Responses of fetal rat bone cells and bone organ cultures to the ionophore,A23187

The ionophore A23187 produced a rapid transient increase in the rate of calcium uptake by isolated fetal rat bone cells. There was no effect on calcium efflux or total cellular calcium. The magnitude of the effect on influx was amplified when the cell were incubated at 4°C. Cellular metabolic functions and resorption of cultured fetal rat bones (release of⁴⁵Ca from pre-labeled long bone) were affected by A23187 in a biphasic manner: cell cyclic AMP (cAMP) was increased by 0.1 and 0.3 g/ml of the ionophore, whereas 10 g/ml was either ineffective or lowered the cAMP levels. The high A23187 concentration abolished the stimulatory effects of parathyroid hormone and methylisobutylxanthine. Concentrations of 0.1 and 0.3 g/ml A23187 stimulated bone resorption. The effect was abolished by calcitonin. Ionophore concentrations above 1 g/ml produced less bone resorption. These higher concentrations antagonized the bone-resorbing effect of parathyroid hormone and 1,25-dihydroxyvitamin D₃. A23187 at 5 and 10 g/ml decreased bone cell lactate and ATP. Thus at low concentrations, A23187 produced effects on bone similar to those of parathyroid hormone, suggesting that calcium is the primary initiator of PTH-induced bone resorption. At the higher concentrations A23187 may have a general inhibitory effect on cell metabolism.     

The ultrastructure of the extracellular phase of bone as observed in frozen thin sections

Summary The fine structure of the extracellular phase of avian medullary bone and embryonic chick femur was examined in thin sections prepared by ultracryotomy and ultramicroincineration. Since contact with solutions was completely avoided, little or no loss or dislocation of mineral constituents could occur. Amorphous bone mineral (ABM) was present in two forms: as 15–30 nm spheres and as a structure-free haze. Removal of all organic material by low temperature ashing left the ABM intact. Crystals were usually associated with the ABM. In newly ossifying regions clusters or nodules of randomly oriented crystals and ABM appeared to coalesce when they reached approximately 1 m in diameter. In highly calcified regions crystals appeared to be oriented along collagen fibers. ABM did not appear to be associated with collagen. Unmineralized collagen was visible in osteoid after staining with dry OsO₄ vapor and it appeared to be diverted around nodules. Structures which resembled matrix vesicles were present. Selected area electron diffraction patterns indicated the presence of hydroxyapatite.     

Cancellous bone in the anterior part of the iliac crest

Summary Calcified tissue in the iliac crest and the adjoining ala of the ilium was investigated by scanning electron micrographs of thick, polished sections from which the marrow had been removed. Some quantitative properties of the trabeculae and of the marrow spaces were obtained from measurements on the images of the polished surfaces. Most of the cortex of the crest was porous, about 25% void, of varying thickness, intruding into the cancellous space in some regions. A structure containing about 35% by volume of bone was found at and near the anterior superior spine. Compact bone of normal appearance began as thin medial and proximal sheets below the crest, and thickened until at 20–30 mm it was substantial. The cancellous bone contained by these structures was varied. Two main zones were distinguished, whose junction ran from just below the anterior superior spine to the lower portion of the iliac fossa. In the lateral zone, adjacent to the crest, there were arch-like structures, commencing from the medial and proximal walls, and meeting, or even crossing, near the centre. The medial zone was distinguished by large marrow cavities and strongly orientated trabeculae. The relative volume of bone was similar in the two zones, falling from a maximum of 15–20% to about 5% in the regions of the anterior inferior spine and the iliac fossa. The average width of the trabeculae was significantly greater in the medial than in the lateral zone (W _b (m)0.16 mm, W_b(l)0.12 mm). Inclusions of very heavily constructed trabeculae, having average widths of about 0.35 mm, were found in both zones.     

