The validity of capillary blood sampling in the determination of human growth hormone concentration during exercise in men.

BACKGROUND: Studies measuring human growth hormone (hGH) in blood during exercise have mainly used venous sampling. The invasive nature of this procedure makes evaluation of hGH impossible in various exercise environments. OBJECTIVE: To determine whether capillary sampling could offer an alternative sampling method. METHODS: Capillary and venous blood samples were collected for determination of hGH at the end of each exercise stage during an incremental exercise test in 16 male club level competitive cyclists (mean (SD) age 30.8 (8.0) years, body mass 72.2 (7.1) kg, body fat 12.9 (3.5)%, peak oxygen consumption 4.18 (0.46) l x min(-1)). Linear regression, from a plot of venous v capillary blood hGH concentration, showed a correlation coefficient of r = 0.986 (p<0.001). When geometric means and log transformations were used, a coefficient of variation of 14.2% was demonstrated between venous and capillary flow for hGH concentration. The mean ratio limits of agreement were 0.62 (1.72)-that is, 95% of the ratios were contained between 0.36 and 1.07, with a mean of 0.62. CONCLUSIONS: Capillary blood sampling is an acceptable alternative to venous sampling for determining hGH concentration during rest and exercise. Sample sites should not be used interchangeably: one site should be chosen and its use standardised.

Exercise metabolism and beta-blocker therapy. An update.

The rationale for the concurrent prescription of beta-blockers and programmes of exercise is that both medication and physical activity can improve the quality of life of patients with cardiovascular disease. Difficulties arise when drugs reduce either the physical ability or the motivation to exercise. This article focuses on the physiological limitations to prolonged aerobic exercise in patients receiving beta-blockers. Possible limiting factors to exercise while taking beta-blockers include reduction in heart rate and cardiac output, local alterations to blood flow, changes to muscle and liver glycogenolysis, and alterations to adipose and intra-muscular lipolysis. The disadvantages and advantages of nonselective and beta 1-selective drugs are discussed, as well as those of drugs that have beta 2-agonist properties. Particular emphasis is placed upon the beta-blocker-induced attenuation of the normal increase in fat oxidation during prolonged exercise. There are physiological advantages, especially for the physically active individual, in prescribing beta 1-selective rather than nonselective drugs in controlled release, rather than conventional release, form. Additionally, there may be further advantages in prescribing drugs which have partial agonist properties at beta 2 receptors.

Exercise metabolism in healthy volunteers taking celiprolol, atenolol, and placebo.

OBJECTIVE: Previous studies have shown that beta 1 selective agents have fewer adverse effects on exercise metabolism than nonselective beta blockers, and this has been attributed to their reduced blockade of beta 2 receptors. This study aimed at determining whether a beta blocker with partial agonist activity at beta 1 and beta 2 receptors (celiprolol) was better than a conventional beta 1 receptor-blocker (atenolol) in prolonging exercise capabilities. METHODS: After four days of treatment with celiprolol 200 mg, atenolol 50 mg, or placebo, 22 healthy volunteers exercised on a treadmill for two hours at 50% of their maximal oxygen uptake. Resting heart rate and blood pressure were recorded before and after exercise. During exercise, fat oxidation, plasma free fatty acids, glycerol, glucose, and ammonia were measured together with heart rate and perceived exertion. RESULTS: Mean exercising heart rate was significantly lower in those taking either of the beta blockers than in those taking placebo, and significantly lower for those taking atenolol rather than celiprolol. Fat oxidation was significantly lower for those taking celiprolol (38.8 (SD 12.2)%, P < 0.01) and atenolol (36.6 (15.9)%, P < 0.01) compared with placebo (45.6 (14.1)%). For the first 15 minutes of exercise, fat oxidation was significantly lower for those taking atenolol (24.6 (12.8)%, P < 0.01) than celiprolol (29.6 (14.3)%). The rise in plasma free fatty acids and glycerol during exercise was also significantly attenuated by both beta blockers in comparison with the rise in those taking placebo (P < 0.01). CONCLUSIONS: Both celiprolol and atenolol reduced fat oxidation compared with placebo. For the first 15 minutes of exercise fat oxidation was preserved by celiprolol, but not atenolol. This preservation of fat oxidation during the early part of exercise may confer some small benefit to patients who take beta blockers and intend to exercise regularly. However, we did not detect significant differences between atenolol and celiprolol in overall mean fat oxidation or perceived exertion in this study.

