Coherence treatment of postmenopausal osteoporosis with growth hormone and calcitonin

Summary Fourteen women with postmenopausal osteoporosis, all having at least one vertebral crush fracture, were randomly assigned to two treatment arms, each lasting 24 months. The coherence treatment group (7 patients) was treated in the following sequence: human growth hormone (hGH) 7 IU subcutaneously daily for 2 months, followed by 3 months of salmon calcitonin (CT), 100 MRC units every other day. After a 3 month rest period, this sequence was repeated twice. The contrast group (7 patients) was treated intermittently with salmon CT given in the same time periods and at the same dose as in the coherence treatment group. Bone mass was measured every 4 months by neutron activation analysis for total body calcium (TBCa) and by single photon absorptiometry for bone mineral content (BMC) of the distal radius. Although there were no significant differences between the two groups (two-way ANOVA), the rate of change in TBCa in the coherence treatment group was significantly different from zero (F=3.8,P<.05) and was +2.3%/year. The increase in bone mass appeared to be sustained throughout the 2 year study, in contrast with previous studies where a plateau effect was observed with calcitonin given alone or continuously with growth hormone. No significant change was found in bone histomorphometric values measured before and after treatment in 4 patients from each group.     

Growth hormone stimulates proliferation and differentiation of normal human osteoblast-like cells in vitro

Summary In this study we investigated the direct, shortterm effects of human growth hormone (hGH) on the biology of normal adult human osteoblast-like (hOB) cells cultured from trabecular bone explants. In Subconfluent cultures, hGH stimulated hOB proliferation in a dose-dependent fashion (P<0.001, n=15) with half-maximal effects at a concentration of 10 ng/ml. These mitogenic effects were detectable within 24 hours as shown by bromodeoxyuridine labeling. In confluent cultures containing mainly quiescent cells, hGH increased levels of alkaline phosphatase (P<0.05, n=10) and to a lesser degree levels of procollagen type I carboxyterminal propeptide (PICP) (P=0.07, n=9). Effects on osteocalcin (bone GLa protein, BGP) levels were highly variable among different cell strains and only 7 of 10 cell strains showed a stimulatory response (P=0.16). We also studied the effects of hGH on osteoblastic production of insulin-like growth factor I (IGF-I) and IGF-II as well as the production of GH-dependent, insulin-like growth factor binding protein 3 (IGFBP-3). Under basal conditions, human osteoblasts produced IGF-II and IGFBP-3 in the conditioned medium. When stimulated with hGH, minor insignificant increase in both IGF-II and IGFBP-3 (125% and 126% of control, respectively) were detectable. No IGF-I was detectable in the conditioned medium under basal conditions or after stimulation with hGH. In conclusion, the results obtained in this study suggest that GH exerts direct anabolic effects on human osteoblasts.     

Human growth hormone and growth hormone releasing hormone: A double-masked,placebo-controlled study of their effects on bone metabolism in elderly women

We treated 42 postmenopausal women with decreased bone mass for 12 weeks with human growth hormone, growth hormone releasing hormone, or placebo. Bone density and biochemical markers were determined before and during treatment, and 4 weeks after withdrawal. Biochemical markers of bone formation and resorption increased significantly in the group treated with growth hormone, whereas no changes were seen in the other groups. After withdrawal of therapy the bone markers declined without reaching baseline values. Bone density in the forearm, spine and proximal femur was unchanged in all groups. We conclude that treatment with growth hormone stimulates bone metabolism in elderly postmenopausal women with decreased bone mass.     

