Evocalcet with vitamin D receptor activator treatment for secondary hyperparathyroidism.

This ad hoc analysis of a previously conducted phase 3 head-to-head comparison study of evocalcet and cinacalcet in secondary hyperparathyroidism patients undergoing maintenance hemodialysis evaluated the efficacy and safety of combined once-daily oral evocalcet and intravenous vitamin D receptor activator treatment stratified by weekly vitamin D receptor activator dose (117, 45, and 91 patients in no, low [< 1.5 µg], and high [≥ 1.5 µg] dose groups, respectively). Effects of vitamin D receptor activator were assessed on the basis of intact parathyroid hormone, corrected calcium, phosphorus, and fibroblast growth factor-23 levels; percent changes from baseline; proportions of patients who achieved target intact parathyroid hormone, corrected calcium, and phosphorus at Weeks 28-30; and adverse drug reactions. Intact parathyroid hormone, corrected calcium, phosphorus, and fibroblast growth factor-23 levels decreased in all groups; phosphorus and fibroblast growth factor-23 levels remained high in the high dose group. In the low and high dose groups, greater proportions of patients achieved the corrected calcium target compared with the no dose group (p = 0.043). Ratios of intact-to-C-terminal fibroblast growth factor-23 decreased in all groups. In low and high dose groups, hypocalcemia was less common than in the no dose group (p = 0.014). Evocalcet with concomitant vitamin D receptor activator demonstrated benefits such that more patients achieved the corrected calcium target and exhibited decreased fibroblast growth factor-23 synthesis; the incidence of hypocalcemia also decreased. Clinical trial registration: ClinicalTrials.gov (NCT02549391) and JAPIC (JapicCTI-153013).

Therapeutic Effects of Add-On Tenapanor for Hemodialysis Patients with Refractory Hyperphosphatemia.

INTRODUCTION: Phosphate binders are used to treat hyperphosphatemia. Some patients have inappropriately controlled serum phosphorus levels, which may occur for many reasons, including a high pill burden and adverse events (AEs). Tenapanor selectively inhibits the passive paracellular transfer of phosphate in the gastrointestinal tract, thereby reducing serum phosphorus levels. This novel mechanism of action may contribute to improved phosphate management. The efficacy and safety of tenapanor have not been evaluated in Japanese patients with high serum phosphorus levels despite treatment with phosphate binders. This study aimed to assess the efficacy and safety of add-on tenapanor therapy for reducing serum phosphorus levels in this population. METHODS: This multicenter, double-blind, randomized, placebo-controlled trial enrolled patients with refractory hyperphosphatemia undergoing hemodialysis. Patients were randomly assigned in a 1:1 ratio to receive tenapanor or placebo as an add-on to their phosphate binder regimen for 6 weeks. Change in serum phosphorus levels at week 6 (day 43) compared with the baseline value (day 1, week 0) (primary endpoint), achievement of target serum phosphorus levels (serum phosphorus level ≤6.0 or ≤5.5 mg/dL), and safety, based on all AEs and drug-related AEs, were among the outcomes evaluated. RESULTS: In total, 24 patients were randomly assigned to the placebo group and 23 to the tenapanor group. The mean serum phosphorus level decreased from 7.01 mg/dL on day 1 to 6.69 mg/dL on day 43 in the placebo group and from 6.77 mg/dL on day 1 to 4.67 mg/dL on day 43 in the tenapanor group. In the placebo and tenapanor groups (modified intent-to-treat population), the mean (standard deviation) change in the serum phosphorus level at day 43 (last observation carried forward [LOCF]) was 0.08 (1.52) mg/dL and -1.99 (1.24) mg/dL, respectively, with a between-group difference of -2.07 (95% confidence interval: -2.89, -1.26; p < 0.001). The target achievement rate (serum phosphorus level ≤6.0 mg/dL at week 6 [LOCF]) was 37.5 and 87.0% in the placebo and tenapanor groups, respectively. Diarrhea was the most common drug-related AE, and it occurred in 8.3 and 65.2% of patients in the placebo and tenapanor groups, respectively. No specific AEs were observed with add-on tenapanor or with phosphate binders. DISCUSSION/CONCLUSION: Therapy with existing phosphate binders and add-on tenapanor resulted in a significant decrease in serum phosphorus level compared with the placebo group in patients with refractory hyperphosphatemia despite treatment with phosphate binders. No new safety signals were raised, and add-on tenapanor was generally well tolerated.

