Bone turnover in postmenopausal osteoporosis. Effect of calcitonin treatment

Impact of Alcohol on Bone Health in People Living With HIV: Integrating Clinical Data From Serum Bone Markers With Morphometric Analysis in a Non-Human Primate Model

People living with HIV (PLWH) represent a vulnerable population to adverse musculoskeletal outcomes due to HIV infection, antiretroviral therapy (ART), and at-risk alcohol use. Developing measures to prevent skeletal degeneration in this group requires a grasp of the relationship between alcohol use and low bone mass in both the PLWH population and its constituents as defined by sex, age, and race. We examined the association of alcohol use with serum biochemical markers of bone health in a diverse cohort of PLWH enrolled in the New Orleans Alcohol Use in HIV (NOAH) study. To explore the effects of alcohol on bone in the context of HIV and ART and the role of estrogen, we conducted a parallel, translational study using simian immunodeficiency virus (SIV)+/ART+ female rhesus macaques divided into four groups: vehicle (Veh)/Sham; chronic binge alcohol (CBA)/Sham; Veh/ovariectomy (OVX); and CBA/OVX. Clinical data showed that both osteocalcin (Ocn) and procollagen type I N-propeptide (PINP) levels were inversely associated with multiple measures of alcohol consumption. Age (>50 years) significantly increased susceptibility to alcohol-associated suppression of bone formation in both female and male PLWH, with postmenopausal status appearing as an additional risk factor in females. Serum sclerostin (Scl) levels correlated positively with measures of alcohol use and negatively with Ocn. Micro-CT analysis of the macaque tibias revealed that although both CBA and OVX independently decreased trabecular number and bone mineral density, only OVX decreased trabecular bone volume fraction and impacted cortical geometry. The clinical data implicate circulating Scl in the pathogenesis of alcohol-induced osteopenia and suggest that bone morphology can be significantly altered in the absence of net change in osteoblast function as measured by serum markers. Inclusion of sophisticated tools to evaluate skeletal strength in clinical populations will be essential to understand the impact of alcohol-induced changes in bone microarchitecture. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Comparative Effect of Zoledronate at 6 Versus 18 Months Following Denosumab Discontinuation

Discontinuation of denosumab treatment is associated with rapid bone loss that could be prevented in many patients by zoledronate (ZOL) infusion given 6 months after the last denosumab injection. The effects, however, of zoledronate administration at a later time point are unknown. We aimed to compare the 1-year effect of ZOL infusion given 6 versus 18 months following the last Dmab injection. In this extension of a previously reported 2-year randomized clinical trial, we included initially treatment-naive postmenopausal women, who became osteopenic after approximately 2.5 years of denosumab therapy, and were subjected to a single ZOL infusion at 6 months (early-ZOL, n = 27) versus 18 months (late-ZOL, n = 15) after the last Dmab injection. Annual changes in lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD), and markers of bone turnover (P1NP, CTx) at 6 and 12 months following ZOL infusion were assessed. LS BMD was maintained in both early-ZOL (+ 1.7%) and late-ZOL (+ 1.8%) infusion with no difference between groups (p = 0.949). FN BMD was maintained in early-ZOL (+ 0.1%) and increased in late-ZOL (+ 3.4%) infusion with no difference between groups (p = 0.182). Compared to 6 months after last Dmab injection, the overall LS BMD change of the late-ZOL group (- 3.5%) was significantly different (p = 0.007) from that of the early-ZOL group (+ 1.7%). P1NP and CTx gradually increased in the early-ZOL group, while profoundly decreased and remained suppressed in the late-ZOL infusion. A ZOL infusion 18 months following the last Dmab injection is still useful in terms of BMD maintenance and BTM suppression. However, there is no clear clinical benefit compared to the early infusion, while any theoretical advantage is counterbalanced from the expected bone loss, especially at the LS, and the risk of rebound-associated fractures.Trial Registration: NCT02499237; July 16, 2015.

