatomic and physiologic determinants.

Prescribed, supervised exercise training has proved valuable in the rehabilitation of selected coronary patients. However, long distance (marathon) running has limited cardiovascular value in the rehabilitation of patients for a majority of occupations, which involve predominantly upper extremity effort. The age of patients with coronary heart disease and the severity of the lesions preclude the wide application of marathon running to the general coronary heart disease population. Less than 6/1000 subjects with coronary heart disease have been estimated as potentially being able to achieve by high-level training a maximum Vo2 sufficient to complete a marathon race in 5 hours. The hazards of high-level-activity-induced cardiac arrest that is reversible mandates the availability of CPR equipment and personnel in the immediate vicinity of all coronary patients and most coronary-prone patients who are undertaking such heroic activity. Over-publicized marathon running by a few subjects has aroused unrealistic expectations for the majority of coronary heart disease subjects and probably similarly for a considerable number of coronary-prone subjects, many of whom have "silent" coronary disease.

Adaptation, Physiological↗
PubMed1977

The exercise electrocardiogram in trained and untrained adolescent males.

Exercise electrocardiograms (Ex ECG) were performed on both trained and untrained adolescent males to determine whether a difference exists between the normal adolescent and normal adult male. Exercise was performed on a mechanically braked bicycle ergometer using an intermittent work load protocol, and the Ex ECG's were analyzed according to J-point displacement and ST segment slope. No J-point depression was seen and the ST segment slope was positive during exercise in both trained and untrained subjects. There was no difference in the J-point displacement or the ST segment slope between the trained and untrained subjects. This study suggests that any J-point depression during exercise may be abnormal in the adolescent male. Training does not have an effect on the J-point or ST segment at maximum exercise.

Adolescent↗
PubMed1976

Panel V: Acceleration of collaterals due to physical activity--dogma or fast. A misguided goal or unrealized objective?--introduction.

The hypothesis drawn from Eckstein's study of dogs [5] suggests that collateral circulation (measured retrograde coronary collateral flow) could be enhanced in man provided that the coronary arteries were partially obstructed before training. The currently available data on the effects of exercise training on arteriosclerotic heart disease subjects with significant, but not complete, obstruction, and without collateral vessels before training, indicate that visible coronary collateral vessels do not develop unless further coronary obstruction progresses to complete or near complete occlusion. Although the above hypothesis is not supported by the angiographic studies to date, final judgment should be held in abeyance until data are presented on the collateral flow and regional myocardial perfusion in exercise-trained human subjects with arteriosclerotic heart disease.

Animals↗
PubMed1976

Exercise training as a therapeutic modality.

At present we have no data to assure us that physical activity changes or prevents the development of coronary atherosclerosis or that it changes the progression of the disease which is already present. The data are excellent that in about 85% of patients with coronary disease, exercise training has beneficial personal and societal effects. However, even this opinion must be subjected to critical scrutiny. Several (controlled and randomized) studies of the effects of exercise training on arteriosclerotic heart disease subjects are in progress, in the United States, in Canada, and in Europe. The National Exercise and Heart Disease Project in the U.S.A has already accessed 600 arteriosclerotic heart disease subjects and expects to attain the target study population of 800 subjects by 1 June 1976. We msut be prepared and willing to accept the results of such rigorously controlled studies. In another four to five years of follow-up, the basis for our present views will be either confirmed or rejected -- although most of us anticipate a validation of our present opinion, viz., exercise training enhances the quality of life, and coping capacity, even though the direct effects on the course of coronary atherosclerosis have not been demonstrated.

Adult↗