Antioxidants in health and disease

Free radical production occurs continuously in all cells as part of normal cellular function. However, excess free radical production originating from endogenous or exogenous sources might play a role in many diseases. Antioxidants prevent free radical induced tissue damage by preventing the formation of radicals, scavenging them, or by promoting their decomposition. This article reviews the basic chemistry of free radical formation in the body, the consequences of free radical induced tissue damage, and the function of antioxidant defence systems, with particular reference to the development of atherosclerosis.

Mutations in the kinase Rsk-2 associated with Coffin-Lowry syndrome

The Coffin-Lowry syndrome (CLS), an X-linked disorder, is characterized by severe psychomotor retardation, facial and digital dysmorphisms, and progressive skeletal deformations. Genetic linkage analysis mapped the CLS locus to an interval of 2-3 megabases at Xp22.2. The gene coding for Rsk-2, a member of the growth-factor-regulated protein kinases, maps within the candidate interval, and was tested as a candidate gene for CLS. Initial screening for mutations in the gene for Rsk-2 in 76 unrelated CLS patients revealed one intragenic deletion, a nonsense, two splice site, and two missense mutations. The two missenses affect sites critical for the function of Rsk-2. The mutated Rsk-2 proteins were found to be inactive in a S6 kinase assay. These findings provide direct evidence that abnormalities in the MAPK/RSK signalling pathway cause Coffin-Lowry syndrome.

Phages will out: strategies of host cell lysis

Most phages accomplish host lysis using a muralytic enzyme, or endolysin, and a holin, which permeabilizes the membrane at a programmed time and thus controls the length of the vegetative cycle. By contrast, lytic single-stranded RNA and DNA phages accomplish lysis by producing a single lysis protein without muralytic activity.

Asymptomatic inflammation and/or infection in benign prostatic hyperplasia

OBJECTIVE

To determine the extent, pattern and clinical significance of asymptomatic histological inflammation and latent infection (National Institute of Health Category IV prostatitis) in benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

The study included 80 patients (from a cohort of 100 consecutive potentially eligible subjects) with a diagnosis of BPH, but no history or symptoms of prostatitis. Histological sections were obtained from specimens collected prospectively at transurethral resection of the prostate (TURP), immunostained for leukocyte common antigen and scanned using a computerized image-analysis system. Foci of inflammation were categorized as glandular, periglandular, stromal or peri-urethral, and the inflammatory cell density graded from 1 to 3. Relationships and correlations were calculated between the volume, degree and type of inflammation, presence and type of bacteria (culture of deep prostatic biopsies), the use of catheters and prostate specific antigen (PSA) levels.

RESULTS

Inflammation was identified in all patients but the mean tissue surface area involved was only 1.1% of the total specimen, with periglandular inflammation being the predominant pattern (0.5%). Of the prostate specimens, 44% showed bacterial growth (in 67% of the catheterized patients and 28% of those uncatheterized; 42% of patients were catheterized before TURP). There was no significant difference between any combination of inflammation pattern, volume or grade of inflammation in those catheterized or not (P=0.15) or culture-positive (pathogenic or not) and culture-negative cases (P=0.06). Neither total PSA or PSA density was significantly correlated (P>0.05) with the amount, degree or distribution of inflammation.

CONCLUSION

Prostatic inflammation is an extremely common histological finding in patients with symptoms of BPH who have no symptoms of prostatitis. There was no correlation between the degree and pattern of inflammation, catheterization, presence of bacteria, serum PSA or PSA density. The clinical significance of asymptomatic Category IV chronic prostatitis associated with BPH has yet to be determined.