Bone metabolism of the jaw in response to bisphosphonate: a quantitative analysis of bone scintigraphy images

We examined the changes in the bone metabolism of the jaw in response to BP treatment, and we used bone SPECT-CT to analyze the site-specific bone metabolism between the jaw and other sites of bone. We compared the changes in the bone metabolism of each part of bone in response to BP treatment by performing a quantitative analysis of bone scintigraphy images between patients treated with low-dose BP for osteoporosis (LBP group; n = 17), those treated with high-dose BP for metastatic bone tumor (HBP group; n = 11), and patients with other oral disease who required bone scintigraphy, with no history of BP treatment (control group; n = 40). The study endpoint was the mean standardized uptake value (SUV) of the uptake of Tc-99 m methylene diphosphonate (MDP) in each group. The mean SUVs of the HBP group were significantly lower at the axial bone of the cervical vertebra, thoracic vertebra, sternum, and rib compared to those of the LBP and control groups. The LBP group's mean SUV was significantly higher at the temporal bone, the anodontia part of the alveolar bone in maxilla, the vital teeth part of alveolar bone in the mandible, and the temporomandibular joint. There was no significant difference among the three groups at the mandibular angle and mandibular ramus. Our analyses revealed that the bone metabolism of the jaw and temporal bone in the BP-treated patients was enhanced, and no suppression of bone remodeling in the jaw by BP was observed.

Zoledronate for the Prevention of Bone Loss in Women Discontinuing Denosumab Treatment. A Prospective 2-Year Clinical Trial

Cessation of denosumab treatment is associated with increases in bone turnover above baseline values and rapid bone loss. We investigated the efficacy of zoledronate to prevent this bone loss in women with postmenopausal osteoporosis who were treated with denosumab (mean duration 2.2 years) and discontinued treatment after achieving osteopenia. Women were randomized to receive a single 5-mg infusion of zoledronate (ZOL) (n = 27) or two additional 60-mg injections of denosumab (Dmab) (n = 30). Both groups were followed for a total period of 24 months. At 24 months lumbar spine-bone mineral density (LS-BMD) was not different from baseline in the ZOL group, but decreased in the Dmab group by (mean ± SD) 4.82% ± 0.7% (p < 0.001) from the 12-month value; the difference in BMD changes between the two groups, the primary endpoint of the study, was statistically significant (p = 0.025). Results of femoral neck (FN)-BMD changes were similar. ZOL infusion was followed by small but significant increases in serum procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide of type 1 collagen (CTX) during the first year and stabilization thereafter. In the Dmab group, bone turnover marker values did not change during the first 12 months but increased significantly at 15 months and in the majority of women these remained elevated at 24 months. Neither baseline nor 12-month bone turnover marker values were associated with BMD changes in either group of women. In the Dmab group, three patients sustained vertebral fractures (two patients multiple clinical, one patient morphometric) whereas one patient in the ZOL group sustained clinical vertebral fractures 12 months after the infusion. In conclusion, a single intravenous infusion of ZOL given 6 months after the last Dmab injection prevents bone loss for at least 2 years independently of the rate of bone turnover. Follow-up is recommended, because in a few patients ZOL treatment might not have the expected effect at 2 years. © 2019 American Society for Bone and Mineral Research.

Biophysics and the nonlinear dynamics instigated by a special hormone

Calcitonin, a potent hypocalcemic hormone, plays a vital role in inhibiting osteoclastic activities and suppressing bone removal. The physiological characteristics of calcitonin have long been discussed, along a few recommending calcitonin as a vestigial hormone. The basis for this article is to discuss the role of low and high levels of calcitonin in normal and osteoprotic bone turnover. The effect of calcitonin on the receptor activator of nuclear factor kappa-ligand and osteoclasts has been demonstrated using numerical simulations. This behavior recommends that treatment of osteoporosis via calcitonin does not provide the required upshots. For effectiveness calcitonin must be advised along with a combined therapy like aspirin which agrees with the experimental results available in the literature.

