Renal protective effects of astragalus root in rat models of chronic kidney disease.

BACKGROUND: Astragalus root is a commonly used herb in traditional Chinese medicine. Although renoprotective effects have been reported in some clinical and experimental studies, the details remain unknown. METHODS: We used 5/6 nephrectomized rats as chronic kidney disease (CKD) models. At 10 weeks, they were divided into four groups, namely, CKD, low-dose astragalus (AR400), high-dose astragalus (AR800), and sham groups. At 14 weeks, they were sacrificed for the evaluation of blood, urine, mRNA expression in the kidney, and renal histopathology. RESULTS: Kidney dysfunction was significantly improved following astragalus administration (creatinine clearance: sham group; 3.8 ± 0.3 mL/min, CKD group; 1.5 ± 0.1 mL/min, AR400 group; 2.5 ± 0.3 mL/min, AR800 group; 2.7 ± 0.1 mL/min). Blood pressure, urinary albumin, and urinary NGAL levels were significantly lower in the astragalus-treated groups than those in the CKD group. Excretion of urinary 8-OHdG, an oxidative stress marker, and intrarenal oxidative stress were lower in the astragalus-treated groups than those in the CKD group. Furthermore, the mRNA expression of NADPH p22 phox, NADPH p47 phox, Nox4, renin, angiotensin II type 1 receptor, and angiotensinogen in the kidney was lower in the astragalus-treated groups compared with the CKD group. CONCLUSION: This study suggests that astragalus root slowed CKD progression, possibly through the suppression of oxidative stress and the renin-angiotensin system.

Comparison of the effects of lanthanum carbonate and calcium carbonate on the progression of cardiac valvular calcification after initiation of hemodialysis.

BACKGROUND: Although mineral metabolism disorder influences cardiac valvular calcification (CVC), few previous studies have examined the effects of non-calcium-containing and calcium-containing phosphate binders on CVC in maintenance hemodialysis patients. The aim of the present study was to compare the effects of lanthanum carbonate (LC) with calcium carbonate (CC) on the progression of CVC in patients who initiated maintenance hemodialysis and to investigate clinical factors related to CVC. METHODS: The current study included 50 subjects (mean age 65 years, 72% males) from our previous randomized controlled trial (LC group, N = 24; CC group, N = 26). CVC was evaluated as CVC score (CVCS) using echocardiography at baseline and 18 months after initiation of hemodialysis. We compared CVCS and the changes between the two groups. We also analyzed the associations between CVCS and any other clinical factors including arterial plaque score (PS) and serum phosphorus levels. RESULTS: Baseline characteristics of study participants including CVCS were almost comparable between the two groups. At 18 months, there were no significant differences in mineral metabolic markers or CVCS between the two groups, and CVCS were significantly correlated with PS (r = 0.39, p < 0.01). Furthermore, changes in CVCS were significantly correlated with average phosphorus levels (r = 0.36, p < 0.05), which were significantly higher in high serum phosphorus and high PS group compared to low serum phosphorus and low PS group (p < 0.05). CONCLUSIONS: In the present study, there were no significant differences between LC and CC with regard to progression of CVC. However, serum phosphorus levels and arterial plaque seem to be important for the progression and formation of CVC in hemodialysis patients.

Pregnant Patient on Hemodialysis Who Showed Remarkable Improvement of Severe Hyperparathyroidism by Strict Serum Phosphorus Control.

We encountered a pregnant hemodialysis patient with severe hyperparathyroidism (HPT). Although her disease was considered to be refractory to medical treatment, the serum intact parathyroid hormone (PTH) level remarkably improved without manifestation of hypercalcemia through only strict serum phosphorus control, mainly via intensification of dialysis. The very strong correlation between the serum phosphorus level and serum intact PTH level suggested the possibility of secondary HPT. She ultimately gave birth to a healthy baby. The clinical course of the patient's HPT and the growth of the child have been good for more than six years.

Newly Developed Rat Model of Chronic Kidney Disease-Mineral Bone Disorder.

AIM: Chronic kidney disease-mineral bone disorder (CKD-MBD) is associated with all-cause and cardiovascular morbidity and mortality in patients with CKD. Thus, elucidating its pathophysiological mechanisms is essential for improving the prognosis. We evaluated characteristics of CKD-MBD in a newly developed CKD rat model. METHODS: We used male Sprague-Dawley (SD) rats and spontaneously diabetic Torii (SDT) rats, which are used as models for nonobese type 2 diabetes. CKD was induced by 5/6 nephrectomy (Nx). At 10 weeks, the rats were classified into six groups and administered with a vehicle or a low- or high-dose paricalcitol thrice a week. At 20 weeks, the rats were sacrificed; blood and urinary biochemical analyses and histological analysis of the aorta were performed. RESULTS: At 20 weeks, hemoglobin A1c (HbA1c) levels, blood pressure, and renal function were not significantly different among the six groups. Serum calcium and phosphate levels tended to be higher in SDT-Nx rats than in SD-Nx rats. The urinary excretion of calcium and phosphate was significantly greater in SDT-Nx rats than in SD-Nx rats. After administering paricalcitol, serum parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) levels were significantly higher in SDT-Nx rats than in SD-Nx rats. The degree of aortic calcification was significantly more severe and the aortic calcium content was significantly greater in SDT-Nx rats than in SD-Nx rats. CONCLUSIONS: We suggest that our new CKD rat model using SDT rats represents a useful CKD-MBD model, and this model was greatly influenced by paricalcitol administration. Further studies are needed to clarify the detailed mechanisms underlying this model.

Comparison of the effects of novel vitamin D receptor analog VS-105 and paricalcitol on chronic kidney disease-mineral bone disorder in an experimental model of chronic kidney disease.

