脊髓损伤后大鼠骨细胞形态学特点

目的：探讨脊髓损伤(Spinal Cord Injury,SCI)后大鼠骨细胞形态学变化特点及在SCI后骨代谢改变中的意义。方法：20只3个月龄SD大鼠均分为SCI组与对照组。SCI组于T10椎体处完全横断脊髓；对照组仅行椎板切除术，6周后处死动物取材。透射电镜观察股骨近段超微结构。原位凋亡染色法计数股骨近段骨细胞凋亡指数。结果：SCI组骨细胞有4种改变：(1)细胞器减少，骨陷窝增大，絮状物质增多、凝聚以及骨陷窝壁嗜锇板层形成等骨细胞性溶骨表现；(2)退变相骨细胞表现为胞质和细胞器出现严重囊性改变如线粒体空泡化，细胞壁不完整，细胞器不清晰；(3)出现核固缩，细胞处于崩解状态为坏死的形态学改变；(4)异染色质凝集、边聚，细胞出芽起泡等典型凋亡样改变。SCI组小梁骨中骨细胞凋亡指数显著高于对照组(P＜0．01)。结论：骨细胞的溶骨、退变、坏死和凋亡样改变是SCI后骨细胞的形态学特征，也可能是SCI后骨代谢偶联失调的细胞学基础。     

Stromal cell structure and relationships in perimedullary spaces of chick embryo shaft bones

 Structure and relationships of stromal cells were studied by light (LM) and transmission electron microscopy (TEM) in the perimedullary spaces that form the growing cortex of the chick embryo tibia. Observation under LM showed that in all perimedullary spaces the interstices between the cells carpeting the bone surface and the endothelial lining contain stromal cells surrounded by an amorphous matrix. Two types of stromal cells were distinguished: stellate and spindle-shaped. All stromal cells are alkaline phosphatase-positive. TEM showed that both types of stromal cells have cytoplasmic processes of various length and calibre, coming into contact with each other as well as with endothelial cells and osteoblasts or bone lining cells. Capillaries were found to have a continuous endothelial lining; occasionally endothelial cells radiate cytoplasmic processes towards stromal cells. Along all the above-mentioned cellular contacts adherens and/or gap junctions were often observed. The results of the present study, together with our previous findings on osteoblast-osteocyte relationships, show that the cells of the osteogenic lineage form a continuous protoplasmic network that extends from the osteocytes to the vascular endothelium, passing through osteoblasts (or bone lining cells) and stromal cells. The occurrence of gap junctions among this cytoplasmic network, namely of junctions enabling metabolic and electric coupling, indicates that it forms a functional syncytium, suggesting the hypothesis that the activity of the cells pertaining to the osteogenic lineage might be regulated not only by diffusion (volume transmission) through the intercellular fluids of systemic (hormones) and local factors (cytokines, etc.) but also by signals issued through the cytoplasmic network of the osteogenic cells (wiring transmission). Accepted: 24 November 1997     

骨的疲劳损伤和修复

骨是人体承担力学功能的器官，习惯性生理运动范围内中等应力／应变水平就能引起骨的疲劳损伤，激烈运动甚至引起骨折。骨疲劳损伤的实质是骨基质上产生比典型裂纹更小的裂纹，此种裂纹也可能出现在胶原和羟基磷灰石晶体水平，但骨能对基质损伤进行修复，即对损伤区的骨质吸收，然后替换新骨质，骨细胞通过损伤的细胞突和调整性细胞死亡发出骨损伤基质吸收的信号骨细胞在骨基质损伤修复过程中起重要的作用。骨的疲劳和修复是骨的一种生理现象，研究者们把此过程用数学，力学模型定量化描述，以达到对骨生理过程更深的认识及临床实践更好的应用。     

