Evidence for abnormal regulation of circulating 1 alpha,25-dihydroxyvitamin D in patients with sarcoidosis and normal calcium metabolism.

The effects of vitamin D, 2.5 mg (100,000 U)/d for 4 d, on serum calcium, serum 25-hydroxyvitamin D (25-OHD), and serum 1 alpha,25-dihydroxyvitamin D [1 alpha,25(OH)2D] were compared in 17 normal subjects and 6 patients with sarcoidosis who had normocalcemia and no history of hypercalcemia. The diagnosis was confirmed histologically in each of them. Vitamin D increased mean serum 25-PHD from 30 +/- 4 to 99 +/- 15 ng/ml (P < 0.001) and did not change mean serum 1 alpha,25(OH)2D (32 +/- 3 vs. 29 +/- 3 pg/ml) or mean serum calcium (9.5 +/- 0.1 vs. 9.6 +/- 0.1 mg/dl) in the normal subjects. In contrast, vitamin D increased mean serum 25-OHD from 19 +/- 3 to 65 +/- 19 ng/ml (p < 0.05), increased mean serum 1 alpha,25(OH)2D threefold from 40 +/- 7 to 120 +/- 24 pg/ml, and increased mean serum calcium from 9.4 +/- 0.2 to 9.8 +/- 0.2 mg/dl (P < 0.01). There was a significant positive correlation between the serum 1 alpha,25(OH)2D and serum calcium in these individuals (r = 0.663, P < 0.01) but not in the normal subjects. The results (a) provide further evidence for abnormal regulation of circulating 1 alpha,25(OH)2D in sarcoidosis and (b) indicate that the abnormality may exist in patients with normal calcium metabolism. Thus, the defect in vitamin D metabolism in sarcoid apparently is more common than was previously recognized.     

Evidence for extrarenal production of 1 alpha ,25-dihydroxyvitamin D in man.

Recent studies provide evidence for extrarenal production of 1 alpha ,25-dihydroxyvitamin D [1 alpha ,25(OH)2D]. To investigate this possibility, serum vitamin D, 25-hydroxyvitamin D (25-OHD), 24,25-dihydroxyvitamin D [24,25(OH)2D], and 1 alpha ,25(OH)2D were measured in eight adult anephric subjects. All were undergoing hemodialysis and three of them were receiving vitamin D, 50,000 or 100,000 U/d. Serum vitamin D was elevated in two of the patients given vitamin D and was abnormally low in the others. Mean serum 25-OHD was increased in patients given vitamin D (94.0 +/- 7.6 ng/ml) and was normal in the others (16.4 +/- 0.9 ng/ml, P less than 0.001). Mean serum 24,25(OH)2D was normal in patients given vitamin D (1.38 +/- 0.27 ng/ml) and was low in the others (0.25 +/- 0.08 ng/ml, P less than 0.001). Serum 24,25(OH)2D correlated significantly with serum 25-OHD (r = 0.848, P less than 0.01). Mean serum 1 alpha ,25(OH)2D determined by receptor assay was 5.8 +/- 1.9 pg/ml in patients who were not given vitamin D and was 14.1 +/- 0.6 in those who were given vitamin D (P less than 0.001). Serum 1 alpha ,25(OH)2D correlated significantly with serum 25-OHD (r = 0.911, P less than 0.01). Mean serum 1 alpha ,25(OH)2D, measured by bioassay, was 8.3 +/- 1.9 pg/ml in patients who were given vitamin D and was 15.9 +/- 2.4 pg/ml in those who were given vitamin D (P less than 0.05). There was a significant correlation between the values for serum 1 alpha ,25(OH)2D obtained with the two methods (r = 0.728, P less than 0.01). The results (a) provide evidence in man for extrarenal production of both 24,25(OH)2D and, by two independent assays, of 1 alpha , 25(OH)2D, and (b) indicate that serum values of the two dihydroxy metabolites of vitamin D in anephric subjects vary with the serum concentration of the precursor 25-OHD.     