The common 'thermolabile' variant of methylene tetrahydrofolate reductase is a major determinant of mild hyperhomocysteinaemia

Mild hyperhomocysteinaemia is a major risk factor for vascular disease and neural tube defects (NTDs), conferring an approximately three-fold relative risk for each condition. It has several possible causes: heterozygosity for rare loss of function mutations in the genes for 5,10-methylene tetrahydrofolate reductase (MTHFR) or cystathionine-beta-synthase (CBS); dietary insufficiency of vitamin co-factors B6, B12 or folates; or homozygosity for a common 'thermolabile' mutation in the MTHFR gene which has also been associated with vascular disease and NTDs. We quantified the contribution of the thermolabile mutation to the hyperhomocysteinaemic phenotype in a working male population (625 individuals). Serum folate and vitamin B12 concentrations were also measured and their relationship with homocysteine status and MTHFR genotype assessed. The homozygous thermolabile genotype occurred in 48.4, 35.5, and 23.4% of the top 5, 10, and 20% of individuals (respectively) ranked by plasma homocysteine levels, compared with a frequency of 11.5% in the study population as a whole, establishing that the mutation is a major determinant of homocysteine levels at the upper end of the range. Serum folate concentrations also varied with genotype, being lowest in thermolabile homozygotes. The MTHFR thermolabile genotype should be considered when population studies are designed to determine the effective homocysteine-lowering dose of dietary folate supplements, and when prophylactic doses of folate are recommended for individuals.

Total antioxidant capacity of seminal plasma is different in fertile and infertile men

OBJECTIVE

To determine if the total antioxidant capacity of seminal plasma is different in fertile and infertile men.

DESIGN

An enhanced chemiluminescence assay applied to seminal plasma from groups of fertile and infertile men.

SETTING

The Assisted Conception Unit, Royal Maternity Hospital, Belfast.

SUBJECTS

Men of proven fertility whose partners had an ongoing pregnancy resulting from IVF and male partners of couples attending our subfertility clinic.

RESULTS

Total antioxidant capacity was significantly higher in seminal plasma from fertile men than from that of infertile men with normozoospermic samples that exhibited reactive oxygen species or asthenozoospermic samples with or without reactive oxygen species activity.

CONCLUSIONS

Seminal plasma from infertile men has lower antioxidant levels than that of fertile men, particularly of patients whose semen have poor sperm motility. The presence of reactive oxygen species activity in sperm of infertile groups also is associated with lower levels of chain-breaking antioxidants in seminal plasma.

Obesity and the lung: 1. Epidemiology

Obesity is the most common metabolic disease in the world and its prevalence has been increasing over several decades. The World Health Organization (WHO) predicts that, by 2015, around 700 million adults will be obese (at least 10% of the projected global population). This will be a huge health and economic burden with associated increases in diabetes, cardiovascular and musculoskeletal disease, and malignancy. While there has been little focus on the impact of obesity on respiratory disease, there are clear effects on pulmonary function and inflammation which will increase the prevalence and morbidity of lung disease. There is an inverse relationship between body mass index and forced expiratory volume in 1 s. Increases in body weight lead to worsening of pulmonary function. The reasons for this include the mechanical effects of truncal obesity and the metabolic effects of adipose tissue. Obesity is linked to a wide range of respiratory conditions including chronic obstructive pulmonary disease, asthma, obstructive sleep apnoea, pulmonary embolic disease and aspiration pneumonia. It is important for those providing care for people with respiratory disease to appreciate the impact of obesity and to provide appropriate advice for weight reduction. Healthcare planners should consider the impact of obesity for future resources in respiratory care.

Measurement of malondialdehyde in plasma by high performance liquid chromatography with fluorimetric detection

The thiobarbituric acid test for malondialdehyde is widely used as an indicator of lipid peroxidation and free radical activity. We describe a simple and sensitive high performance liquid chromatographic (HPLC) method for measuring the malondialdehyde-thiobarbituric acid adduct using fluorimetric detection. Extraction into organic solvent or other complex sample preparation is not required and the assay is sensitive to less than 0.05 mumol/L. This method could easily be applied to any setting where a measure of lipid peroxidation is required.

