Is measuring serum antioxidant capacity clinically useful?
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Antioxidants↗
Biomedical subjects
T P Whitehead
Publications and source records attributed to T P Whitehead.
Enhanced chemiluminescent assay for measuring the total antioxidant capacity of serum, saliva and crevicular fluid.
This paper reports the development of an enhanced chemiluminescent (ECL) assay for measuring the total antioxidant (AO) capacity of serum, saliva and a fluid collectable from the gum margin called gingival crevicular fluid (GCF). The theory behind the assay is explained, and the optimum conditions for the assay, and for storage of reagents and clinical samples is described. Calibration lines were linear (R > or = 0.99; P < 0.0001) and the within batch coefficient of variations for a water soluble vitamin E analogue (Trolox), serum and saliva samples were < 5%. In saliva and GCF, a characteristic AO response not seen in serum of the same patients, was identified. Total peripheral (serum) and local (saliva) AO capacities (mumol/L Trolox) were investigated in patients with (n = 18) and without (n = 16) adult periodontitis. Serum AO status did not differ between groups. Salivary total AO concentrations were lower in the peridontitis (P) group [175 (53) mumol/L] than in the non-periodontitis (NP) group [254 (110) mumol/L1: P < 0.01], as were saliva:serum AO ratio's [0.37 (0.11) versus 0.5 (0.18): P < 0.01]. Periodontitis patients may have a reduced salivary AO concentration, which could result from, or predispose to, the damaging effects of reactive oxygen species (ROS). The potential for ROS production in the oral and periodontal environment may explain the presence of a specific antioxidant in oral fluids that is not detectable in serum. The ECL assay described provides a rapid, simple and reproducible method of measuring total antioxidant defence in small volumes of biological fluids.
Adult↗
The effects of cigarette smoking and alcohol consumption on blood lipids: a dose-related study on men.
The separate and joint effects of cigarette smoking and alcohol consumption on serum concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides were investigated in 46 750 men attending the BUPA Health Screening Centre in London during the period 1983-1987, after allowing for differences in age, body mass index and exercise level. Drinking alcohol was found to raise both total cholesterol and HDL-C concentrations, in such a way that HDL-C as a percentage of total cholesterol increased with increasing alcohol consumption. LDL-C concentrations increased with increasing alcohol consumption in non-smokers, but decreased in those smoking over 10 cigarettes per day. Drinking had no significant effect on triglycerides except at high levels of consumption. Smoking raised total cholesterol, LDL-C and triglycerides, but lowered HDL-C concentrations. In particular, smoking even small amounts could negate any protective benefit in HDL-C concentrations gained from moderate consumption of alcohol. Assuming a desirable lipid profile to consist of low total cholesterol, LDL-C and triglycerides and a high HDL-C value, this is best achieved for men by being a non-smoking moderate drinker.
Adult↗
The effects of cigarette smoking and alcohol consumption on serum liver enzyme activities: a dose-related study in men.
The separate and joint effects of cigarette smoking and alcohol consumption on serum activities of the enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma-glutamyl transferase (GGT) were investigated in 46,775 men attending the BUPA Health Screening Centre in London during the period 1983-1987, after allowing for differences in age, body mass index and exercise level. As expected, all showed a significant positive correlation with alcohol consumption. Cigarette smoking produced a significant increase in GGT activity in all drinking categories bar teetotallers, particularly for those smoking more than 20 cigarettes per day. There were no changes of clinical significance in AST or ALT activities with smoking. We postulate that the combined effects of alcohol and smoking on GGT activity are a result of induction of the enzyme by both alcohol and nicotine. Smoking as well as drinking habits should be taken into account when assessing the significance of an individual's enzyme activities.
Adult↗
Effect of red wine ingestion on the antioxidant capacity of serum.
