On the antioxidant properties of erythropoietin and its association with the oxidative-nitrosative stress response to hypoxia in humans.

AIM: The aim of this study was to examine if erythropoietin (EPO) has the potential to act as a biological antioxidant and determine the underlying mechanisms. METHODS: The rate at which its recombinant form (rHuEPO) reacts with hydroxyl (HO˙), 2,2-diphenyl-1-picrylhydrazyl (DPPH˙) and peroxyl (ROO˙) radicals was evaluated in-vitro. The relationship between the erythopoietic and oxidative-nitrosative stress response to poikilocapneic hypoxia was determined separately in-vivo by sampling arterial blood from eleven males in normoxia and following 12 h exposure to 13% oxygen. Electron paramagnetic resonance spectroscopy, ELISA and ozone-based chemiluminescence were employed for direct detection of ascorbate (A(˙-) ) and N-tert-butyl-α-phenylnitrone spin-trapped alkoxyl (PBN-OR) radicals, 3-nitrotyrosine (3-NT) and nitrite (NO2-). RESULTS: We found rHuEPO to be a potent scavenger of HO˙ (kr = 1.03-1.66 × 10(11) m(-1) s(-1) ) with the capacity to inhibit Fenton chemistry through catalytic iron chelation. Its ability to scavenge DPPH˙ and ROO˙ was also superior compared to other more conventional antioxidants. Hypoxia was associated with a rise in arterial EPO and free radical-mediated reduction in nitric oxide, indicative of oxidative-nitrosative stress. The latter was confirmed by an increased systemic formation of A˙(-) , PBN-OR, 3-NT and corresponding loss of NO2- (P < 0.05 vs. normoxia). The erythropoietic and oxidative-nitrosative stress responses were consistently related (r = -0.52 to 0.68, P < 0.05). CONCLUSION: These findings demonstrate that EPO has the capacity to act as a biological antioxidant and provide a mechanistic basis for its reported cytoprotective benefits within the clinical setting.

Evaluation of a distance-learning immunology and pathology module in a postgraduate biomedical science course.

An electronic presentation of materials for a distance-learning immunology and pathology module from a postgraduate biomedical science course is evaluated. Two different electronic presentation formats for the delivery of the educational material to distance learners are assessed. Responses from users of this material highlighted a preference for a format that has a design tailored to distance learning. There was no significant difference in learning outcome between those taking the module on campus and by distance learning. This suggests that the prerequisites for entry, learning materials and direction given to the students studying by distance learning are adequate for these students to achieve the learning objectives outlined in the course. The evaluation also gave direction for areas within the (CAL) application that can be improved for future students.

Vitamin C decreases intracellular calcium level in human lymphoid cells.

Human lymphocytes have low levels of many antioxidant enzymes however they are know to concentrate vitamin C. Cell injury, including oxidative stress effects, is associated with calcium influx so the influence of vitamin C on the maintenance of calcium levels in leukocytes was studied. Incubation of Molt-3 human lymphoblastoid cells with physiologically relevant concentrations of vitamin C and the calcium ionophore A23187 reversed the calcium influx and increased nuclear protein level associated with the ionophore alone. It is concluded that intracellular vitamin C can inhibit calcium influx into leukocytes so helping to minimise cell damage.

Interactions between vitamins C and E in human subjects.

Despite convincing in vitro evidence, a vitamin C-E interaction has not been confirmed in vivo. This study was designed to examine the effects of supplementation with either vitamin C or E on their respective plasma concentrations, other antioxidants, lipids and some haemostatic variables. Fasting blood was collected before and after intervention from thirty healthy adults in a double-blinded crossover study. Baselines for measured variables were established after 2 weeks of placebo supplementation, followed by daily supplementation with 73.5 mg RRR-alpha-tocopherol acetate or 500 mg ascorbic acid, and placebo, for 6 weeks. A 2 month washout preceded supplement crossover. Mean values showed that plasma lipid standardised alpha-tocopherol increased with ascorbic acid supplementation: from 4.09 (sem 0.51) to 4.53 (sem 0.66) micromol/mmol total cholesterol plus triacylglycerol (P < 0.05), and plasma ascorbic acid increased from 62.8 (sem 14.9) to 101.3 (sem 22. 2) micromol/l (P < 0.005). Supplementation with (RRR)-alpha-tocopherol acetate increased plasma alpha-tocopherol from 26.8 (sem 3.9) to 32.2 (sem 3.8) micromol/l (P < 0.05), and lipid-standardised alpha-tocopherol from 4.12 (sem 0.48) to 5.38 (sem 0.52) micromol/mmol (P < 0.001). Mean plasma ascorbic acid also increased with vitamin E supplementation, from 64.4 (sem 13.3) to 76. 4 (sem 18.4) micromol/l (P < 0.05). Plasma ferric reducing (antioxidant) power and glutathione peroxidase (U/g haemoglobin) increased in both groups, while urate, total cholesterol and triacylglycerol levels decreased (P < 0.05 throughout). Results are supportive of an in vivo interaction between vitamins C and E.

