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Biomedical subjects

C Tyler

Publications and source records attributed to C Tyler.

At least 19 recordsLinked to original sources
PubMed1992

Metabolic correlates of optokinetic stimulation in the central visual system of the frog, Rana pipiens.

The [14C]2-deoxyglucose (2-DG) method was used to identify those structures in the central visual system of Rana pipiens showing increased metabolic activity during binocular and monocular optokinetic stimulation at two pattern velocities (2 deg/sec and 9 deg/sec). Analysis of autoradiograms made with computer-assisted microdensitometry and pseudocolor image-enhancement techniques revealed that the greatest uptake of 2-DG occurred in the pretectal region, which included the large-celled nucleus lentiformis mesencephali (nLM), nucleus pretectalis, and pretectal gray. Both temporal-to-nasal (T-N) and nasal to temporal (N-T) directions of pattern motion were correlated with high levels of 2-DG uptake. However, the nucleus of the basal optic root (nBOR) showed the greatest uptake of 2-DG for the N-T direction, which evokes little or no optokinetic (OKN) response in this species. These results suggest that the major efferent projection from nBOR to nLM may exert its greatest effect upon the ipsilateral pretectum during N-T stimulation. Other regions showing substantial 2-DG uptake included a large region of the ventral thalamus, for all stimulus conditions tested, including those cell groups associated with the retinorecipient neuropil, corpus geniculatum. The pattern of uptake was less closely associated with specific parameters of optokinetic stimulation than was observed in the pretectum and accessory optic nucleus. Like nBOR, the auricular lobe of the cerebellum also showed greatest uptake of 2-DG for the N-T, monocular stimulus condition. The neural circuitry that underlies OKN and its directional asymmetry during monocular stimulation appears to involve a number of structures whose functional interrelationships are yet to be described.

Animals↗
PubMed1991

The North Coast Cholesterol Check Campaign. Results of the first three years of a large-scale public screening programme.

Although cardiovascular disease (CVD) mortality has been declining, CVD is still the major cause of death in Australia and an elevated blood cholesterol level is considered a major contributor. Large-scale community-based screening programmes in other countries have demonstrated that a population approach can be effective in reducing cholesterol levels and the risk of CVD. The North Coast Cholesterol Check Campaign is the largest community-based cholesterol intervention programme in Australia. Since its inception in 1987, 13% of the Region's adult population (over 29,000 persons) have been screened. About half had elevated blood cholesterol levels (greater than or equal to 5.5 mmol/L) and were given dietary counselling to reduce fat intake. Mean blood cholesterol levels were significantly reduced between initial screening and follow-up in all three years. Reductions, after correction for regression, were 8%, 6% and 10%, respectively, in 1987, 1988 and 1989. There was also a consistent and significant 1.5% to 2% reduction in weight. All age/sex cohorts above age 35 were well represented each year although self-referral did bias both initial and follow-up samples towards women and the aged. Nevertheless, the proportion of men and men in their middle age increased during the three years. The proportion of participants with elevated cholesterol levels increased in each successive year while the proportion of participants who complied with referrals to visit their general practitioner and with requests to return for follow-up decreased. Over half of the North Coast adult population has now had a cholesterol test. The rate of increase in testing since the inception of the Campaign has been approximately four times the national rate. North Coast general practitioners have played a major role by catering for the increased community demand for cholesterol testing and by providing an effective referral service for the Campaign. Community-based screening programmes in Australia can detect and beneficially influence large numbers of persons with elevated cholesterol levels. Interventions like the North Coast Cholesterol Check Campaign, when conducted over a number of years, do attract higher risk and less compliant people.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Implementing a public cholesterol screening campaign: the North Coast experience.

