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Biomedical subjects

S F Lewis

Publications and source records attributed to S F Lewis.

62 records · Page 4Linked to original sources
PubMed1980

Non-autonomic component in bradycardia of endurance trained men at rest and during exercise.

Autonomic nervous alterations have generally been held responsible for the bradycardia of the endurance athlete. In order to determine whether there is also a non-autonomic component in the bradycardia of long-term training, we compared the intrinsic heart rate (HR) of highly trained bicyclists (heart volume: 995 +/- 155 ml) with that of untrained men (heart volume: 805 +/- 195 ml) at rest and during bicycle ergometer exercise at 50, 75 and 100% of maximal oxygen uptake (VO2 max.) Intrinsic HR was achieved by combined vagal and beta-adrenergic blockade with atropine and propranolol or metoprolol (cardioselective) injected intravenously. Intrinsic HR was significantly lower in trained (T) than in untrained (UT) at rest and at all levels of exercise. The chronotropic reserve from resting HR to maximal HR was identical in the two groups. Nearly identical intrinsic HRs were achieved with atropine and either beta-adrenergic antagonist. HR differences between T and UT were very similar in magnitude--approximately 13 beats/min--at rest and during exercise at a given percentage of VO2 max, with and without autonomic blockade. Evidence is thus provided for a non-autonomic component in the bradycardia of well-trained men which may be responsible for a parallel downward shift in the relationship between HR and percentage of VO2 max. The lower intrinsic HR in well-trained men might be explained by, i.a. the cardiac enlargement.

Adult↗
PubMedDate not supplied

Transdermal nicotine replacement for hospitalized patients: a randomized clinical trial.

BACKGROUND: This study was undertaken to assess the safety and efficacy of a treatment involving brief counseling and the nicotine patch among hospital inpatients and to identify variables associated with long-term smoking cessation following hospitalization. METHODS: One hundred eighty-five patients were randomly assigned to one of three smoking cessation interventions: (1) A Minimal Care (MC) condition, consisting of a brief physician-delivered motivational message to stop smoking, (2) a Counseling + Active Nicotine Patch (CAP) condition in which patients received the motivational message, a 6-week supply of nicotine patches, and extended bedside and telephone counseling, and (3) a Counseling + Placebo Patch (CPP) condition identical to the CAP condition except the supplied patches contained no nicotine. RESULTS: At 6-month follow-up, abstinence rates for the three treatments were 4.9, 6.5, and 9.7% for the MC, CPP, and CAP treatments, respectively. These differences were not statistically significant. Patients admitted for respiratory disease were more likely to quit than patients with any other diagnosis. The nicotine patch was well tolerated by hospital inpatients. CONCLUSIONS: The initiation of nicotine patch therapy during hospitalization appears to be safe when used among patients carrying a wide range of diagnoses. Our study provided no evidence of the superiority of nicotine patches versus placebo, but this does not preclude the possibility that future research using larger samples might detect differences between patch groups. Hospital interventions for smoking cessation may be most effective among patients hospitalized for a smoking-related illness such as respiratory disease.

Administration, Cutaneous↗
PubMedDate not supplied

Treatment and diagnostic subtype in facial affect recognition in schizophrenia.

Patients with schizophrenia have been described as having deficits in the ability to recognize facial expressions of emotion. We report the results of a study on the effects of global psychopathology, positive and negative symptoms, diagnostic subtype, and antipsychotic medications, on the ability of subjects with schizophrenia to recognize facial affect. Eighteen SCID diagnosed patients with schizophrenia and ten matched controls were evaluated at a drug-free baseline for ability to identify facial expression expressed in a standardized series of photographs, with concurrent measures of global psychopathology, and positive and negative symptoms. At baseline patients were impaired in affect recognition relative to the normals, and impairment was not related to measures of psychopathology or positive or negative symptoms. Performance did not improve with antipsychotic treatment, and patients with paranoid schizophrenia had significantly better affect recognition abilities than non-paranoid patients.

Adult↗
PubMedDate not supplied

Physiologic measurement of exercise and fatigue with special reference to chronic fatigue syndrome.

Oxidative metabolism is the major source of energy for muscle activity, and maximal oxygen uptake (VO2max), the product of maximal cardiac output and maximal arteriovenous oxygen difference, indicates individual capacity for oxidative metabolism and performance of exercise by the large muscles. Strength, a function of muscle cross-sectional area, motor-unit recruitment, and neuromuscular coordination, is the ability to develop force in a single, brief, maximal-effort voluntary contraction of rested muscle. Weakness is a diminished ability of rested muscle to exert maximal force. Fatigue is a loss of maximal force-generating capacity that develops during muscular activity, likely originates within muscle itself, and persists until muscle is fully recovered. Individual perception of motor effort can be determined with standardized rating scales. These concepts are discussed in detail, their relevance to the pathophysiology of exercise in chronic fatigue syndrome is analyzed, and a general strategy of exercise evaluation pertinent to chronic fatigue syndrome is presented.

Exercise↗
PubMedDate not supplied

Somesthetic and electrophysiologic effects of topical 0.025% capsaicin in man.

As a topical agent, capsaicin reportedly blocks pain without otherwise impairing sensation. Ten subjects underwent blinded, multiple-dose application of topical 0.025% capsaicin or control emollient to skin test sites in order to evaluate capsaicin effectiveness and toxicity. Clinical changes in somesthetic perception of pinprick, heat and cold developed, but neurogenic flare responses were unchanged. Clinical and electrophysiologic measures of large fiber and autonomic function were unaffected by capsaicin. This study indicates that 0.025% capsaicin is a safe topical agent with demonstrable clinical effects on small fiber function but not on large fiber or autonomic function.

Administration, Cutaneous↗