生长激素治疗中老年男性骨质疏松的研究进展

骨质疏松是中老年人群中的一种常见病,是中老年人不可避免的一种骨质老化现象。目前全球骨质疏松患者超过1亿人,国内对7省市4.87万人的调查结果显示,60岁以上人群骨质疏松症的患病率为22.6%。骨质疏松可以导致骨折,可明显增加老年人病死率和致残率,调查显示,骨质疏松性骨折后1年内男性死亡率(31﹪)是女性(17﹪)的2倍。有研究表明中老年骨质疏松与生长激素分泌减少有一定关系,小剂量补充治疗后骨骼密度明显增加。本文就生长激素与中老年男性骨质疏松的关系及其补充治疗的可能作用机制作一综述。     

补骨合剂调节大鼠骨髓间充质细胞分化机制的研究

目的：应用体外培养骨髓间充质细胞,在细胞和分子水平观察补骨合剂对细胞分化的影响,探讨补骨合剂治疗骨质疏松症的机制。方法：分离SD大鼠骨髓间充质细胞,通过形态学、碱性磷酸酶、细胞内骨钙素、转化生长因子β1基因表达等指标,对重组人骨形态发生蛋白2(rhBMP2)诱导下的骨髓间充质细胞向成骨细胞分化的程度进行探讨。结果：一定浓度的补骨合剂可促进分化中的骨髓间充质细胞分泌碱性磷酸酶和骨钙素,增强rhBMP2的活性,促进分化中的骨髓间充质细胞表达转化生长因子β1,补骨合剂的这种促进骨髓间充质细胞分化作用与密钙息基本相同。结论：补骨合剂不仅可以增强rhBMP2的活性,促进分化中的骨髓间充质细胞表达转化生长因子β1,大量分泌Ⅰ型胶原,以利于钙盐沉积;还可以促进rhBMP2诱导的骨髓间充质细胞分泌碱性磷酸酶和骨钙素,促进骨髓间充质细胞向成骨细胞表型分化．从而促进钙、磷在骨表面沉积。     

Uninterrupted oral bisphosphonate (pamidronate) therapy of patients with osteoporosis is not associated with chronic stimulation of parathyroid hormone secretion

We have previously reported that long-term uninterrupted treatment of patients with osteoporosis with oral pamidronate is associated with increases in bone mineral content (BMC) of the lumbar spine which could not be explained by the antiresorptive action of the drug alone, raising the possibility of an additional effect of the treatment on skeletal tissue. Administration of suppressive doses of the bisphosphonate to patients with excessive osteoclastic resorption is followed by transient decreases in serum calcium and increases in parathyroid hormone (PTH) concentrations. It is possible, therefore, that chronic pamidronate therapy may stimulate PTH secretion, which in turn has been previously shown to have anabolic effects on the skeleton. To test this hypothesis we examined the changes in serum calcium, PTH and phosphate concentrations every 6 months in 33 patients with vertebral osteoporosis and no biochemical evidence of increased bone turnover, treated with oral pamidronate 150 mg daily. Serum alkaline phosphatase and urinary hydroxyproline excretion decreased significantly by 20% and 28%, respectively, after 6 months of treatment and remained at this level for the following 18 months. These changes were associated with significant increases in spinal BMC, as expected. Serum calcium, PTH and phosphate did not change from baseline values either in the whole group or when the patients were divided according to the use or not of calcium supplements. Our results exclude chronic stimulation of PTH secretion as a factor contributing to long-term increases in bone mass in patients with osteoporosis and adequate calcium intake during continuous oral pamidronate therapy.     

人骨髓基质细胞培养及向成骨细胞的诱导分化

目的研究人骨髓基质细胞体外培养及向成骨细胞诱导分化的实验方法。方法采用梯度离心法获得人骨髓基质细胞，细胞纯化后使用分化培养液将骨髓基质细胞向成骨细胞方向诱导分化。通过形态学观察、生化指标检测、细胞染色和矿化结节测定等方法，确定细胞的功能状态和分化程度。结果显微镜观察显示获得的人骨髓基质细胞生长状况良好，生化指标稳定；经分化培养液培养的细胞增殖速度明显减慢，生长状态平稳。细胞在分化培养过程中，上清液中碱性磷酸酶分泌量明显增加，细胞碱性磷酸酶染色明显浓染，随时间呈显著增强趋势；采用常规培养液培养的骨髓基质细胞，在汇合后不能形成明显的矿化结节。用分化培养液培养的人骨髓基质细胞，在14d时开始出现矿化结节，在21d时呈现密集的茜素红染色矿化结节。结论梯度离心法获得的人骨髓基质细胞生长情况良好，功能状态稳定；体外培养的人骨髓基质细胞在一定条件下可以向成骨细胞方向诱导分化，并具有良好的成骨细胞功能特征，可以满足进一步研究的需要。     

