Biomedical subjects

A Folta

Publications and source records attributed to A Folta.

7 recordsLinked to original sources

PubMed1992

Drug use and effects in older adults in the United States.

Aging markedly influences drug use and drug effects. The purpose of this review is two-fold: (i) to examine how social, economic, and psychological factors, compliance, and prescribing patterns affect drug use in institutionalized and non-institutionalized older adults in the United States, and (ii) to illustrate how physiological aging, actions of drugs, and adverse drug reactions influence drug effects. Recommendations for further study include identification of adverse reactions, and examination of drug taking behavior in older adults who are alone or debilitated. Research is especially needed for those in nursing homes and for those who are old-old (over 85 years).

Aged↗

PubMed1992

Reduced cardiac output and exercise capacity in patients after MI.

This article summarizes the literature and suggests directions for future research concerning rehabilitation potential, impairment, and reduced cardiac output after myocardial infarction (MI). Current evidence suggests that cardiac output and maximal exercise capacity are reduced in some post-MI patients. The conceptual model of rehabilitation potential presented emphasizes the need for careful assessment of the state of underlying pathology present after MI when evaluating the response to exercise or exercise training.

Cardiac Output↗

PubMed1990

Endothelin-1-induced constriction in the coronary resistance vessels and abdominal aorta of the guinea pig.

The purpose of this study was to examine contractile properties of endothelin-1, a newly discovered vasoactive peptide, in guinea pig coronary resistance vessels and abdominal aorta. Changes in perfusion pressure after injections of endothelin-1 were measured using a constant-flow modified Langendorff preparation. The ED10 values of coronary perfusion pressure were about 100-fold less for endothelin-1 than for prostaglandin F2 alpha. After the endothelium was damaged by exposure to free radicals, maximal coronary constriction in response to endothelin-1 (10(-9) moles) was not altered, whereas dilator responses to low doses of endothelin-1 were converted to constrictor responses. Removal of the endothelium from aortic rings significantly increased responsiveness to endothelin-1 and the maximal response to the peptide. In calcium-free medium, endothelin-1 induced small increases both in perfusion pressure in coronary vessels and in tension in the aorta. Reintroduction of calcium in the coronary and aortic preparations produced a rapid increase in perfusion pressure and tension, respectively. Further, endothelin-1-induced coronary constriction was inhibited 59% +/- 7% by nifedipine (10(-7) moles). We conclude that endothelin-1 is a more potent constrictor than prostaglandin F2 alpha in the coronary vasculature. Endothelin-1-induced constriction in the coronary vasculature of the guinea pig is not mediated through an endogenous constricting factor released from the endothelium or a constrictor prostaglandin. Further, endothelin-1-induced dilation in the coronary vasculature and attenuation of endothelin-1-induced contraction in the abdominal aorta of the guinea pig are mediated through the release of a factor from the endothelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Dilator actions of endothelin in coronary resistance vessels and the abdominal aorta of the guinea pig.

Endothelin has been characterized as a potent constricting factor. The purpose of this study was to investigate possible dilator effects of this peptide and to examine whether dilator responses occur through an endothelium-mediated mechanism in guinea pig coronary resistance vessels and isolated aortic rings. Changes in perfusion pressure after bolus injections of endothelin were measured using a constant-flow modified Langendorff preparation with a transducer between the flow pump and the heart. An immediate fall in perfusion pressure, averaging 6 mmHg, was observed after injection of endothelin (10(-14)-10(-12) moles). This effect was maximal at 1 minute and tended to return toward baseline levels within 4 minutes. In response to endothelin (10(-9) M), isolated aortic rings relaxed 35% after being contracted with prostaglandin F2 alpha (10(-7) M). In both preparations, dilation was converted to constriction after endothelium damage by oxygen radicals or endothelium removal (mechanical rubbing). Dilator responses to endothelin were blocked by pretreatment for 30 minutes with indomethacin (14 microM) in the presence of an intact endothelium in coronary resistance vessels, whereas in the abdominal aorta they were not. We conclude that endothelin has significant dilator properties and that this effect is opposed by its constrictor action at higher doses. In addition, dilator responses to endothelin require an intact endothelium in both coronary vessels and abdominal aorta. Finally, endothelin-induced dilation in coronary resistance vessels appears to occur through a cyclooxygenase product-mediated mechanism.