Aerobic metabolism in biological systems produces reactive oxygen species, and defense against such prooxidants requires antioxidant activity, e.g., predominantly vitamins C and E in serum. Recently, flavonoids (polyphenols occurring widely in plants) have been investigated in vitro for their antioxidant activity; whether they are absorbed after ingestion is not clear. Using a chemiluminescent assay of serum antioxidant capacity (SAOC), we have studied the effects in normal individuals of ingesting red wine, white wine, and high doses of vitamin C. In nine subjects who ingested 300 mL of red wine, the mean SAOC was increased by 18% after 1 h and by 11% at 2 h. The same amount of white wine produced 4% and 7% increases, respectively. The ingestion of 1000 mg (5.7 mmol) of ascorbic acid by four subjects increased their mean SAOC by 22% at 1 h and by 29% at 2 h. An in vitro comparison of red wine, white wine, and various fruit juices showed the high antioxidant capacity of red wine in addition to its ability to increase the antioxidant capacity of serum in vivo. The antioxidant effects of various flavonoids and other polyphenols were also studied.
Adult↗
The effects of cigarette smoking and alcohol consumption on blood haemoglobin, erythrocytes and leucocytes: a dose related study on male subjects.
The objective of this study was to quantify the combined dose related effects of cigarette smoking and alcohol consumption on blood haemoglobin concentration, erythrocytes and leucocytes. The subjects consisted of 17,670 males attending for routine health screening, with an average age of 43 years and a range of 16-91 years. The number of cigarettes smoked each day was divided into six categories, and declared alcohol consumption into seven. Of the 42 different combinations of smoking and drinking groups, five were not reported because they contained less than 30 subjects. Haemoglobin concentration was significantly increased in those smoking more than 10 cigarettes per day. Smoking also increased the PCV. Alcohol had no effect on Hb or PCV. The red cell count was reduced by alcohol consumption, with even the lowest consumption producing a significant decrease. Both smoking and drinking raised the MCV in a linear dose relationship. The marked increase in white cell count with smoking was seen even in subjects smoking 10 cigarettes per day or less. It is suggested that social habits such as smoking and drinking should be considered when interpreting blood haematology values. Changes in haematology results could be used to encourage a healthier lifestyle.
Adolescent↗
Serum urate, serum glucose and diabetes.
We have studied the relationship between serum glucose and urate in 260,699 men and 214,118 women from Sweden, and 140,084 men and 30,653 women from the UK. We found an increase in mean serum urate with increasing glucose concentrations up to 7.0 mmol/L in men and 9.0 mmol/L in women. Thereafter increasing glucose values were accompanied by a statistically significant decrease in urate concentrations. This fall was particularly marked in younger subjects. We believe this may have important implications for the free radical status of diabetics.
Adult↗
Defects in diagnostic kits for determination of urate in serum.
Certain diagnostic kits that measure serum urate by the Barham and Trinder principle of enzymic liberation of oxygen and its combination with chromogens can give results for urate in fresh serum that are approximately 20% lower than results from serum stored at ambient temperature for 72 h. In fresh serum, antioxidants compete with chromogen for liberated peroxyl-oxygen. We postulate that during storage the interfering antioxidant substances are destroyed. In some diagnostic kits, L-ascorbate oxidase is added to the reaction, eliminating some but not all of this effect. We discuss defects of several commercially available kits for determination of serum urate and recommend comparing results of these kits with results from the phosphotungstic acid method as a precaution against falsely low results.
Blood Preservation↗
Effect of body mass and other factors on serum liver enzyme levels in men attending for well population screening.
Alcohol abuse is usually regarded as the most likely cause of elevated serum liver enzyme values in those attending for well population screening, but we have found increased body weight to be an important contributing factor. We have measured serum levels of alanine amino-transferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) in approximately 21,000 men attending for routine health screening, and related these to behavioural factors such as alcohol consumption, cigarette smoking, exercise level and obesity. The levels of all three enzymes were positively correlated with levels of alcohol consumption. Decreasing levels of physical activity were associated with increases in mean ALT and GGT levels. Cigarette smoking showed only a weak effect on ALT and AST, which became non-significant after multivariate statistical analysis, but increasing consumption of cigarettes was associated with increased mean levels of GGT. In contrast, all three enzymes showed marked increases in mean levels with increasing body mass index (BMI). The effect of obesity was particularly important in the case of ALT: the prevalence of increased ALT values in obese subjects (BMI greater than or equal to 31 kg/m2) was more than eight times that in those with normal weight (BMI less than or equal to 25 kg/m2), even after allowing for the confounding effect of alcohol consumption. This study is concerned solely with male subjects, but we hope to extend the analysis to females in the near future.