Growth hormone secretion and sensitivity in men with idiopathic osteoporosis

Previous studies have suggested that insulin-like growth factor-I (IGF-I) and its binding proteins (IGFBPs) have a pathogenetic role in idiopathic osteoporosis. To investigate this question further we compared 20 men with idiopathic osteoporosis with 12 healthy, age-matched men regarding growth hormone (GH) secretion and sensitivity. GH samples were drawn every 30 minutes for 24 hours from 12 of the patients and all controls, and cumulated GH secretion (24hGH) was derived. Peak GH secretion (peakGH) was provoked by an insulin tolerance test. There were no differences between the groups in serum IGF-I (162 ± 30 vs 163 ± 47 μg/liter, mean ± SD), IGFBP-3 (2474 ± 263 vs 2568 ± 197 μg/liter), 24hGH (1.34 ± 1.26 vs 0.79 ± 0.43 U), or peakGH (53.0 ± 21.5 vs 44.1 ± 19.8 mU/liter). Patients and controls were given GH (2.4 U/day) for 1 week. Serum levels of markers for bone turnover increased significantly in both groups, with no difference in response to GH between the groups. The increase in urinary bone resorption markers was only significant in the controls. In the patients, but not in the controls, there were significant positive correlations between indices for GH secretion and markers for bone turnover at baseline and significant negative correlations with relative changes in bone markers during GH treatment. In this study no difference in GH secretion was found between men with idiopathic osteoporosis and controls, but the findings suggest that the GH/IGF-I axis could play a regulatory role in bone metabolism in men with this condition.     

Alteration of the circadian rhythm of intact parathyroid hormone and serum phosphate in women with established postmenopausal osteoporosis

Several studies have established that the circulating concentration of intact parathyroid hormone, PTH (1–84), over 24 h follows a circadian rhythm. The importance of this circadian rhythm is not known although some authors have detected alterations in the rhythm in metabolic bone disease and following dietary manipulation. We have studied the circadian rhythm of PTH (1–84) in 8 premenopausal women, 8 postmenopausal women with established osteoporosis and 8 postmenopausal women with no evidence of osteoporosis. Blood samples were obtained at 30-min intervals over a 24-h period and significant differences were found in the profiles of PTH (1–84) and serum phosphate in the three groups studied. Premenopausal women possessed a nocturnal/early morning increase in PTH (1–84) and phosphate (between 2200 and 0700 hours), as did postmenopausal women without osteoporosis. In postmenopausal women with osteoporosis the nocturnal increase in PTH (1–84) and serum phosphate was absent and PTH (1–84) decreased during the period 2200-0700 hours. A shift in acrophase is observed between premenopausal and postmenopausal women without osteoporosis. No acrophase was found in postmenopausal women with osteoporosis for either PTH (1–84) or serum phosphate. No circadian rhythm, acrophase or significant amplitude was observed in serum adjusted calcium or ionized calcium in any group studied. Alterations in the circadian rhythms for PTH (1–84) and serum phosphate occur in patients with postmenopausal osteoporosis that suggest the normal dynamics of PTH (1–84) secretion may play a role in both calcium and phosphate metabolism and the bone remodelling process. Whether these changes are causative or a response to the pathology will require further investigation.     

