Role of calcitriol in phosphate regulation by the chick embryo

Summary Chick embryos were injected on the 14th day of incubation with 100 ng calcitriol. The concentration of Ca in their serum rose significantly 4 hours after the injection and the concentration of Pi started to decrease 10 hours after. When embryos of the same age were injected with a solution containing CaCl₂, the concentrations of both Ca and P rose significantly 2 hours after the injection and remained high until the end of the experiment. The fact that both treatments produced hypercalcemia but had opposite effects on the concentration of Pi does not agree with the idea that the hypophosphatemic response to calcitriol might be secondary to the hypercalcemia which precedes it. The injection of a solution of NaHCO₃ to embryos of the same age failed to produce hypophosphatemia. The fact that calcium salts and bicarbonate, when injected separately, fail to induce hypophosphatemia does not contradict the possibility that the hypophosphatemic response to calcitriol might result from the simultaneous increase in flux of Ca and HCO₃ from the shell. Three days after the injection of calcitriol to 14-day-old embryos, the total amount of Ca and P in the urine was significantly higher than in the controls. The concentration of Ca and P in kidney tissue was also significantly higher in the injected embryos. In addition, calcified precipitates were detected histochemically in the lumen of the kidney tubules from the treated embryos. These results are interpreted as demonstrating that an increase in the excretion of P in the urine is the main mechanism explaining calcitriol-induced hypophosphatemia in the chick embryo. It is suggested that calcitriol acts on kidney tubules inducing either a decrease in the reabsorption of P or an increase in its secretion. Changes in calcium and bicarbonate levels in the filtrate resulting from increased shell resorption might be contributing or alternative mechanisms for the phosphaturia.     

Vitamin D metabolism in magnesium deficient chicks

To determine if alterations in vitamin D metabolism are associated with the development of hypocalcemia in magnesium (Mg) deficiency, we measured plasma Mg, calcium (Ca), phosphorus (P) and vitamin D metabolites in growing chicks pair-fed diets adequate (1000ppm) or low (130ppm) in Mg for up to 15 days. A third group received a low Ca (0.2%) diet adequate in Mg and served as a positive control group in which the classical response to hypocalcemia was demonstrated. A progressive decline in plasma Mg in the Mg deficient chicks was associated with progressive and severe hypocalcemia. There was no rise in plasma 1,25-dihydroxycholecalcifetol (DHCC) in response to hypocalcemia in the Mg deficient chicks. In contrast, chicks fed low dietary Ca with adequate Mg exhibited a 3-fold elevation in circulating 1,25-DHCC and maintained plasma calcium slightly below that of control animals. The failure of the Mg deficient chicks to increase 1,25-DHCC production in response to hypocalcemia was not associated with inadequate circulating 25-hydroxycholecalciferol or increased plasma 24,25-DHCC. 1α-hydroxylase activity, measured in isolated renal tubules, was not elevated in the Mg deficient chicks, compared to controls. A significant correlation between plasma 1,25-DHCC and 1α-hydroxylase activity suggested that metabolic turnover of 1,25-DHCC was not significantly altered by Mg deficiency. The data suggest that the progression of hypocalcemia during Mg deficiency may be related to insufficient production of 1,25-DHCC in response to the prevailing hypocalcemia.     

Vitamin D deficiency in the chick embryo: Effects on prehatching motility and on the growth and differentiation of bones,muscles, and parathyroid glands

Summary Vitamin D-deficient chicken embryos were obtained by feeding laying hens diets in which 3–7 μg calcitriol replaced the vitamin D₃ supplement. A large proportion of the D-deficient embryos failed to complete the prehatching positional changes required to start pulmonary respiration. For this reason most of them became cyanotic and had subcutaneous edema and hemorrhages in the head and neck and died without hatching. Total as well as leg-bone and muscle weights were significantly lower in the deficient embryos than in the controls and these changes probably explain the inability of the embryos to complete the movements required to place the beak in contact with the air chamber and start pulmonary respiration. The histological study of the tibiae showed decreased mineralization with narrower trabeculae and enlarged osteoid seams; bone resorption at the inner surface was also significantly decreased. The ultrastructural study of parathyroid glands showed increased functional activity reflected by increased number and size of cisternae of rough endoplasmic reticulum. Injection of 10 ng calcitriol, 1 μg 24, 25-(OH)₂D₃, or 2 μg 25OHD₃ to deficient embryos on the 14th day of incubation improved hatchability, bone and muscle weights, and both bone mineralization and resorption.     

Mechanisms of Hypercalcemia in Non-Hodgkin Lymphoma and Associated Outcomes: A Retrospective Review

Introduction

The etiology of hypercalcemia in non-Hodgkin lymphoma (NHL) has been most often attributed to either elevated serum levels of 1,25-dihydroxycholecalciferol (calcitriol) or parathyroid-related protein (PTHrP). In a single-center retrospective review, we evaluated the incidence of, and outcomes associated with, hypercalcemia in NHL.