Factors associated with inadequate responses to risedronate in Japanese patients with osteoporosis

Factors associated with an inadequate response (IR) to bisphosphonates have been reported in many countries, but not in Japan, where the approved dose is half the global dose. We analyzed factors associated with IR to risedronate in Japanese patients with osteoporosis. This was a post hoc analysis of 1261 Japanese osteoporosis patients who received risedronate for 1 year in phase III trials. IR was defined as more than one new vertebral fracture (VF) and/or negative change in lumbar spine bone mineral density (BMD) at 1 year. Various baseline and follow-up variables were examined for potential contribution to IR. Of the 1261 subjects, 118 exhibited an IR. At baseline, IR was associated with a higher BMD, lower levels of bone turnover markers (BTM) (serum bone-specific alkaline phosphatase, urinary N-terminal telopeptide of type 1 collagen and C-terminal telopeptide of type 1 collagen), and serum 25-hydroxyvitamin D [25(OH)D] below 16 ng/mL. BTM changes were blunted at 6 months in subjects with IR. On simple regression analysis, all the above variables and poor drug adherence were associated with an IR. On multivariate regression analysis, factors associated with IR were high BMD, vitamin D deficiency at baseline and low BTM at baseline, or a decreased BTM response at 6 months. Low serum 25(OH)D and BTM as well as high BMD at baseline were independent predictors of an IR to risedronate in Japan. These results emphasize the importance of the assessment of serum 25(OH)D and BTM in the management of osteoporosis with bisphosphonates.

The Prevention and Therapy of Osteoporosis: A Review on Emerging Trends from Hormonal Therapy to Synthetic Drugs to Plant-Based Bioactives

Osteoporosis is one of the major health problems worldwide. It is characterized by increased bone fragility and loss of bone matter due to the action of osteoclast cells, which are associated with modified hormone levels and factors such as aging. Bisphosphonates are the primary treatment for osteoporosis. Apart from bisphosphonates, hormone therapy, calcitonin treatment, selective estrogen receptor modulators (SERMs), and strontium ranelate (SR) are some of the other treatments available for osteoporosis. However, these treatments have some side effects, such as oily skin, fluid retention, nausea, long-term toxicity, and even prostate cancer in males, and thus natural therapies that incur fewer side effects are sought. Phytochemicals, antioxidants, and other plant-based bioactives are important in the human diet. They are abundant in fruits and help against various chronic diseases, including bone disorders. Other providers of these important compounds are the medicinal plant parts. In this article, we highlight the various species of plants and herbs that are useful for the treatment of osteoporosis. The prospect of using these plant-based bioactives in amelioration of osteoporosis as an alternative to hormonal and synthetic drug-based therapy is also discussed.

Advances in Controlled Drug Delivery for Treatment of Osteoporosis

Osteoporosis, which is characterized by resorption of bone exceeding formation, remains a significant human health concern, and the impact of this condition will only increase with the "graying" of the worldwide population. This review focuses on current and emerging approaches for delivering therapeutic agents to restore bone remodeling homeostasis. Well-known antiresorptive and anabolic agents, such as estrogen, estrogen analogs, bisphosphonates, calcitonin, and parathyroid hormone, along with newer modulators and antibodies, are primarily administered orally, intravenously, or subcutaneously. Although these treatments can be effective, continuing problems include patient noncompliance and adverse systemic or remote-site effects. Controlled drug delivery via polymeric, targeted, and active release systems extends drug half-life by shielding against premature degradation and improves bioavailability while also providing prolonged, sustained, or intermittent release at therapeutic doses to more effectively treat osteoporosis and associated fracture risk.

Bone Health and Osteoporosis

Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone tissue leading to decreased bone strength and an increased risk of low-energy fractures. Central dual-energy X-ray absorptiometry measurements are the gold standard for determining bone mineral density. Bone loss is an inevitable consequence of the decrease in estrogen levels during and following menopause, but additional risk factors for bone loss can also contribute to osteoporosis in older women. A well-balanced diet, exercise, and smoking cessation are key to maintaining bone health as women age. Pharmacologic agents should be recommended in patients at high risk for fracture.