Methionine synthase D919G polymorphism is a significant but modest determinant of circulating homocysteine concentrations

Elevation in plasma homocysteine concentration has been associated with vascular disease and neural tube defects. Methionine synthase is a vitamin B(12)-dependent enzyme that catalyses the remethylation of homocysteine to methionine. Therefore, defects in this enzyme may result in elevated homocysteine levels. One relatively common polymorphism in the methionine synthase gene (D919G) is an A to G transition at bp 2,756, which converts an aspartic acid residue believed to be part of a helix involved in co-factor binding to a glycine. We have investigated the effect of this polymorphism on plasma homocysteine levels in a working male population (n = 607) in which we previously described the relationship of the C677T "thermolabile" methylenetetrahydrofolate reductase (MTHFR) polymorphism with homocysteine levels. We found that the methionine synthase D919G polymorphism is significantly (P = 0.03) associated with homocysteine concentration, and the DD genotype contributes to a moderate increase in homocysteine levels across the homocysteine distribution (OR = 1.58, DD genotype in the upper half of the homocysteine distribution, P = 0.006). Unlike thermolabile MTHFR, the homocysteine-elevating effects of the methionine synthase polymorphism are independent of folate and B(12) levels; however, the DD genotype has a larger homocysteine-elevating effect in individuals with low B(6) levels. This polymorphism may, therefore, make a moderate, but significant, contribution to clinical conditions that are associated with elevated homocysteine.

The methionine synthase reductase (MTRR) A66G polymorphism is a novel genetic determinant of plasma homocysteine concentrations

Epidemiological evidence has revealed that an elevated plasma homocysteine level (hyperhomocysteinemia) confers an increased risk of cardiovascular disease and neural tube defects. Hyperhomocysteinemia is caused by both nutritional (e.g. folate, vitamins B(6) and B(12)) and genetic factors, including functional polymorphisms of key enzymes involved in homocysteine metabolism. One such enzyme, methionine synthase reductase (MTRR), maintains adequate levels of methylcob(III)alamin, the activated cofactor for methionine synthase, which catalyzes the remethylation of homocysteine to methionine. A common MTRR polymorphism, i.e. a 66 A-->G substitution specifying an isoleucine to methionine substitution (I22M), was recently identified. To assess the influence of this polymorphism on total plasma homocysteine (tHcy), we undertook a genotype/phenotype analysis in a study population of 601 Northern-Irish men, aged 30--49, for which biochemical and genetic data relevant to folate/homocysteine metabolism had already been acquired. The 66AA genotype has a frequency of 29% in this population. We established that there was a significant influence of MTRR genotype on tHcy ranking (P=0.004) and that the 66AA genotype contributes to a moderate increase in tHcy levels across the distribution [OR 1.59 (95% CI: 1.10--2.25) for the 66AA genotype to be in the upper half of the tHcy distribution, P=0.03]. The homocysteine-elevating effect of the 66AA genotype is independent of serum folate, vitamin B(12) and vitamin B(6) levels. Based on published estimates of the enhanced cardiovascular disease risk conferred by defined increments of plasma tHcy, we estimate that 66AA homozygotes have, on average, an approximately 4% increase in cardiovascular disease risk compared to 66GG homozygotes. This study provides the first evidence that the MTRR A66G polymorphism significantly influences the circulating tHcy concentration.

'Settings' based health promotion: a review

Over the past 10 years, 'settings' based health promotion has become a central feature of efforts to promote health that recognize the significance of context. Emerging in part from a perception of an over-reliance on individualistic methods, the approach was built on a profound belief in its value and deployed a range of novel theoretical resources, mainly from organizational sociology and psychology. This initial enthusiasm has been maintained within policy directives, in the published literature and, from our own experience, amongst health promotion practitioners. At the same time, with the maturing of the approach, has come a healthy element of critical review. Drawing upon the literature and based upon our experiences within the Health Education Board for Scotland, this paper seeks to bring together a range of perspectives, casting a critical yet constructive eye on current settings theory and practice. The paper first reviews the nature of settings based work, highlighting the varied bases and expectations that underpin it. Similarly, the many factors that influence the ability of health promoters to deliver such activities are considered. In relation to the construction and delivery of such activity, the paper suggests that there needs to be an explicit and detailed assessment of the nature of the setting, the skills of the health promoter and the associated expectations.