骨松宝颗粒联合骨化三醇治疗老年骨质疏松性股骨粗隆间骨折的临床研究

目的 探讨骨松宝颗粒联合骨化三醇胶丸治疗老年骨质疏松性股骨粗隆间骨折的临床疗效。方法 选取2018年7月-2019年12月新乡医学院第一附属医院收治的82例老年骨质疏松性股骨粗隆间骨折患者，按照随机数字表法将82例患者分为对照组和治疗组，每组各41例。对照组口服骨化三醇胶丸，0.25μg/次，3次/d。治疗组患者在对照组治疗的基础上温水冲服骨松宝颗粒，5 g/次，2次/d。两组患者连续治疗6个月。观察两组的临床疗效，比较两组的视觉模拟评分法（VAS）评分、髋关节功能（Harris）评分、骨密度和血清抗酒石酸酸性磷酸酶5b（TRACP-5b）、胰岛素样生长因子Ⅰ（IGF-Ⅰ）、骨钙素（OC）水平。结果 治疗后，治疗组患者的总有效率比对照组高（95.12%vs 80.49%），差异有统计学意义（P<0.05）。治疗后，两组的VAS评分显著降低，Harris评分显著升高（P<0.05）；且治疗组的VAS评分低于对照组，Harris评分高于对照组（P<0.05）。治疗后，两组的腰椎骨密度明显升高（P<0.05），且治疗组升高的更明显（P<0.05）。治疗后，两组的TRACP-5b水平显著降低，IGF-Ⅰ、OC水平显著升高，差异有统计学意义（P<0.05）；且治疗后治疗组的TRACP-5b水平比对照组低，IGF-Ⅰ、OC水平比对照组高，差异有统计学意义（P<0.05）。结论 骨松宝颗粒联合骨化三醇胶丸治疗老年骨质疏松性股骨粗隆间骨折具有较好的临床疗效，可减轻疼痛程度，改善骨密度，调节血清骨代谢指标。     

骨化三醇加碘油抑制人肝癌MHCC97细胞的研究

目的探讨骨化三醇加碘油对MHCC97肝癌细胞增殖能力的影响及其对肝细胞生长因子（HGF）及受体c-met表达的调控作用。方法分别用10^-6～10^-9mol/L的骨化三醇、0.5%的碘油＋10^-6mol/L浓度的骨化三醇及单用0.5%的碘油处理人肝癌MHC97-H、MHC97-L细胞系,分别作用48、72、96h后,MTT法检测细胞的增殖能力。用骨化三醇、碘油＋骨化三醇处理细胞72h后,酶联免疫法（ELISA）定量测定细胞上清HGF浓度;逆转录聚合酶链式反应（RT-PCR）检测肝癌细胞内维生素D受体（VDR）及c-met mRNA表达。结果MHCC97-H、L两株细胞系均有维生素D受体（VDR）表达。骨化三醇对MHCC97-H、L两株细胞均有不同程度的增生抑制作用,以10^-6mol/L骨化三醇的浓度抑制效果最好,72h效果最佳。第4天碘油加骨化三醇对细胞增生的抑制作用强于单用骨化三醇。MHCC97-H、L细胞均有HGF的分泌,单用骨化三醇处理细胞后,HGF水平下降不明显,而加碘油作用于MHCC97-H细胞后,HGF水平下降明显（P=0.043）。两株细胞均表达c-met mRNA,而用骨化三醇处理细胞后,c-met mRNA表达明显减弱。结论骨化三醇抑制人肝癌细胞MHCC97的增生,骨化三醇对HGF/c-met表达的抑制作用可能是其抗肝癌机制之一;溶于碘油中的骨化三醇能发挥更为持久、有效的作用。     

血液透析滤过串联血液灌流联合骨化三醇冲击治疗对血透患者继发性甲状旁腺功能亢进的临床疗效

目的探讨血液透析滤过串联血液灌流联合骨化三醇冲击治疗对维持性血液透析患者并发继发性甲状旁腺功能亢进的临床疗效。 方法选取2019年01月至2019年06月60例维持性血液透析并发继发性甲状旁腺功能亢进的患者作为研究对象，其中男性42例，女性18例；年龄20～68岁，平均(52±17.2)岁。对照组30例，每周常规血液透析3次，联合骨化三醇冲击治疗；研究组30例，每周常规血液透析1次，血液透析滤过1次，血液透析滤过＋血液灌流1次，联合骨化三醇冲击治疗。观察两组患者血钙、血磷、血甲状旁腺素、碱性磷酸酶(ALP)等各项指标变化，并对两组患者的临床症状进行比较分析。 结果两组患者血甲状旁腺素均降低(P<0.05)；研究组患者的血甲状旁腺素、血磷、碱性磷酸酶明显低于对照组(P<0.05)；对照组治疗后血钙水平上升，较治疗前差异有统计学意义(P<0.05)；研究组治疗前后血钙水平差异无统计学意义(P>0.05)。 结论对维持性血液透析继发甲状旁腺功能亢进患者应用血液透析滤过串联血液灌流联合骨化三醇冲击治疗不仅能有效降低血甲状旁腺素、血磷、碱性磷酸酶水平，不影响血钙水平，且更能改善患者临床症状，提高生活质量。     

