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Biomedical subjects

P Hanson

Publications and source records attributed to P Hanson.

At least 91 records · Page 5Linked to original sources
PubMed1987

Usefulness of a branching treadmill protocol for evaluation of cardiac functional capacity.

A branching treadmill protocol was designed to measure functional capacity in patients with low work capacity and varying ability to walk at speeds used in traditional protocols. A comfortable walking pace is first selected (2.0 to 3.5 mph, 0.25 mph increments) and the workload is then increased every 2 minutes in 1 MET increments (a multiple of the resting oxygen uptake [1 MET = 3.5 ml O2/kg/min]) by adjusting grade. Nine trained (maximal MET = 7.6 +/- 1.6, mean +/- standard deviation) male subjects (age 59 +/- 7 years) with previous myocardial infarction and 9 trained (maximal MET = 11.7 +/- 2.5) male control subjects (age 56 +/- 8 years) completed submaximal and maximal workloads without handrail support. The measured oxygen consumption, volume of oxygen in ml/kg/min (VO2), was compared with the predicted VO2 cost of treadmill walking calculated from speed and grade. A linear regression analysis of predicted versus measured VO2 was performed. There were no significant differences between myocardial infarction and control regression lines. Therefore, a simplified prediction equation for estimated VO2 in myocardial infarction and control subjects is proposed. Overall VO2 prediction = 1.61 + 0.99 x. The main advantage of the branching protocol format is the selection of a stable, brisk walking pace compatible with age and gait, which may improve mechanical efficiency through impedance matching. The protocol is adaptable enough in design so that most patients can complete the exercise test without use of handrails, which is essential for an accurate estimate of VO2 from treadmill speed and grade.

Aged↗
PubMed1987

Epidermal growth factor--interactions with normal and malignant urothelium: in vivo and in situ studies.

Epidermal growth factor (EGF) is excreted in urine in high concentrations and thus incubates with bladder epithelial cells continuously. However, it is not known whether any urothelial cells can bind urinary EGF or respond to it. Using a monoclonal antibody (528) to the binding portion of the human EGF receptor, immunoperoxidase staining demonstrated that the basal cell layer of normal urothelium is richly endowed with cell surface EGF receptors while the superficial cell layer is not. Alternatively, superficial cells of premalignant and malignant urothelium have many surface EGF receptors. Intravesical EGF induces in vivo activity of ornithine decarboxylase and DNA synthesis in rat bladders, with nuclear thymidine incorporation being limited to the basal epithelial cell layer. These studies indicate that urothelium can respond to urinary EGF and that this response parallels the distribution of EGF receptors. These findings combined with the difference in EGF-receptor expression between malignant and normal cells indicate that urinary EGF may play a role in bladder tumor development and/or growth.

Animals↗
PubMed1987

Exercise tolerance changes following renal transplantation.

Maximal exercise capacity was measured in 20 nondiabetic patients with end-stage renal disease before and soon after successful renal transplantation. Maximal oxygen consumption increased significantly in all patients posttransplant. Increases in maximal heart rate and heart rates at 70% of maximal levels were also observed. The changes in maximal oxygen consumption were not significantly correlated with changes in hematocrit. The removal of uremia may result in improved functioning of one or more of the systems involved in oxygen transport and utilization that determine exercise capacity.

Adrenergic beta-Antagonists↗
PubMed1987

Molecular cloning of a brain-specific calcium/calmodulin-dependent protein kinase.

A calcium/calmodulin-dependent protein kinase type II (CaM-K) alpha-subunit cDNA has been cloned from rat brain. This enzyme is encoded by a 5.1-kilobase mRNA expressed exclusively in the brain. Hybridization histochemistry reveals that the CaM-K mRNA expression corresponds to the distribution of the immunoreactive alpha-subunit protein, suggesting that the high enzyme levels in specific brain areas reflect regional differences in gene expression. The sequence of CaM-K alpha-subunit cDNA indicates a 478-amino acid (54-kDa) protein with three functional domains. The domain organization suggests a structural model for calcium/calmodulin-dependent and independent states that might subserve short- and long-term responses to transient stimuli.

