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Biomedical subjects

J Waterhouse

Publications and source records attributed to J Waterhouse.

89 records · Page 5Linked to original sources
PubMed1988

Sleep and circadian rhythms of temperature and urinary excretion on a 22.8 hr "day".

Two groups of subjects (total N = 6) were studied in an isolation chamber for a period of 3 weeks whilst living on a 22.8 hr "day". Regular samples of urine were taken when the subjects were awake, deep body temperature was recorded continuously and polygraphic EEG recordings were made of alternate sleeps. The excretion in the urine of potassium, sodium, phosphate, calcium and a metabolite of melatonin were estimated. Measurements of the quantity and quality of sleep were made together with assessments of the temperature profiles associated with sleep. In addition, cosinor analysis of circadian rhythmicity in urinary variables and temperature was performed. The 22.8 hr "days" affected variables and subjects differently. These differences were interpreted as indicating that the endogenous component of half the subjects adjusted to the 22.8 hr "days" but that, for the other three, adjustment did not occur. When the behaviour of different variables was considered then some (including urinary potassium and melatonin, sleep length and REM sleep) appeared to possess a larger endogenous component than others (for example, urinary sodium, phosphate and calcium), with rectal temperature behaving in an intermediate manner. In addition, a comparison between different rhythms in any subject enabled inferences to be drawn regarding any links (or lack of them) that might exist between the rhythms. In this respect also, there was a considerable range in the results and no links between any of the rhythms appeared to exist in the group of subjects as a whole. Two further groups (total N = 8) were treated similarly except that the chamber clock ran at the correct rate. In these subjects, circadian rhythms of urinary excretion and deep body temperature (sleep stages and urinary melatonin were not measured) gave no evidence for deterioration. We conclude, therefore, that the results on the 22.8 hr "day" were directly due to the abnormal "day" length rather than to a prolonged stay in the isolation chamber.

Adolescent↗
PubMed1987

Twelve year clinical study of patients with hypoxic cor pulmonale given long term domiciliary oxygen therapy.

Patients presenting with chronic obstructive airways disease and hypoxic cor pulmonale were assessed during a period of clinical stability. Seventy two patients (53 male) with a mean age of 60 years were selected for long term oxygen therapy. Mean FEV1 was 0.78 l and forced vital capacity 1.9 l. The mean arterial oxygen tension (PaO2) was 6.1 kPa (46 mm Hg) and the mean arterial carbon dioxide tension (PCO2) 6.9 kPa (52 mm Hg). All patients had a PaO2 of less than 8.0 kPa (60 mm Hg) and 57 patients had a PCO2 of more than 6.0 kPa (45 mm Hg). Pulmonary haemodynamics were measured in 45 patients yielding the following mean values: pulmonary artery pressure 28.3 mm Hg; cardiac output 5.9 l min-1; total pulmonary vascular resistance 59.2 kPa l-1 S. Oxygen delivery systems, including 23 oxygen concentrators, were installed in the patients' homes. Flow rates were adjusted to raise PaO2 to more than 8.0 kPa (60 mm Hg) for at least 15 hours each day and close supervision was maintained. Overall five year survival was 62%, which is better than previously reported for this type of patient; but the 10 year survival was only 26% owing to an observed acceleration in death rate at about this time. Progressive disturbances of the pulmonary circulation were arrested. Mortality was associated with the severity of airflow obstruction, reflecting a continuing pathological process affecting the airways.

Aged↗
PubMed1985

Some effects of melatonin and the control of its secretion in humans.