Several community-based interventions in the United States have indicated that it is possible to economically screen the blood cholesterol levels of large numbers of the population and to assist those with elevated levels to reduce their blood cholesterol. The North Coast Cholesterol Check Campaign was designed to involve existing community health staff and community volunteers in a Health Promotion Campaign to: increase community awareness of the importance of cholesterol levels in relation to coronary heart disease; to offer participants immediate blood cholesterol analysis; and to offer dietary advice to those participants who were above the recommended 5.5 mmol/L level. Fifty-two Cholesterol Check Points were conducted on the North Coast of NSW between 1 September and 15 December, 1987. Each Check Point featured a rapid cholesterol analysis with a finger-prick procedure on the Boehringer-Mannheim Reflotron System and immediate dietary counselling by trained staff for participants with elevated levels. A total of 12,067 persons participated in the Campaign: 43 per cent were found to have cholesterol levels that exceeded the recommended desirable levels set by the Australian National Heart Foundation. A 4-5 month follow up of 61 per cent (3,164) of these individuals indicates that 72 per cent lowered their blood cholesterol levels and 65 per cent reduced their BMI. Mean cholesterol change was 0.65 mmol/L and mean BMI change was 0.51. The results indicate the potential for similar community-based nutrition education programmes to reduce cholesterol levels in Australia. This paper details the rationale for the North Coast Cholesterol Check Campaign and the issues concerned with implementation of the campaign.

Adult↗
PubMed1989

Fluorimetric method for simultaneous estimation of cortisol, corticosterone, and testosterone in plasma.

The simultaneous estimation of steroids in plasma was carried out by the assay of cortisol, corticosterone, and testosterone. The method entails separation by means of thin layer chromatography, followed by conversion to a fluorophore and fluorimetric measurement. Its major advantages are its high specificity, its ability to detect unknown substances, and the ease with which it can be performed. The method has acceptable levels of accuracy and precision and the normal values obtained by it compare well with those given by methods in general use.

Chromatography, Thin Layer↗
PubMed1988

An evaluation of the accuracy of the Reflotron system in the field.

The Reflotron system (Boehringer-Mannheim, West Germany) is a dry-chemistry analyser which has been used in cholesterol screening in the United States and Australia. The accuracy and precision of the instrument for use as a screening device for whole-blood cholesterol levels have been evaluated in clinical settings in both the United States and Australia; however, questions still arise from healthy practitioners about its performance in the field. We selected 30 participants in a community-screening programme to undergo a comparative analysis of cholesterol measurement by the Reflotron system compared with two standard laboratory procedures (one of which was carried out in a World Health Organization accredited laboratory). Analysis of the data showed that, after a minimum of training, results can be obtained on the Reflotron system in a community setting which are acceptable when compared with results that have been obtained on more commonly-used laboratory instruments.

Adult↗
PubMed1976

Overnight urinary 11-hydroxycorticosteroid estimations in diagnosis of Cushing's syndrome.

Overnight specimens of urine were collected from control, obese, and hirsute women and from 11 women with Cushing's syndrome. Urinary 11-hydroxycorticosteroid levels in the group with Cushing's syndrome were significantly higher than in the other three groups. This simple test has proved invaluable when screening for Cushing's syndrome in a busy outpatient clinic.

11-Hydroxycorticosteroids↗
PubMed1972

Plasma and urinary 11-hydroxycorticosteroids in differential diagnosis of Cushing's syndrome.

Morning plasma 11-hydroxycorticoids, urinary 11-hydroxycorticoids, and urinary 17-oxogenic steroids were measured before and during a dexamethasone suppression test. This consisted in the administration by mouth of 2 mg of dexamethasone daily for 48 hours, followed by 8 mg daily for 48 hours. In addition midnight plasma 11-hydroxycorticoids were measured before the start of the test. The subjects investigated were 21 patients with Cushing's syndrome, 27 obese female patients, 10 female patients with the Stein-Leventhal syndrome, and 8 female patients with idiopathic hirsutism.The results showed that the clearest distinction between the groups was made by measurement of the basal urinary 11-hydroxycorticoid excretion, where, in the group of patients with Cushing's syndrome, all the levels were well above the upper limit of normal. In addition raised midnight plasma 11-hydroxycorticoid levels were of great diagnostic value. By using these results together with those of the dexamethasone suppression tests it was possible to make a firm preoperative diagnosis of pituitary-dependent Cushing's syndrome in 90% of patients in this series.

17-Hydroxycorticosteroids↗
PubMed1970

Plasma 11-hydroxycorticoid levels after carbenoxolone sodium.

A definite rise in plasma 11-hydroxycorticoid levels has been shown in eight patients with duodenal ulcer following the oral administration of carbenoxolone sodium. A similar rise was seen in one patient with sarcoidosis whose pituitary A.C.T.H. secretion had been acutely suppressed with dexamethasone. No such rise, however, was seen in three patients suffering from adrenal insufficiency. It is suggested that carbenoxolone acts directly on the adrenal cortex, causing an increased production of corticosteroids.

Addison Disease↗