骨细胞在力学信号感受过程中的作用

目的 综述骨细胞在力学信号感受过程中的作用.资料来源与选择国内外公开发表的相关学术论文及研究报告.资料引用引用文献资料57篇.资料综合主要对骨细胞的生物学特点,骨细胞与成骨细胞之间的差异,骨细胞的特殊结构在力传导中的作用,骨细胞是骨组织的力学感受器,骨细胞力学感受过程中的信息传递,骨细胞与失重性骨丢失等6个方面进行综述.结论 骨细胞是骨组织中的力学感受器,其感受机械刺激,通过细胞网络传递信号,在骨重塑过程中调节成骨细胞和破骨细胞的功能. Abstract： Objective To summarize the roles of osteocytes in bone mechanosensation. Literature resource and selection Related papers and reviews that published at home and abroad. Literature quotation Fifty-seven papers were cited. Literature synthesis Such subjects as biological characteristics of osteocytes, differences between osteocytes and osteoblasts, the roles of special structures of osteocytes in mechanotransduction, the mechanosensors of bone, signal transmission during mechanosensation, the relationship of osteocytes and weightless caused bone loss were reviewed and summarized. Conclusion Osteocytes are the mechanosensors in bone. When mechanical stimuli are sensed, osteocytes regulate the functions of osteoblasts and osteoclasts by the cellular network transmission in the process of bone remodeling.     

股骨颈骨折后股骨头内骨细胞凋亡与Bcl-2蛋白表达的关系及意义

目的　研究股骨颈骨折后股骨头内骨细胞凋亡及Bcl- 2蛋白的表达的关系。　方法　采用光镜观察 (HE)和免疫组织化学 (PV - 90 0 0法 )及原位末端标记法对 6 0例 (分为早、中、晚期组 )股骨颈骨折患者的股骨头标本进行组织学观察、Bcl - 2蛋白及细胞凋亡检测。　结果　6 0例标本中均可见到不同程度的空骨陷窝化 ,并可见骨细胞凋亡。中期组Bcl- 2表达较早晚期组强 ,晚期组细胞凋亡较中期组显著 ,差异均有显著性意义 (P <0 .0 5 )。　结论　Bcl- 2表达可使骨细胞的存活时间延长 ,保持骨细胞的稳定性。在股骨颈骨折后的 10～ 2 0d内 ,可有Bcl- 2蛋白的高表达抑制骨细胞的凋亡。若在此阶段采取恰当的临床治疗 ,则有可能对股骨颈骨折的愈合起到有效作用。     

Wnt signaling and osteoporosis

Major advances in understanding basic bone biology and the cellular and molecular mechanisms responsible for the development of osteoporosis, over the last 20 years, have dramatically altered the management of this disease. The purpose of this mini-review is to highlight the seminal role of Wnt signaling in bone homeostasis and disease and the emergence of novel osteoporosis therapies by targeting Wnt signaling with drugs.     

The temporospatial pattern of energy metabolism coordinates the interactions between the bones and other organ systems

Background

Bones adapt to loads by changing their structure. This biomechanical interaction and the formation/maintenance of bones are orchestrated by three major cell types residing in the bones: osteoblasts, osteocytes, and osteoclasts. Recent findings suggest that, in addition to their biomechanical interactions, bones and other organ systems may also communicate biochemically.

Patterns of osteocytic endothelial nitric oxide synthase expression in the femoral neck cortex: differences between cases of intracapsular hip fracture and controls

Evidence indicates that extensive amalgamation of adjacent resorbing osteons is responsible for destroying the microstructural integrity of the femoral neck’s inferior cortex in osteoporotic hip fracture. Such osteonal amalgamation is likely to involve a failure to limit excessive resorption, but its mechanistic basis remains enigmatic. Nitric oxide (NO) inhibits osteoclastic bone destruction, and in normal bone cells its generation by endothelial nitric oxide synthase (eNOS, the predominant bone isoform) is enhanced by mechanical stimuli and estrogen, which both protect against fracture. To determine whether eNOS expression in osteocytes reflects their proposed role in regulating remodeling, we have examined patterns of osteocyte eNOS immunolabeling in the femoral neck cortex of seven cases of hip fracture and seven controls (females aged 68–96 years). The density of eNOS⁺ cells (mm⁻²) was 53% lower in the inferior cortex of the fracture cases (p < 0.0004), but was similar in the superior cortex. eNOS⁺ osteocytes were, on average, 22% further from their nearest blood supply, than osteocytes in general (p < 0.0001) and the nearest eNOS⁺ osteocyte was 57% further from its nearest canal surface (p < 0.0001). This differential distribution of eNOS⁺ osteocytes was significantly more pronounced in the cortices of fracture cases (p < 0.0001). We conclude that the normal regional and osteonal pattern of eNOS expression by osteocytes is disrupted in hip fracture, particularly at sites that are loaded most by physical activity. These results suggest that eNOS⁺ osteocytes may normally act as sentinels confining resorption within single osteons. A reduction in their number, coupled to an increase in their remoteness from canal surfaces, may thus permit the irreversible merging of resorbing osteons, and thus contribute to the marked increase in the fragility of osteoporotic bone.     