Whether or not the pineal gland has a significant physiological role in humans is not known. There has nevertheless been speculation about the potential therapeutic use of melatonin (in view of its hypnotic and possible zeitgeber properties) in conditions such as insomnia and jet lag, and in shift-workers. Our work concerns the effects of melatonin administration in humans and the interactions between melatonin and other circadian variables. Chronic (one month), timed (1700 h), low-dose (2 mg daily) melatonin administration to normal subjects without environmental control consistently increased evening fatigue and slightly modified the 24 h prolactin rhythm without effect on cortisol, growth hormone, luteinizing hormone, thyroxine, testosterone or self-rated mood. In five out of 11 subjects the endogenous melatonin rhythm was advanced by one to three hours. During fractional desynchronization of circadian rhythms by increasing imposed 'day' length (26-29 h, 24 days, 500 lux), 5 mg melatonin per os at lights-out in two subjects resulted in better entrainment of the fatigue rhythm to the zeitgeber than in five out of six control subjects, without major consistent effects on other measured circadian variables. Using a new radioimmunoassay for 6-hydroxymelatonin sulphate (aMT6s), the major melatonin metabolite, we have shown that the urinary aMT6s rhythm is closely correlated to that of melatonin in plasma and is completely suppressed by an acute dose of atenolol (100 mg per os), a peripheral beta-adrenergic antagonist. During fractional desynchronization by increasing imposed 'day' length in one subject and decreasing imposed 'day' length in two subjects, the urinary aMT6s rhythm behaved similarly to that of core temperature. The results suggest that fatigue (or alertness) may be entrained by melatonin, but whether critical performance rhythms can be suitably manipulated remains to be clarified. It is likely that melatonin production is linked to the so-called 'strong' circadian oscillator.

Circadian Rhythm↗
PubMed1985

Cancer data systems.

Explore the source record for details and available documents.

Abstracting and Indexing↗
PubMed1983

Clinical experience with the oxygen concentrator.

The oxygen concentrator is an accepted means of delivery of long term domiciliary oxygen treatment. Conditions of use, however, need to be carefully defined. Fourteen concentrators were used for one year by patients with hypoxaemic chronic obstructive airways disease, and mechanical reliability, patient compliance with a regimen of 15 hours' use a day, smoking habits, and variation in arterial gas tensions studied. Though many patients failed to achieve either the desired daily use or the recommended arterial oxygen tension, problems were generally minor and could probably be overcome by careful supervision and planning. Overall the concentrator appeared to be the most economical means of providing oxygen treatment at home and was much preferred by patients who had previously used oxygen cylinders.

Blood Gas Analysis↗
PubMed1979

Are breast-fed babies still getting a raw deal in hospital?

After preliminary validation of test weighing under ward conditions the fluid intake and weight gain of 39 breast-fed and 25 artificially fed infants were compared. All were fed every four hours for six feeds a day, and the breast-fed infants received dextrose supplements only. The average intake and weight gain of the breast-fed group was significantly less than that of the group fed artificially.When cows'-milk supplements are withheld from breast-fed infants a four-hourly regimen provides insufficient stimulus to lactation for their needs in the first week of life. If more than lip service is to be paid to the mother who desires to breast-feed in hospital, early and more frequent feeding should be practised.

Body Weight↗
PubMed1979

Factors affecting neonatal jaundice.

Plasma bilirubin was estimated on 690 term infants on about the 6th day of life. Perinatal factors were recorded and the results analysed. Hyperbilirubinaemia was defined as a level greater than 205 micromol/1 (12 mg/100 ml) and this was present in 20% of cases. Three factors--epidural analgesia, breast feeding, and poor weight recovery--showed highly significant associations with jaundice. The relative importance of these is discussed and compared with recent reports. Induction of labour, for reasons other than postmaturity, and a gestational age less than 39 weeks showed a slightly increased incidence of jaundice. There was no correlation with other factors tested including oxytocic drug administration. Despite the high incidence (20%) of hyperbilirubinaemia, only 2.5% infants needed treatment and none required exchange transfusion. Radical changes in obstetric management or infant feeding are not indicated.

Anesthesia, Epidural↗
PubMed1970

Sequelae of neonatal jaundice.

A total of 371 newborn infants falling into 3 groups, non-haemolytic jaundice, haemolytic jaundice, and non-jaundiced controls, have been reassessed in the 6th year of life as regards neurological, audiological, and psychological function. Neurological handicap was concentrated among the infants of low birth weight and was not related to jaundice, apart from one case of athetoid cerebral palsy with deafness. No other cases of perceptive deafness were discovered. Intelligence testing on the Stanford Binet scale showed no relation between depth of jaundice and I.Q.These findings support the majority of reports in the literature that reduction in intelligence does not occur in non-haemolytic jaundiced babies with serum bilirubin below about 20 mg./100 ml. In haemolytic jaundice slight doubt remains. There is no indication for changing present standards for exchange transfusion.