Nasal salmon calcitonin blunts bone microstructure alterations in healthy postmenopausal women

In healthy postmenopausal women, nasal salmon calcitonin blunted distal radius and tibia bone microstructure degradation.

INTRODUCTION

Nasal salmon calcitonin (NSC) has been reported to lower vertebral fracture risk by 33%, but to modestly increase spine areal bone mineral density (aBMD) by 1.5%. Thus, NSC may also influence bone microstructure, another known determinant of bone strength.

METHODS

In a randomized, double-blind, placebo-controlled trial, we investigated the effects of 200 IU/day NSC on distal radius and tibia bone microstructure (by high-resolution 3-dimensional peripheral quantitative computerized tomography), aBMD (by dual-energy X-ray absorptiometry), and serum bone turnover markers in healthy postmenopausal women.

RESULTS

Mean age was 57.6 ± 0.8 (±SEM) and 57.4 ± 0.7 in NSC (n = 45) and placebo groups (n = 45), respectively. Mean femoral neck T-score was in the osteopenic range; prevalent vertebral fracture was 4% in each group. There was no observed between-group difference in the primary outcome distal radius BV/TV (-2.8 ± 0.6% vs. -4.3 ± 1.0%, NS). By 2 years, the decrease in distal radius total density vs. baseline was 4.4 ± 0.7% in controls and 2.1 ± 0.6% in NSC-receiving patients (p < 0.05). Distal radius and tibia cortical thickness decreased by 3.7 ± 1.0 and 2.4 ± 0.5% in placebo (p < 0.05 vs. baseline for both), respectively, but not in the NSC group. Distal radius total density and cortical thickness changes were lower in NSC group than in placebo (p < 0.05 for both) in the subgroup with baseline C-terminal telopeptides (CTX) above the median. By 6 and 12 months, serum CTX decreased by 17.3 ± 6.2 and 19.1 ± 6.6% (both p < 0.05 vs. baseline), respectively, in NSC, but remained stable in controls (NS vs. baseline). There was no difference in aBMD. NSC was well tolerated, with less arthralgia than the placebo group (14 vs. 26, p < 0.05).

CONCLUSION

Nasal salmon calcitonin blunted the degradation of distal radius and tibia bone microstructure in healthy postmenopausal women.

Hypocalcitonemia in Handigodu Disease: a spondylo epi (meta) physeal dysplasia

Handigodu Disease (HD) is a disorder of the osteoarticular system which is highly prevalent in several villages of two districts viz, Shimoga and Chikmaglur of the state of Karnataka, southern India. The scientific name of the disease is Spondylo-epi-(meta) physeal Dysplasia, Autosomal Dominant variety, Handigodu syndrome. The same has been listed in the International Classification of Skeletal Dysplasias. The calcium homeostasis study was lack in HD. The serum calcium, phosphorus, parathyroid hormone and calcitonin levels after overnight fast state, and 24 hour urinary excretion of calcium and phosphorus were quantified. The decreased level of calcitonin associated with decreased serum total calcium and urinary calcium in HD were observed. The levels of parathyroid hormone, serum phosphorus and urinary phosphorus remain unchanged among HD affected. The Vitamin D3 levels also noticed unchanged in HD affected. Since calcitonin has antiresorption effect on bone, the observed low calcitonin in HD may imply reosrption of bone leading to deformity and causes hypocalcaemia and hypocalciuria. The hypocalcitonemia without change in iPTH associated with hypocalcaemia may be a mutation in Vit D receptor (VDR) or may be an epiphenomenon.

Vertebral anti-fracture efficacy of strontium ranelate according to pre-treatment bone turnover

Osteoporotic post-menopausal women patients in two randomised trials comparing the anti-fracture efficacy of strontium ranelate with placebo were separated into tertiles according to their baseline levels of biochemical markers of bone formation and resorption. The vertebral anti-fracture efficacy of strontium ranelate was shown to be independent of baseline bone turnover levels.

