L-3,4-dihydroxyphenylalanine-induced of norepinephrine from the rat heart.
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Biomedical subjects
Publications and source records attributed to L Landsberg.
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OBJECTIVE: To assess whether the regular elicitation of the relaxation response produces sustained physiologic changes coincident with symptomatic relief or improved psychological state. DESIGN: Prospective, cohort pilot study. SETTING: Clinical research center within a teaching hospital. PATIENTS: Thirteen athletic men, mean age 44.8 years, with borderline or labile hypertension, taking no medication. All 13 completed the study. INTERVENTIONS: Three baseline assessments of psychological state, symptom checklist, and assessment of autonomic response to infusion of beta agonist (isoproterenol). Daily relaxation response exercises for five consecutive weeks followed by repeat assessment of all parameters. Discontinuation of relaxation exercises for subsequent five weeks followed by repeat assessment of all parameters. MEASUREMENTS AND MAIN RESULTS: After eliciting the relaxation response, subjects demonstrated significant decreases in anxiety (p less than 0.014) and somatic symptoms (p less than 0.02). Psychological and somatic variables returned toward baseline after the subsequent discontinuation of relaxation exercises. No significant concomitant change in urinary catecholamines, heart rate response to isoproterenol, blood pressure, pulse rate, or serum cholesterol was demonstrated. CONCLUSION: The regular elicitation of the relaxation response can improve psychological performance and reduce symptoms. However, the physiologic mechanism whereby these psychological and symptomatic improvements occur remains poorly understood and warrants further investigation.
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OBJECTIVE: Several studies have shown that hostility, as measured by the Minnesota Multiphasic Personality Inventory-derived Cook-Medley Hostility Scale (Ho), is positively associated with several cardiovascular risk factors, possibly accounting for the relationship between Ho scores and cardiovascular mortality. This study was undertaken to examine associations between hostility and cardiovascular risk factors representing the metabolic syndrome in 1,081 older men who participated in the Normative Aging Study. METHODS: Subjects included men who completed the Minnesota Multiphasic Personality Inventory in 1986 and who participated in a subsequent laboratory examination within 1 to 4 years. Total and subscale Ho scores were computed, and associations with anthropometric data, cigarette smoking, dietary information, serum lipids, blood pressure, and fasting glucose and insulin levels were examined. RESULTS: The total Ho score was positively associated with waist/hip ratio, body mass index, total caloric intake, fasting insulin level, and serum triglycerides. The Ho score was inversely related to education and high-density lipoprotein cholesterol concentration. Path analysis also suggested that the effects of hostility on insulin, triglycerides, and high-density lipoprotein cholesterol were mediated by its effects on body mass index and waist/hip ratio, which, in turn, exerted their effects on lipids and blood pressure through insulin. CONCLUSIONS: The results are consistent with those of prior research and also suggest that, in older men, hostility may be associated with a pattern of obesity, central adiposity, and insulin resistance, which can exert effects on blood pressure and serum lipids. Furthermore, effects of hostility on the metabolic syndrome appear to be mediated by body mass index and waist/hip ratio.
BACKGROUND: Orientation sessions are sometimes used to habituate subjects before exercise stress testing. The extent of habituation in older subjects has not been clearly defined. Additionally, the use of repetitive maximal stress testing as an orientation method may not be necessarily applicable in the aged. METHODS: To determine if the employment of a submaximal orientation session would effect cardiopulmonary cycle ergometer exercise results, 266 older adults (68.6 +/- 5.0 years) male (n = 100) and female (n = 166) subjects participated in this study. One hundred thirty-one subjects received an orientation before stress testing. One hundred thirty-five did not. RESULTS: Analysis of resting values revealed no significant differences. Separate gender analysis was performed at submaximal workloads. Men were examined at 0, 60, and 105 Watts; women at 0, 45, and 75 Watts. Oriented subjects displayed significantly lower heart rates for both males and females at all submaximal workloads. Oxygen uptake was significantly lower for oriented women at 45 Watts (P < or = .05) and men at 60 Watts (P < or = .05). Oriented males displayed significantly lower systolic blood pressure at 0 Watts (P < or = .05), 60 Watts (P < or = .01), and 105 Watts (P < or = .05). The oriented group reached ventilatory threshold (VeT) at a higher workload (P < or = .001), lower heart rate (P < or = .001), and higher VO2 uptake (P < or = .05). Nonoriented subjects obtained a significantly higher maximal heart rate than oriented subjects (147 +/- 15.7 beats per minute (bpm) vs. 140 +/- 17.1 bpm, P < or = .01). Separate gender analysis revealed a significant difference (P < or = .01) in maximal heart rate in males (oriented = 137.4 +/- 18.8 bpm vs. nonoriented = 147.7 +/- 15.7 bpm). Although nonoriented women achieved a higher maximal heart rate, the difference was not significant (146.9 +/- 15.8 bpm vs. 142.6 +/- 16.0 bpm). CONCLUSION: These results indicate that both male and female older subjects display significant modification in physiologic performance from habituation after a single submaximal exercise orientation session. This effect was greater at submaximal than maximal workloads, and appears to be greater than that previously reported in younger subjects.
Epidemiologic and clinical studies suggest an association between hyperinsulinemia (and insulin resistance) and hypertension. This relationship is not present in secondary forms of hypertension and may persist despite adequate antihypertensive therapy. Normotensive offspring of hypertensive parents are also, as a group, insulin resistant and hyperinsulinemic. The association of hyperinsulinemia (and insulin resistance) with hypertension is more marked in the obese but present in lean hypertensive as well. Physiological mechanisms by which insulin might increase blood pressure include sympathetic nervous system stimulation and enhancement or renal sodium reabsorption. Evidence exists linking both of these mechanisms to hypertension. Insulin is also independently associated with myocardial infarction and microalbuminuria, two long term complications of high blood pressure. Experimentally induced decreases in insulin resistance and hyperinsulinemia, furthermore, have been associated with decreased blood pressure. In summary, the evidence suggests that hyperinsulinemia (and insulin resistance) exerts a pro-hypertensive effect that may be important in the pathogenesis of hypertension and hypertensive complications in some patients with essential hypertension.