Mechanisms of action of bisphosphonates: similarities and differences and their potential influence on clinical efficacy

Summary Bisphosphonates (BPs) are well established as the leading drugs for the treatment of osteoporosis. There is new knowledge about how they work. The differences that exist among individual BPs in terms of mineral binding and biochemical actions may explain differences in their clinical behavior and effectiveness. Introduction The classical pharmacological effects of bisphosphonates (BPs) appear to be the result of two key properties: their affinity for bone mineral and their inhibitory effects on osteoclasts. Discussion There is new information about both properties. Mineral binding affinities differ among the clinically used BPs and may influence their differential distribution within bone, their biological potency, and their duration of action. The antiresorptive effects of the nitrogen-containing BPs (including alendronate, risedronate, ibandronate, and zoledronate) appear to result from their inhibition of the enzyme farnesyl pyrophosphate synthase (FPPS) in osteoclasts. FPPS is a key enzyme in the mevalonate pathway, which generates isoprenoid lipids utilized for the post-translational modification of small GTP-binding proteins that are essential for osteoclast function. Effects on other cellular targets, such as osteocytes, may also be important. BPs share several common properties as a drug class. However, as with other families of drugs, there are obvious chemical, biochemical, and pharmacological differences among the individual BPs. Each BP has a unique profile that may help to explain potential clinical differences among them, in terms of their speed and duration of action, and effects on fracture reduction.     

Electron microscopy of osteocytes and the pericellular matrix in rat trabecular bone

The fine structure of the osteocytes and of the immediately adjacent bone matrix has been studied in the jaws of young rats demineralized with EDTA. The events marking the life cycle of the cell and their effects on the pericellular bone substance have been grouped into 3 phases. 1. The formative period, where the osteocyte resembles an osteoblast but shows a gradual decrease in the amount of endoplasmic reticulum and in the size of the Golgi complex. 2. The beginning of resorption (osteocytic osteolysis) which is characterized by a further decrease of the secretory organelles and the jagged appearance of the perilacunar border. Later in this phase there is further development and activity of the lysosomes resulting in increased widening of the lacuna and accumulation in the lacuna of fibrillar and flocculent material. 3. The eventual degeneration and death of the cell. No evidence of regeneration (osteoplasia) has been observed.

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Zusammenfassung Die Feinstruktur der Osteozyten und der unmittelbar angelagerten Knochenmatrix wurde an den Kiefern junger mit EDTA demineralisierten Ratten untersucht. Die Ereignisse, welche den Lebenszyklus der Zelle und ihre Wirkung auf die pericelluläre Knochensubstanz markieren, wurden in 3 Phasen eingeteilt: 1. die bildende Periode, während welcher der Osteocyt dem Osteoblasten gleicht, jedoch eine stufenweise Abnahme der Menge von endoplasmatischem Reticulum und in der Größe des Golgi-Apparates zeigt; 2. der Resorptionsbeginn (Osteozyten-Osteolyse), welcher durch eine weitere Abnahme der sekretorischen Organellen und das zackige Aussehen der perilacunären Grenze charakterisiert ist; 3. schließlich die Degeneration und der Tod der Zelle. Der Nachweis einer Regeneration (Osteoplasie) konnte nicht erbracht werden.

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Résumé L'ultrastructure des ostéocytes et de la matrice osseuse adjacente a des été étudiée au niveau maxillaires de jeunes rats, après décalcification à l'E.D.T.A. Les événements caractéristiques du cycle d'évolution de la cellule et ses effets sur la substance osseuse péricellulaire, peuvent être groupés en 3 stades: 1. La période de formation, pendant laquelle l'ostéocyte, analogue à l'ostéoblaste, montre, cependant, une diminution progressive en ergastoplasme et une réduction de l'appareil de Golgi. 2. La phase de résorption (ostéolyse ostéocytaire) caractérisée par l'apparition des lysosomes et leur activité, provoquant un élargissement de la lacune, où s'accumule du matériel fibrillaire et floconneux. 3. La dégénérescence éventuelle et la mort de la cellule. Une régénérescence cellulaire (ostéoplasie) n'a pas été observée.