Acute effects of beta blockade and exercise on mood and anxiety.

OBJECTIVE: To measure the previously reported beta blocker induced adverse changes in mood state and anxiety measures, and to determine if prolonged aerobic exercise attenuates such mood modifications. METHODS: After 4 days of drug treatment with comparable doses of propranolol (40 and 80 mg), metoprolol (50 and 100 mg), or placebo, mood (POMS) and anxiety states (STAI) were assessed in healthy volunteers, before and after 1 h of treadmill walking exercise at 50% maximum oxygen uptake. RESULTS: Compared to placebo, resting "tension", "depression", and "total mood disturbance" were significantly higher on propranolol 80 mg, but all were reduced with exercise. "Fatigue" and "confusion" were also higher on propranolol, and were unaffected by exercise. "Fatigue" was also higher than placebo after exercise on metoprolol 100 mg. "Anxiety" was unaffected by drug treatment or exercise. CONCLUSIONS: The evidence that beta blockers, and particularly propranolol, have adverse effects on mood was confirmed. It would be preferable to prescribe a beta blocker which does not adversely alter mood states. However, exercise significantly reduced the measures of "tension" and "depression" which were adversely increased by propranolol. Exercise prescription may therefore not only be compatible with beta blockade, but a highly desirable adjuvant therapy.

Exercise metabolism during 1 hour of treadmill walking while taking high and low doses of propranolol, metoprolol, or placebo.

Aerobic exercise and beta-blocking drugs are regularly prescribed as treatment for hypertension and as a prophylactic for patients at risk from coronary heart disease and for those recovering from an infarct. Some beta blockers, particularly non-beta 1-selective drugs, may make exercise more difficult, possibly by interfering with substrate metabolism during exercise. This study examined the effects of low and high doses of a beta 1-selective blocker, metoprolol, and a non-selective beta blocker, propranolol, on exercise metabolism. The study involved 20 healthy subjects (10 men, 10 women) who walked on a treadmill at 50% of their maximal oxygen uptake for 1 h on five occasions, separated by 7 days. On each of the five occasions they received one of the following treatments, given in random order: placebo, metoprolol 50 mg, metoprolol 100 mg, propranolol 40 mg, or propranolol 80 mg, all taken twice daily. Fat oxidation, expressed as a percentage of total energy expenditure, was significantly lower than with placebo for all of the active treatments except metoprolol 50 mg (placebo: 42.7 +/- 11.6%; metoprolol 50 mg: 38.7 +/- 14.1%, p = NS; metoprolol 100 mg: 36.3 +/- 13.7%, p = 0.05; propranolol 40 mg: 31.2 +/- 9.3%, p = 0.01; propranolol 80 mg: 29.5 +/- 10.9%, p = 0.01); and significantly lower with propranolol than with metoprolol (propranolol 40 mg: p = 0.0036; propranolol 80 mg: p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise metabolism in healthy volunteers taking atenolol, high and low doses of metoprolol CR/Z0K, and placebo.

1. Exercise and beta-adrenoceptor blockade have important roles in the prevention and treatment of cardiovascular disease, but fatigue and a reduced capacity to exercise are commonly reported side effects of beta-adrenoceptor blockers. The reduced capacity to exercise may be partly caused by a reduction in fat metabolism. 2. We investigated the effects of atenolol 50 mg, metoprolol CR/Z0K 50 mg, metoprolol CR/Z0K 100 mg and placebo, on heart rate, energy expenditure, fat oxidation, plasma free fatty acids, glycerol, glucose, lactate, ammonia and perceived exertion during 2 h of treadmill walking at 40% of maximal oxygen uptake in 20 healthy volunteers. 3. Compared with placebo (38.0%), total fat oxidation was significantly lower on atenolol 50 mg (30.1%) and metoprolol CR/Z0K 100 mg (31.0%), but not on metoprolol CR/Z0K 50 mg (33.7%). Reductions in fat oxidation correlated well (r2 = 0.970) with reductions in exercising heart rate, and probably reflected the degree of beta 1-adrenoceptor blockade. Maximum plasma ammonia concentration was reached after 45 min of exercise on atenolol, 60 min on metoprolol CR/Z0K 100, and 75 min on metoprolol CR/Z0K 50, and was higher than placebo on all active drug treatments. 4. The greater reduction in fat oxidation with atenolol may be a reflection of a peak in plasma concentration, which is avoided with a controlled release preparation.