Adult↗
The Middle East external quality assessment scheme for clinical chemistry.
The establishment and first 7 years' operation of an external quality assessment scheme for clinical chemistry in the Middle East region are described. The scheme utilises specimens distributed previously in the UK, and the performance of participating laboratories is assessed relative to the UK consensus values, taking account of method. Variance Index scoring has been used to quantitate performance, and there has been an improvement in average scores during the operation of the scheme. There are currently 88 participants, though some laboratories which failed to return results regularly were removed from the scheme. The consensus values from the scheme itself have now been validated, and in future the scheme should operate independently.
Blood Chemical Analysis↗
Chemiluminescent and bioluminescent immunoassays.
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Journal Article↗
An assessment of the sources of dietary salt in a British population.
An epidemiological study was conducted in the market town of March, Cambridgeshire, to assess the quantitative importance of cooking and table salt to total dietary salt intake by the use of a fused mixture of lithium carbonate and sodium chloride. Men and women aged 20-60 participated in a 12 day study with sequential 24 h urine collections to assess salt sources over a 7 day period. Total salt consumption estimated from urinary chloride excretion amounted to 10.6 +/- 0.55 (SEM) g in 33 men and 7.4 +/- 0.29 (SEM) g in 50 women. The cooking salt eaten was only 0.45 +/- 0.09 (SEM) g in men and women, with men eating more table salt (0.77 g/day) than women (0.46 g/day). Discretionary sources, i.e. cooking and table salt use, contributed only 15% to the total intake. Salt from manufacturing foods and catering in purchased food therefore provided on average 85% of total salt intake. These results are consistent even when an allowance is made for the slightly poorer pouring quality of the lithium-tagged salt. The importance of food as a source of salt was reflected in the significant relationship between the weight of the individual and the amount of salt eaten (for males P less than 0.05 and for females P less than 0.001). Cooking salt consumption did not relate to the amount of salt derived from purchased food nor did table salt use relate to the amount of salt in cooked foods.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
High density lipoprotein cholesterol is not a major risk factor for ischaemic heart disease in British men.
The concentration of high density lipoprotein cholesterol (HDL cholesterol) in serum was measured at initial examination in a large prospective study of men aged 40-59 drawn from general practices in 24 British towns. After an average follow up of 4.2 years 193 cases of major ischaemic heart disease had been registered in 7415 men in whom both HDL cholesterol and total cholesterol values had been measured. The mean HDL cholesterol concentration was lower in the men with ischaemic heart disease ("cases") compared with other men, but the difference became small and non-significant after adjustment for age, body mass index, blood pressure, cigarette smoking, and concentration of non-HDL cholesterol. The higher mean concentration of non-HDL cholesterol in "cases" remained highly significant after adjustment for other factors. Men in the highest fifth of non-HDL cholesterol values had over three times the risk of major ischaemic heart disease compared with men in the lowest fifth. Multivariate analysis showed that non-HDL cholesterol was a more powerful predictor of risk than the HDL to total cholesterol ratio. These British findings were compared with six other prospective studies. All the larger studies showed similar results, suggesting that HDL cholesterol is not a major risk factor in the aetiology of ischaemic heart disease.
Adult↗
An enhanced chemiluminescent enzyme immunoassay for serum carcinoembryonic antigen based on a modification of a commercial kit.
A conventional colorimetric peroxidase end-point (ortho-phenylenediamine substrate), used in an enzyme immunoassay for carcinoembryonic antigen, employing plastic beads as solid support, has been replaced by a much faster (30 seconds versus 30 minutes) enhanced chemiluminescent assay for the peroxidase label. Para-iodophenol was used to enhance the light emission from the peroxidase catalysed chemiluminescent reaction between luminol and hydrogen peroxide. Values for precision and carcinoembryonic antigen concentration obtained with the chemiluminescent and colorimetric versions of the immunoassay on 62 serum specimens were in good agreement.