性激素受体及相关生长因子在前列腺基质细胞中的表达

目的：探讨前列腺基质增生的发病机制与性激素以及相关生长因子的关系。方法：应用RT－PCR的方法研究了在人前列腺不同细胞类型中Smoothelin的表达，研究了雄、雌激素受体及相关生长因子在前列腺基质细胞中的表达，以及它们在前列腺基质细胞分化中表达的变化。结果：Smoothelin是前列腺平滑肌细胞特异性的标记蛋白；雄激素受体（AR）、碱性成纤维细胞生长因子（bFGF)、角化细胞生长因子（KGF）主要在前列腺成纤维细胞中表达，而雌激素受体（ER）、转移生长因子β1（TGFβ1）主要在平滑肌细胞中表达。结论：前列腺基质增生与雌激素受体和转移生长因子β1的过度表达密切相关。     

Establishment from mouse growth cartilage of clonal cell lines with responsiveness to parathyroid hormone,alkaline phosphatase activity,and ability to produce an endothelial cell growth inhibitor

Summary Three clonal cell lines with differences in responsiveness to parathyroid hormone (PTH), alkaline phosphatase activity, and ability to produce an endothelial cell growth inhibitor(s) during more than 3 years, more than 58 passages, in culture were established from growth cartilage (GC) of mouse ribs. In sparse, cultures the three clonal cell lines, MGC/T1.4, MGC/T1.17, and MGC/T1.18, all showed fibroblast-like morphology. However, as they became confluent, MGC/T1.4 cells became polygonal and then multilayered. MGC/T1.18 cells also became polygonal, but showed contact inhibition. MGC/T1.17 cells remained fibroblastic in confluent cultures and formed nodules when cultured for more than 7 days after they became confluent. These nodules calcified in the presence of β-glycerophosphate. Glycosaminoglycan (GAG) synthesis in the parent uncloned line, MGC/T1 cells, at early passages was about 50–75% of that of primary cultures of mouse GC cells. The GAG syntheses in the three clonal lines were much lower than that of primary cultures of GC cells Moreover, the sizes of proteoglycan monomers synthesized by these cells were not the same as that of cartilage-specific proteoglycan. The three clonal lines mainly synthesized type I collagen. PTH increased the intracellular cyclic AMP level in MGC/T1, MGC/T1.4, T1.17, and T1.18 cells: their maximal levels, observed after 2 minutes, were, respectively, about 160, 150, 70, and 200 times that of controls. The activity of alkaline phosphatase in MGC/T1.17 cells was higher than that in primary cultures of mouse GC cells, whereas those in MGC/T1 and T1.4 cells were comparable with that of GC cells, and that in MGC/T1.18 was lower. The three clonal lines, and especially MGC/T1.4, secreted a heat-stable, nondializable, growth inhibitor(s) of endothelial cells into the culture medium. Because of their different properties, these cell lines should be useful for studies on endochondral ossification, the actions of PTH on skeletal cells, and anti-angiogenesis factors.     

骨质疏松症成骨细胞生物学特征的体外研究

目的 建立成人和骨质疏松症成骨细胞培养方法；体外探讨骨质疏松成骨细胞特征性表型的变化。方法 取年轻人和骨质疏松患者，采用骨碎片培养和酶消化技术，分离、培养成骨细胞，体外观察细胞生长和转化状况，并用生物化学、放射免疫和RT—PCR技术检测成骨细胞表型。结果 骨碎片培养和多阶段酶消化相结合，可获得数量多、纯度高的成骨细胞；体外培养条件下，生长中、晚期的骨质疏松症成骨细胞可向成纤维细胞样细胞形态转化，骨钙素、碱性磷酸酶和I型胶原的分泌功能部分丧失，并表达非特异性Ⅲ型胶原，而呈现成纤维细胞样变。结论 骨质疏松成骨细胞可发生退变，并有可能是骨质疏松症发生骨基质成分不足、骨基质钙化不完全、骨组织结构改建不良的重要因素之一。     