Acetylcholine↗

PubMed1989

Exercise and functional capacity after myocardial infarction.

This paper summarizes the literature on the effects of both inpatient and outpatient exercise programs on functional capacity in patients categorized as having mild, moderate, severe and very severe left ventricular damage after myocardial infarction (MI). Current evidence suggests that inpatient activities of daily living programs do not improve functional capacity as measured by a predischarge exercise stress test. In contrast, outpatient exercise training programs can improve functional capacity through augmentation of skeletal muscle arteriovenous oxygen difference (oxygen extraction) in nearly all patients with mild left ventricular damage, in most patients with moderate damage and in a few patients with severe damage. The recently developed conceptual model of functional capacity in post-MI patients presented in this paper underscores the need for assessment of the level of structural and functional impairment of the left ventricle before the nurse prescribes any type of exercise program. It also enables the nurse to begin to explain why post-MI patients differ in their response to exercise. Further research is needed, however, before the model can be used for predicting exercise outcomes in the clinical setting.

Activities of Daily Living↗

PubMedDate not supplied

The relationship of resting and exercise blood pressure in subjects with essential hypertension before and after drug treatment with propranolol.

OBJECTIVE: To investigate the relationship between clinic resting blood pressure (BP) and exercise BP in subjects with established essential hypertension during placebo and propranolol-treated phases. DESIGN: Prospective, placebo-controlled, cross-over trial. SETTING: University-affiliated medical center. PATIENTS: A convenience sample of 38 patients with essential hypertension, 34 men and four women, who ranged in age from 22 to 62 years (mean = 44 years, SD = 10.7). Subjects were diagnosed with mild to moderate diastolic or mixed systolic/diastolic essential hypertension at least 1 year before study entry. They had no clinical evidence of secondary hypertension, diabetes, heart, liver, pulmonary, or renal disease. OUTCOME MEASURES: Resting and exercise BP. INTERVENTION: Antihypertensive medication was tapered off and subjects were free of all prescription drug treatment for 2 weeks. They received placebo for an additional 2 weeks. Subjects then received treatment with propranolol at a dose necessary to control resting blood pressure for 4 to 6 weeks. At the end of both the untreated and treated phases, subjects were given a graded maximal exercise test on a bicycle ergometer. RESULTS: Propranolol effectively reduced mean resting and maximal exercise BP. The nonsignificant correlation between clinic resting and maximal exercise systolic BP was low in both phases. The correlation between clinic resting and maximal exercise diastolic BP was only moderate, but statistically significant (untreated, r = 0.43; p < 0.01; treated, r = 0.53; p < 0.001). For systolic BP or diastolic BP, there were no significant relationships between percent drop in BP because of propranolol at rest or maximal exercise. Clinic resting BP was not a valid predictor of maximal exercise BP. Degree of control of clinic resting BP was not a valid predictor of control observed at maximal exercise. CONCLUSIONS: Resting BP should not be used as a predictor of BP during maximal exercise in the untreated condition or with treatment with propranolol.

Adult↗

PubMedDate not supplied

Preexisting physical activity level and cardiovascular responses across the Valsalva maneuver.

To determine the effect of preexisting physical activity level on resting cardiovascular measures and the intensity of cardiovascular responses across the Valsalva Maneuver (VM), 131 young (30-55 years) and 67 older (greater than 55 years) healthy adults, classified into sedentary, active, semitrained, or trained groups, were studied. Resting heart rate (HR) was lower in all trained subjects. In contrast, resting diastolic blood pressure was lower in young but not older trained subjects. During the VM, the expected fall in systolic blood pressure (SBP) from baseline during strain was less in young trained but not older trained subjects. Physical training significantly lessened the intensity of SBP and HR responses during the overshoot phase of the VM only in young subjects, most often in young males.

Adult↗