Amino Acid Sequence↗
PubMed1987

Cardiovascular responses to military antishock trouser inflation during standing arm exercise.

Military antishock trousers (MAST) inflated to 50 mmHg were used with 12 healthy males (mean age 28 +/- 1 yr) to determine the effects of lower-body positive pressure on cardiac output (Q), stroke volume (SV), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MABP), total peripheral resistance (TPR), and O2 uptake (VO2) during graded arm-cranking exercise. Subjects were studied while standing at rest and at 25, 50, and 75% of maximal arm-cranking VO2. At each level, rest or work was continued for 6 min with MAST inflated and for 6 min with MAST deflated. Order of inflation and deflation was alternated at each experimental rest or exercise level. Measurements were obtained during the last 2 min at each level. Repeated-measures analysis of variance revealed significant increases (P less than 0.001) in Q, SV, and MABP and a consistent decrease in HR with MAST inflation. There was no apparent change in Q/VO2 between inflated and control conditions. There was no effect of MAST inflation on VO2 or TPR. MAST inflation counteracts the gravitational effect of venous return in upright exercise, restoring central blood volume and thereby increasing Q and MABP from control. HR is decreased consequent to increased MABP through arterial baroreflexes. The associated decrease in TPR is not observed, being offset by the mechanical compression of leg vasculature with MAST inflation.

Adult↗
PubMed1987

Isometric exercise: cardiovascular responses in normal and cardiac populations.

Isometric exercise produces a characteristic pressor increase in blood pressure which may be important in maintaining perfusion of muscle during sustained contraction. This response is mediated by combined central and peripheral afferent input to medullary cardiovascular centers. In normal individuals the increase in blood pressure is mediated by a rise in cardiac output with little or no change in systemic vascular resistance. However, the pressor response is also maintained during pharmacologic blockade or surgical denervation by increasing systemic vascular resistance. Left ventricular function is normally maintained or improves in normal subjects and cardiac patients with mild impairment of left ventricular contractility. Patients with poor left ventricular function may show deterioration during isometric exercise, although this pattern of response is difficult to predict from resting studies. Recent studies have shown that patients with uncomplicated myocardial infarction can perform submaximum isometric exercise such as carrying weights in the range of 30 to 50 lb without difficulty or adverse responses. In addition, many patients who show ischemic ST depression or angina during dynamic exercise may have a reduced ischemic response during isometric or combined isometric and dynamic exercise. Isometric exercises are frequently encountered in activities of daily living and many occupational tasks. Cardiac patients should be gradually exposed to submaximum isometric training in supervised cardiac rehabilitation programs. Specific job tasks that require isometric or combined isometric and dynamic activities may be evaluated by work simulation studies. This approach to cardiac rehabilitation may facilitate patients who wish to return to a job requiring frequent isometric muscle contraction. Finally, there is a need for additional research on the long-term effects of isometric exercise training on left ventricular hypertrophy and performance. The vigorous training regimens currently utilized by international class and professional athletes should stimulate longitudinal studies of physiologic and pathophysiologic outcomes of intense isometric exercise training programs.

Adrenergic beta-Antagonists↗
PubMed1986

Carnitine status, plasma lipid profiles, and exercise capacity of dialysis patients: effects of a submaximal exercise program.

