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Biomedical subjects

J D Posner

Publications and source records attributed to J D Posner.

11 recordsLinked to original sources
PubMed1992

Patterns of self-care needs and interventions related to biologic response modifier therapy: fatigue as a model.

Many patients receiving biologic response modifier (BRM) therapy experience fatigue as a significant and, at times, dose-limiting side effect. For this reason, a multiinstitutional pilot study was designed to collect data about the needs and self-care interventions of patients who had undergone at least one prior treatment with a BRM and had experienced fatigue as a symptom. Information was also obtained on the extent to which the needs and self-care interventions identified by patients compared with those perceived by their family members and nurses. Of the 16 patients who participated in the study, seven were being treated with interleukin-2 (IL-2), eight with interferon alfa (IFN-alpha), and one with tumor necrosis factor (TNF). The study found no significant correlation between the degree or duration of fatigue and the BRM or dosage administered. Not surprisingly, patient and family member responses correlated fairly well. However, in several parameters, including the degree and duration of fatigue, nurses' perceptions did not correlate at all with those of the patient. While 46% of nurse responses matched those of the patient as to useful self-care interventions, only 17% of nurses accurately identified factors or events that patients perceived as worsening fatigue. Further, there was no correlation among patient, family member, and nurse responses on interventions that could be used by others to help the patient cope with fatigue. The overall results of this pilot study indicate that nurses need to be more attuned to assessing fatigue as a side effect of BRM therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Cancer Care Facilities↗
PubMed1992

Low to moderate intensity endurance training in healthy older adults: physiological responses after four months.

OBJECTIVE: To determine the physiological adaptations in previously sedentary healthy older men and women (mean age = 68) to a 16-week low-to-moderate-intensity exercise program. DESIGN: Randomized, controlled trial. SETTING: An exercise facility and testing laboratory in a gerontological research institute. PARTICIPANTS: Two-hundred forty-seven community-dwelling older persons free of significant cardiovascular, pulmonary, or uncontrolled metabolic disease, anemia, electrolyte abnormality, resting BP of 165/90 or greater, or chronic disease affecting the ability to exercise on a bicycle. INTERVENTION: Subjects were randomly assigned to either an exercise (n = 166) or attention control group (n = 81). Exercisers trained thrice weekly for 40 minutes on a cycle ergometer (5-minute warm up, 30 minutes at training heart rate (THR), 5-minute cool down). THR was set at 70% of peak heart rate attained on a maximal exercise test (mean = 115 +/- 15). Control subjects attended weekly group talks. Testing took place before and after the program. RESULTS: Peak attained oxygen uptake (VO2max) increased 8.5% in exercisers and decreased slightly in controls (p less than .001) and oxygen uptake at ventilatory threshold (VeT VO2) increased by 3.5% in exercisers and decreased by 3% in controls (p less than .001). This pattern of a greater increase in VO2max than VeT VO2 is different from that seen in young and middle-aged subjects. CONCLUSION: This study demonstrated that a large scale training program is feasible for healthy older people, that physiologic improvements can be measured after 16 weeks of low-to-moderate-intensity training, and that mechanisms of adaptation to exercise may be different in elderly subjects from those in younger ones.

Adaptation, Physiological↗
PubMed1992

Muscle metabolism in track athletes, using 31P magnetic resonance spectroscopy.

We tested whether preferred running event in track athletes would correlate with the initial rate of phosphocreatine (PCr) resynthesis following submaximal exercise. PCr recovery was measured in the calf muscles of 16 male track athletes and 7 male control subjects following 5 min of repeated plantar flexion against resistance. Pi, PCr, and pH were measured using phosphorus magnetic resonance spectroscopy (31P MRS) with an 8-cm surface coil in a 1.8-T magnet. During exercise, work levels were gradually increased to deplete PCr to 50-60% of the initial value. No drop in pH was seen in any of the subjects during this exercise. The areas of the PCr peaks following exercise were fit to monoexponential curves. Two or three tests were performed on each subject and the results averaged. Athletes were divided into three groups based on their primary event: sprinters running 400 m or less, middle-distance athletes running 400-1500 m, and long-distance athletes running farther than 1500 m. The maximal rates of PCr resynthesis (mmol.min-1.kg-1 muscle weight) were 64.8 +/- 8.6, for long-distance runners; 41.4 +/- 11, for middle-distance runners; 32.0 +/- 7.0, for sprinters; and 38.6 +/- 10, for controls (mean +/- SE). The faster PCr recovery rates seen in long-distance runners compared with sprinters indicate greater oxidative capacity, which is consistent with the known differences between athletes in these events.

Adolescent↗
PubMed1992

The use of nuclear magnetic resonance to evaluate muscle injury.

Magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) are new and powerful tools to study tissue biochemistry, and to provide precise anatomical visualization of soft tissue structures. This review focuses on the use of these techniques to study exercise-induced muscle injury. MRS measurements show an increase in the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) 1-7 d after eccentric exercise. This increase in Pi/PCr could be due to either increases in extracellular Pi or small increases in resting muscle metabolism. Increased Pi/PCr is also seen during training programs and may indicate persistent muscle injury. Increased resting Pi/PCr with injury was not associated with altered metabolism during exercise. Elevations in resting Pi/PCr have been used to show increased susceptibility of dystrophic muscle to exercise-induced injury. Progressive clinical deterioration in dystrophic dogs is marked by impaired muscle metabolism, and the presence of low oxidative muscle fibers not seen in normal dogs. MRI shows increased proton T2 relaxation times following eccentric exercise that last up to 80 d after injury, and can reflect muscle edema as well as longer lasting changes in the characteristics of cell water. MRI demonstrate precise localization of the injured area, with large differences in both location and degree of injury in different subjects following the same exercise protocol. Thus, MRS can provide information on the metabolic response to injury, while MRI provides information regarding the site and extent of the injury. These tools have promise in helping to understand exercise-induced muscle injury.