生长激素干预肝癌细胞及共培养脐静脉内皮细胞生长

目的 观察重组人生长激素(rhGH)对人肝癌细胞株SMMC-7721和Bel-7402,共培养脐静脉内皮细胞株ECV304增殖的影响.方法 ECV304及其与Bel-7402、SMMC-7721共培养三组分别行rhGH 50及250μg/L、贝伐单抗50 mg/L及其联合rhGH 250 μg/L的干预.Bel-7402和SMMC-7721分别接受两浓度rhGH干预.流式细胞术测细胞周期比.逆转录-聚合酶链反应(RT-PCR)/酶联免疫吸附试验(ELISA)法测定肝癌细胞血管内皮细胞生长因子(VEGF)mRNA/蛋白表达.结果 Bel-7402表达生长激素受体(GHR),SMMC-7721不表达GHR;两剂量rhGH干预后Bel-7402的PI指数(42.69.4±0.40和44.10±0.19)较空白组(39.40±0.48)明显升高,同环境ECV304的PI指数显著升高[(45.62±O.87)%和(47.64 ±1.28)%,呈浓度依赖(P<0.05);贝伐单抗干预后,Bel-7402共培养ECV304的PI指数显著下降[(42.69 ±1.05)%和(42.84±0.77)%,P<0.05).与对照组[mRNA/蛋白:(14.179±3.110)ns/L/0.171±0.064]比较,两rhGH浓度干预,Bel-7402表达VEGF mRNA/蛋白水平也显著增加[(125.499 4-2.680)和(131.312 4-2.560)ng/L/0.296 ±0.024和0.460 ±0.037,P<0.05];SMMC-7721各组均未出现类似情况.结论 rhGH明显促GHR阳性表达人肝癌细胞株Bel-7402增殖,促其过量分泌VEGF致共培养内皮细胞ECV304增殖.     

Factors related to spinal mobility in patients with postmenopausal osteoporosis

Quality of life in patients with spinal osteoporosis is impaired by the decline of spinal mobility. However, the factors related to the spinal mobility in these patients are still unclear. We evaluated the possible factors affecting spinal mobility in patients with postmenopausal osteoporosis. A total of 128 postmenopausal women with osteoporosis aged over 50 years (mean, 70 years) were included in this study. The thoracic and lumbar kyphosis angles and range of motion (ROM) of the total spine were measured in the upright position and at maximum flexion/extension with a computer-assisted device. The paravertebral muscle thicknesses (PVMT) of thoracic and lumbar spine in the upright position were measured using an ultrasound unit. The number of vertebral fractures was evaluated with radiographs of the spine. Isometric back extensor strength (BES) was evaluated with a strain-gauge dynamometer. Correlations between these variables were then analyzed. Age ( r =–0.412), lumbar kyphosis angle ( r =–0.284), BES ( r =0.369), PVMT at the lumbar spine ( r =0.227) and the number of vertebral fractures ( r =–0.260) showed significant correlations with total spinal ROM ( P <0.05). However, no significant correlations were observed between the total spinal ROM and PVMT at the thoracic spine ( r =–0.069) or thoracic kyphosis angle ( r =–0.138). Multiple regression analysis revealed that the BES was the most significant contributor to the total spinal ROM. The present study suggests a possible association between BES and spinal mobility in patients with postmenopausal osteoporosis.     

Influence of growth hormone on maintenance of capillary-like structures in an in vitro model of stromal vascular tissue--results from morphometric analysis

The in vitro development of a vascular stroma might be a solution for the engineering of vascularized tissues, however, in vitro stability of capillary-like structures is limited. In order to test the influence on maintenance of capillary-like structures, human growth hormone (hGH) was added in concentrations of 0.5, 5, 50, and 500 ng/mL in an in vitro model of stromal vascular tissue. The angiogenic response and maintenance of capillary-like structures were analyzed by means of confocal laser scanning microscopy (CLSM) and image analysis after 8, 16, and 32 days of culture. The highest angiogenic response was observed with a concentration of 50 ng/mL hGH. With the addition of 50 and 500 ng/mL, the length of capillary-like structures could be maintained on high levels up to the 32nd day of culture, whereas with 5 ng/mL values dropped to the level of the control group. The proposed technique of analysis allows quantification of capillary-like network formation and might be useful for tissue engineering applications.     

