Decrease in bone levels of 1,25-dihydroxyvitamin D in women with subcapital fracture of the femur

Summary In a previous study we were able to show that in women over the age of 45 the level of 1,25-dihydroxyvitamin D (1,25(OH)₂D) in bone, but not in serum, is significantly reduced when compared with younger women. In the present study we measured the concentration of 1,25(OH)₂D in sera and bones of 19 female patients with subcapital fractures of the femur, mean age 78±2 years. We were able to show that serum levels of 1,25(OH)₂D were within the normal range, while bone levels were markedly reduced compared to levels in femoral bone obtained from young female cadavers or to the previously reported levels in non-osteoporotic elderly women. Thus, reduced levels of 1,25(OH)₂D in bones of elderly women may lead, together with other factors, to subcapital fractures.Holder of Prof. T. Reichstein Professorial Chair     

1,25(OH)2D3抑制嘌呤霉素氨基核苷酸肾病大鼠足细胞凋亡

目的 观察1，25（OH）2D3对嘌呤霉素氨基核苷酸（PAN）肾病大鼠足细胞凋亡的影响。 方法 72只雄性SD大鼠随机分为健康对照组（NC）、PAN组和1，25（OH）2D3治疗组 [1，25（OH）2D3 0.2 μg·kg-1·d-1灌胃]。一次性尾静脉注射PAN 100 mg/kg体质量建立足细胞损伤的PAN肾病动物模型。于3、7、14、21 d分批处死动物，分别检测不同时间点尿蛋白量（24 h）和肾功能。光镜和透射电镜观察肾组织学改变。TUNEL法检测足细胞凋亡。RT-PCR、免疫荧光、免疫组化分别检测nephrin、TGF-β1 mRNA和蛋白的表达。Western印迹检测磷酸化（p）-Smad2/3的表达。 结果 （1）PAN组各时间点BUN、Scr、尿蛋白量（24 h）[7 d时，（20.26±4.87） mg比（1.01±0.41） mg，P < 0.01]均高于同期的NC组，而肾小球足细胞显著减少[14 d时，(10.9±4.2) 个/肾小球切面比(31.9±6.2)个/肾小球切面，P ＜ 0.01]，且足突增宽融合。1，25（OH）2D3治疗组各时间点尿蛋白量（24 h）[7 d时（9.95±3.82） mg]和BUN、Scr显著低于PAN组（P < 0.05），且肾脏病理改变减轻。（2）PAN组7 d时nephrin mRNA和蛋白的表达显著降低，nephrin由正常的沿毛细血管襻线状分布向颗粒状、团快状改变，足细胞凋亡数显著增加[14 d时，（37.4±7.9）个/肾小球切面]。与PAN组相比，1，25（OH）2D3治疗组各时间段nephrin mRNA和蛋白的表达显著增加，且保持着正常的沿毛细血管襻线状分布，足细胞凋亡数显著减少[14 d时，(21.9±6.2) 个/肾小球切面，P < 0.01]。（3）PAN组TGF-β1 mRNA和蛋白的表达以及p-Smad2/3蛋白的表达均高于NC组（P < 0.01），1，25（OH）2D3治疗组TGF-β1 mRNA和蛋白的表达以及p-Smad2/3蛋白的表达低于PAN组（P < 0.01）。 结论 1，25（OH）2D3能有效地抑制PAN诱导的足细胞凋亡，减少尿蛋白，其对足细胞损伤的保护作用可能与抑制TGF-β1信号通路有关。     

Ascorbate Increases the 1,25 Dihydroxyvitamin D3-Induced Monocytic Differentiation of HL-60 Cells

1,25 Dihydroxyvitamin D₃ (calcitriol) induces differentiation of HL-60 leukemia cells. We studied the in vitro effect of a physiological concentration of ascorbate as potentiator of 1,25 dihydroxyvitamin D₃ [(OH)₂D₃] activity by determining different markers of differentiation: nitroblue tetrazolium reduction, nonspecific esterase activity, and the expression of CD11b and CD14 surface antigens. Nitroblue tetrazolium reduction and nonspecific esterase activity increased up to 50% in the presence of both 1,25 (OH)₂D₃ plus 0.2 mM ascorbate (ASC), compared with (OH)₂D₃ as a unique agent. ASC also increased the expression of specific surface antigens (CD11b and CD14) during differentiation induced by 1,25 (OH)₂D₃, the effect being more pronounced after 48 hours of treatment with 10⁻⁸ M 1,25 (OH)₂D₃. Furthermore, 1,25 (OH)₂D₃ alone increased intracellular cAMP level during differentiation, and the addition of ASC increased its concentration from 60 to 100% above the level reached with 1,25 (OH)₂D₃ as unique agent. ASC did not enhance the antiproliferative effect of calcitriol, suggesting that it only affects the ability of 1,25 (OH)₂D₃ to promote differentiation of HL-60 cells. Received: 9 June 1995 / Accepted: 19 February 1996     