When using vitamin D, the most important clinical problems are hypercalcemia, hyperphosphatemia, and vascular calcification. VS-105 is a novel vitamin D receptor (VDR) analog. In the present study, we compared the effects of VS-105 and paricalcitol on chronic kidney disease-mineral bone disorder (CKD-MBD) in a CKD rat model. We used male Sprague-Dawley (SD) rats and performed 5/6 nephrectomy at 8-9 weeks. At 10 weeks, the rats were classified into five groups and administered vehicle, low-dose paricalcitol (LP, 0.1µg/kg), high-dose paricalcitol (HP, 0.3µg/kg), low-dose VS-105 (LV, 0.2µg/kg), and high-dose VS-105 (HV, 0.6 µg/kg) three times a week for 10 weeks. There were no significant differences in blood pressure or renal function among the five groups. Alhough serum calcium levels were comparable between the LP and LV groups, they were higher in the HP group than in the HV group. Serum phosphate levels were higher in the paricalcitol-treated groups than in the VS-105-treated groups and paticularly higher in the HP group than in the other groups. The urinary excretion of phosphate was greater in the VS-105-treated groups than in the paricalcitol-treated groups. Serum parathyroid hormone (PTH) levels decreased and serum fibroblast growth factor-23 (FGF23) levels were elevated after administering paricalcitol and VS-105; however, serum FGF23 levels were remarkably elevated in the paricalcitol-treated groups. Further biochemical analyses revealed that the calcium content of the aorta was higher in the paricalcitol-treated groups than in the VS-105-treated group. VDR and Klotho expression in the kidney was significantly higher in the VS-105-treated groups than in the paricalcitol-treated groups although both agents increased these expressions. Our data suggest that VS-105 had a lesser effect on CKD-MBD than paricalcitol except in the case of serum PTH levels. The mechanism appears to be associated with the difference in VDR and Klotho expression.

Serum FGF23 levels may not be associated with serum phosphate and 1,25-dihydroxyvitamin D levels in patients with Fanconi syndrome-induced hypophosphatemia.

Fibroblast growth factor 23 (FGF23) is regulated by sustained phosphate supplementation and restriction. However, few studies have investigated FGF23 levels in patients with Fanconi syndrome. Therefore, we evaluated intact and C-terminal FGF23 and FGF23-associated parameters in four patients with Fanconi syndrome. Serum intact and C-terminal FGF23 levels were extremely low. Although serum phosphate and 1,25-dihydroxyvitamin D levels improved to or above the normal range within 1 year of treatment with oral phosphate and calcitriol, serum FGF23 levels remained low. Serum FGF23 levels in patients with Fanconi syndrome might be regulated by novel factors other than serum phosphate and 1,25-dihydroxyvitamin D levels.

Dietary phosphorus restriction by a standard low-protein diet decreased serum fibroblast growth factor 23 levels in patients with early and advanced stage chronic kidney disease.

BACKGROUND: Elevated serum fibroblast growth factor 23 (FGF23) levels are associated with mortality, cardiovascular disease, and disease progression in patients with chronic kidney disease (CKD). Although recent studies demonstrated that FGF23 levels decreased in response to dietary restriction of phosphorus and/or use of phosphate binders, research on the effects of a standard low-protein diet is lacking. METHODS: The effects of a standard low-protein diet on serum FGF23, intact parathyroid hormone, and 1,25-dihydroxyvitamin D levels were investigated in patients with early (n = 15) and advanced (n = 20) CKD. RESULTS: Serum FGF23 levels decreased in both groups. Changes in FGF23 levels correlated with changes in 24 h urinary phosphorus excretion in the advanced CKD group. Decreased serum intact parathyroid hormone levels were observed only in the advanced CKD group and increased serum 1,25-dihydroxyvitamin D levels only in the early CKD group. CONCLUSIONS: These findings suggest that consuming standard low-protein diet decreased serum FGF23 levels in patients with CKD. Serum FGF23 levels may therefore be a useful marker to monitor the effects of a low-protein diet in early and advanced stage CKD.

Parathyroid enlargement at dialysis initiation in patients with chronic kidney diseases.

The kidney chiefly maintains homeostasis of water, electrolytes, and other solutions. When kidney function is reduced, mineral metabolism is disrupted. Mineral and bone disorder in patients with chronic kidney disease associates with increased cardiovascular risk and mortality; however, management of chronic kidney disease-mineral and bone disorder in predialysis patients remains controversial. This study investigates the association between parathyroid enlargement at dialysis initiation and hyperparathyroidism management in dialysis patients. We enrolled 72 patients at dialysis initiation in this study. Using parathyroid sonography, we categorized patients based on presence (detected group; N = 18) or absence (undetected group; N = 54) of enlarged parathyroid glands and assessed the clinical characteristics and laboratory findings. A literature review of ultrasound evaluations of secondary hyperparathyroidism was conducted. Ultrasonography revealed enlarged parathyroid glands in 18 patients (25%). Serum intact parathyroid hormone levels were high in patients with enlarged parathyroid glands; however, of the 29 patients with intact parathyroid hormone levels <240 pg/mL, four had enlarged parathyroid glands. Eight of the 29 patients with serum phosphorus and calcium levels within the optimal range had enlarged parathyroid glands. Twenty of these 29 patients were followed up at 38 ± 17 months (at least 3 months): enlarged parathyroid glands were detected in 6. During follow-up, serum intact parathyroid hormone levels were significantly higher in the detected group compared with the undetected. In conclusion, enlarged parathyroid glands are frequently detected at dialysis initiation, potentially predicting the persistence of secondary hyperparathyroidism and the need for strict management.