音猬因子修饰的骨髓间充质干细胞治疗大鼠骨质疏松的实验研究

目的探讨转染音猬因子的骨髓间充值干细胞移植对卵巢切除骨质疏松大鼠的治疗作用。 方法选取40只雌性SD大鼠，分为假手术组、模型组、骨髓间充值干细胞（BMSCs）移植组和音猬因子修饰的骨髓间充值干细胞（Shh-BMSCs）移植组，每组10只动物。假手术组手术中仅摘除卵巢附近的脂肪组织，但不摘除卵巢。其余的3组均进行双侧的卵巢切除手术，建立骨质疏松模型，在骨质疏松造模后的2个月，BMSCs移植组和Shh-BMSCs移植组分别通过大鼠的尾静脉注射BMSCs与Shh-BMSCs（第四代，约2*10⁶个干细胞），模型组动物注射等量PBS液体。在干细胞移植2 w后，检测尾静脉中血清钙、磷、碱性磷酸酶水平，同时采用双能X射线骨密度仪测量大鼠的股骨、腰椎及全身骨密度，micro-CT扫描进行胫骨的形态计量学指标分析。 结果（1）与假手术组相比，模型组的大鼠骨小梁厚度、骨小梁数量和骨体积分数均明显减少，大鼠的骨密度、血清钙与碱性磷酸酶明显降低，而大鼠的血清磷水平明显升高，差异有统计学意义（P<0.05），以上表明骨质疏松大鼠模型成功制备。（2）与模型组相比，BMSCs组的大鼠血清钙和和碱性磷酸酶明显升高，而血清磷水平明显降低，差异有统计学意义（P<0.05）。与模型组、BMSCs组相比，Shh-BMSCs组大鼠血清钙、碱性磷酸酶水平明显升高，而血清磷水平明显降低，差异有统计学意义（P<0.05）。（3）同模型组的骨密度相比，BMSCs组大鼠的骨密度明显升高，差异有统计学意义（P<0.05）；与模型组、BMSCs组相比，Shh-BMSCs组大鼠的骨密度明显升高，差异有统计学意义（P<0.05）。（4）同模型组相比，BMSCs组的大鼠骨小梁厚度、骨小梁数量和骨体积分数均明显增加，差异有统计学意义（P<0.05），与模型组和BMSCs组相比，Shh-BMSCs组的大鼠骨小梁厚度、骨小梁数量和骨体积分数均明显增加，差异有统计学意义（P<0.05）。 结论Shh-BMSCs细胞移植后能够治疗大鼠卵巢切除后的骨质疏松。     

Intermittent treatment with parathyroid hormone (PTH) as well as a non-peptide small molecule agonist of the PTH1 receptor inhibits adipocyte differentiation in human bone marrow stromal cells

