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Effect of vitamin B-6 status on Selenium metabolism in the ratBeilstein, Michael A. 17 December 1990 (has links)
Graduation date: 1991
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Effect of controlled vitamin B-6 intake and pyridoxine supplementation on B-6 status of smokersSindihebura-Ruhumba, Pascaline 05 May 1999 (has links)
Previous studies have found that smoking may have a negative effect on
vitamin B-6 indices and have demonstrated a possible association between smoking
and depressed plasma pyridoxal-5'-phosphate (PLP) concentration. Individuals with
plasma PLP values below the adequate level of 30 nmoles/L might benefit from
consumption of vitamin B-6 supplements, but no data are available on vitamin B-6
status in smokers consuming a controlled vitamin B-6 intake and receiving a vitamin
B-6 supplement. The objectives of this research were to assess vitamin B-6 status in
smokers as compared to non-smokers receiving a controlled diet and to evaluate the
effect of an oral vitamin B-6 supplementation in these subjects.
The vitamin B-6 (B-6) status of 5 (four males / one female) smokers (S) and 4
(three males / one female) non-smokers (NS) was assessed. A constant diet was fed
for 20 days and provided 1.95 mg of B-6 or 1.65 mg of B-6 for males and females,
respectively. For the last 10 days, an additional 2-mg of pyridoxine (PN) was given
daily. Blood samples were collected on days 1.7, 11.14 and 21; and 24 hour urine samples were collected daily. Urinary 4-pyridoxic acid (4-PA) and total B-6 (UB6)
excretion, plasma B-6 vitamers (PLP, PN, pyridoxal and 4-PA) and red blood cell
PLP (RBC PLP) concentrations, as well as plasma alkaline phosphatase activity
(APA) were determined. Mean plasma PLP, 4-PA, and RBC PLP concentrations
were significantly lower (P [less than or equal to] 0.05) at all time points in S compared to NS. With a
daily supplement of 2-mg vitamin B-6, the mean plasma PLP concentration of S
increased 85.8% but was 48.5% lower than that of NS consuming 1.65-1.95 mg/d of
B-6. Mean plasma pyridoxal concentrations were not different between S and NS
before and after supplementation. Excretion of 4-PA was not significantly different
between S and NS, but the mean values of 4-PA excretion were consistently greater
in NS compared to that of S throughout the 20-day study. The percent of ingested B-6 excreted as 4-PA for the S and NS was 38 and 49 in the non-supplemented period,
and 47 and 53 in the supplemented period, respectively, indicating that non-smokers
excreted more 4-PA than smokers. However, the difference in 4-PA excretion
between S and NS was not significantly different both before and after
supplementation (P>0.05). In addition, there was no significant difference between S
and NS for plasma PN concentration, AP, and UB6 excretion for both periods.
Results suggested an adverse effect of smoking on B-6 metabolism, thus an increased
requirement of vitamin B-6 in smokers. A 2-mg PN supplement was sufficient to
bring the concentration of plasma PLP in smokers to the level suggested as adequate,
but it didn't bring it to the level of non-smokers. / Graduation date: 1999 Read more
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Effects of vitamin B-6 supplementation and exercise to exhaustion on nitrogen balance, total urinary nitrogen & urinary urea in trained male cyclistsSkoog, Ingrid A. 22 July 1993 (has links)
Graduation date: 1994
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Effect of varying levels of vitamin B-6 intake on lymphocyte mitogenic response and vitamin B-6 concentration in human peripheral blood mononuclear cellsKwak, Ho-Kyung 26 July 2001 (has links)
Two studies were conducted to determine the effect of varying vitamin B-6 (B-
6) status on lymphocyte mitogenic response and pyridoxal 5'-phosphate (PLP)
concentration in peripheral blood mononuclear cells (PBMC) in young women. In the
first study, women were fed 1 mg/d for the first week and 1.5, 2.1 and 2.7 mg/d during
2 weeks of each of the subsequent 3 experimental periods. Plasma PLP and urinary 4:
pyridoxic acid (4-PA) were increased with increasing B-6 intake. B-6 intake > 2.1 mg
significantly enhanced lymphocyte proliferation, and non-significantly increased
plasma interleukin-2 concentration. Lymphocyte proliferation was significantly
correlated with B-6 intake, erythrocyte aminotransferase activity coefficients and
plasma PLP. PBMC PLP tended to increase after 2 weeks of 2.7 mg B-6 intake, and
was significantly correlated with plasma PLP. In the second study, women consumed
their normal diets whose estimated mean dietary B-6 intake was 0.9 mg for 27 d. For
the last 20 d, all subjects were given a multivitamin supplement containing 1.8 mg B-
6, and half of the subjects were given an additional 50 mg of B-6 supplement. Plasma
PLP and urinary 4-PA were significantly higher in the group with 50 mg B-6, but
lymphocyte proliferation did not significantly differ between the groups. After 10 d of
supplementation, lymphocyte proliferation was significantly higher than the other time
points. A significant increase in PBMC PLP was observed after 3 days and 20 days
following 50 mg and multivitamin supplementation only, respectively. After 20 days
of supplementation, there was no significant difference of mean PBMC PLP between
the groups. PBMC PLP was significantly correlated with plasma PLP, PL and 4-PA.