枕下-颞下联合入路颞骨良性肿瘤切除术-附3例报告

目的:介绍枕下-颞下联合入路切除颞骨良性肿瘤的方法及体会。方法:对3例颞枕骨化纤维瘤、颞骨纤维异常增殖症、颞骨血管瘤的巨大颞骨良性肿瘤,均采用枕下-颞下联合入路(倒钩形切口)。辅以显微外科技术进行手术摘除肿瘤。结果:3例均基本完整切除肿瘤,无颅内外感染、脑脊液漏、迷路及颅神经损伤等并发症,经术后随访1.5年～2年未发现肿瘤复发。结论:采用枕下-颞下联合入路切除颞枕骨良性肿瘤可获理想的暴露,最大范围切除肿瘤,可避免损伤毗邻的颅神经、血管以及内耳结构,值得推广。     

Down-Regulation of Osteoblastic Cell Differentiation by Epidermal Growth Factor Receptor

The role of epidermal growth factor receptors (EGF-R) in osteogenic cell differentiation was investigated using preosteoblastic MC3T3-E1 (MC3T3) cells and osteoblast-like ROS 17/2.8 (ROS) cells. When cultured in the presence of β-glycerophosphate (GP) and ascorbic acid (AA), MC3T3 cells underwent spontaneous differentiation into osteoblasts which was confirmed as they expressed osteoblast markers such as alkaline phosphatase (ALP), bone sialoprotein (BSP) and osteocalcin (OC). Interestingly, the number of EGF-binding sites decreased during their differentiation into osteoblasts, and the osteogenic protein-1 (OP-1) treatment, which accelerated their differentiation, lowered the number of EGF-binding sites even further. On the other hand, ROS cells with high expression levels of osteoblast markers and no EGF-R, after being transfected with human EGF-R cDNA (EROS cells), expressed numerous EGF-binding sites as well as EGF-R mRNA and protein; in the process, they ceased to express osteoblast markers, indicating their dedifferentiation into osteoprogenitor cells. Both MC3T3 and EROS cells showed increased cell growth in response to EGF, whereas ROS cells did not. These results imply that the EGF/EGF-R system in osteogenic cells has a crucial function in osteoblast phenotype suppression and osteogenic cell proliferation.     

Calcaneus Bone Mineral Density is Lower Among Men and Women with Lower Physical Performance

Fracture risk is influenced by both bone strength and by falls. Measures of physical function and performance are predictors of falls. However, the interrelationships among bone mineral density (BMD), regular physical activity, and measures of physical performance are not well known. We studied 447 community-dwelling Japanese people aged 40 years and over (96 men and 351 women) to examine the association of calcaneus BMD with measures of physical performance (grip strength, walking speed, chair stand, and functional reach) and regular physical activity. Calcaneus BMD decreased with age by approximately 25% in men and 42% in women. Measures of physical performance decreased with age by approximately 30% in both genders, however, performance on the chair stand test declined by approximately 60%. There were only minimal differences in performance measures and calcaneus BMD between people with and those without regular physical activity in both genders, and most differences were not significant. However, there were significant BMD increases of 3–6% per standard deviation (SD) increase in all performance measures for women and a 7% increase in BMD per SD increase in grip strength for men, after adjusting for age. These associations remained after additional adjustment for body mass index and regular physical activity. These findings suggest that bone density and physical function decline markedly in both men and women with age, and that low BMD and poor function tend to occur together, which would increase fracture risk more than either risk factor alone. Received: 9 August 1999 / Accepted: 4 February 2000     

Gonadal Steroids and Bone Metabolism in Young Castrated Male Rats

At 45 days of age, 40 male Wistar rats were castrated, then randomly divided into four groups, S.C. injected for 60 days after surgery either with 17β-estradiol (E) 10 μg/kg BW/48 hours, progesterone (P) 140 μg/kg BW/48 hours, dihydrotestosterone (D) 2 μg/kg BW/48 hours, E + P + D same doses, or solvent alone (CX). Ten other rats were sham-operated (SH) and used as controls. Animals were put in balance to determine Ca and phosphorus (Pi) intestinal apparent absorption (IA Ca, IA Pi) and urinary pyridinium crosslinks excretion. Plasma was collected for measurement of intact-parathyroid hormone (PTH), calcitonin (CT), insulin-like growth factor I (IGF-I), 1,25 dihydroxyvitamin D (1,25(OH)₂D), Ca, and Pi. Orchidectomy induced marked seminal vesicles atrophy and increased plasma CT, PTH, and Ca concentrations. IA Ca was significantly higher in P rats, however, neither castration nor any other treatment had significant effects. Orchidectomy decreased femoral length, dry weight, and Ca content, whereas E or D given alone or together with P improved endochondral growth and enhanced femoral Ca content. Again, bone mineral density was lowered by orchidectomy and reestablished by both E and EPD, even above SH values, this effect being more important at the metaphyseal levels. Urinary pyridinium cross-links excretion and plasma osteocalcin concentrations were higher in the CX animals than in the controls. Although E and D given alone did reduce both biochemical turnover markers, they showed additive effect when given together (EPD). In conclusion, in the young castrated male rat, E was more efficient than D for preventing bone loss, the most important effect being induced by a combination of E + P + D. Received: 28 June 1999 / Accepted: 12 January 2000     

