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Biomedical subjects

S D Anderson

Publications and source records attributed to S D Anderson.

At least 127 records · Page 7Linked to original sources
PubMed1981

Comparison of two methods of assessing physical performance in patients with chronic airway obstruction.

The results of a 12-minute walking test and the maximum working capacity (Wmax) achieved on a bicycle ergometer were compared in 25 patients with chronic obstructive lung disease. There was a significant correlation between the distance walked in 12 minutes and the Wmax that each patient could achieve on the bicycle ergometer (r = .68, p less than .001). The maximum oxygen uptake on both tests was not significantly different.

Adult↗
PubMed1981

Arterial plasma histamine levels at rest, and during and after exercise in patients with asthma: effects of terbutaline aerosol.

Eight asthmatic patients and two normal subjects performed two identical exercise tests 140 minutes apart (first test preceded by inhalation of saline and the second by terbutaline sulphate). A ninth asthmatic patient exercised twice after placebo 40 minutes apart. Arterial plasma levels of histamine and cyclic AMP, expiratory flow rates and volumes were measured at rest and during and after exercise. After the first test the mean +/- SEM fall in PEFR was 45.2 +/- 2.6%. In five asthmatics there was an increase in plasma histamine (mean +/- SEM 14.8 +/- 3.3 pmol ml-1) coinciding with exercise-induced asthma (EIA). Histamine levels returned to pre-exercise values within 30 minutes. After terbutaline these five patients had histamine levels greater than those observed before, during, or after the first test. This effect may have been the result of changes in pulmonary microcirculation. After the second test the levels decreased indicating no further release of histamine in response to exercise. No EIA occurred in these patients after terbutaline. The other patients and the two normal subjects had little or no change in histamine throughout the study. The one patient in whom exercise was repeated after placebo demonstrated less histamine release and less EIA after the second test.

Adult↗
PubMed1981

Drugs affecting the respiratory system with particular reference to asthma.

In 70-80% of asthmatic patients, an attack of asthma will follow 6-10 min of strenuous exercise. The increase in airway resistance is accompanied by hyperinflation and arterial hypoxemia and makes it difficult to continue or resume exercise. The past 10 yr have seen major advances in the prevention and treatment of exercise-induced asthma (EIA). The beta-sympathomimetic drugs, when administered as aerosols, have been shown to be most effective in reversing the airway obstruction, hyperinflation, and exercise-induced hypoxemia in patients with asthma. When administered as aerosols prior to exercise, the increase in airways resistance, hyperinflation, and hypoxemia are blocked in about 90% of patients. In addition to the sympathomimetic agents, sodium cromoglycate will also ameliorate or prevent EIA in 60-70% of patients. Oral administration of beta-sympathomimetics or methylxanthines is less efficacious in the prevention or treatment of EIA. Delay in absorption from the gastrointestinal tract requires at least 1-2 h before a significant response is observed. Prevention of EIA requires an adequate blood level, possibly because a high concentration of the drug does not reach the airway when the drug is given by the oral route. More importantly, aerosol administration prevents EIA at a fraction of the dose required orally. The side effects, such as nausea, tachycardia, and skeletal muscle tremor commonly observed following oral bronchodilator administration are rare with aerosol therapy.

Adrenergic alpha-Antagonists↗
PubMed1981

Protein quality and the cost of selected commercial protein supplements.

The biologic value and the cost of three commercial protein supplements were compared using casein as the control. Each product was fed to rats as the sole protein source supplying 10 percent of the energy in a semipurified diet. Nonfat dry milk was equal to casein in PER, but the PERs of low-fat soy powder and high-protein supplement were significantly lower than the PER of casein. Nitrogen balance was positive for all protein supplements, but low-fat soy powder was significantly lower than the others. cost comparison per gram of protein showed low-fat soy powder to be the least expensive, nonfat dry milk to be slightly higher in cost, and the high-protein supplement to be the most expensive.

Animals↗
PubMed1980

Some ECMR properties in relation to other signals from the auditory periphery.