Carcinoembryonic Antigen↗
Serum uric acid, serum glucose and diabetes: relationships in a population study.
The relationships between serum uric acid, serum glucose and diabetes have been examined in a survey of 7735 middle-aged men drawn at random from general practices in 24 British towns. There was a positive relationship between serum glucose and serum uric acid concentrations up to about 8.0 mmol/l; at higher levels of glucose, serum uric acid decreased. Uric acid levels were significantly reduced in insulin-dependent diabetics and in those on oral hypoglycaemics and also in 'non-diabetics' with casual glucose levels greater than 10 mmol/l. Both uric acid and glucose concentrations were positively related to body mass index; only uric acid was positively related to alcohol intake. Men on antihypertensive treatment had raised levels of uric acid (significant) and glucose (non-significant). The positive relationship between serum uric acid and serum glucose could not be explained by associations with body mass index, alcohol intake, age, social class, gout or treatment for hypertension. It probably reflects the biochemical interaction between serum glucose and purine metabolism, with increased excretion of uric acid during hyperglycaemia and glycosuria.
Adult↗
Effect of cigarette smoking, pulmonary inflammation, and lung disease on concentrations of carcinoembryonic antigen in serum and secretions.
A specific radioimmunoassay for carcinoembryonic antigen was used to investigate aspects of its measurement in lung disease. The results confirm that serum carcinoembryonic antigen concentrations are higher in healthy smokers and patients with chronic obstructive bronchitis than in healthy non smokers (p less than 0.01). Corticosteroid treatment reduced the concentration in nine patients with bronchitis (p less than 0.05). Other inflammatory lung diseases (bronchiectasis, pneumonia, fibrosing alveolitis) are not associated with a raised serum carcinoembryonic antigen concentration. The sputum concentrations were about 100 times those found in serum and there was a positive correlation (r = 0.611 2p less than 0.01) between the concentrations in sputum and serum in patients with bronchitis. No preferential rise in sputum concentration was found in current smokers or patients with lung carcinoma (n = 16). A higher ratio of carcinoembryonic antigen to albumin concentration (p less than 0.05) was, however, found in lavage fluid obtained from the tumour site than in fluid from "normal" lung in the same patients, suggesting an increase in carcinoembryonic antigen secretion in the vicinity of the tumour. Despite this "local" effect the sputum concentration does not, however, appear to be a useful marker of lung carcinoma and the measurement could not be used as a screening test.
Bronchitis↗
Enhanced luminescent quantitation of horseradish peroxidase conjugates: application in an enzyme immunoassay for digoxin.
A p-iodophenol-enhanced luminescent end-point has been incorporated into a commercially available heterogeneous competitive enzyme immunoassay for digoxin based on a horseradish peroxidase-digoxin conjugate. The luminescent end-point could be completed in less than 1 min and significantly reduced overall assay time. Results for the assay obtained using enhanced luminescence showed good agreement with those obtained using a colorimetric end-point (correlation coefficient 0.98). Both assays gave acceptable precision within the therapeutic range. The incubation time for the luminescent immunoassay was reduced to 15 min and still gave differentiation between sub-therapeutic, therapeutic and toxic levels of digoxin.
Colorimetry↗
An examination of the hexokinase method for serum glucose assay using external quality assessment data.
Hexokinase methods for serum glucose assay appeared to give slightly but consistently higher inter-laboratory coefficients of variation than all methods combined in the UK External Quality Assessment Scheme; their performance over a two-year period was therefore compared with that for three groups of glucose oxidase methods. This assessment showed no intrinsic inferiority in the hexokinase method. The greater variation may be due to the more heterogeneous group of instruments, particularly discrete analysers, on which the method is used. The Beckman Glucose Analyzer and Astra group (using a glucose oxidase method) showed the least inter-laboratory variability but also the lowest mean value. No comment is offered on the absolute accuracy of any of the methods.
Autoanalysis↗