Whereas continuous PTH infusion increases bone resorption and bone loss, intermittent PTH treatment stimulates bone formation, in part, via reactivation of quiescent bone surfaces and reducing osteoblast apoptosis. We investigated the possibility that intermittent and continuous PTH treatment also differentially regulates osteogenic and adipocytic lineage commitment of bone marrow stromal progenitor/mesenchymal stem cells (MSC). The MSC were cultured under mildly adipogenic conditions in medium supplemented with dexamethasone, insulin, isobutyl-methylxanthine and troglitazone (DIIT), and treated with 50 nM human PTH(1–34) for either 1 h/day or continuously (PTH replenished every 48 h). After 6 days, cells treated with PTH for 1 h/day retained their normal fibroblastic appearance whereas those treated continuously adopted a polygonal, irregular morphology. After 12–18 days numerous lipid vacuole and oil red O-positive adipocytes had developed in cultures treated with DIIT alone, or with DIIT and continuous PTH. In contrast, adipocyte number was reduced and alkaline phosphatase staining increased in the cultures treated with DIIT and 1 h/day PTH, indicating suppression of adipogenesis and possible promotion of early osteoblastic differentiation. Furthermore, intermittent but not continuous PTH treatment suppressed markers of differentiated adipocytes such as mRNA expression of lipoprotein lipase and PPARγ as well as glycerol 3-phosphate dehydrogenase activity. All of these effects of intermittent PTH were also produced by a 1 h/day treatment with AH3960 (30 μM), a small molecule, non-peptide agonist of the PTH1 receptor. AH3960, like PTH, activates both the cAMP and calcium signaling pathways. Treatment with the adenylyl cyclase activator forskolin for 1 h/day, mimicked the anti-adipogenic effect of intermittent PTH, whereas pretreatment with the protein kinase-A inhibitor H89 prior to intermittent PTH resulted in almost complete conversion to adipocytes. In contrast, the MAP kinase inhibitor PD 98059 failed to prevent the anti-adipocytic effect of intermittent PTH, suggesting that the inhibitory effect of PTH on adipocyte differentiation is predominantly cAMP-dependent. These results demonstrate a differential effect of PTH1 receptor agonists on the adipocytic commitment and differentiation of adult human bone marrow mesenchymal stem cells. This response may represent an additional mechanism that contributes to the overall bone anabolic action of intermittent PTH.     

In vitro study of osteoblastic cells from patients with idiopathic osteoporosis and comparison with cells from non-osteoporotic controls [1]

We have examined bone cells derived from iliac crest trabecular explants of 30 patients with idiopathic osteoporosis and 45 control subjects in order to determine whether intrinsic abnormalities in osteoblast function may contribute to the decreased bone formation observed in this disease. Bone cells isolated from all subjects expressed several in vitro characteristics of the osteoblast phenotype including adenylate cyclase responsiveness to parathyroid hormone (PTH) and prostaglandin E₁ (PGE₁), basal and 1,25(OH)₂D₃-stimulated alkaline phosphatase activity and osteocalcin production. Results were compared amongst three subject groups: young controls less than 40 years old, older controls over 40 years old, and osteoporotics. Osteoporotic cells were found in general to be fully active in vitro. There were no differences between osteoporotic and control cells in their basal levels of adenylate cyclase, or alkaline phosphatase, in their growth rates, or cell morphology. The cyclic AMP (cAMP) response to PTH was significantly lower in osteoporotic cells (71%,p<0.01) and older control cells (64% ,p<0.005) relative to the response in cells from younger controls, suggesting that the decreased responsiveness in osteoporotic cells was due to subject age rather than the osteoporotic state. At the same time, the cAMP responses to PGE₁ and cholera toxin were similar in cells from all three subject groups. The response to forskolin was reduced to about 40% in osteoporotic cells compared with controls, but this was not mirrored by similar differences in the responses to PTH, PGE₁ or cholera toxin, suggesting that the availability of catalytic subunits is not rate-limiting in these cells. l,25 (OH)₂D₃-stimulated osteocalcin production was 220% higher in osteoporotics than in older controls, but the numbers tested were small and the difference did not reach significance. The one significant abnormality we observed in osteoporotic cells was in alkaline phosphatase activity: 1,25(OH)₂D₃-stimulated alkaline phosphatase activity was twofold higher in osteoporotics than in younger (p<0.05), older (p<0.05) and pooled controls (p<0.025). The significance of this finding is unknown, but we postulate that it may reflect an intrinsic abnormality in osteoblast function in patients with idiopathic osteoporosis.     