Rationale for the development and current status of calcitriol in androgen-independent prostate cancer

Calcitriol, the principal active metabolite of vitamin D, has significant antineoplastic activity in pre-clinical models of prostate cancer and many other tumor types. Reported mechanisms of activity include inhibition of proliferation and cell cycle arrest, induction of apoptosis, and reduction of invasiveness and angiogenesis. Different mechanisms may be responsible in different tumor types and under different experimental conditions. Importantly, preclinical data suggest that calcitriol acts in a synergistic and/or additive manner when combined with antineoplastic agents that are relevant to prostate cancer, including dexamethasone and several classes of cytotoxic agents. The antineoplastic effects of calcitriol occur at concentrations that substantially exceed the normal physiologic range and cannot be safely achieved with conventional daily dosing. Intermittent administration of calcitriol has allowed significant dose escalation. In combination with weekly docetaxel, the agent produced encouraging results in a single-institution phase II study. An international placebo-controlled randomized trial that is currently under way will provide more robust information about the safety and efficacy of this combination.     

Are new vitamin D analogues in renal bone disease superior to calcitriol?

Progression of chronic kidney disease is associated with an early reduction in serum calcitriol levels; thus, therapy with calcitriol should be initiated early in the course of chronic kidney disease to prevent the development of secondary hyperparathyroidism. Initial studies demonstrated a potential role of calcitriol in the prevention of growth retardation in children with chronic kidney disease prior to dialysis. But the optimal parathyroid hormone (PTH) levels that will maximize growth response during calcitriol treatment remain to be defined. Therapy with calcitriol has been shown to control the biochemical and skeletal manifestations of secondary hyperparathyroidism, but patients developed hypercalcemia, hyperphosphatemia and adynamic osteodystrophy. Thus, new vitamin D analogues with a lower hypercalcemic response have been developed. Although comparative studies are lacking, current evidence indicates that these new active vitamin D sterols (19-nor-paracalcitol and doxercalciferol) adequately control secondary hyperparathyroidism with minimal changes in serum calcium and phosphorus levels during treatment with calcium-containing binders. The long-term effect of such therapies on the skeleton and the process of vascular calcifications remain to be evaluated.This work was presented in part at the IPNA Seventh Symposium on Growth and Development in Children with Chronic Kidney Disease: The Molecular Basis of Skeletal Growth, 1–3 April 2004, Heidelberg, Germany     

Maxacalcitol is a possible less phosphatemic vitamin D analog

The phosphatemic property of maxacalcitol, a newly developed artificial active vitamin D analog, has not been compared with that of calcitriol. Non-diabetic hemodialysis patients with plasma intact parathyroid hormone (PTH) levels greater than 300 pg/mL were included in this analysis. They were treated with either maxacalcitol or calcitriol for 24 weeks. In total, 80 patients were treated with maxacalcitol and 46 were treated with calcitriol. Pretreatment circulating levels of intact PTH, calcium (Ca) and inorganic phosphate (Pi) were comparable in both treatment groups. Both treatments significantly decreased plasma intact PTH levels (P<0.0001) and increased serum Ca levels (P<0.0001). However, the intact PTH levels were significantly lower in the maxacalcitol group after 24 weeks of the treatments (P<0.01). The decreasing tendency of plasma intact PTH level was significantly evident in the maxcalcitol group (P<0.01). However, the increasing tendency of the serum Pi level was significantly greater in the calcitriol group (P<0.05). Thus, maxacalcitol is a possible less phosphatemic active vitamin D agent, if not non-phosphatemic agent, which might reduce the risk of extraskeletal calcification.     

Prevention and therapy of osteoporosis: the roles of plain vitamin D and alfacalcidol

Severe vitamin D deficiency was identified only in the first decades of the last century as the most common aetiology of rickets in children and osteomalacia in adults. It was later shown that vitamin D is not, as had been supposed, the biologically active principle for healing bone disease but must be hydroxylated in the liver and then finally in the kidney to become 1,25-dihydroxy-cholecalciferol, a biologically highly active renal hormone. This study reviews the various principles, mechanisms, and approaches to the treatment of different forms of osteoporosis using vitamin D, alfacalcidol, and calcitriol therapy regimens.     