1alpha,25-dihydroxyvitamin D(3)-induced myeloid cell differentiation is regulated by a vitamin D receptor-phosphatidylinositol 3-kinase signaling complex

1alpha,25-dihydroxyvitamin D(3) (D(3)) promotes the maturation of myeloid cells and surface expressions of CD14 and CD11b, markers of cell differentiation in response to D(3). To examine how these responses are regulated, THP-1 cells were grown in serum-free medium and incubated with D(3). This was associated with rapid and transient increases in phosphatidylinositol 3-kinase (PI 3-kinase) activity. Furthermore, induction of CD14 expression in response to D(3) was abrogated by (a) the PI 3-kinase inhibitors LY294002 and wortmannin; (b) antisense oligonucleotides to mRNA for the p110 catalytic subunit of PI 3-kinase; and (c) a dominant negative mutant of PI 3-kinase. In THP-1 cells, induction of CD11b expression by D(3) was also abrogated by LY294002 and wortmannin. Similarly, LY294002 and wortmannin inhibited D(3)-induced expression of both CD14 and CD11b in peripheral blood monocytes. In contrast to CD14 and CD11b, hormone-induced expression of the Cdk inhibitor p21 in THP-1 cells was unaffected by either wortmannin or LY294002. These findings suggest that PI 3-kinase selectively regulates D(3)-induced monocyte differentiation, independent of any effects on p21.     

Demonstration of a lack of change in serum 1 alpha,25-dihydroxyvitamin D in response to parathyroid extract in pseudohypoparathyroidism.

Studies were carried out to compare the effects of parathyroid extract (PTE) on serum and urinary calcium (Ca) and phosphorus (P), serum 25-hydroxyvitamin D (25-OHD), serum 24,25-dihydroxyvitamin D (24,25(OH)2D), serum 1 alpha,25-dihydroxyvitamin D (1 alpha,25(OH)2D), and urinary cyclic AMP in two normal subjects, two patients with hypoparathyroidism (HP) and six patients with pseudohypoparathyroidism (PHP), some of whom were on suboptimal treatment with vitamin D. Two of the patients with PHP were studied while on long-term treatment with 1 alpha,25-(OH)2D3. Before PTE, serum 1 alpha, 25(OH)2D was at the lower limit of normal in one patient and was abnormally low in the other five patients. None of these individuals was on treatment with 1 alpha,25(OH)2D3. Serum 25-OHD and 24,25(OH)2D were either increased or at the upper limit of normal in the patients given vitamin D and were normal in the other patients. PTE lowered the serum P and increased the serum 1 alpha,25(OH)2D, serum and urinary Ca, urinary P, and urinary cyclic AMP in the normal subjects and patients with HP. In individual studies, changes in serum 1 alpha,25(OH)2D and serum Ca occurred in parallel before, during, and after PTE. In contrast, PTE had very little effect in the patients with PHP. Whereas there were highly significant positive correlations between serum 1 alpha,25(OH)2D in each of the normal subjects and patients with HP, there were significant correlations in only one of the patients with PHP. An increase in serum Ca in response to PTE was observed in one of the two patients with PHP who were on long-term treatment with 1 alpha,25(OH)2D3. In these individuals, PTE produced only slight increases in serum 1 alpha,25(OH)2D. Serum 25-OHD and 24,25(OH)2D were not changed by PTE in any of the subjects or patients. The results provide evidence that hypocalcemia in HP and PHP arises in part from low circulating 1 alpha,25-(OH)2D, and indicate that the lack of change in serum 1 alpha,25(OH)2D with PTE in patients with PHP is related to impaired renal adenylate cyclase and phosphaturic responses. These and previous results support the idea that diminished renal production of 1 alpha,25(OH)2D, because of a defect in the parathyroid hormone-responsive adenylate cyclase system, may be a contributing factor in the pathogenesis of the abnormal calcium metabolism in PHP.     

