PubMed Health⌕ Search

Biomedical subjects

F Schreiner

Publications and source records attributed to F Schreiner.

4 recordsLinked to original sources
PubMed1986

Absence of renal 25-hydroxycholecalciferol-1-hydroxylase activity in a pig strain with vitamin D-dependent rickets.

Cholecalciferol-1-hydroxylase activities were estimated in renal cortex homogenates and mitochondrial preparations from three groups of 6- to 12-week-old pigs. Five animals suffering from an inherited form of vitamin D-deficiency rickets showed symptoms of florid rickets when used for this study. Six pigs were normocalcemic heterozygous litter mates of the rachitic strain and three pigs were normal controls (German land-race and wild pigs). The renal cortex homogenates and mitochondrial preparations were incubated for 5-30 min at 37 degrees C with 25-(26-27-methyl-3H) OHD3 as substrate. 1,25(OH)2D3 was subsequently identified in normal phase (Zorbax-Sil) and reversed phase (Zorbax-ODS) HPLC eluates. 1-hydroxylase activities were demonstrated in both normal controls and heterozygote offspring and were ten times above minimum detectability of the assay. The km was 255 +/- 74 (SD) and 278 +/- 85 nmol X 1(-1) in controls and heterozygote offspring, respectively. The Vmax in the two groups was between 0.11 and 0.794 and decreased with age of the animals. Km and Vmax did not differ between the two groups. In homozygous, hypocalcemic rachitic animals no 1-hydroxylase activity was detectable in either homogenates or mitochondrial preparations. Addition of kidney homogenate from a rachitic animal to a homogenate from a normal pig did not specifically depress 1-hydroxylase activity in the mixture. Treatment of rachitic pigs with 1.0 microgram/day of 1,25(OH)2D3 for 4 weeks also had no effect on 1-hydroxylase activity. It is concluded that the rachitic pigs suffer from an inborn error of renal 1,25(OH)2D3 production.(ABSTRACT TRUNCATED AT 250 WORDS)

24,25-Dihydroxyvitamin D 3↗
PubMedDate not supplied

Predictive value of thyroglobulin changes for the efficacy of thyroid remnant ablation.

The aim of this case-control study was to determine the utility of the evaluation of changes in serum thyroglobulin (Tg) levels before and after 1311 diagnostic total body scan (TBS) in patients with thyroid cancer to predict the efficacy of radioiodine ablation. Among 134 consecutive patients with differentiated thyroid carcinoma (DTC) who had undergone a thyroidectomy and TBS prior to radioiodine ablation, we selected those subjects with no evidence of distant metastases and with two consecutive assessments of Tg before TBS and radioiodine ablation within a period of four weeks. With this selection procedure 27 patients (22 with papillary and five with follicular carcinomas) were included in our evaluation. The ablation therapy was considered successful when the TBS performed one year after treatment did not show any or less than 1% cervical 131I uptake, Tg levels remained below 3 ng/mL, and clinical and instrumental examinations were negative for the presence of relapses. These criteria divided the selected patients into two subsets: patients with successful radioiodine ablation and patients with residual thyroid tissue. The majority of patients with unsuccessful ablation showed an increase in serum Tg levels, while most of the patients with successful ablation showed a steady decrease in Tg concentrations. Statistical analysis evidenced that the increase in Tg levels after TBS was related to unsuccessful ablation (P > or = 0.01). By contrast, the rate of thyroid remnants with 131I uptake did not show any relationship with the outcome of ablation therapy. The group of patients with increasing Tg levels after TBS had a relative risk of 3.3 of unsuccessful ablative therapy compared to the group with stable or decreasing Tg levels. This study supports the concept that by monitoring Tg levels in patients who undergo diagnostic TBS before radioiodine ablation it is possible to obtain useful information about the efficacy of 131I therapy.

Adult↗