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Plasma alpha tocopherol in disorders of the human reproductive system

Perera, Doreen Mala Damayanthi; (2003) Plasma alpha tocopherol in disorders of the human reproductive system. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Attempts were made to develop a radioimmunoassay for the measurement of alpha tocopherol in plasma. The immunogen, alpha tocopheryl succinate-BSA-conjugate, was synthesised: rabbits were immunised with this immunogen and their gamma globulins formed precipitins with the conjugate. Antiserum curves were constructed with the IgG of immunised rabbits and with IgG of a non-immunised rabbit as a control. Specific binding of 3H alpha tocopherol to immunised rabbit IgG could not be demonstrated since the control rabbit IgG produced a binding curve similar to those of immunised rabbit IgG. Hence attempts were made to establish a competitive protein binding (CPB) assay using a) rat liver cytosol alpha tocopherol binding protein and b) human erythrocyte membrane alpha tocopherol binding sites. Binding agents were isolated from both these sources. However the binding of 3H alpha tocopherol to rat liver cytosol binding sites was insufficient for the development of a CPB assay, and, using erythrocyte membrane alpha tocopherol binding sites, specifically bound tritiated alpha tocopherol could not be separated from non-specifically bound tracer. Therefore to study the alpha tocopherol status in human reproductive disorders, a spectrophotometric method for plasma vitamin E determination, a high performance liquid chromatography procedure for alpha tocopherol assay and a colorimetric method for total lipid measurement were used. No significant differences were found in the levels of alpha tocopherol or alpha tocopherol/total lipid ratios between normal men and male patients with oligospermia, impotence or sperm agglutination, or between normal women and females with premenstrual syndrome. Using equilibrium dialysis it was found that approximately 0.6% of the total plasma alpha tocopherol concentration was unbound and the mean unbound alpha tocopherol was calculated to be 0.12?mol/l in the normal subjects. Similar results were obtained for all the patient groups. Negative correlations were observed between the percentage unbound alpha tocopherol and both total alpha tocopherol and lipid levels suggesting that a mechanism may exist which regulates the concentration of unbound alpha tocopherol in plasma. Since disorders of the human reproductive system are commonly associated with abnormal testosterone production and since there is evidence to suggest that alpha tocopherol may have a functional role in steroidogenesis, the relationship between plasma alpha tocopherol and plasma testosterone was explored in a) normal men and women (normal alpha tocopherol and testosterone levels), b) females with hirsutism (normal alpha tocopherol and testosterone in excess) and c) hypogonadal males with beta thalassaemia major (deficient in both alpha tocopherol and testosterone). No correlations were found between the two parameters in any of the above groups. Testicular stimulation with human chorionic gonadotrophin significantly increased plasma testosterone concentrations in the thalassaemics despite their markedly deficient alpha tocopherol levels but the response was sub-optimal. Hence in these subjects vitamin E deficiency may be partially responsible for reduced testicular function. Additionally, unprocessed and freeze dried/hexane extracted whole sera from immunised rabbits were used to investigate specific binding characteristics to alpha tocopherol by radioimmunoassay, electrophoresis and enzyme linked immunosorbent techniques.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Plasma alpha tocopherol in disorders of the human reproductive system
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Health and environmental sciences; Plasma alpha tocopherol; Reproductive system
URI: https://discovery.ucl.ac.uk/id/eprint/10103672
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