Apoptosis induction by 1alpha,25-dihydroxyvitamin D3 in prostate cancer

Calcitriol [1alpha,25-dihydroxyvitamin D3] is the natural ligand of the vitamin D receptor (VDR). Using cultured prostate cancer (PC) cell lines, LN-CaP and ALVA-31, we studied the effects of 1alpha,25(OH)2-Vitamin D3 (VD3) on expression of several apoptosis-regulating proteins including: (a) Bcl-2 family proteins (Bcl-2, Bcl-X(L), Mcl-1, Bax, and Bak); (b) the heat shock protein 70-binding protein BAG1L; and (c) IAP family proteins (XIAP, cIAP1, and cIAP2). VD3 induced decreases in levels of antiapoptotic proteins Bcl-2, Bcl-X(L), and Mcl-1, BAG1L, XIAP, cIAP1, and cIAP2 (without altering proapoptotic Bax and Bak) in association with increases in apoptosis. In contrast to VDR-expressing LN-CaP and ALVA-31 cells, VDR-deficient prostate cancer line Du-145 demonstrated no changes in apoptosis protein expression after treatment with VD3. In sensitive PC cell lines, VD3 activates downstream effector protease, caspase-3, and upstream initiator protease caspase-9, the apical protease in the mitochondrial ("intrinsic") pathway for apoptosis, but not caspase-8, an initiator caspase linked to an alternative ("extrinsic") apoptosis pathway triggered by cytokine receptors. VD3 induced declines in antiapoptotic proteins and also stimulated cytochrome c release from mitochondria by a caspase-independent mechanism. Moreover, apoptosis induction by VD3 was suppressed by overexpressing Bcl-2, a known blocker of cytochrome c release, whereas the caspase-8 suppressor CrmA afforded little protection. Thus, VD3 is capable of inhibiting expression of multiple antiapoptotic proteins in VDR-expressing prostate cancer cells, leading to activation of the mitochondrial pathway for apoptosis.     

1 alpha,25-dihydroxyvitamin D3 suppresses proliferation and immunoglobulin production by normal human peripheral blood mononuclear cells.

Activated B and T lymphocytes from normal human subjects are known to have the specific high-affinity receptor for 1,25-dihydroxyvitamin D3 (1,25-(OH)2-D3). In an attempt to determine a functional role for the sterol in such cells, we studied the effect of 1,25-(OH)2-D3 on DNA synthesis and Ig production by normal human peripheral blood mononuclear (PBM) cells activated in vitro by the polyclonal lymphocyte activators pokeweed mitogen and phytohemagglutinin, and the specific antigen dermatophyton O. A dose-dependent inhibition of [3H]thymidine incorporation was observed in cells incubated with 1,25-(OH)2-D3 in concentrations ranging from 10(-10) to 10(-7) M. Production of IgG and IgM, determined by enzyme-linked immunosorbent assay, was similarly inhibited by increasing concentrations of 1,25-(OH)2-D3. Half-maximal inhibition of DNA and Ig synthesis was found at 10(-10) to 10(-9) M 1,25-(OH)2-D3. This suppressive effect was specific for 1,25-(OH)2-D3; of the other vitamin D metabolites examined, only 10(-7) M 24R,25 dihydroxyvitamin D3 (24,25-(OH)2-D3) had a similar inhibitory effect. 1,25-(OH)2-D3 was not cytotoxic and did not affect unactivated PBMs. These data demonstrate that 1,25-(OH)2-D3 is a potent inhibitor of human PBM Ig production in vitro and suggest that this action is mediated through the hormone's antiproliferative effect on Ig-producing B cells and/or helper T cells.     

Radioligand receptor assay for 25-hydroxyvitamin D2/D3 and 1 alpha, 25-dihydroxyvitamin D2/D3.