Vitamin D and Estrogen Receptor Polymorphisms and Bone Mineral Changes in Postpartum Women

BsmI restriction fragment length polymorphism (RFLP) of the vitamin D receptor (VDR) gene and PvuII RFLPs of the estrogen receptor (ER) gene and their relation to changes in areal bone mineral density (BMD) were examined in 43 healthy postpartum Finnish women aged 31.3 (SD 4.7) years. BMD was measured by dual energy X-ray absorptiometry at lumbar spine, right femoral neck, and dominant distal radius immediately after delivery, 1 month after resumption of menses, and 1 year thereafter. The RFLPs were represented as Bb (BsmI) and Pp (PvuII), the capital letters denoting the absence of and the small letters the presence of the restriction sites. The frequency of VDR alleles was as follows: bb (20.9%), Bb (60.5%), and BB (18.6%), and that of ER alleles was pp (39.5%), Pp (51.2%), and PP (9.3%). Altogether, BMD decreased significantly during postpartum amenorrhea at all sites [the mean bone loss ranging from −1.2 (SD 3.6)% at the distal radius to −3.7 (2.9)% at the femoral neck], and increased after resumption of menses [the 1-year follow-up BMD values ranging from −1.0 (2.4)% at the femoral neck to +3.3 (4.0)% at the lumbar spine as compared with baseline]. No obvious genotype-related differences were found between these changes. These results suggest that the BsmI and PvuII polymorphisms may not have substantial influence on BMD changes postpartum. Received: 20 November 1998 / Accepted: 30 September 1999     

自体微小颗粒骨复合碱性成纤维细胞生长因子修复节段性骨缺损的实验研究

目的 探讨自体微小颗粒骨复合碱性成纤维细胞生长因子(basic fibroblast growth factor，bFGF)治疗骨缺损的效果，为其临床应用提供实验依据。方法 将36只新西兰白兔双侧桡骨中上段制成骨缺损模型，分别植入自体微小颗粒骨、bFGF和自体微小颗粒骨与bFGF的复合物，同时设空白对照组，分别手术后第2、4、8周进行大体观察，X检查及组织学检查。术后第8周进行骨密度测定，比较修复骨缺损的疗效。结果 经大体观察、组织学及X线检查发现，术后第8周自体微小颗粒骨复合bFGF能更有效地修复节段性骨缺损，对照组无骨愈合迹象。术后第8周骨密度测定证明自体微小颗粒骨复合bFGF组骨密度值明显高于对照组。结论 自体微小颗粒骨复合bFGF组成骨速度快，成骨量多，修复骨缺损的能力明显强于自体微小颗粒骨组及单纯bFGF组。     

大肠癌患者骨髓微转移的基因研究

目的 探讨大肠癌患者骨髓中微转移基因检测的意义。方法 应用聚合酶链式反应－单链构象多态性分析（ＰＣＲ－ＳＳＣＰ）／银染技术,检测５１例大肠癌患者手术前、后不同时间骨髓中ｐ５３和Ｋ－ｒａｓ基因的突变状况。结果 ５１例患者术前骨髓中基因突变阳性者１９例,阳性率３７．２５％。阳性检出与Ｄｕｋｅ’ｓ分期、淋巴转移显著相关。术后经２～３个疗程的化疗后,１９例基因突变阳性的患者中１１例转阴。结论 大肠癌患者骨