Efficacy and safety of once-monthly risedronate in osteoporosis subjects with mild-to-moderate chronic kidney disease: a post hoc subgroup analysis of a phase III trial in Japan.

Limited data are available on the safety and efficacy of anti-resorptive agents, particularly once-monthly bisphosphonates, for use in osteoporotic patients with chronic kidney disease (CKD). We conducted a post hoc analysis of data from a 12-month, randomized, double-blind, phase III study to evaluate the safety and efficacy of once-monthly risedronate (RIS-OM) 75 mg tablets in Japanese osteoporosis patients with mild-to-moderate CKD. Patients who received RIS-OM 75 mg were stratified by baseline estimated glomerular filtration rate (eGFR; ≥ 90, ≥ 60 to < 90, or ≥ 30 to < 60 mL/min/1.73 m2). Safety endpoints were incidence of adverse events (AEs) and percent change from baseline in eGFR, serum creatinine, calcium, and phosphorus. Efficacy endpoints were percent change from baseline in lumbar spine bone mineral density (BMD) and bone turnover markers (BTMs). In 420 patients included (age 67.7 ± 6.7 years, women 98.8%), the incidence of all AEs, gastrointestinal disorders, acute phase reaction, non-vertebral fractures, and renal and urinary disorders was not significantly different among subgroups. Interaction between subgroups and time was significant for eGFR (p = 0.010) and serum creatinine (p = 0.001) but considered to be regression to the mean and clinically insignificant. BMD significantly increased while BTMs significantly decreased from baseline with a similar degree of change among the subgroups. In conclusion, RIS-OM 75 mg showed consistent safety and efficacy in suppressing bone turnover and increasing BMD in Japanese primary osteoporosis patients with mild-to-moderate CKD. These results should, however, be interpreted with caution because the number of patients with moderate CKD was limited.

Association of Circulatory Iron Deficiency With an Enlarged Heart in Patients With End-Stage Kidney Disease.

OBJECTIVES: High prevalence of iron deficiency (ID) and cardiomyopathy have been observed in patients with end-stage kidney disease (ESKD). Our objective was to clarify associations between ID and cardiac remodeling in patients with ESKD. DESIGN AND METHODS: A cross-sectional study was conducted using 1974 Japanese patients with ESKD at the initiation of maintenance dialysis. Levels of hemoglobin (Hb), iron status, and cardiac enlargement as assessed by the cardiothoracic ratio (CTR) were determined immediately before the first hemodialysis session. Circulatory ID was defined as transferrin saturation (TSAT) < 20%, and stored ID was defined as ferritin level <100 ng/dL. RESULTS: The mean age was 67 years. Median CTR was 54.0%. The prevalence of circulatory and stored ID was found to be 38% and 34%, respectively. CTR was higher in patients with circulatory ID than in those without. Even in ESKD patients without overhydration, significant negative association was observed between TSAT and CTR. Higher odds ratios in parallel with higher CTR categories compared with the reference category of CTR <45% were found in patients with TSAT <20% on multinomial analysis, but ferritin did not show any significant associations. The odds ratio for CTR >54% showed an upward trend in patients with TSAT <20% (odds ratio: 1.3) and <10% (odds ratio: 1.6) compared with the reference, even after adjusting for confounding variables such as Hb and ferritin. However, that phenomenon was eliminated by adding usage of an iron agent. CONCLUSIONS: Circulatory ID is closely associated with an enlarged heart independent of ferritin and Hb. Iron supplementation in the predialysis phase of chronic kidney disease may prevent cardiac remodeling independent of Hb level in patients chronic kidney disease.

Pharmacodynamics of evocalcet for secondary hyperparathyroidism in Japanese hemodialysis patients.