Applications of computer-aided learning in biomedical sciences: considerations in design and evaluation.

Multimedia computer-aided learning (CAL) is an area that has become increasingly prevalent in biomedical science. Here we describe the advances that have taken place in the computing industry that have led to this trend. We also outline areas within the subject of biomedical science that can most benefit from using multimedia CAL as a teaching aid. Furthermore, issues concerning the design of CAL (i.e. iterative design, structure, development tools) are discussed. As the evaluation of CAL is an essential part of the iterative design process, we look at new approaches to evaluation that have emerged in response to the superficial focus on usability that many evaluations take.

Frequency of fruit and vegetable consumption and blood antioxidants in the Caerphilly cohort of older men.

OBJECTIVE: To assess the number of portions of fruit and vegetables consumed daily by a large representative sample of older men, and to determine how blood antioxidant (vitamins E, A and carotenoids) concentrations vary with fruit and vegetable consumption. DESIGN: Cross-sectional study of free-living men. SUBJECTS: Men aged 55-69 y (dietary data, n=1957; blood data, n=1874) participating in Phase III (1989-1993) of the Caerphilly and Speedwell Collaborative Heart Disease Studies. METHODS: Dietary data were obtained by semi-quantitative food-frequency questionnaire and blood samples were analysed for antioxidant vitamins. Men were subdivided into groups on the basis of portions per day of fruit and vegetables. Within these sub-groups, mean and 95% ranges of intakes and of blood antioxidant levels were obtained. Log transformations were performed where appropriate. RESULTS: Only 4.3% of the men met the recommended target of five portions, while 33.3% of the men consumed one or fewer portions of fruit and vegetables per day. Those men who consumed the poorest diets with respect to fruit and vegetable intakes were more likely to be from lower socio-economic classes, drink more alcohol and be current smokers. Fruit and vegetable intake reflected plasma concentrations of antioxidants, which showed a dose-response relationship to frequency of consumption. CONCLUSIONS: Older men in the UK consume much less fruit and vegetables than current recommendations. Major difficulties are likely to be encountered in trying to meet a dietary target that is clearly much higher than the fruit and vegetable consumption of large sections of the older population in the UK. SPONSORSHIP: This work was supported by the Medical Research Council.

Antioxidant enzymes, inflammatory indices and lifestyle factors in older men: a cohort analysis.

We examined the relationship between blood antioxidant enzyme activities, indices of inflammatory status and a number of lifestyle factors in the Caerphilly prospective cohort study of ischaemic heart disease. The study began in 1979 and is based on a representative male population sample. Initially 2512 men were seen in phase I, and followed-up every 5 years in phases II and III; they have recently been seen in phase IV. Data on social class, smoking habit, alcohol consumption were obtained by questionnaire, and body mass index was measured. Antioxidant enzyme activities and indices of inflammatory status were estimated by standard techniques. Significant associations were observed for: age with alpha-1-antichymotrypsin (p < 0.0001) and with caeruloplasmin, both protein and oxidase (p < 0.0001); smoking habit with alpha-1-antichymotrypsin (p < 0.0001), with caeruloplasmin, both protein and oxidase (p < 0.0001) and with glutathione peroxidose (GPX) (p < 0.0001); social class with alpha-1-antichymotrypsin (p < 0.0001), with caeruloplasmin both protein (p < 0.001) and oxidase (p < 0.01) and with GPX (p < 0.0001); body mass index with alpha-1-antichymotrypsin (p < 0.0001) and with caeruloplasmin protein (p < 0.001). There was no significant association between alcohol consumption and any of the blood enzymes measured. Factor analysis produced a three-factor model (explaining 65.9% of the variation in the data set) which appeared to indicate close inter-relationships among antioxidants.

Effect of preparatory information prior to elective total hip replacement on post-operative physical coping outcomes.

The aim of the study was to evaluate the effect of preparatory information on a patient's post-operative physical coping outcomes following a Total Hip Replacement (THR). The research design was quasi-experimental. Eighty-two healthy individuals, scheduled for an elective THR were used and selected using non-random techniques, and placed into one of two groups on an alternating basis. The subjects in the experimental group were given procedural, sensory and coping information relating to the whole surgical procedure of a THR. In addition, written information was provided for each experimental subject to support the verbal information. Subjects in the control group only received the advice and support that would routinely be given to THR patients by ward, medical and nursing staff. The study measured a number of physical outcomes using a "Physical Indicators of Coping Questionnaire" developed to measure physiological and physical outcomes post-operatively. In addition, a Linear Analogue Coping Scale was developed to assess a patient's personal perception of their overall coping ability with the THR. The study demonstrated that preparatory information, given pre-operatively, post-operatively and pre-discharge had positive effects on the physical recovery and coping outcomes measured. Subjects in the experimental group had significantly less post-operative intramuscular analgesia, mobilized sooner with a Zimmer frame and walking sticks and lastly, their length of stay was on average, 2 days less than the control group. The Linear Analogue Coping Scale demonstrated that patients in the experimental group did perceive they were coping more effectively post-operatively. Preparatory information of various types and in different forms appear to have positive effects on the ability of patients to cope with and recover physically from a THR in the immediate post-operative period.