Some basic characteristics of monkey and human acoustic emissions are reviewed and some new data presented. These characteristics are discussed in relation to the sensorineural output of the cochlea. Input--output functions and the frequency dispersal in the waveform of acoustic emissions (AE) from monkeys are described. New findings include changes in the human AE during trains of clicks and sustained suppression of the AE after short bursts of noise of moderate intensity. The similarly of click-evoked AE latencies and whole-nerve action potential (AP) latencies for low stimulus level toneburst stimuli, and the apparent discrepancy between these latencies and those of single cochlear nerve-fibre action potentials and derived impulse responses is discussed. It is argued that at low stimulus levels AE are generated either coincident with the primary cochlear impulse or very soon afterwards. It is proposed that the AE generator is peripheral to the afferent synapse of the inner hair cells because of the lack of adaptation effects in AE. However, attention is drawn to changes in the waveform of the click-evoked AE with increasing stimulus intensity and with diuretic intoxication, that qualitatively parallel known changes in single nerve-fibre firing properties. These observations are consistent with the concept that AE are a product of a sharply tuned and vulnerable cochlear filter mechanism.

Animals↗
PubMed1980

Plasma cyclic AMP levels in response to exercise and terbutaline sulphate aerosol in normal and asthmatic subjects.

A study was performed to investigate changes in plasma cyclic adenosine monophosphate (cyclic AMP), peak expiratory flow and arterial blood gas tensions in response to running exercise and terbutaline sulphate aerosol in asthmatic patients regularly receiving sympathomimetic bronchodilator aerosols. Seven normal subjects were controls. Placebo aerosol was administered 20 min before the first exercise study and 1.0-1.25 mg terbutaline sulphate substituted 20 min after the first test and again 20 min before the second test. Blood gas tensions, expiratory flow and cyclic AMP were measured at rest, during and after exercise. Exercise induced a significant increase in cyclic AMP in both asthmatic and normal subjects. The change in plasma levels was not significantly different between groups. Cyclic AMP values were higher at rest and during exercise with terbutaline sulphate compared with placebo for both groups. Terbutaline sulphate blocked the marked fall in peak expiratory flow and arterial oxygen tension observed in the asthmatic subjects following the first test. Values for cyclic AMP following exercise were not significantly different between asthmatic and normal subjects. In contrast to other reports our asthmatics have a marked increase in cyclic AMP in response to exercise and to a beta-sympathomimetic aerosol.

Adult↗
PubMed1979

The evoked cochlear mechanical response in laboratory primates. A preliminary report.

The evoked cochlear mechanical response has been recorded in two species of laboratory primates, Macaca irus and Erythrocebus patas. The responses are very similar to those obtained in humans although the response to each click is of shorter duration. The response is vulnerable to the ototoxicity of furosemide and etacrynic acid and to noise exposure. At and near threshold an active generator of mechanical energy within the cochlea is proposed. The significance of such a generator and a possible source are discussed.

Animals↗
PubMed1979

Limitation of work performance in normal adult males in the presence of beta-adrenergic blockade.

The effect on work performance of a single oral dose of the cardio-selective beta-adrenoreceptor blocking agent, metoprolol, was compared with an equipotent dose of the non-selective agent, propranolol, in the same subjects. A number of biochemical and physiological variables including heart rate, oxygen consumption, ventilation, lactate, free fatty acid and glucose levels were measured. Following exercise in the presence of both active drugs, subjects complained of excessive leg fatique. For the group there was a significant reduction in the total work performed and the maximum heart rate achieved on both drugs. There was a significant correlation between plasma levels of metoprolol, reduction in total work performed and reduction in maximum heart rate. By contrast, after propranolol, there was a wide variation in work performed at a time when the reduction in maximum heart rate was similar for all subjects. This suggests for propranolol that a reduction in heart rate alone is an inappropriate guide to the impairment of work performance. There was a fail in the circulating level of free fatty acids at the end of exercise in the presence of both drugs and it is possible that this biochemical variable contributed to the decrease in work performance.