INTRODUCTION

Bone turnover (BTO) levels vary among women at risk of osteoporotic fracture. Strontium ranelate is an anti-osteoporotic treatment increasing bone formation and reducing bone resorption. It was hypothesised that its anti-fracture efficacy would be independent of baseline BTO levels.

METHODS

Post-menopausal women with osteoporosis from two pooled studies were stratified in tertiles according to baseline levels of two BTO markers: bone-specific alkaline phosphatase (b-ALP, n = 4995) and serum C-telopeptide cross-links (sCTX, n = 4891). Vertebral fracture risk was assessed over 3 years with strontium ranelate 2 g/day or placebo.

RESULTS

In the placebo group, relative risk of vertebral fractures increased with BTO tertiles by 32% and 24% for patients in the highest tertile for b-ALP and CTX, respectively, compared to those in the lowest tertile. In the strontium ranelate group, incidences of vertebral fracture did not differ significantly across BTO tertiles. Significant reductions in vertebral fractures with strontium ranelate were seen in all tertiles of both markers, with relative risk reductions of 31% to 47% relative to placebo. Risk reduction did not differ among tertiles (b-ALP: p = 0.513; sCTX: p = 0.290).

CONCLUSION

The vertebral anti-fracture efficacy of strontium ranelate was independent of baseline BTO levels. Strontium ranelate offers clinical benefits to women across a wide range of metabolic states.

Bone turnover markers: understanding their value in clinical trials and clinical practice

While bone mineral density (BMD) by dual-energy X-ray absorptiometry is the primary method of determining fracture risk, assessing bone turnover may add valuable information for the management of patients with low bone mass. Bone turnover markers (BTMs) are used in clinical trials where they can provide essential information on the biological efficacy of osteoporosis treatments. In such population-based studies, BTMs can predict fracture risk independent of BMD. When combined with BMD, they improve the fracture risk estimate above and beyond BMD alone in postmenopausal osteoporotic women. Since changes in bone turnover after the initiation of therapy with bone resorption inhibitors occur much more rapidly than changes in BMD, treatment efficacy could, in theory, be determined within weeks of using BTMs. However, such predictive value is limited by the large biological variability of these biochemical markers, even though newer automated methods have reduced their analytical variability. Consequently, widespread adoption as a means of predicting treatment efficacy in fracture prevention for individual patients cannot yet be recommended. BTMs may be useful for monitoring adherence to antiresorptive therapy and may aid in identifying patients for whom antiresorptive therapy is most appropriate. Thus, although BTMs are currently confined to clinical research applications, further improvement in assay precision may extend their diagnostic value in clinical settings.

Effect of nano-calcium-enriched milk on calcium metabolism in ovariectomized rats

This study was designed to examine the effect of different kinds of calcium enrichment on serum and urine indices of mineral status in ovariectomized rats. Twenty-four 7-week-old Sprague-Dawley female rats were divided into four groups, ovariectomized, and fed diets containing the following: (1) Control, non-Ca-enriched milk; (2) OVX1, calcium carbonate-enriched milk; (3) OVX2, ionized Ca-enriched milk; and (4) OVX3, nano-Ca-enriched milk. After 18 weeks of feeding, the food efficiency ratio in the nano-Ca-fed group was significantly lower compared with those in the Control and OVX2 groups. There was no difference in serum and fecal Ca among the groups. The bone/total alkaline phosphatase ratio was significantly higher in rats fed milk enriched with nano-Ca (59%) and calcium carbonate (62%) than in control (44%) animals. Urinary Ca was the highest in the nano-Ca-enriched group; however, urinary excretions of deoxypyridinoline and hydroxyproline were significantly decreased in the nano-Ca-enriched group. The present results indicate that consumption of nano-Ca-enriched milk resulted in an increase of urinary excretion of calcium and a decrease in deoxypyridinoline and hydroxyproline in ovariectomized rats.

