Subdental synchondrosis and anatomy of the axis in aging: a histomorphometric study on 30 autopsy cases

During skeletal development the two ossification centers of the odontoid process are separated from the corpus of the axis by a subdental synchondrosis. This synchondrosis is thought to close and disappear spontaneously in adolescence although this has never been studied in detail. The basis of the dens is of clinical relevance as type II dens fractures are located here. To characterize the morphological architecture of the axis with particular attention to the subdental synchondrosis, the complete axis was harvested from thirty age-matched and gender-matched patients of the three different age groups at autopsy. The subdental synchondrosis and the bone structure of the dens, the basis of the dens and the body of C2 were analyzed by radiography, histology and quantitative histomorphometry. At the macroscopic level the persistency of the subdental synchondrosis in the adult cervical spine was detected in 87% (26 of 30) of the specimens. Histomorphometry revealed a residual disc blastema with an average size of 25.8% of the sagittal depth of the basis of the dens at this level. Bony integration of the synchondrosis was poor throughout all ages. Histologically a cartilaginous matrix composition of the subdental synchondrosis persisted throughout all groups. The trabecular microarchitecture demonstrated a significant reduction of bone volume and trabecular number as well as an increased trabecular separation within the basis of the dens as compared to the corpus or the dens of C2. This histomorphometric data regarding a poor integration of the synchondrosis into the trabecular network and the reduced bone mass within the basis of the dens might offer a previously underestimated explanation for the occurrence of type II dens fractures and their association with pseudoarthrosis, respectively.Matthias Gebauer and Christian Lohse contributed equally to this study and therefore share first authorship.     

1α-Hydroxyvitamin D2 Partially Dissociates Between Preservation of Cancellous Bone Mass and Effects on Calcium Homeostasis in Ovariectomized Rats

Vitamin D metabolites can prevent estrogen depletion-induced bone loss in ovariectomized (OVX) rats. Our aim was to compare the bone-protective effects of 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), 1α,25-dihydroxyvitamin D₂ (1,25(OH)₂D₂), 1α-hydroxyvitamin D₃ (1α(OH)D₃), and 1α-hydroxyvitamin D₂ (1α(OH)D₂) in OVX rats. 1α(OH)D₃ and 1α(OH)D₂ are thought to be activated in the liver to form 1,25(OH)₂D₃ and 1,25(OH)₂D₂, respectively. Forty-four 12-week-old female Fischer-344 rats were either OVX or sham-operated (SHAM). Groups of OVX rats (n = 7 each) received vehicle alone, 1,25(OH)₂D₃, 1,25(OH)₂D₂, 1α(OH)D₃, or 1α(OH)D₂, starting 2 weeks after surgery. All vitamin D metabolites were administered orally at a dose of 15 ng/day/rat. Urine and blood samples were collected 6, 9, 12, and 16 weeks after surgery. Serum samples were analyzed for total calcium and phosphate. Calcium, phosphate, creatinine, and free collagen cross-links (ELISA) were determined in urine. After tetracycline double labeling, the rats were sacrificed 16 weeks postsurgery, and the proximal tibiae and the first lumbar vertebrae were processed undecalcified for static and dynamic bone histomorphometry. 1,25(OH)₂D₃ and, to a slightly lesser extent, 1,25(OH)₂D₂ elevated vertebral cancellous bone mass in OVX rats to a level beyond that observed in SHAM animals, and both compounds increased serum calcium and urinary calcium excretion to similar extents. 1α(OH)D₃ and 1α(OH)D₂ resulted in a 64% and 84%, respectively, inhibition of ovariectomy-induced vertebral cancellous bone loss. In the proximal tibial metaphysis, all vitamin D metabolites tested could only partially prevent post-OVX trabecular bone loss, with a tendency for 1α(OH)D₃ to be the least active compound. The effects of 1α(OH)D₃ and 1α(OH)D₂ on calcium homeostasis differed markedly, however. The mean increase in urinary calcium excretion over the whole experiment was fivefold for 1α(OH)D₃, whereas the corresponding increase for 1α(OH)D₂ was only twofold. We conclude that, compared with 1α(OH)D₃, 1α(OH)D₂ combined at least equal or higher bone-protective activity in OVX rats with distinctly less pronounced effects on calcium homeostasis. This effect was not due to a differential action of the corresponding main activation products, 1,25(OH)₂D₃ and 1,25(OH)₂D₂. Received: 2 May 1996 / Accepted: 18 October 1996     

