Search PubMed⌕ Search

Biomedical subjects

P Garcia-Webb

Publications and source records attributed to P Garcia-Webb.

12 recordsLinked to original sources
PubMed1992

Inhibition of human lymphocyte coproporphyrinogen oxidase activity by metals, bilirubin and haemin.

Coproporphyrinogen III oxidase activity in human lymphocytes was found to be inhibited by cadmium and mercury but not by lead. The organo-metal compounds tributyltin and methylmercury were effective inhibitors of this haem biosynthetic pathway enzyme. Haemin (the ultimate product of the pathway) and bilirubin (a product of haem catabolism) were also shown to be inhibitory. Kinetic studies performed under initial velocity conditions showed that bilirubin was a non-competitive inhibitor and that one bilirubin molecule was bound to both the enzyme and enzyme substrate complex. The analysis also showed haemin to be a non-competitive inhibitor in which two haemin molecules bind to the enzyme whereas the enzyme substrate complex accepts only one haemin molecule. The possible physiological significance of the inhibition of coproporphyrinogen III oxidase activity by haemin and bilirubin is discussed.

Bilirubin↗
PubMed1992

Biological responses to overload training in endurance sports.

Five subjects undertook 10 days of twice daily interval training sessions on a treadmill followed by 5 days of active recovery. On days 1, 6, 11, and 16 the subjects were required to undertake a test of submaximal and maximal work capacity on a treadmill combined with a performance test consisting of a run to exhaustion with the treadmill set at 18 km.h-1 and 1% gradient. Also on these days a pre-exercise blood sample was collected and analysed for a range of haematological, biochemical and immunological parameters. The subjects experienced a significant fall in performance on day 11 which had returned to pretraining levels on day 16. Serum ferritin concentrations were depressed significantly from pretraining concentrations at the conclusion of the recovery period while the expression of lymphocyte activation antigens (CD25+ and HLA-DR+) was increased both after the training phase and the recovery phase. The number of CD56+ cells in the peripheral circulation was depressed at the conclusion of the recovery period. Several parameters previously reported to change in association with overload training failing to reflect the decrease in performance experienced by subjects in this study, suggesting that overtraining may best be diagnosed through a multifactorial approach to the recognition of symptoms. The most important factor to consider may be a decrease in the level of performance following a regeneration period. The magnitude of this decreased performance necessary for the diagnosis of overtraining and the nature of an "appropriate" regeneration period are, however, difficult to define and may vary depending upon the training background of the subjects and the nature of the preceding training. It may or may not be associated with biochemical, haematological, physiological and immunological indicators. Individual cases may present a different range of symptoms and diagnosis of overtraining should not be excluded based on the failure of blood parameters to demonstrate variation. However, blood parameters may be useful to identify possible aetiology in each separate case report of over-training. An outstanding factor to emerge from this study was the difficulty associated with an objective diagnosis of overtraining and this is a possible reason why there have been new accounts of overtraining research in the literature.

Adult↗
PubMed1992

Transferrin index: an alternative method for calculating the iron saturation of transferrin.

We surveyed 140 clinical chemistry laboratories in Australia to establish which laboratory methods they used to determine serum iron status: 125 measured serum iron (Fe), 85 measured transferrin (TRF), 47 measured total iron-binding capacity (TIBC), and 14 measured both TRF and TIBC. Of the 55 laboratories routinely reporting TRF saturation (TS), 16 calculated TS directly as (Fe/TIBC) x 100, and 9 used [Fe/(TRF x 2)] x 100. Thirty laboratories measured TRF and converted it to an equivalent TIBC concentration; the derived TIBC was then used to calculate TS. We measured iron, TIBC, and TRF concentrations in 94 control subjects, 59 patients with alcoholic liver disease (ALD), and 20 with proven genetic hemochromatosis (GH). TS was compared with a transferrin index (TI = Fe/TRF) to determine whether both methods were sensitive for GH screening and which method gave the fewest false-positive results with discrimination limits of > 55% and > 1.0, respectively. All GH patients were detected by both TS and TI at these limits. One control subject had a TI > 1.0, whereas three control subjects had a TS > 55%. Nine patients with ALD had a TI > 1.0 and 11 ALD patients had a TS > 55%. Some iron-overload patients had lower than expected TS values compared with TI, possibly because of ferritin interference in the TIBC assay. Also, the precision of the TRF assay was better than that of the TIBC assay: CVs of 1.85-3.68% vs 6.17%. We therefore recommend that calculated TI replace TS in screening for iron overload.

Australia↗
PubMed1979

The 1977 Busselton children's survey.