Comparison of individual antioxidants of sperm and seminal plasma in fertile and infertile men

OBJECTIVE

To measure individual antioxidants in sperm and seminal plasma from fertile and infertile men to determine if any particular antioxidant is reduced in infertile men.

DESIGN

Semen samples were prepared by a discontinuous Percoll gradient to separate sperm and seminal plasma, and the antioxidant concentrations of each were assessed. Samples also were screened for phorbol ester-induced reactive oxygen species (ROS) activity.

SETTING

Departments of Obstetrics and Gynaecology, and Clinical Biochemistry, The Queen's University of Belfast, Northern Ireland.

PATIENT(S)

Fifty-nine male patients attending our infertility center: 18 men whose wives had ongoing pregnancies from IVF with normozoospermic semen profiles, 20 infertile men with normozoospermic and 21 men with asthenozoospermic semen profiles.

MAIN OUTCOME MEASURE(S)

Ascorbate, urate, sulphydryl groups, tocopherol and carotenoid concentrations were measured in sperm and seminal plasma from fertile and infertile men.

RESULT(S)

In seminal plasma, ascorbate contributes almost twice as much as urate and thiol levels are about one third of ascorbate. Ascorbate levels in seminal plasma of asthenozoospermic individuals (+ROS) are significantly reduced. In sperm, thiols contributed most and ascorbate only a fraction of the total.

CONCLUSION(S)

In seminal plasma, ascorbate, urates, and thiols are the major antioxidants present. In contrast, within sperm, this group is the major contributor. In samples exhibiting ROS activity, ascorbate concentrations in the seminal plasma are significantly reduced.

Black tea consumption does not protect low density lipoprotein from oxidative modification

OBJECTIVE

To investigate the in vivo and in vitro effects of black tea on the oxidative modification of low density lipoprotein (LDL).

DESIGN

The antioxidant activity of the tea was studied in vitro by measuring the resistance of the LDL to oxidative modification in the presence of copper. The effects of tea consumption in vivo were investigated in two settings. Firstly, to assess the acute effects of tea consumption, five fasting healthy subjects ingested 600 mls (50.7+/-5.4 mg flavonoids) of black tea and peripheral venous blood was collected at 0, 30, 60, 90, 120 and 180 min after consumption. Secondly, to assess the effects of chronic tea consumption, a randomised crossover trial of tea (126.8+/-13.5 mg flavonoids) and coffee consumption was carried out in ten healthy subjects.

RESULTS

Black tea extract increased the resistance of LDL in vitro in a concentration dependent manner. There was no significant change in total plasma antioxidant capacity or susceptibility of the LDL to oxidation over the 3 h period after consumption of black tea. The four-week crossover study in which coffee was used as a control against the black tea showed no significant difference in the total plasma antioxidant capacity or susceptibility of LDL to oxidation between the tea and coffee groups. Serum lipids, including total cholesterol, triglycerides, LDL cholesterol and HDL cholesterol did not change significantly throughout the study.

CONCLUSIONS

The consumption of moderate quantities of black tea acutely or for one week does not increase plasma total antioxidant capacity or alter the susceptibility of LDL to oxidation.

Cigarette smoking and age-related macular degeneration in the EUREYE Study

OBJECTIVE

To examine the association between cigarette smoking and age-related maculopathy (ARM) including age-related macular degeneration (AMD) in the European population.

DESIGN

Cross-sectional study.

PARTICIPANTS

Four thousand seven hundred fifty randomly sampled > or =65-year-olds from 7 study centers across Europe (Norway, Estonia, United Kingdom, France, Italy, Greece, and Spain).