Effect of preparatory information prior to elective total hip replacement on psychological coping outcomes.

The objective of this study was to evaluate the effects of preparatory information on psychological coping outcomes among total hip replacement (THR) patients. A quasi-experimental design within an ethnographic clinical context was used. Eighty-two healthy individuals, scheduled for elective THR were recruited for the study and nonrandom selection techniques were used. The subjects in the experimental group were given procedural, sensory and coping information relating to the whole surgical procedure of a THR. In addition, written information was given to support the verbal information. Subjects in the control group received only the advice and support that would routinely be given to THR patients by ward, medical and nursing staff. The main outcomes were measured using standard questionnaires, Hospital Anxiety and Depression Scale (HADS) measuring anxiety and depression, Rosenburg Self-Esteem Scale measuring self-esteem, and Health Illness Questionnaire measuring sense of control. Lastly, a Linear Analogue Coping Scale was developed and applied to assess a subject's personal perception of coping with a THR. Providing information had positive effects on the psychological coping outcomes measured. Subjects in the experimental group had significantly less anxiety and depression with a high self-esteem and sense of control. The Linear Analogue Coping Scale demonstrated a strong correlation between how subjects believed they were coping and that measured using the standard questionnaires. The study concluded that preparatory information of various types and in different forms appears to have positive effects on psychological coping outcomes for THR patients, which may have influenced postoperative recovery.

Serum antioxidant potential, and lipoprotein oxidation in female smokers following vitamin C supplementation.

A single blind placebo controlled trial was carried out to assess the effect of high dose vitamin C supplementation on the antioxidant potential, and extent of lipoprotein oxidation of serum in female smokers. Sixteen apparently healthy subjects were randomised into two groups of eight. One group received 1 g of vitamin C for 14 days the other group received a placebo for 14 days. Serum antioxidant potential (TRAP) was measured and lipoprotein oxidation was assessed by measuring serum malondialdehyde like material. Despite significant increases in serum C concentrations in the supplemented group, serum TRAP values did not change significantly over the course of the trial. Serum malondialdehyde like material also failed to show any temporal variation.

Total radical-trapping antioxidant potential (TRAP) of plasma: effects of supplementation of young healthy volunteers with large doses of alpha-tocopherol and ascorbic acid.

A randomized, placebo-controlled double-blind supplementation trial was conducted on 32 adults to assess the effect of dl-alpha-tocopherol (1 g/day for 28 days) or ascorbic acid (AA) (1 g/day for 28 days) separately or in combination on the total radical-trapping antioxidant potential (TRAP) of plasma. Subjects were divided into 4 groups of 8 and received the following: Group 1, placebo; Group 2, ascorbic acid; Group 3, alpha-tocopherol; Group 4, alpha-tocopherol and AA. Antioxidant potential was assessed using the TRAP technique (a specific measure of the capacity of the secondary antioxidants, vitamins E, C, reduced thiol compounds and urate in plasma to resist controlled in vitro peroxidation). TRAP values were estimated at baseline and after treatment (day 29). Group means of the antioxidant vitamins at baseline were within normal values for both ascorbic acid (62-82 mumol/l) and alpha-tocopherol (24-29 mumol/l). Despite marked increases post-supplementation in plasma alpha-tocopherol levels in Groups 3 (94%) and 4 (91%) and in AA levels in Groups 2 (82%) and 4 (32%), there were no significant differences (analysis of variance) between the 4 treatment groups for TRAP values on day 29. Paired-t-testing revealed significant (P < 0.01) increases in post-supplementation TRAP values in Groups 2 and 3.

Vitamin C and vitamin E--synergistic interactions in vivo?

The synergistic relationship between ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E) in the inhibition of lipid peroxidation has been known for some time and is now well established in vitro systems. The possibility that ascorbic acid may also reduce tocopheroxyl radicals in vivo is a subject of some interest and speculation. Although not all experiments have failed to suggest a synergistic antioxidant interaction, recent data indicate that the postulated synergism between these vitamins might be relatively unimportant compared with other metabolic processes.

Serum total free radical trapping ability in acute myocardial infarction.

Serum total free radical trapping abilities (TRAP experimental) were measured in 15 patients with acute myocardial infarction (AMI) and compared to sex- and age-matched controls. TRAP experimental values were significantly lower (p less than 0.01) in the AMI group. Theoretical trapping abilities were also calculated and compared with experimentally derived values. In the AMI group there was no significant difference between the experimental and calculated TRAP, but in the control group experimental values were significantly higher (p less than 0.01) than calculated values. In the control group regression analysis revealed that alpha-tocopherol and ascorbate taken together most closely explained the radical trapping ability of sera, with a regression equation: TRAP experimental = 562.9 + 2.082 (alpha-tocopherol + ascorbate). In the AMI group no relationship between the serum antioxidants and TRAP experimental was observed.