Carnitine status, blood lipid profiles, and exercise capacity were evaluated in a combined group of hemodialysis (N = 4) and continuous ambulatory peritoneal dialysis (N = 6) patients before and after an 8-week submaximal exercise program. Maximal aerobic capacity (VO2max) was only 18.5 +/- 5.9 (mean +/- SD) mL O2/kg/min, well below the expected 30 to 35 mL O2/kg/min for age-matched sedentary controls. Plasma short-chain acylated carnitine levels, which were two to three times normal values, were reduced after the exercise program, but the long-chain acylcarnitines were significantly reduced during acute exercise. Muscle biopsies of the vastus lateralis were performed at rest in five patients prior to and after the 8-week exercise program. Total carnitine in skeletal muscle was 3.09 (.076 SD) mumol/g ww, with only 11.3% acylated prior to the exercise program, which was much lower than the 4.25 +/- 1.27 mumol/g ww, with 28.5% acylated in a group of healthy athletic subjects (N = 28). Muscle free carnitine concentrations decreased significantly following the 8-week training period, with only a slight reduction in total carnitine. The percent of acylated carnitine was therefore significantly increased (P less than 0.05) from 11.3% to 25.2% after the experimental period. Pretraining carnitine palmitoyl transferase activity at rest was 0.57 +/- 0.28 nmol palmitoyl carnitine formed/5 min/mg mitochondrial protein, which was not changed by exercise training v 1.80 +/- 0.51 nmol/5 min/mg protein in 28 healthy normals (P less than 0.001). Free fatty acid concentrations were reduced significantly during acute exercise as a result of the exercise training program whereas other plasma lipids were not altered. (ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Dietary carnitine intake related to skeletal muscle and plasma carnitine concentrations in adult men and women.

The purpose of this investigation was to determine if there was any relationship between dietary carnitine intake and the concentrations of carnitine in skeletal muscle and blood plasma in healthy adult men and women. Subjects (14 men, 14 women, fasted 8 h) reported to the Biodynamics Laboratory where they completed a 24-h diet recall questionnaire. Resting muscle biopsy (vastus lateralis) and blood plasma samples were taken and assayed for free, short-chain, and long-chain acyl carnitine concentrations. Dietary carnitine intake was estimated from data on concentrations in food. There was no significant relationship between either protein or carnitine intake with skeletal muscle carnitine concentrations. There was a significant relationship between both dietary carnitine (r = 0.50) and protein (r = 0.48) intake with blood plasma total acid soluble carnitine concentrations (p less than 0.01) in all subjects.

Adult↗
PubMed1986

Exercise capacity in hemodialysis, CAPD, and renal transplant patients.

Eighteen hemodialysis, 12 chronic ambulatory peritoneal dialysis (CAPD), and 20 renal transplant patients performed maximal treadmill exercise tests. Heart rates and blood pressures were determined every minute and maximal oxygen consumption was measured directly. Exercise capacity as measured by VO2 max is low in dialysis patients and similar to sedentary normal individuals in renal transplant patients. Maximal heart rates were significantly lower in hemodialysis patients than transplant recipients. The lower exercise tolerance in end-stage renal disease indicates that most patients regardless of the treatment mode could benefit from attempts through exercise training to increase physical working capacity.

Adult↗
PubMed1985

Left ventricular responses to upright isometric handgrip and deadlift in men with coronary artery disease.

Isometric exercise is usually discouraged for patients with coronary artery disease (CAD) because of the possible adverse effects of increased blood pressure on left ventricular (LV) function. Cardiovascular and LV responses to upright handgrip and deadlift were compared in 10 normal men (mean age 52 years) and 14 men (mean age 54 years) with documented CAD or myocardial infarction who were in a supervised exercise program. Handgrip and deadlift were each performed at 30% maximal effort for 3 minutes. LV technetium-99m multigated radionuclide angiograms, electrocardiogram and blood pressure were measured during the final 60 seconds. CAD patients had a significantly lower LV ejection fraction at rest (41%) than normal subjects (57%). Both groups showed equal and significant increases in heart rate, systolic and diastolic pressure during handgrip and deadlift. These responses were all significantly greater in both groups during deadlift. No significant changes in LV ejection fraction occurred in either group during handgrip or deadlift. LV wall motion abnormalities were present in 9 of 14 CAD patients at rest and increased with handgrip (11 men) and deadlift (13 men). No LV abnormalities occurred in normal subjects. These data indicate cardiovascular responses are similar in normal and exercise-trained CAD patients during upright submaximal isometric exercise using small or large muscle groups. Radionuclide measurements of global LV function remain stable in both groups, during similar conditions of increased systolic pressure afterload. However, LV wall motion abnormalities are aggravated in CAD patients during isometric exercise.