Biomarkers for osteoporosis management: utility in diagnosis, fracture risk prediction and therapy monitoring

Osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration of bone tissue, resulting in an increased risk of fracture. While the level of bone mass can be estimated by measuring bone mineral density (BMD) using dual X-ray absorptiometry (DXA), its measurement does not capture all the risk factors for fracture. Quantitative changes in skeletal turnover can be assessed easily and non-invasively by the measurement of serum and urinary biochemical markers; the most sensitive markers include serum osteocalcin, bone specific alkaline phosphatase, the N-terminal propeptide of type I collagen for bone formation, and the crosslinked C- (CTX) and N- (NTX) telopeptides of type I collagen for bone resorption. Advances in our knowledge of bone matrix biochemistry, most notably of post-translational modifications in type I collagen, are likely to lead to the development of new biochemical markers that reflect changes in the material property of bone, an important determinant of bone strength. Among those, the measurement of the urinary ratio of native (alpha) to isomerized (beta) CTX - an index of bone matrix maturation - has been shown to be predictive of fracture risk independently of BMD and bone turnover. In postmenopausal osteoporosis, levels of bone resorption markers above the upper limit of the premenopausal range are associated with an increased risk of hip, vertebral, and nonvertebral fracture, independent of BMD. Therefore, the combined use of BMD measurement and biochemical markers is helpful in risk assessment, especially in those women who are not identified as at risk by BMD measurement alone. Levels of bone markers decrease rapidly with antiresorptive therapies, and the levels reached after 3-6 months of therapy have been shown to be more strongly associated with fracture outcome than changes in BMD. Preliminary studies indicate that monitoring changes of bone formation markers could also be useful to monitor anabolic therapies, including intermittent parathyroid hormone administration and, possibly, to improve adherence to treatment. Thus, repeated measurements of bone markers during therapy may help improve the management of osteoporosis in patients.

The effects of oral calcitonin on bone collagen maturation: implications for bone turnover and quality

Anti-resorptive strategies may affect bone collagen maturation differently depending on the mode of action. Orally administrated calcitonin resulted in a dose dependent inhibition of bone resorption but did not change bone collagen maturation. This may reflect aspects of bone quality.

INTRODUCTION

The aim of the present study was to evaluate the effect of oral calcitonin on bone collagen maturation measured as the ratio between the degradation products of newly synthesized C-telopeptides of type I collagen (alphaalphaCTX) and mature isomerized betabetaCTX in postmenopausal women.

METHODS

Participants were from a phase II study. A total of 168 postmenopausal women were included and treated with placebo, 0.15, 0.4, 1, or 2.5 mg calcitonin daily. The non-isomerized alphaalphaCTX and isomerized betabetaCTX were measured in 24-hour urine samples obtained at baseline, and after 1 day, 1 month and 3 months of therapy.

RESULTS

Calcitonin, significantly and dose-dependently inhibited bone resorption by up to 50% as measured by alphaalphaCTX and isomerized betabetaCTX. Bone collagen maturation measured as the ratio between alphaalphaCTX and betabetaCTX remained unchanged during treatment with calcitonin.

CONCLUSIONS

Calcitonin dose-dependently and significantly reduced both alphaalphaCTX to betabetaCTX levels in urine without affecting the alphaalphaCTX to betabetaCTX ratio. This is in direct contrast to other anti-resorptive therapies, in which strong treatment-dependent effect on the endogenous age profile of bone has been observed. These data highlight that even though the treatments may have comparable effects on BMD, endogenous bone composition, which may be associated to bone quality, is strongly affected by the type of intervention, in which calcitonin display highly divergent effects from that of other anti-resorptives.

Salmon calcitonin: a review of current and future therapeutic indications

Salmon calcitonin, available as a therapeutic agent for more than 30 years, demonstrates clinical utility in the treatment of such metabolic bone diseases as osteoporosis and Paget's disease, and potentially in the treatment of osteoarthritis. This review considers the physiology and pharmacology of salmon calcitonin, the evidence based research demonstrating efficacy and safety of this medication in postmenopausal osteoporosis with potentially an effect on bone quality to explain its abilities to reduce the risk of spine fracture, the development of an oral salmon calcitonin preparation, and the therapeutic rationale for this preparation's chondroprotective effect in osteoarthritis.