A health survey of 551 high school students in the coastal town of Busselton, Western Australia, was undertaken in November, 1977. Physical measurements showed that approximately 17% of the boys and 24% of the girls were overweight (115% or more of their standard weight for height and age). Blood pressures ranged from 108/64 mmHg at 13 years to 129/70 mmHg at 17 years for boys, and 109/63 mmHg to 116/66 mmHg for girls of the same age group. Fasting plasma glucose, cholesterol and triglyceride values were also obtained. Twenty-seven per cent of the girls and 17% of the boys were regular smokers, a habit often acquired by the age of 12 years. Most of the children watched television from two to four hours daily during the week, and for longer periods at weekends. Although most had satisfactory levels of physical fitness, there was a trend towards poor performance in overweight children, and there was a significant decrease in participation in regular sports by the older teenagers.

Adolescent↗
PubMed1979

Postoperative pancreatitis as a complication of biliary surgery.

Forty patients who underwent biliary surgery were investigated for postoperative pancreatic disturbance as measured by the amylase creatinine clearance ration (ACCR). Its relevance to preoperative pancreatitis, exploration of the common bile duct, and operative cholangiography were examined. The results suggested that a recent clinically proven episode of pancreatitis did not predispose to a postoperative recurrence following biliary surgery. Similarly, cholecystectomy alone did not produce a postoperative pancreatic disturbance. However, exploration of the common bile duct did frequently cause a postoperative elevated ACCR, and hence we recommend that duct exploration should be performed as carefully and as atraumatically as possible. The small number of patients who did not have operative cholangiograms prevented statistical evaluation of the effect of this procedure on the pancreas. However, information from elsewhere suggests that the plasma amylase level is not likely to be raised by cholangiography.

Amylases↗
PubMed1978

The effect of age, sex and other factors on blood chemistry in health.

Quantitative data is presented concerning the influence that age, sex, the menopause, oral contraception, blood group and time of blood collection have on 19 commonly-determined blood chemistry values. The data were derived from 1000 healthy blood donors in whom blood sampling conditions were standardised to conform with those applying to hospital out-patients. Statistical techniques were used to allow for the effects of analytical variation and to enable the effects of the various factors and their interactions to be expressed in a practically useful manner. Age and sex effects are shown to be the rule and to interact in many instances. Creatinine, urea, glucose, cholesterol, potassium and globulin show a tendency to increase in concentration with age, while total protein, albumin, calcium, inorganic phosphate and iron levels tend to fall progressively. Evidence is given to suggest that many of the changes occurring in women at about 50 years should be attributed to hormonal changes. In all instances when the menopause has a significant influence there is a rise in the concentration of the constituent concerned. It is proposed that other laboratories should assemble age and sex stratified reference ranges from (a) figures given for the mean values for defined age and sex groups, adjusted if necessary to allow for different analytical bias, (b) figures given for nonsystematic biological variation, and (c) their own measurements of analytical precision. Details of the necessary procedure are given, allowance being made for logarithmic transformation of the results where necessary.

Adolescent↗
PubMed1978

Towards unified analyses in chemical pathology.

The use of different units, methods and instruments in chemical pathology has produced a situation in which different laboratories may produce numerically different results for the same analysis. The more complete use of SI, the introduction to Australia of reference methods and the production in Australia of a pool of reference material will reduce the extent of this problem.

Chemistry Techniques, Analytical↗
PubMed1976

Biological and analytical variation of commonly determined blood constituents in healthy blood donors.

The relative contributions of analytical error and non-systematic biological variation to the reference range for 19 commonly-determined blood chemistry values have been estimated during the course of studying 1000 healthy blood donors. Estimates of non-systematic biological variations are arrived at by determining the variation found in donors matched for factors known to affect blood chemistry such as age and sex, and deducting the within-batch analytical error which applied. Comparison of the within-batch and between-batch analytical precision with the biological variation showed that the percentage increases in the normal range attributable to between-batch analytical error varies between 1 and 29%. This contribution is particularly large in the case of the electrolytes and amounts to no less than 29% in the case of calcium. Apart from well-known relationships a remarkable lack of correlation between the concentration of the different constituents in health is demonstrated.

Adolescent↗
PubMedDate not supplied

Biochemical screening of hospitalized geriatric patients.

Blood specimens were collected from 50 hospitalized geriatric patients with a range of chronic diseases. Analyses were conducted for 12 plasma components. Additional tests were performed on patients with abnormal results in the first tests. Of the 50 patients, 21 (42 per cent) had biochemical abnormalities, often unexpected on the basis of current diagnoses. It is suggested that routine biochemical screening should be conducted on geriatric patients at regular intervals.

Aged↗