Adult↗
PubMed1978

Evidence that raphe-spinal neurons mediate opiate and midbrain stimulation-produced analgesias.

The present experiments were undertaken to assess the role of neurons in the nucleus raphe magnus (NRM) in mediating opiate and stimulation-produced analgesias. A cannode for both electric stimulation and local opiate microinjection was placed in the midbrain preiaqueductal gray region of decerebrate or chloralose-urethane anesthetized cats. Microelectrodes recorded the responses of medullary NRM neurons. Raphe-spinal neurons were identified by antidromic activation from the cerevical spinal cord. Fifteen of 20 raphe-spinal cells tested were excited by electrical stimulation of the midbrain. Of 49 NRM neurons tested, 26 were excited by either systemic or midbrain injection of opiate agonist. Twelve of 33 NRM cells tested by midbrain microinjection were excited. In 10 the effect was reversed by naloxone. Seventeen raphe-spinal neurons were tested; 5 showed naloxone-reversible excitation to either midbrain or intravenous injection of opiates. NRM neurons respond to auditory and somatic stimuli; at least half respond maximally to somatic stimuli of noxious intensity. These findings are consistent with the hypothesis that the raphe-spinal projection mediates opiate and electrical stimulation-produced effects from midbrain sites. The properties of raphe-spinal neurons suggest that they are part of a negative feedback system which monitors and limits the output of spinal dorsal horn pain-transmission neurons.

Action Potentials↗
PubMed1978

Long-term trial of an alpha adrenoceptor blocking drug (Indoramin) in asthma. A preliminary report.

Eight patients suffering from both asthma and migraine underwent a clinical trial for 3 months of indoramin, an alpha adrenoceptor antagonist with antihistamine and antiserotonin activity. Patients were told indoramin was prescribed for migraine prophylaxis. In three asthmatic patients there was a marked increase in airflow meter (AFM) readings which were recorded daily, the remaining five showing no significant change or a decrease in AFM readings. Indoramin did not appear to potentiate the action of the beta sympathomimetic aerosols. It is suggested that a small population of asthmatic patients may derive therapeutic benefit from an alpha adrenoceptor antagonist. Seven of the eight patients experienced a 50% decrease in the frequency of their migraine headaches.

Adolescent↗
PubMed1977

An evaluation of oral hexoprenaline sulphate (Ipradol) in exercise-induced asthma.

The effect of hexoprenaline sulphate (1 mg) administered orally on the fall in peak expiratory flow rate (PEFR) after exercise was investigated in 20 asthmatic patients. Compared with placebo, the fall in PEFR expressed as a percentage of the resting value (measured immediately before exercise) was less in 16 of the 20 patients in the presence of hexoprenaline sulphate. This consistent amelioration of exercise-induced asthma has not been observed in this laboratory with similar drugs (such as salbutamol and terbutaline). While eight patients were afforded significant protection by the hexoprenaline sulphate, a fall in PEFR after exercise was within the normal range (less than 10% of the resting value) in only four patients.

Adolescent↗
PubMed1977

Nucleus raphe magnus inhibition of spinal cord dorsal horn neurons.

In decerebrate cats, electrical stimulation of nucleus raphe magnus (NRM) of the medulla produced marked inhibition of spinal neurons in lumbosacral dorsal horn. Only neurons with high threshold inputs were inhibited. These cells were located in lamina I and in or near laminae V and VI. The duration of inhibition produced was related to the stimulus train length. An ipsilateral lesion of the dorsolateral funiculus at L1 markedly reduced the inhibition of neurons caudal to the lesion. Although NRM stimulation was the most effective, inhibition from more lateral sites could be obtained at higher stimulus intensities. NRM induced inhibition is probably mediated by a direct projection via the dorsolateral funiculus to spinal dorsal horn laminae I, II, V and VI. The results are discussed in relation to proposed mechanisms underlying the analgesia produced by NRM stimulation.

Animals↗