An evaluation of the Taxi Subsidy Scheme for the Disabled.

This paper reports on an evaluation of the Taxi Subsidy Scheme for the Disabled (TSSD). The evaluation focused on members of the TSSD in terms of their eligibility for Home and Community Care (HACC) Program Services. Using a probability sample in the Brisbane metropolitan area, the project found evidence that at least 79 per cent of TSSD members (under the relevant category) were entitled to such membership, as they also fulfil the requirements prescribed under the Home and Community Care Act 1985. However, the evaluation also found evidence that current utilisation of HACC Program Services does not truly reflect the need for these services within the community.

To run or not to run? That is the question: exercise and reduced risk of coronary heart disease.

The recent National Fitness Survey has drawn attention to the population's low level of physical (aerobic) fitness and low level of activity. About one-third of middle-aged men and one-half of middle-aged women in England are unfit for continuous walking at a normal pace of about 3 mph. Similar fitness levels were shown for the Welsh population. At the same time, coronary heart disease (CHD) accounts for about 26% of deaths in England, and for 2.5% of the NHS expenditure. The suggestion that low fitness levels and low levels of physical activity are associated with a high incidence of CHD has been widely voiced since Morris's first study, and has more recently been the subject of editorials in the British Heart Journal and the BMJ.

The impact of a short course of three lipid lowering drugs on fat oxidation during exercise in healthy volunteers.

We examined the impact of three lipid lowering drugs on fat oxidation during a 120 minute treadmill walk, at an exercise intensity of 50% maximal oxygen uptake (VO2 max). Subjects (N = 24) were healthy male volunteers with normal serum chemistry, assigned to three groups (n = 8). Group A received simvastatin 20 mg twice daily, Group B received gemfibrozil 600 mg twice daily, Group C received acipimox 600 mg twice daily. Each subject performed two 120 minute walks, once with drug, and once with placebo (4 days treatment plus a final dose on the morning of the exercise trial). Treatment order was reversed for half of each group. Compared to placebo, simvastatin treatment, had no impact on fat oxidation (40.9 +/- 8.6% vs 40.9 +/- 9.7%), or on plasma concentration of free fatty acids (FFA), glycerol or glucose. Treatment with gemfibrozil, showed lower fat oxidation (32.3 +/- 13.9% vs 39.7 +/- 7.9%), and lower plasma concentrations of FFA and glycerol, but differences did not reach significance at the 0.05 level. Acipimox treatment, produced significantly lower fat oxidation (36.9 +/- 12.8% vs 50.2 +/- 16.1%, P = 0.011), and lower plasma concentrations of FFA and glycerol (P = < 0.0001 and P = < 0.0001, respectively). Plasma glucose showed a trend toward lower values with acipimox (P = 0.088). These data demonstrate that selective lipid lowering drugs can reduce fat availability for exercise metabolism, placing increased demands on carbohydrates which may reduce exercise tolerance.

The treatment of elderly hypertensive patients.

Treatment of hypertension in the elderly has hitherto been considered to be potentially dangerous. Three recent studies have clearly shown that in selected elderly hypertensives, blood pressure reduction very effectively reduces cardiovascular complications without causing unacceptable adverse effects. The impact on non-fatal stroke was most striking although a reduction in coronary events was also achieved. Thiazide diuretics were used in all three trials, and beta-blockers were used in two. Thiazide diuretics had a major beneficial effect. In this review the applicability of these results to the whole unselected population of elderly hypertensives is considered, and the choice of therapy in different subgroups of patients discussed.