METHODS

Participants underwent an eye examination and digital retinal photography. The images were graded at a single center. Smoking history was ascertained by a structured questionnaire administered by trained fieldworkers. Multinomial and binary logistic regressions were used to examine the association between smoking history and ARM grade and type of AMD, taking account of potential confounders and the multicenter study design.

MAIN OUTCOME MEASURES

Photographic images were graded according to the International Classification System for ARM and stratified using the Rotterdam staging system into 5 exclusive stages (ARM 0-3 and ARM 4, also known as AMD). Age-related macular degeneration also was classified as neovascular AMD or geographic atrophy (GA).

RESULTS

One hundred fifty-eight cases were categorized as AMD (109 neovascular AMD and 49 GA); 2260 had no signs of ARM (ARM 0). Current smokers had increased odds of neovascular AMD (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.4-4.8) or GA (OR, 4.8; 95% CI, 2.1-11.1), whereas for ex-smokers the odds were around 1.7. Compared with people with unilateral AMD, those with bilateral AMD were more likely to have a history of heavy smoking in the previous 25 years (OR, 5.1; 95% CI, 1.3-20.0). The attributable fraction for AMD due to smoking was 27% (95% CI, 19%-33%). There was no consistent association with ARM grades 1 to 3 and smoking.

CONCLUSIONS

These findings highlight the need for increasing public awareness of the risks associated with smoking and the benefit of quitting smoking. Patients with unilateral disease who are current smokers should be advised of the risk of second-eye disease.

Plasma chain-breaking antioxidants in Alzheimer's disease, vascular dementia and Parkinson's disease

We studied the plasma chain-breaking antioxidants alpha carotene, beta carotene, lycopene, Vitamin A, Vitamin C, Vitamin E and a measure of total antioxidant capacity, TAC, in 79 patients with Alzheimer's disease (AD), 37 patients with vascular dementia (VaD), 18 patients with Parkinson's disease and dementia (PDem), and 58 matching controls, together with 41 patients with Parkinson's disease (PD) and 41 matching controls. Significant reductions in individual antioxidants were observed in all dementia groups. When compared to controls, the following were reduced: Vitamin A in AD (p < 0.01) and VaD (p < 0.001); Vitamin C in AD (p < 0.001), VaD (p < 0.001) and PDem (p < 0.01); Vitamin E in AD (p < 0.01) and VaD (p < 0.001); beta carotene in VaD (p = 0.01); lycopene in PDem (p < 0.001). Lycopene was also reduced in PDem compared to AD (p < 0.001) and VaD (p < 0.001). Antioxidant levels in PD were not depleted. No significant change in TAC was seen in any group. The reduction in plasma chain-breaking antioxidants in patients with dementia may reflect an increased free-radical activity, and a common role in cognitive impairment in these conditions. Increased free-radical activity in VaD and PDem could be associated with concomitant AD pathology. Individual antioxidant changes are not reflected in TAC.

Effect of hemodialysis on total antioxidant capacity and serum antioxidants in patients with chronic renal failure

Cardiovascular disease is the major cause of mortality in patients receiving hemodialysis for chronic renal failure. Increased lipid peroxidation and depletion of chain-breaking antioxidants may contribute to increased risk of atherosclerosis. We have therefore assessed the effect of a single episode of hemodialysis on antioxidant status in 22 patients and control subjects. Overall, total antioxidant capacity of serum was increased in dialysis patients, but there was a marked reduction after hemodialysis [571 +/- 31 vs 342 +/- 22 mumol/L Trolox (water-soluble vitamin E analog) equivalents, P &lt; 0.001]. The increase in total antioxidant capacity before hemodialysis was almost entirely due to relatively high serum urate. Among individual chain-breaking antioxidants, dialysis led to a decrease in urate (398 +/- 15 vs 136 +/- 12 mumol/L, P &lt; 0.001), ascorbate (10.5 +/- 1.7 vs 5.9 +/- 1.0 mumol/L, P &lt; 0.01), and lipid-corrected tocopherol (4.70 +/- 0.56 vs 4.26 +/- 0.39 mumol/mmol cholesterol, P &lt; 0.05). Protein thiol groups increased after dialysis (328 +/- 16 vs 422 +/- 22 mumol/L, P &lt; 0.001), whereas albumin remained unchanged (40.1 +/- 1.1 vs 41.0 +/- 1.6 g/L, not significant). Although total antioxidant capacity of serum is increased in hemodialysis patients, depletion of key chain-breaking antioxidants may lead to accelerated atherogenesis.