BACKGROUND: This study investigated the pharmacokinetics, pharmacodynamics, and safety of multiple doses of evocalcet in Japanese secondary hyperparathyroidism (SHPT) patients receiving hemodialysis. METHODS: In this multicenter, open-label study, conducted between August 2013 and March 2014, 27 patients received multiple doses of 1 and 4 mg evocalcet for 14 days, followed by an extension period of multiple doses of 8 and 12 mg evocalcet for 7 days using an intra-patient dose escalation protocol. Pharmacodynamic parameters consisted of measurement of intact parathyroid hormone (PTH), serum-corrected calcium, serum phosphorus and intact fibroblast growth factor 23 concentrations. Safety was assessed by analysis of adverse events. RESULTS: Plasma evocalcet levels reached steady state 3 days after the first day of administration. Pharmacodynamic analyses showed that evocalcet effectively reduced intact PTH and serum-corrected calcium levels. Adverse events (AEs) occurred in 29.6 and 62.5% of patients receiving multiple doses of 1 or 4 mg, respectively. The AE 'blood calcium decreased' occurred in eight patients (33.0%) after multiple doses of 4 mg. All events were mild, except for one patient with a moderate AE (abnormal liver function) and one patient with a severe adverse drug reaction (blood calcium decreased). CONCLUSION: Multiple doses of evocalcet reduced intact PTH levels with a concomitant decrease in serum calcium levels. Evocalcet was well tolerated in SHPT patients receiving hemodialysis.

Magnesium prevents phosphate-induced vascular calcification via TRPM7 and Pit-1 in an aortic tissue culture model.

Previous clinical and experimental studies have indicated that magnesium may prevent vascular calcification (VC), but mechanistic characterization has not been reported. This study investigated the influence of increasing magnesium concentrations on VC in a rat aortic tissue culture model. Aortic segments from male Sprague-Dawley rats were incubated in serum-supplemented high-phosphate medium for 10 days. The magnesium concentration in this medium was increased to demonstrate its role in preventing VC, which was assessed by imaging and spectroscopy. The mineral composition of the calcification was analyzed using Fourier transform infrared (FTIR) spectroscopic imaging, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) mapping. Magnesium supplementation of high-phosphate medium dose-dependently suppressed VC (quantified as aortic calcium content), and almost ablated it at 2.4 mm magnesium. The FTIR images and SEM-EDX maps indicated that the distribution of phosphate (as hydroxyapatite), phosphorus and Mg corresponded with calcium content in the aortic ring and VC. The inhibitory effect of magnesium supplementation on VC was partially reduced by 2-aminoethoxy-diphenylborate, an inhibitor of TRPM7. Furthermore, phosphate transporter-1 (Pit-1) protein expression was increased in tissues cultured in HP medium and was gradually-and dose dependently-decreased by magnesium. We conclude that a mechanism involving TRPM7 and Pit-1 underpins the magnesium-mediated reversal of high-phosphate-associated VC.

A phase 3, multicentre, randomized, double-blind, placebo-controlled, parallel-group study to evaluate the efficacy and safety of etelcalcetide (ONO-5163/AMG 416), a novel intravenous calcimimetic, for secondary hyperparathyroidism in Japanese haemodialysis patients.

BACKGROUND: Secondary hyperparathyroidism (SHPT) is a major complication associated with chronic kidney disease. We evaluated the efficacy and safety of etelcalcetide (ONO-5163/AMG 416), a novel intravenous calcimimetic, in Japanese haemodialysis patients with SHPT. METHODS: In this phase 3, multicentre, randomized, double-blind, placebo-controlled, parallel-group study, etelcalcetide was administered three times per week at an initial dose of 5 mg, and subsequently adjusted to doses between 2.5 and 15 mg at 4-week intervals for 12 weeks. A total of 155 SHPT patients with serum intact parathyroid hormone (iPTH) levels ≥300 pg/mL were assigned to receive etelcalcetide (n = 78) or placebo (n = 77). The primary endpoint was the proportion of patients with decreased serum iPTH to the target range proposed by the Japanese Society for Dialysis Therapy (60-240 pg/mL). The major secondary endpoint was the proportion of patients with ≥30% reductions in serum iPTH from baseline. RESULTS: The proportion of patients meeting the primary endpoint was significantly higher for etelcalcetide (59.0%) versus placebo (1.3%). Similarly, the proportion of patients meeting the major secondary endpoint was significantly higher for etelcalcetide (76.9%) versus placebo (5.2%). Serum albumin-corrected calcium, phosphorus and intact fibroblast growth factor-23 levels were decreased in the etelcalcetide group. Nausea, vomiting and symptomatic hypocalcaemia were mild with etelcalcetide. Serious adverse events related to etelcalcetide were not observed. CONCLUSIONS: This study demonstrated the efficacy and safety of etelcalcetide. As the only available intravenous calcium-sensing receptor agonist, etelcalcetide is likely to provide a new treatment option for SHPT in haemodialysis patients.