A competitive protein binding assay for measurement of the plasma concentration of 1 alpha, 25-dihydroxyvitamin D3 [1alpha, 25-(OH)2D3] has been extended to include the immediate precursor of this hormone, 25-hydroxyvitamin D3 (25-OHD3). In addition, the assay system is capable of measuring the two metabolic products of ergocalciferol, namely. 25-hydroxyvitamin D2 (25-OHD2) and 1alpha, 25-dihydroxyvitamin D2 [1alpha, 25-(OH)2D2]. The target tissue assay system consists of a high affinity cytosol receptor protein that binds the vitamin D metabolites and a limited number of acceptor sites on the nuclear chromatin. By utilizing a series of chromatographic purification steps, a single plasma sample can be assayed for any of the four vitamin D metabolites either individually or combined. Therefore, the assay procedure allows for both the quantitative and qualitative assessment of the total active vitamin D level in a given plasma sample. To show that the binding assay was capable of measuring 1alpha, 25-(OH)2D2 as well as 1alpha, 25 (OH)2D3, two groups of rats were raised. One group, supplemented with vitamin D3, produced assayable material that represented 1alpha, 25-(OH)2D3. The other group, fed only vitamin D2 in the diet, yielded plasma containing only 1alpha, 25-(OH)2D2 as the hormonal form of the vitamin. The circulating concentrations of the two active sterols were nearly identical (15 ng/100 ml) in both groups, indicating that the competitive binding assay can be used to measure both hormonal forms in plasma. In a separate experiment, 1alpha, 25-(OH)2D2 was generated in an in vitro kidney homogenate system using 25-OHD2 as substrate. Comparison of this sterol with 1alpha, 25-(OH)2D3 in the assay system showed very similar binding curves; the D2 form was slightly less efficient (77%). Comparison of the respective 25-hydroxy forms (25-OHD2 vs. 25-OHD3) at concentrations 500-fold that of 1alpha, 25-(OH)2D3, again suggested that the binding of the D2 metabolite was slightly less efficient (71%). Finally, the assay was employed to measure the total active vitamin D metabolite pools in the plasma of normal subjects and patients with varying degrees of hypervitaminosis D. The normal plasma levels of 25-OHD and 1alpha, 25-(OH)2D measured in Tucson adults were 25-40 ng/ml and 2.1-4.5 ng/100 ml, respectively. Both sterols were predominately (greater than 90%) in the form of vitamin D3 metabolites in this environment. Typical cases of hypervitaminosis D exhibited approximately a 15-fold increase in the plasma 25-OHD concentration, and a dramatic changeover to virtually all metabolites existing in the form of D2 vitamins. In contrast, the circulating concentration of 1alpha, 25-(OH)2D was not substantially enhanced in vitamin D-intoxicated patients. We therefore conclude that hypervitaminosis D is not a result of abnormal plasma levels of 1alpha, 25-(OH)2D but may be cuased by an excessive circulating concentration of 25-OHD.     

Development of a double antibody radioimmunoassay for quantitation of 1 alpha,25-dihydroxyvitamin D

A sensitive radioimmunoassay (RIA) for 1 alpha,25-dihydroxyvitamin D [1 alpha,25(OH)2-D] with a double antibody (DAB) separation technique to separate free from bound antigen has been developed. The hormone was extracted from 1 ml serum or plasma by Extrelut columns and normal phase high performance liquid chromatography and quantitated in the DAB-RIA. The detection limit of the assay was 3.75 ng/l. The intraassay variation coefficients were 15.9% and 10.5% for samples with 1 alpha,25(OH)2D3 concentrations of 54 ng/l and 130 ng/l, respectively. The interassay variation coefficients were 18.0% and 16.7% for these two concentrations. Mean (and SD) values for 1,25(OH)2D in serum of 40 healthy subjects and 38 patients with chronic renal failure who did not receive 1,25(OH)2D3 were 62.8 ng/ml (22.2) and 12.4 ng/ml (9.8), respectively. The mean value for 7 patients with primary hyperparathyroidism was 66.5 ng/ml (35.8) before surgery. These results compared well with those of an established charcoal-based RIA. Compared to charcoal-based RIAs, the DAB-RIA is faster and requires less laborious assay procedures.     