Electron spin resonance spectroscopic detection of oxygen-centred radicals in human serum following exhaustive exercise

Free radicals or oxidants are continuously produced in the body as a consequence of normal energy metabolism. The concentration of free radicals, together with lipid peroxidation, increases in some tissues as a physiological response to exercise - they have also been implicated in a variety of pathologies. The biochemical measurement of free radicals has relied in the main on the indirect assay of oxidative stress by-products. This study presents the first use of electron spin resonance (ESR) spectroscopy in conjunction with the spin-trapping technique, to measure directly the production of radical species in the venous blood of healthy human volunteers pre- and post-exhaustive aerobic exercise. Evidence is also presented of increased lipid peroxidation and total antioxidant capacity post-exercise.

Mechanical properties of tendons: changes with sterilization and preservation

Tendon allografts are commonly used to replace damaged anterior cruciate ligaments (ACL). Some of the sterilization and preservation techniques used by tissue banks with tendon allografts are thought to impair the mechanical properties of graft tissues. The tensile mechanical properties of porcine toe extensor tendons were measured using a dynamic testing machine following either freezing, freeze-drying, freezing then irradiation at 25 kGy (2.5 MRad), freeze-drying then irradiation, or freeze-drying then ethylene oxide gas sterilization. There was a small but significant difference in Young's modulus between the frozen group (0.88 GPa + 0.09 SD) and both the fresh group (0.98 GPa 1 0.12 SD) and the frozen irradiated group (0.97 GPa 1 0.08 SD). No values of Young's modulus were obtained for the freeze-dried irradiated tendons. The ultimate tensile stress (UTS) of the freeze-dried irradiated group (4.7 MPa 1 4.8 SD) was significantly different from both the fresh and the frozen irradiated groups, being reduced by approximately 90 percent. There were no significant changes in UTS or Young's modulus between any of the other groups. If irradiation is to be used to sterilize a tendon replacement for an ACL it must take place after freeze-drying to maintain mechanical properties.

Determination of thiamine by high-performance liquid chromatography

High-performance liquid chromatographic methods for the determination of thiamine (vitamin B1) in foodstuffs or biological tissues and fluids are outlined and discussed. The methods are often similar and interchangeable, sample extraction and clean up procedures being the major difference. Most of the methods use either ultraviolet or fluorescence detection. Fluorescence detection requires either precolumn or postcolumn oxidation of thiamine to thiochrome. A number of methods are recommended and problems with standardization are emphasized.

Brisk walking, fitness, and cardiovascular risk: a randomized controlled trial in primary care

STUDY OBJECTIVE

To examine the effects of 30 min of self-paced, non-supervised, brisk walking, 5 days per week on the health and fitness of people aged 50-65 years.

DESIGN

Randomized controlled trial. Members of the intervention group (n = 21) were directed to walk briskly for 30 min, 5 days per week, for 12 weeks. Individuals were given the choice to complete the 30 min of walking in one session or in shorter bouts of no less than 10 min. They were asked to record in a diary the time spent walking and the number of steps taken during a single walk using a pedometer. Participants in the control group (n = 10) were asked to maintain their habitual lifestyle and not change their activity or dietary habits. Measurements of body mass index (BMI), waist/hip ratio (WHR), blood pressure, functional capacity, total cholesterol, triglyceride, and lipoprotein subfractions were taken before and after the program. Changes in 10-year risk estimate for coronary heart disease and stroke were calculated using Framingham risk equations.