Calcium Overload Accelerates Phosphate-Induced Vascular Calcification Via Pit-1, but not the Calcium-Sensing Receptor.

AIM: Vascular calcification (VC) is a risk factor of cardiovascular and all-cause mortality in patients with chronic kidney disease (CKD). CKD-mineral and bone metabolism disorder is an important problem in patients with renal failure. Abnormal levels of serum phosphate and calcium affect CKD-mineral and bone metabolism disorder and contribute to bone disease, VC, and cardiovascular disease. Hypercalcemia is a contributing factor in progression of VC in patients with CKD. However, the mechanisms of how calcium promotes intracellular calcification are still unclear. This study aimed to examine the mechanisms underlying calcium-induced calcification in a rat aortic tissue culture model. METHODS: Aortic segments from 7-week-old male Sprague-Dawley rats were cultured in serum-supplemented medium for 10 days. We added high calcium (HiCa; calcium 3.0 mM) to high phosphate (HPi; phosphate 3.8 mM) medium to accelerate phosphate and calcium-induced VC. We used phosphonoformic acid and the calcimimetic R-568 to determine whether the mechanism of calcification involves Pit-1 or the calcium-sensing receptor. RESULTS: Medial VC was significantly augmented by HPi+HiCa medium compared with HPi alone (300%, p＜0.05), and was associated with upregulation of Pit-1 protein. Pit-1 protein concentrations in HPi+HiCa medium were greater than those in HPi medium. Phosphonoformic acid completely negated the augmentation of medial VC induced by HPi+HiCa. R-568 had no additive direct effect on medial VC. CONCLUSION: These results indicated that exposure to HPi+HiCa accelerates medial VC, and this is mediated through Pit-1, not the calcium-sensing receptor.

Mineral Composition of Phosphate-Induced Calcification in a Rat Aortic Tissue Culture Model.

AIM: High phosphorus conditions promote vascular calcification (VC) in both chronic kidney disease (CKD) patients and experimental models. However, the composition of medial calcification has not been accurately determined, so the objective of this study was to evaluate the mineral composition of calcification in a tissue culture model, not a cell culture system. METHODS: Aortic rings obtained from male Sprague-Dawley rats were incubated in serum-supplemented medium for 10 days. The inorganic phosphate (Pi) concentration of the medium was increased to induce VC, which was assessed by histology, imaging, and spectroscopy. The mineral composition of the calcification was analyzed using Fourier transform infrared (FTIR) spectroscopic imaging, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) mapping. RESULTS: The calcium content significantly increased only in aortic rings cultured for 10 days in the high-Pi medium (HiP: 3.8 mmol/L). The concentration of the phosphate transporter Pit-1 in the aortic tissue exposed to HiP was higher than that in the control incubated sections. The FTIR images and spectra indicated that PO4(3-) was mostly distributed as hydroxyapatite in the medial calcification of aortic rings cultured in HiP. A small quantity of carbonate was identified. The SEM-EDX overlay map demonstrated that phosphorus and calcium simultaneously accumulated and localized in the area of medial calcification induced by exposure to HiP. CONCLUSION: This is the first report of accurate determination of the chemical composition of aortic medial calcification. Exposure to high Pi concentration augments aortic calcification via an increase in Pit-1, which mainly contains calcium phosphate.

Transcranial direct current stimulation improves swallowing function in stroke patients.

