锶及掺锶羟磷灰石的研究进展

微量元素锶在骨基质形成中的重要作用已经引起人们的注意,含锶羟磷灰石生物材料在临床骨缺损修复中的应用也逐渐增多,此类骨替代生物活性材料在骨质缺损修复中的降解性,骨诱导性以及对细胞的毒性等生物学特征一直受到医学界的关注。本文就这方面的研究作一综述。     

雷奈酸锶治疗人工关节磨损颗粒诱导骨溶解的实验研究

目的研究雷奈酸锶治疗人工关节磨损微粒诱导骨溶解的作用,探讨防治人工关节置换术后假体松动的可能性。方法采用小鼠建立Co—Cr-Mo微粒诱导骨溶解的颅骨模型,分为4组：A组为空白组,B组为颗粒对照组,C组为低剂量治疗组,D组为高剂量治疗组。28d后取出颅骨进行HE染色观察颅骨骨溶解面积,通过EUSA方法检测TNF—α和RANKL的表达,qRT-PCR方法检测RANKL和OPG的表达并分析RANKL／OPG比率变化。结果雷奈酸锶可以明显抑制微粒诱导的骨溶解,对下调TNF-α和RANKL蛋白有确切的疗效,而且这种改变与雷奈酸锶的剂量有关。虽然其对OPG基因转录的抑制作用不太明显,但是对RANKL基因转录和RANKL／OPG基因转录比率的调节与HE染色切片上骨溶解程度相一致。结论雷奈酸锶能够抑制小鼠颅骨骨溶解模型中TNF-α和RANKL的表达,并下调RANKL/OPG基因转录比率,从而抑制了由微粒诱导的骨溶解,为临床预防人工关节置换术后假体松动提供了理论依据。     

Strontium fructose 1, 6‐diphosphate alleviate cyclophosphamide‐induced oligozoospermia by improving antioxidant and inhibiting testicular apoptosis via FAS/FASL pathway

This study investigated the treatment effects of a new compound, strontium fructose 1, 6‐diphosphate (FDP‐Sr), in cyclophosphamide (CP)‐induced oligozoospermia. FDP‐Sr, with extra high‐energy supply, could reverse male hypogonadism in the testis. Male Wistar rats were randomly divided into three groups: control group (vehicle treated), CP group and CP + FDP‐Sr group. Both CP group and CP + FDP‐Sr groups were orally administered CP (20 mg kg^?1) consecutively for the first 7 days to establish CP‐induced testicular toxic models. Subsequently, CP group was given orally distilled water per day, whereas CP + FDP‐Sr group was received FDP‐Sr (200 mg kg^?1) for 49 days. Compared to the CP group, the FDP‐Sr group showed significantly increased levels of serum testosterone, testis relative weights and epididymal sperm counts in rats. In addition, rats treated by FDP‐Sr showed the recuperative activities of testicular marker enzymes and normalised levels of antioxidants in tissue. Testicular protection of FDP‐Sr was further demonstrated by enhancing expression of P450scc, reducing ability of FAS/FASL and generating cytoprotection in the histopathological study. FDP‐Sr appeared to possess an ability to attenuate CP‐induced reproduction toxicity via the activation of antioxidants and steroidogenesis enzymes, and alleviate oligozoospermia via inhibition of testicular apoptosis by FAS/FASL pathway.     

Effects of Oxytetracycline on Mineralization of Bone in Young Rats

The metabolism of minerals and collagen in young rats receiving oxy—tetracycline was studied by employing double—isotope techniques. the dosage of the antibiotic was adjusted to obtain plasma concentrations comparable with human therapeutic levels. Reduced mineralization and possibly increased resorption of bone were observed after oxy tetracycline administration, whereas no effect on the rate of collagen synthesis could be detected.     

Efficacy,effectiveness and side effects of medications used to prevent fractures

There is an increasing number of effective therapies for fracture prevention in adults at risk of osteoporosis. However, shortcomings in the evidence underpinning our management of osteoporosis still exist. Evidence of antifracture efficacy in the groups of patients who most commonly use calcium and vitamin D supplements is lacking, the safety of calcium supplements is in doubt, and the safety and efficacy of high doses of vitamin D give cause for concern. Alendronate, risedronate, zoledronate and denosumab have been shown to prevent spine, nonspine and hip fractures; in addition, teriparatide and strontium ranelate prevent both spine and nonspine fractures, and raloxifene and ibandronate prevent spine fractures. However, most trials provide little information regarding long‐term efficacy or safety. A particular concern at present is the possibility that oral bisphosphonates might cause atypical femoral fractures. Observational data suggest that the incidence of this type of fracture increases steeply with duration of bisphosphonate use, resulting in concern that the benefit–risk balance may become negative in the long term, particularly in patients in whom the osteoporotic fracture risk is not high. Therefore, reappraisal of ongoing use of bisphosphonates after about 5 years is endorsed by expert consensus, and ‘drug holidays’ should be considered at this time. Further studies are needed to guide clinical practice in this area.     

Management of osteoporosis in the elderly

ABSTRACT

Background: Osteoporosis is predominantly a condition of the elderly, and the median age for hip fracture in women is approximately 83 years. Osteoporotic fracture risk is multifactorial, and often involves the balance between bone strength and propensity for falling.

Objective: To present an overview of the available evidence, located primarily by Medline searches up to April, 2009, for the different management strategies aimed at reducing the risk of falls and osteoporotic fractures in the elderly.

Results: Frailty is an independent predictor of falls, hip fractures, hospitalisation, disability and death in the elderly that is receiving increasing attention. Non-pharmacological strategies to reduce fall risk can prevent osteoporotic fractures. Exercise programmes, especially those involving high doses of exercise and incorporating balance training, have been shown to be effective. Many older people, especially the very elderly and those living in care institutions, have vitamin D inadequacy. In appropriate patients and given in sufficient doses, vitamin D and calcium supplementation is effective in reducing both falls and osteoporotic fractures, including hip fractures. Specific anti-osteoporosis drugs are underused, even in those most at risk of osteoporotic fracture. The evidence base for the efficacy of most such drugs in the elderly is incomplete, particularly with regard to nonvertebral and hip fractures. The evidence base is perhaps most complete for the relatively recently introduced drug, strontium ranelate. Non-adherence to treatment is a substantial problem, and may be exacerbated by the requirements for safe oral administration of bisphosphonates.

Conclusion: Evidence-based strategies are available for reducing osteoporotic fracture risk in the elderly, and include exercise training, vitamin D and calcium supplementation, and use of evidence-based anti-osteoporotic drugs. A positive and determined approach to optimising the use of such strategies could reduce the burden of osteoporotic fractures in this high-risk group.     

LiSr4(BO3)3:Ce3+ phosphor as a new material for ESR dosimetry

LiSr₄(BO₃)₃:0.01Ce³⁺ phosphor was investigated to assess its potential as a material for measurements of radiotherapeutic doses with electron spin resonance (ESR). The ESR spectrum of the phosphor irradiated with ⁶⁰Co features five ESR signals. An isochronal annealing experiment has shown that the strongest of these signals is associated with the same trap center as the 473 K peak on the TL glow curve of this material. The dose–response is linear in the studied range from 0.89 to 90.30 Gy. Fading of the signal was also investigated.