In both studies, no strong relationship was found between PBMC PLP and lymphocyte
proliferation. The findings from these studies demonstrate no further benefit of a
higher B-6 intake than 2.1 mg on lymphocyte mitogenic response, once the response
was significantly enhanced with B-6 intake 0.8 mg higher than the current
recommendation. Finally, results from two studies suggest that the current
recommendation of vitamin B-6 for young women may not be adequate to maximize
lymphocyte mitogenic response and PLP concentration in PBMC. / Graduation date: 2002 Read more
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Supplemental vitamin B-6 and endurance exercise effects on plasma catecholamines of trained male cyclistsYoung, Jennifer Charity 05 April 1996 (has links)
This study examined the effect of vitamin B-6 supplementation and exhaustive
submaximal exercise on plasma catecholamine concentrations, and the relationship
between plasma catecholamines and fuel use, heart rate and oxygen consumption. Five
trained men (age= 18-35 years; V0₂max=53 ml 0₂/kg/min.) participated in two controlled
dietary periods that were identical except for the addition of 20 mg/d pyridoxine (PN)
supplementation during the second period. On the seventh morning of each period, fasted
subjects exercised to exhaustion on a cycle ergometer at 74.5% ± 7.8 V0₂max. Blood
was drawn pre-exercise (twice), 60 minutes into exercise, immediately post-exercise and
60 minutes post-exercise. Plasma was analyzed for norepinephrine, epinephrine, glucose,
pyridoxal 5'-phosphate (PLP), lactic acid, glycerol and free fatty acids (FFA). Heart rate
and oxygen consumption were measured pre-exercise and at 10-minute intervals during
exercise. Mean plasma PLP concentration was significantly higher during the
supplemented versus the nonsupplemented trial at all time points. There were no
statistically significant differences in mean plasma catecholamine concentrations or mean
plasma fuel concentrations between the nonsupplemented and supplemented trials at any of
the time points examined. There were significant changes in the mean plasma
concentrations of norepinephrine, lactic acid, glycerol and FFA over time in both trials.
Respiratory exchange ratios (R) were higher during the supplemented trial compared to the
nonsupplemented trial, but the differences did not attain statistical significance. There
were no significant differences in mean exercise times to exhaustion or mean heart rates
between the trials. The overall mean oxygen consumption during exercise was
consistently higher during the supplemented versus the nonsupplemented trial and the
difference attained significance (p=0.016) at one time point (10 min.). The mean oxygen
consumption during rest was lower during supplementation versus nonsupplementation,
but the difference was not statistically significant. The percent plasma volume change
(PVC) was significantly greater at post-exercise, relative to pre-exercise, during the
supplemented versus the nonsupplemented trial. The percent PVC also increased
significantly over time during the supplemented but not the nonsupplemented trial. These
results suggest that 20 mg/d of vitamin B-6 supplementation does not effect plasma
catecholamine concentrations, fuel utilization or heart rate at rest or during submaximal
exercise to exhaustion. The results may suggest a higher oxygen consumption during
exhaustive exercise after PN supplementation. / Graduation date: 1996 Read more
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