Calcitrol (1alpha,25-dihydroxyvitamin D3) inhibits androgen glucuronidation in prostate cancer cells

Calcitriol (1alpha,25-dihydroxyvitamin D(3)), the active metabolite of vitamin D, has recently emerged as a promising therapeutic agent in the treatment of prostate cancer, the second most common cause of cancer death in American males. In the present study, we have analyzed the effects of calcitriol treatment on the expression and activity of the UDP-glucuronosyltransferase (UGT) 2B15 and 2B17 in prostate cancer LNCaP and 22Rv1 cells. These two enzymes share a crucial role in the inactivation of androgens in the human prostate. We report that calcitriol treatment results in lower glucuronide conjugation of the active androgen dihydrotestosterone and its reduced metabolites androstane-3alpha-diol and androsterone in LNCaP cells. The same treatment also drastically decreased the mRNA and protein levels of UGT2B15 and UGT2B17 in LNCaP and 22Rv1 cells. Using casodex, an androgen receptor (AR) antagonist, and AR-specific small interfering RNA probes, we show that calcitriol requires a functional AR to inhibit the expression of the UGT2B17 gene in LNCaP cells. By contrast, transient transfection and site-directed mutagenesis experiments revealed that calcitriol down-regulates UGT2B15 promoter activity through a responsive region between positions -171 and -113 bp. In conclusion, the present study identifies the vitamin D receptor activator calcitriol as a negative regulator of the UGT2B15- and UGT2B17-dependent inactivation of androgens in prostate cancer LNCaP cells. Androgens promote prostate cancer cell proliferation; thus, the reduction of their inactivation could have a limiting effect of the calcitriol antiproliferative properties in prostate cancer cells.     

Inhibitory effect of erythromycin on interleukin 8 production by 1 alpha,25-dihydroxyvitamin D3-stimulated THP-1 cells.

We have recently reported that long-term administration of erythromycin at a low dose reduced the number of neutrophils and concentrations of interleukin 8 (IL-8) in bronchoalveolar lavage fluid in patients with chronic lower respiratory tract disease. To investigate the mechanism of action of erythromycin, we evaluated its effect on IL-8 production in the 1 alpha,25-dihydroxyvitamin D3-stimulated human monocytic cell line THP-1. Erythromycin at a concentration of 10 micrograms/ml significantly reduced IL-8 production by THP-1 cells stimulated with lipopolysaccharide (10 ng/ml) and 1% normal human serum compared with the amount produced by untreated cells (untreated cells, 2,448 pg/ml; erythromycin-treated cells, 872 pg/ml). Our results suggest that erythromycin may impair IL-8 production by alveolar macrophages, ultimately reducing neutrophil accumulation in the airspace.     

Fibroblast growth factor 23, parathyroid hormone, and 1alpha,25-dihydroxyvitamin D in surgically treated primary hyperparathyroidism

OBJECTIVE: To determine whether fibroblast growth factor 23 (FGF23) contributes to the hypophosphatemia of primary hyperparathyroldism. PATIENTS AND METHODS: Thirteen adult patients with primary hyperparathyroidism had serum collected before and after parathyroidectomy for analysis of inorganic phosphorus, calcium, 1alpha,25-dihydroxyvitamin D (1alpha,25[OH]2D), parathyroid hormone (PTH), FGF23, creatinine, and bone-specific alkaline phosphatase (BSAP). Patients were recruited between July 24, 2003, and February 11, 2004. RESULTS: Before surgery, patients had elevated serum calcium and PTH concentrations. Serum phosphorus concentrations were in the low-normal range. The FGF23 concentrations were not elevated in patients with primary hyperparathyroidism compared with healthy controls. Within 24 hours of surgery, serum calcium, PTH, 1alpha,25(OH)2D, and BSAP concentrations were lower (P < .002 for all) and phosphorus concentrations were higher (P = .003) than in the preoperative state. The FGF23 concentrations were similar 1 day and 6 weeks after surgery. The FGF23 concentrations did not correlate with serum phosphorus, calcium, PTH, 1alpha,25(OH)2D, creatinine, or BSAP concentrations in the preoperative or postoperative state. CONCLUSION: Parathyroid hormone is the major regulator of serum phosphorus concentrations in patients with primary hyperparathyroidism. Fibroblast growth factor 23 does not appear to play a role in phosphorus homeostasis in patients with surgically treated primary hyperparathyroidism.     

The role of 1 alpha, 25-dihydroxyvitamin D in the mediation of intestinal hyperabsorption of calcium in primary hyperparathyroidism and absorptive hypercalciuria.