A choice-reaction time task utilizing congruent and incongruent colour/word stimuli: another reaction to Stroop.

A choice reaction time task was devised, using incongruent colour/word (Stroop-type) and congruent colour/word stimuli. A significant difference was found between reaction times to the two stimulus types with the Stroop-type stimuli eliciting longer reaction times. It is argued that traditional hypotheses about channel limitation can not explain this finding; the suggestion that the delay may lie in the decision-making process is put forward.

Long-term follow-up of 500 patients with mild to moderate hypertension who had successfully completed a 3-month general practice study of a timolol-bendrofluazide combination ('Prestim').

A sample of 500 patients with mild to moderate hypertension, who had been successfully controlled on once daily timolol/bendrofluazide at the end of a 3-month general practice study, was followed up after approximately 1 year of treatment. Physicians who had participated in the trial were questioned on the current status of these patients. Out of 479 reports received, data showed that 358 (75%) patients were still normotensive 47 weeks after starting treatment with timolol/bendrofluazide and in a further 8 patients other antihypertensive agents had been added to this therapy. Of the 113 patients no longer receiving timolol/bendrofluazide, only 38 (7.9%) had stopped therapy due to adverse effects. It is concluded that the results are a further indication that timolol/bendrofluazide offers an acceptable and balanced long-term form of therapy in hypertension for both the patient and the physician.

Visual analysis of body movements by neurones in the temporal cortex of the macaque monkey: a preliminary report.

Movement provides biologically important information about the nature (and intent) of animate objects. We have studied cells in the superior temporal sulcus of the macaque monkey which seem to process such visual information. We found that the majority of cells in this brain region were selective for type of movement and for stimulus form, most cells responding only to particular movements of the body or some part of it. A variety of cell types emerged, including cells sensitive to: translation of bodies in view, movements into view (appearance) or out of view (disappearance) and the articulation and rotation of the body/head. Directional selectivity for cells sensitive to translation tended to lie along one of 3 orthogonal Cartesian axes centred on the monkey (towards/away, left/right and up/down). One type of rotation sensitive cell was tuned to rotation about one or more of these axes, a second type was sensitive to different head rotations which brought the face to confront the monkey or turned the face away. Reconstructions of cell positions indicated that cells of the same type were clumped anatomically both across the surface of the cortex and perpendicular to the surface.

Bioenergetic studies in adult patients recovering from semi-starvation.

A model of energy-nitrogen balance developed in animals was adapted to the study of human bioenergetics. By creating balance conditions and steady-state formula infusion rates, each of the needed components of energy and nitrogen balance can now be measured with a high level of accuracy. A comprehensive description of energetic efficiency at the whole body level is possible using appropriate mathematical modeling. Key questions in human bioenergetics await these results, and our laboratory is currently undertaking these studies.

Visual cells in the temporal cortex sensitive to face view and gaze direction.

The direction of eye gaze and orientation of the face towards or away from another are important social signals for man and for macaque monkey. We have studied the effects of these signals in a region of the macaque temporal cortex where cells have been found to be responsive to the sight of faces. Of cells selectively responsive to the sight of the face or head but not to other objects (182 cells) 63% were sensitive to the orientation of the head. Different views of the head (full face, profile, back or top of the head, face rotated by 45 degrees up to the ceiling or down to the floor) maximally activated different classes of cell. All classes of cell, however, remained active as the preferred view was rotated isomorphically or was changed in size or distance. Isomorphic rotation by 90-180 degrees increased cell response latencies by 10-60 ms. Sensitivity to gaze direction was found for 64% of the cells tested that were tuned to head orientation. Eighteen cells most responsive to the full face preferred eye contact, while 18 cells tuned to the profile face preferred averted gaze. Sensitivity to gaze was thus compatible with, but could be independent of, sensitivity to head orientation. Results suggest that the recognition of one type of object may proceed via the independent high level analysis of several restricted views of the object (viewer-centred descriptions).