Patients with end-stage renal disease undergoing hemodialysis have a high
incidence of oxidative stress-related diseases. This study evaluated oxidative stress
and inflammatory markers in patients undergoing hemodialysis before and during
vitamin E supplementation. Blood samples were obtained before and after dialysis
during two separate dialysis sessions to establish baseline measurements. For the
next two months, subjects consumed 400 IU RRR-α-tocopherol daily. At one
month and two months of supplementation, blood samples were also obtained
before and after dialysis. Circulating concentrations of α- and γ-tocopherols and
their metabolites (carboxyethyl-hydroxychromans, α- and γ-CEHCs), vitamin C,
and uric acid were determined by HPLC with electrochemical detection. C-reactive
protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were
measured using standard clinical assays. F₂-isoprostanes were evaluated using an
enzyme immunoassay. Dietary vitamins E and C were assessed using two 24-hour
recalls. In response to vitamin E supplementation, plasma α-tocopherol
concentrations increased from 18 ± 1.7 μM to 31 ± 5.4 μM (p<0.0001), while γ-tocopherol
concentrations decreased from 2.8 ±1.0 μM to 1.7 ± 0.6 μM (p=0.001). Additionally, serum vitamin E metabolites increased, α-CEHCs from 68 ± 20
pmol/ml to 771 ± 161 (p<0.0001) and γ-CEHC from 837 ± 161.8 pmol/ml to 1136
± 225.9 (p=0.0083). Both CEHCs are well above reported normal values
(p<0.0001). Dietary antioxidants (vitamins E and C) were low in most subjects;
thus, plasma ascorbic acid levels were low in most subjects, but high in a few,
resulting a wide range of responses (88 ± 84 μM). Nonetheless, ascorbic acid
concentrations decreased significantly after dialysis to 33 ± 34 μM (p=0.0124), but
were unaffected by vitamin E supplementation. Indeed, many parameters
decreased significantly by dialysis but were unchanged by vitamin E
supplementation, including plasma concentrations of uric acid and TNF-α. Both
IL-6 and F₂-isoprostane concentrations were elevated in the subjects but were
unaffected by either vitamin E supplementation or dialysis. CRP increased
significantly after dialysis (p=0.0161, ANOVA main effect), but in the vitamin E
supplemented subjects CRP concentrations were slightly lower before dialysis , but
increased following dialysis (p=0.0041, ANOVA interaction). Taken together, the
data suggest that there is a complex relationship between chronic inflammation and
oxidative stress. Longer supplementation with vitamin E might be necessary in
order to observe beneficial effects. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27051 |
| Date | 11 June 2002 |
| Creators | Smith, Kylie Sheree |
| Contributors | Traber, Maret G. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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