The cuase for the intestinal hyperabsorptionof calcium (Ca) in various forms of hypercalciurias was explored by a careful measurement of plasma 1 alpha, 25-dihydroxycholecalciferol [1 alpha, 25-(OH)I D] and by an assessment of intestinal Ca absorption and of parathyroid function. In 18 cases of primary hyperparathyroidism (PHPT), the mean plasma concentration of 1 alpha, 25-(OH)2D was significantly increased (4.9 +/- 2.2 SD ng/dl vs. 3.4 +/- 0.9 ng/dl for the control group), and was significantly correlated with fractional Ca absorption (alpha) (r = 0.80, P less than 0.001). Plasma 1 alpha, 25-(OH)2D was also correlated with urinary Ca (P less than 0.05), but not with serum Ca or phosphorus (P), P clearance, urinary cyclic AMP, or serum immunoreactive parathyroid hormone. In 21 cases of absorptive hypercalciuria (AH), plasma 1 alpha, 25-(OH)2D was elevated in one-third of cases, and the mean value of 4.5 +/- 1.1 ng/dl was significantly higher than that of the control group (P less than 0.01). Since relative hypoparathyroidism may be present, the normal absolute value of plasma 1 alpha, 25-(OH)2D, found in two-thirds of cases of AH, may be considered to be inappropriately high. Moreover, in the majority of cases of AH, the data points relating plasma 1 alpha, 25-(OH)2D and alpha fell within 95% confidence limits of values found in non-AH groups (including PHPT). The results suggest that the intestinal hyperabsorption of Ca in PHPT aw AH may be vitamin D dependent. However, the disturbance in vitamin D metabolism may not be the sole cause for the high Ca absorption in AH, since in some patients with AH, the intestinal Ca absorption appears to be inapp     

Evidence that 1,25-dihydroxyvitamin D3 inhibits the hepatic production of 25-hydroxyvitamin D in man

Previous in vitro studies in rachitic rat liver suggested that 1,25-dihydroxyvitamin D inhibits the hepatic production of 25-hydroxyvitamin D (25-OHD). An investigation therefore was carried out in eight normal subjects to determine whether concomitant administration of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] would alter the response of serum 25-OHD to challenge with vitamin D. In control studies, vitamin D, 100,000 U/d for 4 d, significantly increased mean serum 25-OHD, from 26.3 +/- 2.9 to 66.7 +/- 12.6 ng/ml (P less than 0.01). In contrast, 1,25(OH)2D3, 2 micrograms/d for 4 d, completely prevented an increase in serum 25-OHD in response to the same dose of vitamin D in the same individuals (25.1 +/- 2.2 vs. 27.4 +/- 5.3 ng/ml, NS). In a post-control study in seven of the normal subjects, vitamin D again significantly increased mean serum 25-OHD, from 18.2 +/- 3.1 to 42.8 +/- 4.7 ng/ml (P less than 0.001). In each of the three studies, mean serum calcium, phosphorus, and creatinine did not change and remained within the normal range. Whereas mean urinary calcium did not change in response to vitamin D alone during the 4 d of the two control studies, it increased significantly in the study in which vitamin D and 1,25(OH)2D3 were given together. A dose-response inhibition of the response of serum 25-OHD to vitamin D by 1,25(OH)2D3 was demonstrated in two of the normal subjects. The results provide evidence that 1,25(OH)2D3 inhibits the hepatic synthesis of its precursor 25-OHD in man.     