Short-term recombinant human growth hormone therapy does not modify growth hormone, thyrotropin and prolactin responses to thyrotropin-releasing hormone in adult dialysis patients.

BACKGROUND: We recently have reported the first randomized, controlled study on the effects of short-term recombinant human growth hormone (rhGH|| therapy on the nutritional status of a group of malnourished adult dialysis patients. In order to evaluate whether rhGH administration exerts any influence on GH, thyrotropin (TSH|| and prolactin (PRL|| responses to TSH-releasing hormone (TRH||, we assessed these responses before and after rhGH therapy. METHODS: GH, PRL and TSH responses to TRH before and 1 month after rhGH therapy in a group of adult dialysis patients were evaluated. Seventeen dialysis patients (11 on continuous ambulatory peritoneal dialysis/six on haemodialysis|| were studied (rhGH group, n=8; control group, n=9||. In the rhGH group, 0.2 IU/kg/day rhGH was administered subcutaneously. Each patient was tested with TRH (400 microg bolus i.v.|| on two separate occasions, just before and immediately after the treatment period. RESULTS: rhGH treatment did not modify baseline serum GH concentrations (6.6+/-2.7 vs 4.1+/-1.1 microg/l||, paradoxical GH responses to TRH (six out of eight patients||, GH peak (11.9+/-4.6 vs 11.2+/-5.3 microg/l, NS|| or area under the secretory curve of GH (GH AUC; 19.1+/-4.5 vs 12.1+/-3.1 microg/h/l||. Both basal PRL (35.5+/-7.1 vs 36.7+/-8.6 microg/l|| and TSH (2.3+/-1.1 vs 2.8+/-1.7 mU/l|| concentrations, as well as their responses to TRH stimulation (PRL peak, 59.9+/-16.6 vs 59. 5+/-11.8 microg/l; TSH peak, 6.2+/-2.6 vs 7.1+/-3.9 mU/l||, were also unaffected by rhGH therapy. CONCLUSION: These results suggest that short-term rhGH therapy does not significantly influence the magnitude of the somatotropic, lactotropic or thyrotropic response to TRH in adult dialysis patients. However, this finding has to be interpreted with caution due to the two different patient groups included in this study.     

In vivo expression of human growth hormone by genetically modified murine bone marrow stromal cells and its effect on the cells in vitro

Human growth hormone (hGH) is frequently used clinically for growth abnormalities in children and also in adults with growth hormone deficiency. The hormone is usually administered to the individuals by frequent injections. In the present study we investigated the potential of bone marrow stromal cells as vehicles to deliver the GH in vivo by infusion of cells transduced with hGH cDNA into mice femurs. The effect of the hormone on the transduced cells in vitro was also assessed. Bone marrow stromal cells established from a mouse model of human osteogenesis imperfecta mice (oim) were transduced with a retrovirus containing hGH and neomycin resistance genes. The hGH-expressing cells were selected in a medium containing G418 and were then assessed for the hGH expression in vitro. The selected cells synthesized 15 ng/10(6) cells of hGH per 24 h in vitro and exhibited alkaline phosphatase activity when they were treated with the human recombinant bone morphogenetic protein 2 (rhBMP-2). The transduced cells also proliferated faster than the LacZ transduced cells but they did not exhibit a higher rate of matrix synthesis. When 2 x 10(6) hGH+ cells were injected into the femurs of mice, hGH was detected in the serum of the recipient mice up to 10 days after injection. The highest level of growth hormone expression, 750 pg/ml, was detected in the serum of the recipient mice I day after injection of the transduced cells. hGH was also detected in the medium conditioned by cells that were flushed from the femurs of the recipient mice at 1, 3, and 6 days after cell injection. These data indicate that bone marrow stromal cells could potentially be used therapeutically for the delivery of GH or any other therapeutic proteins targeted for bone. The data also suggest that GH may exert its effects on bone marrow stromal cells by increasing their rate of proliferation.