Blood Pressure↗
PubMed1985

Exercise blood pressure and baroreflex function in borderline hypertensive and normotensive young men.

1. Resting carotid baroreflex sensitivity and blood pressure responses to standardized conditions of rest and exercise were measured in 17 borderline hypertensive males and 12 normotensive males. 2. The borderline hypertensive group had significantly higher systolic and diastolic blood pressures during orthostatic rest and isometric handgrip exercise and higher systolic blood pressure during supine rest and submaximum and maximum treadmill exercise. 3. The borderline hypertensive group had an attenuation of baroreflex sensitivity compared with the normotensive group. Resting baroreflex sensitivity was significantly correlated with absolute systolic blood pressure during supine rest, orthostatic rest, isometric handgrip exercise and submaximum treadmill exercise. 4. The results indicate that blood pressure is regulated at a significantly higher level during rest and exercise in borderline hypertension and is associated with reduced baroreflex sensitivity measured at supine rest.

Adult↗
PubMed1984

Comparison of supervised and unsupervised exercise training after coronary bypass surgery.

Functional capacity and cardiovascular responses to serial graded treadmill testing ( GXT ) were compared in 180 patients who performed prescribed unsupervised exercise and 24 patients who were referred for supervised exercise after coronary artery bypass surgery (CABS). The groups were men similar in age range, number of bypass grafts, preoperative left ventricular impairment and number of days hospitalized. All patients received similar predischarge exercise monitoring and began a progressive home walking or cycling program. Initial GXT (T1) was performed 44 +/- 9 days postoperatively. Both groups were instructed to continue prescribed exercise at 75 to 85% maximal heart rate (HR) for 30 to 40 minutes 3 days (supervised) or 5 days ( unsupervised ) per week. The second GXT (T2) was performed 115 +/- 27 days after CABS. In each group there were significant (p less than 0.01) increases in exercise capacity and HR from T1 to T2. However, there were no significant differences in maximal exercise capacity and HR between groups at T1 or T2. Improvement in functional capacity was not influenced by therapeutic beta blockade. These findings indicate that prescribed unsupervised exercise can be performed safely and results in similar functional improvements compared with supervised exercise after uncomplicated CABS.

Adrenergic beta-Antagonists↗
PubMed1983

Effects of acute moderate-intensity exercise on carnitine metabolism in men and women.

The purpose of this investigation was to describe the dynamics of carnitine metabolism during an acute episode of exercise. Twenty-eight subjects (14 male; 14 female) exercised for 40 min on a bicycle ergometer at 55% of their maximal aerobic capacities. Blood samples were obtained at rest, 10, 20, 30, and 40 min of exercise, and 15-min postexercise. Muscle biopsies of the vastus lateralis were performed before and after exercise. Results demonstrated that the percent of acylated plasma carnitine increased significantly (P less than 0.05) across all subjects from 17.3% at rest to 22.3% by 40 min of exercise and continued to increase to 22.8% 15-min postexercise. Total muscle carnitine levels fell significantly (P less than 0.001) across all subjects from 4.21 (1.27) (means +/- SD) mumol/g wet weight at rest to 3.29 (1.27) mumol/g wet weight after exercise. Well-trained males and females had almost identical levels of muscle carnitine [4.35(1.86) and 4.34 (0.64) mumol/g wet weight, respectively]. These levels were somewhat higher but not significantly higher than their moderately trained counterparts [3.86(1.34) and 4.28(1.18) males and females, respectively]. Carnitine palmitoyl transferase (E.C. 2.3.1.21) activity also declined significantly (P less than 0.05) across all subjects after exercise. This study is the first to demonstrate a potential loss of acylated carnitine forms from muscle to plasma during acute exercise, possibly reflecting an increase in carnitine turnover. Alterations in carnitine status may represent another metabolic adaptation to chronic exercise training.

Adult↗