良性原发性甲状旁腺功能亢进症患者血清1,25-二羟基维生素D3水平变化

目的探讨良性原发性甲状旁腺功能亢进症(primary hyperparathyproidism,PHPT)患者血清1,25-二羟基维生素D3[1,25-dihydroxyvitamin D3,1,25(OH)2D3]水平变化及与甲状旁腺激素(parathyroid hormone,PTH)、血钙、血磷的关系。方法良性PHPT患者56例为观察组,同期体检健康者1118例为对照组,采用电化学发光法检测2组血清1,25(OH)2D3、PTH水平,比色法测定血钙水平,磷钼酸盐法测定血磷水平。比较2组维生素D缺乏[1,25(OH)2D3<20μg/L]、严重缺乏[1,25(OH)2D3<10μg/L]的比率及不同年龄分层患者血清1,25(OH)2D3水平变化,Pearson法分析观察组维生素D缺乏、严重缺乏患者血清1,25(OH)2D3与PTH、血钙及血磷的相关性。结果观察组维生素D缺乏比率、严重缺乏比率(94.64%、46.43%)高于对照组(62.79%、14.13%)(P<0.05);Pearson相关分析显示,观察组血清1,25(OH)2D3与PTH、血钙及血磷均无线性相关性(r=-0.226,P=0.352;r=-0.274,P=0.256;r=0.073,P=0.593)。观察组年龄18~40岁、>40~60岁、>60岁患者血清1,25(OH)2D3[(10.76±3.17)、(10.61±5.01)、(10.72±4.85)μg/L]低于对照组[18~40岁:(18.19±9.86)μg/L,>40~60岁:(17.18±9.19)μg/L,>60岁:(17.91±10.52)μg/L](P<0.05);观察组维生素D缺乏患者血清PTH[(818.86±233.49)ng/L]、血钙[(2.98±0.59)mmol/L]、血磷[(0.78±0.17)mmol/L]与维生素D严重缺乏患者[(640.09±622.69)ng/L、(2.96±0.69)mmol/L、(0.75±0.20)mmol/L]比较差异无统计学意义(P>0.05);观察组维生素D缺乏、严重缺乏患者血清1,25(OH)2D3与PTH(r=-0.360,P=0.060;r=0.071,P=0.723)、血钙(r=-0.225,P=0.250;r=-0.228,P=0.252)、及血磷(r=0.239,P=0.221;r=-0.208,P=0.297)均无线性相关。结论良性PHPT患者血清1,25(OH)2D3低于正常人群,维生素D缺乏比率较高,且血清1,25(OH)2D3与PTH、血钙及.血磷无线性相关。     

Measurement of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D2 and 25,26-dihydroxyvitamin D2 in a single plasma sample by mass fragmentography

A specific and sensitive assay for the measurement of the concentration of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D2 and 25,26-dihydroxyvitamin D2 in a single plasma sample is described, using stable isotope dilution mass fragmentography. After addition of appropriate deuterium-labelled internal standards, plasma samples were treated with acetonitrile to precipitate protein, and vitamin D metabolites were extracted on prepacked microparticulate reverse-phase cartridges. Further purification was achieved using straight-phase cartridges and high-performance liquid chromatography. Gas chromatography-mass spectrometry was carried out after appropriate derivatisation of samples and standards. The method has been evaluated in terms of specificity, recovery of added standards, and reproducibility.     

Roles for the heliodynamic hormones, all trans retinoic acid and 1 alpha, 25-dihydroxyvitamin D3, in control of the hematopoietic cell cycle

It is now well established that the production of primary hematopoietic cells is controlled at different levels of the biological organization. Bone marrow (BM) stromal cells, the extracellular matrix (ECM), polypeptide hematopoietic growth factors (HGF) as well as endogenous cell-division cycle (CDC) related factors play a dominant role in this control. Recent information suggest that the 2 lipophilic hormones, transRA and 1 alpha,25D3, depending on and/or perhaps mediating solar energy, play a role in the maintenance of BM homeostasis. Here we show that both transRA and 1 alpha,25D3: a) modulate the growth and/or stimulate the adipocytic differentiation of fibroblastic stromal cells (F-CFU); b) inhibit the synthesis and extracellular processing but stimulate the solubilization of matrix collagen; c) modulate the clonal growth of myeloid progenitor cells (GM-CFU) in synergy with HGFs; and d) inhibit the production of lactic acid in standard, normal long-term BM cultures (LTBMC). Comparative analysis of normal, preleukemic and leukemic BM cells in LTBMC indicated a positive correlation between the induction of terminal differentiation and reduced lactate production elicited by transRA or 1 alpha,25D3. These results raise a hypothesis according to which the terminal differentiation induced by the helicodynamic hormones is dependent on the mitochondrial aerobic ATP-generating system whose impairment may be a critical step during the process of leukemic transformation.