Hypocalcemia reduces insulin turnover but not insulin-mediated glucose metabolism in piglets

Disturbances of glucose metabolism similar to type II diabetes are often accompanied by low extra cellular calcium concentrations, as shown in periparturient ruminants. Hypocalcemia reduces insulin secretion and possibly endogenous glucose production, but whether hypocalcemia also affects peripheral actions of insulin is not clear. The problem was investigated with piglets in this study. Insulinmediated turnover of glucose and the clearance of insulin were measured in 7 control piglets (+D) and in 10 piglets with inherited calcitriol deficiency (−D). The measurements involved continuous intravenous infusions of insulin (1, 2, 5, 7.5 and 10 mU·kg⁻¹·min⁻¹) and glucose to maintain a glucose concentration of 7 mmol · l⁻¹ (combined insulin and glucose clamps). Both groups of piglets were studied under normo- and hypocalcemic conditions. During hypocalcemia and with equal insulin infusion rates, −D and +D piglets attained significantly higher (28%–133%) steady state insulin concentrations in plasma than during normocalcemia. This showed that the clearance rates of insulin during hypocalcemia were 48% lower in +D and 20% lower in −D piglets than during normocalcemia. With equivalent insulin infusion rates +D piglets developed significantly higher (15%–48%) steady state insulin concentrations in plasma than −D piglets, indicating that the clearance rate of insulin was higher in the calcitriol-deficient state. The relationship between insulin concentration in plasma and glucose turnover (measured with [3-³H]glucose) was not influenced by the calcemic and vitamin D status of the piglets. This indicated that the peripheral action of insulin on glucose metabolism was not influenced by the extracellular calcium concentration and vitamin D status. Received: March 2001 / Accepted in revised form: July 2002 Correspondence to C. Schlumbohm     

Interferon Gamma,but not Calcitriol Improves the Osteopetrotic Phenotypes in ADO2 Mice

ADO2 is a heritable osteosclerotic disorder that usually results from heterozygous missense dominant negative mutations in the chloride channel 7 gene (CLCN7). ADO2 is characterized by a wide range of features and severity, including multiple fractures, impaired vision due to secondary bony overgrowth and/or the lack of the optical canal enlargement with growth, and osteonecrosis/osteomyelitis. The disease is presently incurable, although anecdotal evidence suggests that calcitriol and interferon gamma‐1b (IFN‐G) may have some beneficial effects. To identify the role of these drugs for the treatment of ADO2, we utilized a knock‐in (G213R mutation in Clcn7) ADO2 mouse model that resembles the human disease. Six‐week‐old ADO2 heterozygous mice were administered vehicle (PBS) or calcitriol or IFN‐G 5 times per week for 8 weeks. We determined bone phenotypes using DXA and μCT, and analyzed serum biochemistry and bone resorption markers. ADO2 mice treated with all doses of IFN‐G significantly (p<0.05) attenuated the increase of whole body aBMD and distal femur BV/TV gain in both male and female compared to the vehicle group. In contrast, mice treated with low and medium doses of calcitriol showed a trend of higher aBMD and BV/TV whereas high dose calcitriol significantly (p<0.05) increased bone mass compared to the vehicle group. The calcium and phosphorus levels did not differ between vehicle and IFN‐G or calcitriol treated mice; however, we detected significantly (p<0.05) elevated levels of CTX/TRAP5b ratio in IFN‐G treated mice. Our findings indicate that while IFN‐G at all doses substantially improved the osteopetrotic phenotypes in ADO2 heterozygous mice, calcitriol treatment at any dose did not improve the phenotype and at high dose further increased bone mass. Thus, use of high dose calcitriol therapy in ADO2 patients merits serious reconsideration. Importantly, our data support the prospect of a clinical trial of IFN‐G in ADO2 patients.     

NOD/Lt小鼠腹腔注射1,25-(OH)2D3诱发免疫耐受的机制

目的　探讨1, 25 (OH)2D3 阻断NOD/Lt小鼠发生1型糖尿病的免疫机制。方法　60只4周龄NOD/Lt小鼠(25g)分为2组,组1隔天腹腔注射1, 25 (OH)2D3 (5μg/kg),组2腹腔注射花生油作为对照。所有小鼠在第1天和第15天腹腔注射环磷酰胺以加速糖尿病的发生,第30天处死并观察。免疫组化检测Bcl 2,Bax在胰岛和T淋巴细胞的表达;流式细胞仪检测T淋巴细胞亚群分布及凋亡率;RT PCR检测Th1 /Th2 亚群的漂移。结果　1, 25 (OH)2D3 处理组糖尿病发病率下降,脾T淋巴细胞凋亡率增加〔(55. 8±5. 4)% vs(28. 9±3. 6)%,P<0. 05〕;CD4 Th2 亚群增加(IL 4和IL 10mRNA显著增加, P<0. 01)。结论　1, 25 (OH)2D3 通过加速T淋巴细胞的凋亡以减轻细胞免疫反应并最终延缓胰岛β细胞的凋亡,并使CD4 Th1 亚群向CD4 Th2 亚群漂移,导致NOL/Lt小鼠1型糖尿病发病率下降。