中药骨康对去卵巢大鼠腰椎骨形态计量学的影响

目的 探讨中药骨康对卵巢切除大鼠骨质疏松症的治疗作用。方法 选择6m龄SD大鼠48只。随机分为假手术模型组（Sham）、手术模型组（OVX）、尼尔雌醇组（E2）、中药骨康组。切除大鼠卵巢3m后。大鼠骨质疏松症模型制备成功，分别给予尼尔雌醇、中药骨康灌胃治疗，并与Sham组和OVX组对照。治疗3m后，体内双荧光标记，取第2腰椎包埋切片。全自动图像分析及松质骨骨形态计量学软件处理。观察中药对骨形态计量学参数的影响。结果 卵巢切除后大鼠骨小梁面积百分数（％Tb．Ar）下降35．84％，骨小梁数量（Tb．N）下降16．60％，骨小梁宽度（Tb．Th）下降25．79％，表明绝经后骨质疏松症动物模型成立。骨康治疗3个月后，与OVX组相比，Oc．N／mm^2下降42．80％，有显著性差异（P〈0．01）；％Tb．Ar、Tb．Th、Tb．N和MAR有上升趋势（P〉0．05）；15．Sp，％L．Pm、BFR／BS、BFR／TV和Oc．N／mm，BFR／BV有下降趋势（P〉0．05）。结论 中药骨康具有降低骨转换以及促进骨形成和抑制骨吸收的双重作用，说明中药骨康对骨质疏松有明显的治疗作用。     

骨形态计量学评价低钙对大鼠皮质骨的作用研究

目的 评价低钙饮食对大鼠皮质骨的影响。方法 3月龄SD普通级雄性大鼠40只，随机分为5组。第1、2组饲养1个月，分为正常对照组(1mol，ca1．0％)和极低钙组VLCD(1mol，Ca0．1％)，余下3组饲养3个月，分为正常对照组(3mol，Ca1．0％)、极低钙组VLCD(3mol，Ca0．1％)和低钙组LCD(3mol，Ca0．3％)。各组动物喂养包含对应钙含量的精制饲料，处死前进行双荧光标记。实验结束时，取左侧胫骨中段行骨形态计量学检测。结果 无论是低钙饮食1个月，还是3个月，无论是极度缺钙，还是仅有轻微的钙不足，胫骨中段横截面皮质骨始终未出现显著意义的变化，但骨内膜骨吸收有增加的趋势。结论 低钙对皮质骨作用不明显，这可能与机体在低钙状态下动用骨骼的次序或快慢有关。     

Histomorphometry of bone marrow biopsies in primary osteomyelofibrosis/-sclerosis (agnogenic myeloid metaplasia) - correlations between clinical and morphological features

Summary Histomorphometry was performed on representative trephine biopsies of the bone marrow on admission of 50 patients (21 male, 29 female-age 67 years) with so-called primary osteomyelofibrosis/-sclerosis (OMF) not preceded by any other subtype of chronic myeloproliferative disorders. This study was firstly aimed at testing correlations between histological features (amount of haematopoiesis, cytological aspects of mega-karyocytes, density of reticulin and collagen fibres and degree of osteosclerosis) and laboratory data, as well as spleen size and duration of relevant prediagnostic symptoms. Secondly, we concentrated on a discrimination of OMF patients into two sub-groups according to bone marrow morphology and clinical variables. Statistical evaluation of histomorphometric variables and haematological findings disclosed that there was a progressive fibro-osteosclerotic process in the evolution of disease features. Increase in medullary fibrosis was significantly paralleled by an abnormal or pleomorphic megakaryopoiesis in the bone marrow: there was an increase in irregularity of perimeters for megakaryocytes and naked nuclei combined with smaller sizes of these elements including the nuclei. Additionally, there was a greater number of pycnotic bare nuclei. A number of morphometric features (density of fibres, degree of osteosclerosis, amount of haematopoiesis) were associated with corresponding clinical data (spleen size, length of preclinical history). By consideration of a set of basic histomorphometric variables our co-hort of 50 patients could be divided into an early hyperplastic subtype with no or minimal medullary reticulin and another group with conspicuous fibrotic and osteosclerotic alterations of the bone marrow. It was noticeable that we found no significant correlation between amount of haematopoiesis or marrow cellularity with splenomegaly. This result suggests that splenic haematopoiesis (myeloid metaplasia) may represent an autonomous or neoplastic process and not only compensation for a failing fibro-osteosclerotic bone marrow.Supported by a grant from the Deutsche Forschungsgemeinschaft (DFG-Th 390/1-1)     

Extended treatment of primary osteoporosis by sodium fluoride combined with 25 hydroxycholecalciferol

Summary Nineteen patients suffering from primary osteoporosis, all having at least one vertebral collapse, initially received 50 mg of sodium fluoride alone per day for 6–18 months. Subsequently fluoride was associated with 25–50g of 25 OH cholecalciferol (calcifediol) per day for 6–18 months in 12 of these patients and 9 were treated for 31–58 months. As control group, 9 patients were given placebo for 6–18 months. The effect of the treatment was assessed by three methods: 1) the metacarpal index (MI) determined by radiogrammetry, 2) the calcium content of the hand bone (Ca) measured by local neutron activation, 3) the iliac bone histomorphometry. MI and (Ca) did not change significantly at any time in any group. In each group there was a significant increase in trabecular bone volume, osteoid volume, osteoid surfaces and a significant decrease in mineralization fronts. On the other hand, the changes in osteoblastic surfaces, osteoclastic surfaces, number of osteoclasts/mm2 were not significant in any group. No change was observed in the placebo group. These data suggest that the increase in the trabecular volume of fluorided bone is mainly due to the increase in osteoid which itself is due to a bone mineralization defect despite the association of calcifediol. This is probably one of the reasons why (Ca) does not change significantly.     