Association between baseline values of bone turnover markers and bone mineral density and their response to raloxifene treatment in Japanese postmenopausal women with osteoporosis

It has been well established that raloxifene improves bone turnover, increases bone mineral density (BMD), and reduces the risk of fractures. However, it remains obscure which patients are more likely to respond to treatment with raloxifene in patients with postmenopausal osteoporosis. The purpose of this study was to investigate associations between baseline values of BMD and bone turnover markers (BTMs) and changes of those values after 1-year treatment with raloxifene. Sixty-eight Japanese postmenopausal women with untreated osteoporosis were selected for this study, among whom 58 patients (mean age 70.40 +/- 9.2 years) completed this study. Lower baseline values of BMD at the lumbar spine, the femoral neck, and the distal radius were significantly correlated with greater increases of BMD at those corresponding sites after 1-year treatment with raloxifene. On the other hand, higher baseline values of bone-specific alkaline phosphatase (BAP) and serum N-terminal telopeptide of type I collagen (NTx) were significantly correlated with greater reductions of BAP and NTx, respectively, after 1-year treatment with raloxifene. Although longer and larger studies with fracture endpoints are needed, our findings suggest that baseline values of BMD and BTMs can be used to predict subsequent skeletal response to raloxifene therapy in Japanese postmenopausal women with osteoporosis.

Effects of calcitonin on the biomechanics, histopathology, and radiography of callus formation in rats

BACKGROUND

This study was designed to examine the effect of salmon calcitonin on fracture repair.

METHODS

A transverse middiaphyseal fracture of the right tibia was surgically induced, and stabilized by an intramedullary Kirschner wire. Eighty male Wistar rats were arbitrarily assigned to four groups of 20 animals each. Groups I and II were the controls and did not receive any medication but did receive placebo injections. The other two groups received 5 IU/kg/day salmon calcitonin intramuscularly for 6 weeks (Group III) or for 10 weeks (Group IV) postoperatively. The formation and healing of the bones were determined by radiographic and histopathological analyses and by biomechanical tests.

RESULTS

In radiographic examinations, there were no statistically significant differences between groups I and III at week 6 or between groups II and IV at week 10. However, the histopathological evaluation scores were higher in the calcitonin group at the early stage (6 weeks) of fracture healing, which indicates a more mature callus formation (P < 0.05). The values for maximum torsional moment during fracture were higher in the calcitonin group in both stages of fracture healing (P < 0.01).

CONCLUSIONS

This study could have two important clinical implications. (1) Higher scores for the histopathological evaluation and a greater resistance to moment force applied at an early stage (week 6) of fracture healing imply that calcitonin intake might enable us to allow earlier mobilization and weight-bearing in clinical cases with rigid fixation. (2) At a late stage of fracture healing (week 10), the significantly better (P < 0.0001) results obtained in the biomechanical parameters used might imply that calcitonin intake could enable us to perform early implant removal, and strongly suggest that the strength and quality of the callus formation could be improved by administering calcitonin following a fracture.

Three-month changes in bone turnover markers and bone mineral density response to raloxifene in Japanese postmenopausal women with osteoporosis