SETTING

Three urban general practices patients: 31 healthy, sedentary 50- to 65-year-old participants recruited following contact by their general practitioner.

MAIN RESULTS

The mean time spent walking by the intervention group was 27.72 (+/-9.79) min/day: their adherence to the protocol was 90.3%. Significant decreases in systolic and diastolic blood pressure, reduction in stroke risk, and increased functional capacity were found within the walking group between baseline and 12-week measurements. No changes were found in these parameters within the control group. Significant reductions in 10-year risk of CHD were observed in both groups. No significant changes were found in lipid levels or anthropometric measurements in either group.

CONCLUSIONS

The study provides evidence for the benefit to fitness and cardiovascular risk of the "30-min brisk walking, 5 days a week" message to people aged 50-65 years who participated in an unsupervised home-based walking program. Further study to overcome the problem of poor recruitment and determine the minimum effective dose of exercise to improve cardiovascular risk prediction scores is required.

Electron spin resonance spectroscopy, exercise, and oxidative stress: an ascorbic acid intervention study

Oxygen free radicals are highly reactive species that are produced in increased quantities during strenuous exercise and can damage critical biological targets such as membrane phospholipids. The present study examined the effect of acute ascorbic acid supplementation on exercise-induced free radical production in healthy subjects. Results demonstrate increases in the intensity of the alpha-phenyl-tert-butylnitrone adduct (0.05 +/- 0.02 preexercise vs. 0.19 +/- 0.03 postexercise, P = 0.002, arbitrary units) together with increased lipid hydroperoxides (1.14 +/- 0.06 micromol/l preexercise vs. 1.62 +/- 0.19 micromol/l postexercise, P = 0.005) and malondialdehyde (0.70 +/- 0.04 micromol/l preexercise vs. 0.80 +/- 0.04 micromol/l postexercise, P = 0.0152) in the control phase. After supplementation with ascorbic acid, there was no significant increase in the electron spin resonance signal intensity (0.02 +/- 0. 01 preexercise vs. 0.04 +/- 0.02 postexercise, arbitrary units), lipid hydroperoxides (1.12 +/- 0.21 micromol/l preexercise vs. 1.12 +/- 0.08 micromol/l postexercise), or malondialdehyde (0.63 +/- 0.07 micromol/l preexercise vs. 0.68 +/- 0.05 micromol/l postexercise). The results indicate that acute ascorbic acid supplementation prevented exercise-induced oxidative stress in these subjects.

Training effects of short bouts of stair climbing on cardiorespiratory fitness, blood lipids, and homocysteine in sedentary young women

OBJECTIVES

To study the training effects of eight weeks of stair climbing on Vo2max, blood lipids, and homocysteine in sedentary, but otherwise healthy young women.

METHODS

Fifteen women (mean (SD) age 18.8 (0.7) years) were randomly assigned to control (n = 7) or stair climbing (n = 8) groups. Stair climbing was progressively increased from one ascent a day in week 1 to five ascents a day in weeks 7 and 8. Training took place five days a week on a public access staircase (199 steps), at a stepping rate of 90 steps a minute. Each ascent took about two minutes to complete. Subjects agreed not to change their diet or lifestyle over the experimental period.

RESULTS

Relative to controls, the stair climbing group displayed a 17.1% increase in Vo2max and a 7.7% reduction in low density lipoprotein cholesterol (p < 0.05) over the training period. No change occurred in total cholesterol, high density lipoprotein cholesterol, triglycerides, or homocysteine.

CONCLUSIONS

The study confirms that accumulating short bouts of stair climbing activity throughout the day can favourably alter important cardiovascular risk factors in previously sedentary young women. Such exercise may be easily incorporated into the working day and therefore should be promoted by public health guidelines.