BACKGROUND: Poststroke dysphagia can persist, leading to many complications. OBJECTIVE: We investigated whether noninvasive brain stimulation to the pharyngeal motor cortex combined with intensive swallowing therapy can improve dysphagia. METHODS: A total of 20 patients who had dysphagia for at least 1 month after stroke were randomly assigned to receive 10 sessions lasting 20 minutes each of either 1-mA anodal transcranial direct current stimulation (tDCS) or a sham procedure to the ipsilesional pharyngeal motor cortex, along with simultaneous conventional swallowing therapies. We evaluated swallowing function with the dysphagia outcome and severity scale (DOSS) before, immediately after, and 1 month after the last session. RESULTS: Anodal tDCS resulted in an improvement of 1.4 points in DOSS (P = .006) immediately after the last session and 2.8 points (P = .004) 1 month after the last session. The sham tDCS group improved 0.5 points (P = .059) after the last session and 1.2 points (P = .026) 1 month after the final session. The improvements in the anodal tDCS group were significantly greater than those in the sham tDCS group (P = .029 after the last session, and P = .007 1 month after the last session). CONCLUSIONS: Anodal tDCS to the ipsilesional hemisphere and simultaneous peripheral sensorimotor activities significantly improved swallowing function as assessed by the DOSS.

Effect of lanthanum carbonate treatment on bone in Japanese dialysis patients with hyperphosphatemia.

Lanthanum carbonate (LC), a newly developed non-calcium-containing phosphate binder, has been shown to possess high phosphate-binding capacity and safety when used for hyperphosphatemia in patients with chronic kidney disease undergoing dialysis. The effects of LC on bone metabolism in Japanese dialysis patients have not been investigated; therefore, we performed histomorphometric analysis on bone from dialysis patients with hyperphosphatemia. This was a prospective, open-label study in Japanese chronic kidney disease patients on dialysis, with a flexible daily dosage of 750-4500 mg to achieve target phosphorus levels of 3.5-5.5 mg/dL (1.10-1.78 mmol/L). Bone biopsy samples for histomorphometric analysis were obtained at baseline and after treatment with LC. The median bone lanthanum level increased during the LC treatment from 54.1 µg/kg at baseline to 4270.9 µg/kg at three years. After one year of treatment with LC, two cases with an initial classification of osteitis fibrosa improved toward normal bone turnover. The diagnosis of normal remained the same for up to three years. We also noted that two cases with a baseline classification of adynamic bone disease improved after one year, and was maintained for three years. Our data suggest that LC is effective not only for treating hyperphosphatemia, but also for improving renal osteodystrophy in Japanese dialysis patients.

Mechanism of phosphate-induced calcification in rat aortic tissue culture: possible involvement of Pit-1 and apoptosis.

BACKGROUND: Hyperphosphataemia is a known contributing factor in the progression of vascular calcification in dialysis patients. The cellular mechanisms underlying phosphate-induced calcification are still unclear despite intense study, so in this study, we investigated the possible involvement of the type III sodium-dependent phosphate cotransporter, Pit-1, in an aortic tissue culture model. METHODS: Aortic segments from 9-week-old male Sprague-Dawley rats were incubated in serum-supplemented medium for 10 days. The phosphate concentration of the medium was elevated to induce calcification, which was assessed by histology and calcium content. Phosphonoformic acid (PFA) was used to inhibit phosphate uptake. The involvement of apoptosis was examined using the terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate (dUTP) nick-end labelling (TUNEL) assay, caspase 3 activation, and inhibition of apoptosis using a general caspase inhibitor. Phenotypic changes in vascular smooth muscle cells (VSMC) were assessed using expression of osteochondrogenic differentiation markers. RESULTS: Medial vascular calcification was induced in aortas cultured in a high phosphate medium. PFA decreased the rates of calcification and apoptosis of VSMC in the media, concomitant with calcification. Caspase inhibitor reduced calcification. No phenotypic transition of VSMC was seen in this model. CONCLUSIONS: These results indicate that phosphate uptake through the type III sodium-dependent phosphate cotransporter, Pit-1, leads to induction of apoptosis and subsequent calcification of VSMC.

Regulation of fibroblast growth factor 23 production in bone in uremic rats.