Comparison between radial bone mineral density measured by single photon absorptiometry and histomorphometric bone mass parameters measured on iliac crest biopsies

Summary Bone mineral density (BMD) measured by single photon absorptiometry (SPA) with a Moolsgard 1100^® device on the distal and proximal part of the radius was compared with histomorphometric parameters measured on iliac crest biopsies in 37 patients suffering from various bone disorders. In the whole population, a good correlation was observed between the cancellous bone volume (Cn-BV/TV) measured on iliac crest biopsies and BMD from both the proximal part of the radius (r=0.76, p < 0.001) and the distal part of the radius (r=0.73, p < 0.001). Significant, although weaker correlations, were also found between the cortical width and the BMD from the distal part (r=0.37, p < 0.001) and the proximal part (r=0.44, p < 0.001) of the radius. In the 14 untreated osteoporotic patients, only a significant Spearman correlation was observed between the iliac Cn-BV/TV and the proximal radial BMD (r=0.69, p < 0.05). It is thus not clear, whether radial proximal BMD correctly indicates cortical bone density in osteoporotic patients or not. The large internal variability of each of the two investigated methods and the small group of osteoporotic patients might explain the lack of correlation between the two methods in this group.     

Glucocorticoid-induced inhibition of osteoblastic bone formation in ewes: A biochemical and histomorphometric study

The mechanisms underlying glucocorticoid-induced osteoporosis in humans are a defect in bone formation associated with increased bone resorption. The latter may be due to elevated parathyroid hormone (PTH) levels induced by the impairment of intestinal calcium absorption caused by corticosteroids. In this study we analysed the effects of corticosteroids in old ewes, a potential model for the study of human bone turnover. Two groups of seven 9-year-old female sheep were selected. The first group was injected intramuscularly with a daily dose of 30 mg methylprednisone (MP) during the first 2 months and 15 mg during the last month. After 2 and 3 months of treatment, blood samples were taken. At the end of the experiment the animals were slaughtered and the iliac crest kept for bone histomorphometry. Serum osteocalcin (sOC) rapidly and markedly decreased in the MP-treated group compared with controls (–77%;p<0.01). In contrast, at the end of the experiment serum calcium and PTH levels were similar in both groups. Histomorphometric analysis showed a significant reduction in the wall width of trabecular packets. Dynamic parameters reflecting bone formation at the tissue and cell levels were significantly lower in the MP-treated group than in controls, with a highly significant decrease in the mineralization rate (MAR: –63%,p<0.05) and double-labeled perimeter (dLPm/B.Pm: –92%p<0.05). The bone formation rate (BFR/B.Pm) also decreased by 84% and the adjusted apposition rate (Aj.AR) by 80%. The increase in the total formation period was mainly due to an increase in the inactive period. Significant correlations were found between sOC and MAR, dLPm/B.Pm and BFR/B.Pm (withr respectively 0.67, 0.76 and 0.51). In conclusion, the effects of corticosteroid on ewe bone remodeling are essentially characterized by a major bone formation defect without evidence of secondary hyperparathyroidism, although this cannot be totally excluded by our results. Ewes treated with glucocorticoids could represent a good model for evaluating the effects of drugs candidates for all bone conditions characterized by reduced bone formation resulting from osteoblastic depression.     

Acute effects of deflazacort and prednisone on rates of mineralization and bone formation

The aims of this study were to determine (1) whether acute suppression of bone formation could be evaluated after the administration of corticosteroids in man by quantitative bone histomorphometry; and (2) whether there were significant differences between the effects of prednisone and its analog deflazacort. Thirteen patients who needed high-dose corticosteroid therapy were randomly allocated to two groups of treatment (prednisone or deflazacort). Quantitative bone histomorphometry, using the technique of triple labeling, and biochemical measurements of bone turnover were studied. There were no differences in biochemical indices of bone turnover between prednisone and deflazacort at the beginning and end of the 15 days of treatment course. During corticosteroid treatment, there were no significant changes in biochemical indices of bone turnover but a significant decline in total alkaline phosphatase (P<0.01). Histomorphometric indices, as revealed by measurements of tetracycline interval and extent of labeling, showed no significant differences in either mineral apposition rate or bone formation rate in the two groups. We conclude that the acute glucocorticoid suppression of bone turnover by glucocorticoids is not detectable within the first 2 weeks of treatment by histomorphometric techniques. No differences in bone effects of prednisone and deflazacort were detected in this short-term study.     

骨宝对正常大鼠骨组织形态学影响的定量研究

分别用５、１５ｇ／ｋｇ的骨宝给３月龄ＳＤ大鼠灌胃、每周６次，１８０ｄ。不脱钙骨制片，用图象定量法，测量大鼠胫骨近有小梁。结果：高剂量骨宝组与对照组比较，骨吸收减少３１％，骨面积增中３９％。