Animals↗
PubMed1990

Effects of exercise training in the elderly on the occurrence and time to onset of cardiovascular diagnoses.

To examine the long-term effects of aerobic exercise on the occurrence and time to onset of cardiovascular diagnoses, 184 initially healthy older subjects were randomized into either a long-term exercise group (Group A, n = 80), a short-term exercise group (Group B, n = 42), or a contract control group (Group C, n = 62). After completion of two years in the study, data on new cardiovascular diagnoses and time to onset of these diagnoses in each of the three groups were compared. The occurrence rates for new onset diagnoses were as follows: Group A, 2.5%; Group B, 2%; and Group C, 13%; the average time to onset was greatest for the long-term exercisers and shortest for the contact control group (P less than or equal to .02). The results suggest that a regular program of exercise may have cardiovascular benefits for those over 60 years of age.

Aged↗
PubMed1988

Benefits of exercise in old age.

Although exercise capacity declines with age, the decline appears to be slight when measured in healthy, physically active subjects. There is growing evidence that exercise has a positive influence on increasing healthy function and decreasing the impact of diseases common in the elderly. While the dose-response relationship between physical activity and health benefits continues to be studied, there is some evidence that even low- and moderate-intensity exercise programs in older people result in tangible improvements in many physical and psychologic parameters.

Aged↗
PubMed1987

Ventilatory threshold: measurement and variation with age.

The purpose of this study is to present measurement of ventilatory threshold (VeT) and maximal oxygen uptake (VO2max) in a large group of predominantly older subjects using a bicycle ergometer and an automated measuring system. One hundred and twenty-seven healthy elderly subjects (mean age: 68) and 44 young and middle-aged subjects (mean age: 39) underwent a maximal exercise test with breath-by-breath measurement of ventilation and gas exchange variables. Ventilatory threshold was determined by visual inspection of the breakpoints in the VE/VO2 and PETO2 data curves. Additional measures were made in a subset of subjects to determine the reproducibility and interobserver variability of VeT and the relationship between VeT and the venous lactate threshold (LaT). Day-to-day reproducibility of VeT was good with a mean difference in VO2 at VeT on two occasions of 40.23 +/- 125 ml/min. Interobserver variability was low (intraclass correlation coefficient of r = 0.941) and VeT was found to correlate to LaT (r = 0.79, P less than 0.05) with LaT occurring a mean 2.3 min after VeT. VeT declined significantly with age in both males and females but less rapidly than VO2max. Both VO2max and VeT were found to vary with age, sex, height, and weight in a stepwise multiple-linear regression analysis. Age-associated changes in skeletal muscle composition may be in part responsible for the less precipitous decline in VeT with age compared with VO2max.

Adult↗
PubMed1986

Exercise capacity in the elderly.

One of the primary manifestations of ageing is a reduced ability to respond to physiologic challenges. With aging, the ability to perform exercise and physical work declines and is reflected in the reduction in maximal oxygen consumption. Although this decline is influenced to some degree by the state of health and age, it seems that maintenance of regular physical activity significantly counteracts the loss of aerobic capacity. In healthy old age, the cardiovascular system is able to compensate for certain age-associated declines in cardiac function. A program of endurance training, even when begun in old age, can restore more youthful levels of physical fitness and results in tangible improvements in certain resting, submaximal and maximal indicators of exercise capacity. With comprehensive preexercise clinical screening, physical training can be conducted safely with minimal musculoskeletal problems in the aged. The long-term effects of exercise on morbidity, mortality and psychologic function in old age are unknown.

Adult↗
PubMed1979

Chronic respiratory failure and physical reconditioning: case study of an elderly obese woman.

A case is described of a 67 year old obese white woman who had a history of multiple medical problems and who was in chronic respiratory failure but responded poorly to intermittent positive pressure breathing, chest physiotherapy, and supplementary oxygen. She was treated successfully with a 600 k.cal diet and a 26-day physical reconditioning programme. Reconditioning techniques included free and treadmill walking, stair climbing, bench stepping, light calisthenics, and breathing retraining. Improvements were noticed in blood gases, spirometry, electrocardiogram, motor coordination, and physical working capacity.

Aged↗
PubMed1976

Airway occlusion pressures in awake and anesthetized goats.

The pressures generated by the inspiratory muscles as they contract isometrically during airway occlusion seem to be a measure of respiratory neuron efferent activity. The ventilatory and occlusion pressure responses to increasing levels of CO2 were studied in goats, awake and anesthetized, with and without inspiratory flow resistance. Hypercapnia was produced by rebreathing. Randomly, during rebreathing, inspiratory airflow was prevented on single breaths. Ventilation and pressures developed during the first 100, 200, 300 and 400 milliseconds of an inspiratory effort against a complete occlusion increased linearly with CO2 in both awake and anesthetized animals. Anesthesia reduced both the ventilatory and occlusion pressure responses to CO2. Inspiratory resistance increased occlusion pressure responses in awake goats but not in the same animals when anesthetized. Inspiratory airflow resistance seems to augment respiratory efferent activity as reflected in the pressure responses only in conscious goats. Thus the response to an inspiratory resistance seems to depend on the state of consciousness.

Airway Resistance↗