BACKGROUND: Fibroblast growth factor 23 (FGF23) regulates renal phosphate reabsorption and 1alpha,25-dihydroxyvitamin D [1,25(OH)(2)D(3)] metabolism. Patients with chronic kidney disease (CKD) have increased levels of circulating FGF23, but the direct regulation of this elevation of FGF23 is incompletely understood. METHOD: We measured plasma parameters in uremic rats fed a high-phosphorus diet and then performed parathyroidectomy (PTX) to determine its effect. We also investigated FGF23 mRNA expression in various tissues to identify the major source of circulating FGF23. RESULT: The uremic rats displayed dramatic changes in plasma FGF23 levels, consistent with increased expression of FGF23 in bone. Elevated FGF23 was associated with phosphate and parathyroid hormone (PTH). After PTX, the elevated FGF23 had decreased, consistent with decreased expression of FGF23 in bone. Significant decreases in plasma FGF23 were associated with PTH and 1,25(OH)(2)D(3), but not phosphate. CONCLUSION: Elevated plasma FGF23 levels in uremic rats reflect the increased expression of FGF23 in bone. The expression of FGF23 in bone may be regulated by a PTH-1,25(OH)(2)D(3) axis-dependent pathway and another PTH-dependent and 1,25(OH)(2)D(3)-independent pathway in uremic rats. The pathway may be decided by the degree of renal dysfunction.

Comparison of sevelamer hydrochloride with colestimide, administered alone or in combination with calcium carbonate, in patients on hemodialysis.

Since hyperphosphatemia in hemodialysis patients can cause secondary hyperparathyroidism and promotes vascular calcification, serum phosphate (Pi) levels must be controlled by phosphate binders. Although sevelamer and colestimide are known as similar non-calcium, non-aluminum phosphate binders in hemodialysis patients, there are no studies that compare the effects of the two agents as either a monotherapy or in combination with calcium carbonate (CaCO3). We randomly allocated 62 hemodialysis patients with hyperphosphatemia to treatment with sevelamer (3.0 g/day) and colestimide (3.0 g/day). During the study, 35 subjects dropped out, leaving 13 in the sevelamer group and 14 in the colestimide group. After a 2-week CaCO3 washout, all subjects received the monotherapy for 4 weeks and then CaCO3 (3.0 g/day) was added for another 4 weeks. Serum corrected calcium levels tended to decrease in both groups during the washout period and monotherapy, but there was no significant difference between the two groups after the addition of CaCO3. Although the calcium x phosphorus product (Ca x P) in the two groups increased during the washout period, there was no significant change or difference between the two groups during monotherapy. However, the addition of CaCO3 significantly reduced serum Pi at Week 8 compared to that at Week 0 in both groups, and significantly lowered Ca x P only in the sevelamer group, but not in the colestimide group(.) In this short-term study, sevelamer and colestimide similarly ameliorated hyperphosphatemia, but the combination of sevelamer and CaCO3 was more effective than colestimide with CaCO3 in controlling the Ca x P product, and it may improve cardiovascular mortality in hemodialysis patients.

[Basic and clinical aspects of calcimimetics. The clinical effect and usefulness of Cinacalcet as a calcimimetics on three CKD-5D patients undergoing hemodialysis with refractory secondary hyperparathyroidism].

In this part, we reports the experience of treatment by calcimimetics for 3 hemodialyzed patients with refractory secondary hyperparathyroidism. They purchased own expense, and used "Cinacalcet" as calcimimetics (Sensipar(R) 30 mg/tablet, by AMGEN co. Ltd. in USA) . Serum Ca, P, and intact-PTH decreased certainly in 3 cases after cinacalcet therapy. Especially the reduction of intact-PTH is obviously. The any adverse effect did not observed by 30 mg/tablet/day prescription except mild epigastralgia in a case. We were able to experience the marked suppressive effect on parathyroid gland by cinacalcet as calcimimetics in Japanese patients with refractory secondary hyperparathyroidism undergoing hemodialysis.

Highly concentrated calcitriol and its analogues induce apoptosis of parathyroid cells and regression of the hyperplastic gland--study in rats.

