AGE CHANGES IN THE CRYSTAL CHEMISTRY OF BONE APATITE *
AGE CHANGES IN THE CRYSTAL CHEMISTRY OF BONE APATITE *
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骨磷灰石晶体化学的年龄变化 *
DOI：
10.1111/j.1749-6632.1965.tb34837.x
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发表时间：
1965
影响因子：
5.2
通讯作者：
J. Menczel
中科院分区：
文献类型：
--
作者：
Aaron S. Posner;R. A. Harper;S. A. Muller;J. Menczel
过去的研究表明，年轻动物的骨骼比年老动物的骨骼代谢更活跃。”Jowsey3 使用显微放射成像技术发现，人类骨骼结构与年龄相关的显着变化，例如年轻人的骨骼更新率较高，而老年人的骨骼更新率明显较低。 Milhaud 和他的同事报告说，与年轻大鼠相比，成年大鼠的可交换钙质量和肠道对钙的吸收有所减少。4 在人类中也发现了与年龄相关的钙吸收变化。 ~ 25 日龄大鼠对 Srs" 和 Caa5 的摄取量比一岁大鼠高 40 至 50 倍。'。还发现老年大鼠的钙骨骼吸收比年轻大鼠差得多。6 最近的研究表明，长期摄入氟化物会导致骨磷灰石晶体尺寸增大。？-'O 从这些观察结果推断，晶体尺寸的增加有助于下面的实验部分是为了观察骨磷灰石晶体是否随着实验动物的成熟而增大。本文将研究可能影响硬组织反应性的另一个因素，即矿物相的化学完整性。对合成和生物磷灰石的研究表明，硬组织中的磷灰石磷酸钙不具有理想的化学计量 Ca,,(PO,),(OH)。羟基磷灰石，但约缺钙 10%。”，l2 此外，当然，硬组织磷灰石与化学计量羟基磷灰石不同，因为它们含有许多取代和/或吸附在晶体表面上的离子，如碳酸盐、柠檬酸盐、镁等。13 在低 Ca/P 比磷灰石的情况下，相邻正磷酸盐氧之间的氢键已显示以中和缺失的钙离子所需的比例存在。 L4-1h 当硬组织磷灰石或合成的缺钙羟基磷灰石被加热到 300°C 至 600°C 之间（具体温度因每种材料而异）时，会发生脱水，并形成焦磷酸盐，其数量与缺钙量成正比。” 为了使两个正磷酸盐 (POq-3) 基团在脱水时缩合形成焦磷酸盐（P20,J 单位），它们必须通过氧之间的氢键连接像CaHPO这样的化合物含有通过氢键连接的磷酸盐，在加热时会形成焦磷酸盐，而不含氢键的纯羟基磷灰石不会脱水形成焦磷酸盐。事实上，缺钙的磷灰石通常在化学和物理上不如化学计量的羟基磷灰石稳定。'g初步工作2”表明，通过加热骨头形成的焦磷酸盐的量随着骨头的年龄而减少。本文描述的实验
Past studies have shown that bone from young animals is metabolically more active than that of older animals.', Considerable variations of human bone structure in relation to age, such as a high turnover in young adults, and a remarkably lower turnover rate in older individuals, were found by Jowsey3 using microradiography. Milhaud and his co-workers have reported that the mass of exchangeable calcium and the intestinal absorption of calcium are reduced in adult rats as compared to younger ones.4 Changes in calcium absorption in relation to age were also found in h u m a n ~ . ~ The uptake of Srs" and Caa5 by 25-day-old rats was found to be 40 to 50 times higher than that of one year old rats.'. It was also found that the skeleton incorporation of calcium was much poorer in old than in young rats.6 Recent studies showed that bone apatite crystals increase in size as a result of prolonged fluoride ingestion.?-'O It was inferred from these observations that an increase in crystal size contributes to a reduction in the chemical and, thereby, the metabolic activity of bone mineral. The following experiment was designed, in part, to see if bone apatite crystals enlarge with the maturation of an experimental animal. Another factor which may influence the reactivity of hard tissues, the chemical perfection of the mineral phase will be investigated in this paper. It has been suggested from studies on synthetic and biological apatites that the apatitic calcium phosphate of hard tissue does not have the stoichiometry Ca,,(PO,),(OH), as found in ideal hydroxyapatite but is about ten per cent deficient in calcium.", l2 In addition, of course, hard tissue apatites differ from stoichiometric hydroxyapatite in that they contain many ions, such as carbonate, citrate, magnesium, and others, substituted and/or adsorbed on crystal surfaces.13 In the case of low Ca/P ratio apatites, hydrogen bonds between adjacent orthophosphate oxygens have been shown to be present in the proportion necessary to neutralize the missing calcium ions. L4-1h When hard tissue apatites, or synthetic, calcium-deficient hydroxyapatites are heated to somewhere between 300°C and 600°C (the exact temperature is specific to each material) dehydration results and pyrophosphate is formed in amounts proportional to the calcium deficiency." In order for two orthophosphate (POq-3) groups to condense upon dehydration to form a pyrophosphate (P20,J unit they must be connected by a hydrogen bond between oxygen atoms of adjacent groups. A compound like CaHPO,, which contains phosphates linked by hydrogen bonds, will form pyrophosphate upon heating while pure hydroxyapatite which contains no hydrogen bonds, does not dehydrate to form pyrophosphate.lR In fact, calciumdeficient apatites are generally chemically and physically less stable than stoichiometric hydroxyapatite.'g Preliminary work2" has shown that the amount of pyrophosphate formed by heating bone decreased with the age of the bone. The experiment described herein