The administration of an active vitamin D3 analogue reduced the serum concentrations of 1-84 and truncated parathyroid hormone in pseudohypoparathyroidism type Ib patients

Abstract

Proteolytic modifications of parathyroid hormone (PTH) is one of mechanisms for regulating the secretion of full-length (1-84)PTH from parathyroid glands. Therefore, not only (1-84)PTH but also other PTH fragments, such as carboxy-terminal (C-terminal) PTH fragments [1,2] and N-terminally truncated fragments such as (7-84)PTH can be measured by commercially available two-site total PTH (T-PTH) assays. The development of whole PTH (W-PTH) assays specific for full-length (1-84)PTH has enabled us to distinguish between N-terminally truncated PTH and full-length (1-84)PTH. W-PTH/T-PTH ratios were calculated and used as an index of PTH N-terminal truncations. Both serum W-PTH and T-PTH levels were elevated in untreated PHP Ib patients. The administration of alfacalcidol reduced both the W-PTH and T-PTH levels; however, the W-PTH/T-PTH ratios were stable. Serum calcium levels were significantly and negatively correlated with both the W-PTH and T-PTH levels, but not with the W-PTH/T-PTH ratios. Thus, the administration of an active vitamin D 3 analogue did not seem to have a major effect on the rate of PTH N-terminal truncation, even though it did reduce the secretion of both full-length and truncated PTH. Possibly, active vitamin D 3 attenuates the effect of elevated calcium on PTH N-terminal truncation in PHP Ib patients.

Fibroblast Growth Factor-23 and Vitamin D Metabolism in Subjects with eGFR ≥60 ml/min/1.73 m²

“…This assay has intra- and inter-assay CV of 3.4-5.4% and 4.3-7.1%, respectively [20,21]. Serum 1,25(OH) 2 D was measured with a 1,25(OH) 2 D RIA kit (Immunodiagnostic Systems Limited, Boldon, England), as described previously [28]. Serum 25-OH-D and 24,25(OH) 2 D levels were determined using a modified HPLC-tandem mass-mass spectrometry method with an atmospheric pressure chemical ionization (LC-APCI-MS/MS) (HPLC system; Shimadzu, Kyoto, Japan, and LC-APCI-MS/MS System; Applied Biosystems, Foster City, Calif., USA) [29,30].…”

Significance of urinary C-megalin excretion in vitamin D metabolism in pre-dialysis CKD patients

“…Serum calcium was corrected based on serum albumin, which was calculated as corrected calcium (cCa), as previously reported 26 . Serum wholePTH, which reacts with biologically active full-length PTH (1–84), was measured using a wholePTH assay (Scantibodies Laboratory, Inc. Santee, CA), which is a two-site immunoradiometric assay that exclusively measures PTH (1–84), with intra- and coefficients of variation (CVs) less than 2.3–6.1% and 2.9–8.9%, respectively 15,26,44,45 . Serum FGF23 was determined using a fully automated random access chemiluminescence immunoanalyzer device, the CL-JACK System [Kyowa Medex Co. Ltd., Tokyo, Japan; intra-assay CV 2.7–3.4%, inter-assay CV 1.9–6.3% (internal data)] 16,19 .…”

Development of a high-power solid-state switch using static induction thyristors for a klystron modulator

“…The characteristics that are measured from a test sample for pulsed-power applications are reported to be as follows: the hold-on voltage is 5.5 kV, and the turn-on time is 35 ns, with di/dt ¼95 kA/μs [16]. Because these values are sufficient for our purpose, we decided to develop a solid-state switch using SI thyristors.…”

“…Another candidate for a semiconductor device that is suitable for the solid-state switch is the Static Induction Thyristor (SI-thyristor) because it has fast switching characteristics as well as a high holding voltage and a high current [15,16]. Two types of solid-state switches with different types of SI thyristors were developed for the JLC project and were successfully tested at KEK; these meet the specifications that the hold-off voltage is 45 kV, the peak current is 6 kA, the pulse duration is 6 μs, and the repetition rate is 50 pps using forced oil cooling [17,18].…”