Four years after transurethral microwave thermotherapy 23% of the initially treated group were satisfied with the result. Two-thirds had received supplementary BPH treatment. Preoperatively less obstructed patients and those with low initial irritative scores responded more favorably to transurethral microwave thermotherapy treatment.
25-Hydroxylation of vitamin D2 and D3 was studied in subcellular fractions from human liver, using a technique based on isotope dilution-mass spectrometry. The mitochondrial fraction fortified with isocitrate catalysed 25-hydroxylation of vitamin D3 at a rate of about 10 pmol/mg protein X min. Under the same conditions, the rate of 25-hydroxylation of vitamin D2 was less than 2 pmol/mg protein X min. Crude microsomes fortified with NADPH catalysed 25-hydroxylation of vitamin D3 to a very low extent, and this activity was not linear with the amount of microsomal protein. A higher rate of conversion was obtained with a partially purified cytochrome P-450 fraction in the presence of NADPH-cytochrome P-450 reductase and NADPH. This fraction also catalysed 25-hydroxylation of 1 alpha-hydroxyvitamin D3 and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol. 25-Hydroxylation of vitamin D2 could not be detected, neither with crude microsomes, nor with the microsomal cytochrome P-450 fraction. Since the assay for 25-hydroxyvitamin D2 was less sensitive than that for 25-hydroxyvitamin D3, these experiments do not rule out the presence of some 25-hydroxylase activity towards vitamin D2 in the microsomes. The results are discussed in relation to previous work in which a lower toxicity has been reported for vitamin D2 than for vitamin D3 in some mammalian species.
The effects of high calcium intake on vitamin D metabolism were investigated. To the normal diet of 14 healthy men, 2 g calcium were added daily for 6-7 weeks. The mean serum concentration of 25-hydroxyvitamin D3 increased from 73 +/- 7 to 94 +/- 6 nmol l-1 (P less than 0.05, Student's unpaired t-test; P less than 0.01, paired t-test) in the subjects receiving calcium, whereas there was only a minimal increase, from 67 +/- 5 to 71 +/- 4 nmol l-1 in a control group on a normal diet. At the end of the study the difference between the test group and the controls was highly significant (P less than 0.005). The calcium loading caused a statistically significant depression of the serum levels of 1,25-dihydroxyvitamin D. The results obtained are in agreement with previous studies in rats and indicate that calcium intake is of some importance for the serum level of 25-hydroxyvitamin D3. The findings are discussed in relation to our previous finding that there is a relationship between high 25-hydroxyvitamin D3 levels and hypercalciuria in renal-stone formers.
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