Anti-tumor effect of vitamin A and D on head and neck squamous cell carcinoma

Objectives: Vitamin A and D₃ have a very strong differentiation induction effect. Study design: We examined the anti tumor effect on head and neck squamous cell carcinoma (HNSCC) by treatment with several vitamins having strong differentiation induction effects in vitro. Methods: We used KB cell that an oral floor squamous cell carcinoma, vitamins as all-trans retinoic acid (ATRA), 4-[3,5-bis (trimethylsilyl) benzamido] benzoic acid (TAC-101), 1,25(OH)₂D₃ (calcitriol) and 22-oxa-1,25-(OH)₂D₃ (OCT). We determined receptors of vitamin A and D₃ using RT-PCR. Furthermore, we investigated the proliferation of tumor cells in concentration dependency using [³H]TdR uptake method, apoptosis and apoptosis related factors using TUNEL method and real-time PCR, cell cycle changes using flow cytometry, changing of the sensitivity of using MTT method, cytokine production and the angiogenesis factor using ELISA, by treatment with these vitamins. Results: The deficit of RAR-β was found in the KB cell. Each vitamin suppressed the cell proliferation, induced apoptosis, and cell cycle arrest, upregulated sensitivity of the chemotherapeutics drugs and downregulated several angiogenesis factors and an apoptotic factor; survivin. Conclusions: These results support the idea that vitamin A, D₃ and their derivatives are useful for preventing and/or treating patients with HNSCC.     

尿毒症透析患者不同剂量钙三醇治疗继发性甲状旁腺功能亢进的疗效观察

目的 比较常规剂量钙三醇与较大剂量冲击疗法防治尿毒症维持性透析患者继发性甲状旁腺功能亢进(SHPT)的疗效.方法 48例尿毒症透析患者,分常规治疗组(A组)22例,钙三醇0.25～0.5 μg/d,同时补钙,治疗时间6个月;未治疗组(B组)21例,皆因经费困难不愿意治疗;冲击治疗组(C组)21例(其中16例来自A组),钙三醇每周4μg,分2次于血液透析后口服,观察3个月.结果 A组与B组比较,血清甲状旁腺激素(PTH)、碱性磷酸酶(AKP)差异无统计学意义(P>0.05),但A组中,低血钙、高血磷得到部分纠正(P>0.05),骨痛、肌肉抽搐、无力、皮肤瘙痒等症状均有改善.结论 较大剂量间歇冲击治疗能有效治疗尿毒症血液透析患者SHPT.     

1,25(OH)_2D_3对NOD小鼠1型糖尿病的免疫干预及其机制研究

目的观察1,25(OH)2D3对雌性非肥胖糖尿病(NOD)小鼠糖尿病发病率、胰岛炎的影响,以及外周免疫器官脾脏T淋巴细胞亚群的变化,血清细胞因子干扰素γ(IFN-γ)、白细胞介素-4(IL-4)及一氧化氮(NO)的水平,从而更好地揭示1,25(OH)2D3的免疫调节机制。方法离乳(21 d龄)的雌性NOD小鼠(80只)随机分为两组:第1组给予1,25(OH)2D3(5μg/kg)隔日1次腹腔注射,共7周,作为实验组。第2组给予等量花生油作为对照组(40只),给药时间、方法同前。10周龄时腹腔注射环磷酰胺以加速糖尿病。加速1周后各取15只通过酶联免疫吸附试验(ELISA)法检测IFN-γI、L-4水平,生化比色法检测NO水平,流式细胞仪分析脾组织T细胞亚群的变化。其余继续观察。小鼠在被确诊糖尿病或环磷酰胺加速后1个月处死,观察胰腺病理变化、糖尿病发病率及血钙水平。结果实验组发病率(12%)明显低于对照组(56%),P<0.01;实验组胰岛炎症分数较对照组明显降低P<0.01,炎症程度也明显减轻;实验组血清IL-4较对照组明显升高[(52±9)ng/Lvs(33±3)ng/L],P<0.01;IFN-γ、NO较对照组显著降低[(71±16)ng/Lvs(141±11)ng/L,(78±28)ng/Lvs(118±19)ng/L],P均<0.01;脾脏淋巴细胞经流式细胞仪测定,结果显示实验组T细胞CD4+、CD8+亚群较对照组显著升高,CD4+亚群为47±6与35±4(P<0.01),CD8+亚群为11.6±3.6与7.8±1.5(P<0.05),而CD4+/CD8+亚群分别为4.3±0.9与4.6±0.9(P>0.05),两组差异无统计学意义;实验组血钙较对照组稍高,但NOD小鼠可以很好耐受。结论1,25(OH)2D3可以预防环磷酰胺加速的NOD小鼠糖尿病的发生,并可减轻胰岛炎。其机制:①可能与增加Th2型细胞因子的全身表达,降低Th1型细胞因子的全身表达,从而调节Th1/Th2型细胞因子比例失衡有关。②可能与增加抑制性T细胞数目,促进CD4+T细胞由Th1向Th2亚群转化有关。该实验同时证实了NO在糖尿病的发生机制中起一定作用。