Anemia, Hemolytic↗
PubMedDate not supplied

A comparison of circadian rhythms in work performance between physically active and inactive subjects.

This study compared circadian rhythms in physiological, subjective, and performance measures between groups exhibiting different levels of habitual physical activity. Fourteen male subjects, aged 19-29 years, were assigned to a physically active (group I, n = 7) or a physically inactive (group II, n = 7) group on the basis of leisure-time physical activity. Rectal temperature, oral temperature, resting pulse rate, subjective arousal and sleepiness were measured at 02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 in a counter-balanced sequence for each subject. Whole-body flexibility, back and leg strength, grip strength (right and left), flight time in a vertical jump, PWC150, and self-chosen work-rate were also recorded at each time point. At least 8h separated each test session. Subjects avoided exercise 48h prior to, and during the experiment. Data were subjected to the group cosinor method. Group I evidenced 1.5-2.5 times greater rhythm amplitudes than Group II for oral temperature, subjective arousal, sleepiness, flexibility, left and right grip strength, submaximal heart rate, and self-chosen work-rate (p < 0.05). Oral temperature and arousal for Group I were lower than Group II only at 06:00. Early morning troughs in most of the performance measures were significantly greater for Group I (p < 0.05). The groups did not differ with respect to phasing of the rhythms (p < 0.05). These results confirm with physical performance measures that rhythm amplitudes are higher for physically fit subjects. This could be attributed to greater early-morning troughs in the measures for active individuals. Since the subjects were sedentary immediately prior to testing, it is plausible that these findings are training effects of physical activity.

Adult↗
PubMedDate not supplied

Dissecting circadian performance rhythms: implications for shiftwork.

Safety on shift systems will depend, at least in part, on the adjustment of shiftworkers' circadian (c.24h) rhythms in performance capabilities which will in turn depend on their underlying control. In the present study three volunteers lived on a 30h 'day' and performed a range of tasks every 2h (while awake) to allow estimates of the relative magnitude of the endogenous (body clock) and exogenous (masking) components of their rhythms to be made. Performance rhythms were found to differ considerably in this respect with, for example, speed on a 4-choice serial reaction time task appearing to be largely endogenously determined while that on a 5-target Sternberg task was more dependent on exogenous (i.e., 30h) factors. This implies that performance measures may adjust at very different rates to one another to night work, and hence that the optimal form of shift system may vary according to the precise demands of the shiftworker's task.

Adult↗
PubMedDate not supplied

Some chronobiological considerations related to physical exercise.

Variables associated with physical activity show circadian rhythms in resting subjects; these rhythms have both exogenous (due to the individual's lifestyle and environment) and endogenous (due to the "body clock") components. During exercise, many of the rhythms persist, even though some show decreasing amplitude with increasing severity of exercise. Whilst the value of physical fitness is not disputed (for elite athletes, for individuals who just want to be physically fit, or for patients undertaking physical rehabilitation regimens), there are certain times of the day when special care is needed. These times are soon after waking--when there is the possibility of an increased risk of cardiovascular morbidity and damage to the spine--and late in the day--when there is an increased risk of respiratory difficulties. Since physical exercise is inextricably linked with thermoregulation, there are special considerations to bear in mind when exercise takes place in cold or hot environments. Further, due to the effects of the body clock, exercise and activity during night work and after time-zone transitions presents problems peculiar to these circumstances. In addition, the menstrual cycle affects physical performance, and these circatrigintan rhythms interact with the circadian ones. Bearing in mind these factors, advice that is based upon knowledge of circadian and circatrigintan rhythms can be given to all those contemplating physical activity. Chronobiologically, there is advantage in undertaking physical activity programmes towards the middle of the waking day and not at times when a sleep or nap has just been taken.

Chronobiology Phenomena↗