BACKGROUND: Controlling hyperplasia of the parathyroid gland (PTG) is important in the management of secondary hyperparathyroidism (SHPT). Regression of the hyperplastic PTG requires a decrease in the number of parathyroid cells (PTCs), so the present study investigated cell death caused by toxic agents or by clinically usable vitamin D metabolites. METHODS: The PTGs of Sprague-Dawley rats, which had been 5/6-nephrectomized and fed a high-phosphate diet for 12 weeks, were treated with two consecutive direct injections (DI) of calcitriol, maxacalcitol, paricalcitol, doxercalciferol or phosphate-buffered saline containing either 0.01% or 90% ethanol (0.01-ET or 90-ET, respectively). Laboratory data, including serum levels of intact parathyroid hormone (intact-PTH), were obtained before and after the treatments. The PTGs were excised 24 h after the final injection and evaluated for PTC apoptosis using light and electron microscopy, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) method and DNA electrophoresis. RESULTS: Treatment with any of the vitamin D metabolites and 90-ET significantly decreased the serum intact-PTH level, but only the latter significantly decreased the serum Ca level. Either treatment markedly increased the number of TUNEL-positive PTCs, but not in PTG treated with 0.01-ET. In PTGs treated with DI of any vitamin D metabolites was there ladder formation on DNA electrophoresis, as well as the characteristic morphological features of apoptosis in both the light and electron microscopic studies. CONCLUSIONS: DI of vitamin D metabolites may be effective in controlling not only the PTH level, but also PTG hyperplasia, in advanced SHPT by, at least in part, apoptosis-induced cell death. Our study was performed in rats.

[Arteriosclerosis and vascular calcification in chronic kidney disease (CKD) patients].

Chronic kidney disease (CKD) patients are belonging to high risk patients to atherosclerosis with vascular calcification. These patients are well recognized advanced arteriosclerosis with vascular medial calcification, with high risk of cardiovascular death. With basic investigated results, the mechanism of vascular calcification is making clear. A lot of various factors which participate in calcification have been specified. Especially, in long term dialysis patients, the very high grade vascular calcification with advanced atherosclerosis is common with calcium/phosphate/PTH and skeletal problem. This CKD related metabolic bone disorder (CKD-MBD) highly induced and progressed vascular calcification. Participates in vascular calcification. It is extremely important in order to prevent vascular calcification to manage serum phosphorus, serum calcium and parathyroid function within the suitable range. In addition, hyperphosphatemia is becoming the powerful risk factor for patients' survival. The new powerful phosphate binder is developing. The beneficial effect of the new agent on patients' survival is now focused.

Binding of highly concentrated maxacalcitol to the nuclear vitamin D receptors of parathyroid cells.

BACKGROUND: Injection of maxacalcitol (OCT) directly into the parathyroid gland (PTG) is a clinically safe and effective treatment for advanced secondary hyperparathyroidism (A-SHPT) resistant to conventional medical treatment. In the present study, the degree of nuclear localization of directly injected OCT in parathyroid cells (PTC) was investigated by microautoradiography (mARG) in a model of A-SHPT. METHODS: The 5/6 nephrectomized Sprague-Dawley rats were fed a high-phosphate and low-calcium diet for 8 weeks and consequently the level of vitamin D receptor (VDR) in their PTC severely decreased. The bilateral PTG were surgically exposed and only the left gland were directly injected with 3H-OCT (DI-3H-OCT). The time course of the changes in both radioactivity and localization of 3H-OCT in the bilateral glands was analysed using a bioimaging analyser system and mARG, respectively. A very high dose of unlabelled calcitriol was administered intravenously (IV-1,25D3) prior to DI-3H-OCT, as a competitive study. RESULTS: Peak radioactivity levels in the directly injected and intact PTG occured immediately and 1 h, respectively, after DI-3H-OCT, and the difference was about 50-fold higher in the treated gland. The of mARG showed a marked concentration of silver grains in the nuclei of PTC in the gland treated with DI-3H-OCT and that concentration was significantly suppressed by IV-1,25D3. CONCLUSIONS: Direct injection of OCT into the PTG enables the administration of the highly concentrated drug for specific binding to nuclear vitamin D binding sites, including VDR of PTC, which markedly suppresses the parathyroid hormone, improves the response to calcium and vitamin D and induces apoptosis in PTC.