It has been well established that raloxifene (RLX) improves bone turnover, increases bone mineral density (BMD), and reduces the risk of fractures. However, it remains obscure how to monitor the therapeutic effects of RLX, while numerous clinical trials for other antiresorptive agents have suggested that greater short-term reductions of bone turnover markers (BTMs) can predict greater increases in BMD and greater reduction in risk of future fractures. The purpose of this study was to investigate associations between short-term reductions of BTMs and subsequent changes of BMD after 1-year treatment with RLX. Seventy-three Japanese postmenopausal women with untreated osteoporosis were selected for this study. Reductions in BTMs [bone-specific alkaline phosphatase (BAP) or serum N-terminal telopeptide of type I collagen (NTx)] after 3 months did not correlate with increases of BMD at any major sites (lumbar spine, femoral neck, total neck, and distal 1/3 radius) either after 6 months or after 12 months. Our results suggest that short-term reductions or 3-month reductions of BTMs with RLX treatment cannot be used to predict increases of BMD. However, this does not directly mean that short-term reductions or 3-month reductions of BTMs with RLX treatment cannot be used to predict risk reduction of future fractures or the ultimate effects of RLX on bone. Further studies with fracture endpoints in longer observation and larger number of patients are warranted to establish how to monitor the therapeutic effects of RLX or early identification of responders or nonresponders to RLX treatment.

The impact of clothing style on bone mineral density among women in Turkey

To investigate the effect of veiled clothing style on bone mineral density (BMD). The BMD measurements were performed on the femoral neck and the lumbar spines of adult female population with two different types of clothing taking calcium daily in the normal range according to the proper technique utilizing dual energy X-ray absorptiometry (DEXA). In the lumbar spine measurements, the BMD was measured 1.0020 +/- 0.177 gr/cm2 in cases with veiled clothing style while it was measured 1.0793 +/- 0.169 gr/cm2 in cases with unveiled clothing style (P = 0.049, t = 1.98). In the femoral neck measurements, the BMD was measured 0.8428 +/- 0.146 gr/cm2 in cases with veiled clothing style while it was measured 0.8532 +/- 0.177 in cases with unveiled clothing style (P = 0.548, t = 0.457). Although a decrease in BMD values was observed in both regions with veiled clothing style, only the change in the lumbar spine BMD measurements was statistically significant. These findings suggest that the veiled clothing style may have an adverse effect on BMD by interfering with the sun exposure which is believed to have a key role in bone strength.

Is a change in bone mineral density a sensitive and specific surrogate of anti-fracture efficacy?

Anti-resorptive agents perturb steady state remodeling; they suppress, but do not abolish, the birth rate of new basic multicellular units (BMUs). In doing so, remodeling goes to completion with bone formation in the many BMUs created before treatment but now with fewer resorption cavities appearing concurrently. As a result, cortical porosity and trabecular stress concentrators decrease reducing bone fragility. From this improved bone strength, steady state is re-established at a slower remodeling rate that again produces bone fragility but more slowly as fewer new BMUs, each with a less negative BMU balance, produce cortical thinning and porosity, trabecular thinning and loss of connectivity while bone fragility progresses rapidly in controls. Thus, the fracture risk reduction--the incidence of fractures in patients treated with an anti-resorptive agent relative to the incidence in controls--is the net effect of the slowing or partial reversal of fragility and then reduced progression of structural abnormalities in treated patients and continued structural decay in controls. Although some morphological features in treated patients and controls may be captured in the bone mineral density (BMD) measurement, many are not. The early increase in BMD is largely determined by the pre-treatment remodeling rate whereas the later and more modest BMD increase is a function of the degree of suppression of remodeling and secondary mineralization. When pre-treatment remodeling rate is low, the increase in BMD is small but the fracture risk reduction (relative to controls with comparable baseline characteristics) is no different to that in patients with high baseline remodeling (relative to their controls) and a greater BMD increase. Therefore, a small increase in BMD does not mean treatment has failed and a large increase in BMD is not indicative of a greater fracture risk reduction.

Clinical application of biochemical markers of bone turnover

With the ageing population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to every day clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis and follow-up of such pathologies have markedly grown. Together with clinical and imaging techniques, biochemical tests play an important role in the assessment and differential diagnosis of metabolic bone disease. In recent years, the isolation and characterisation of cellular and extracellular components of the skeletal matrix have resulted in the development of molecular markers that are considered to reflect either bone formation or bone resorption. These biochemical indices are non-invasive, comparatively inexpensive and, when applied and interpreted correctly, helpful tools in the diagnostic and therapeutic assessment of metabolic bone disease. This review provides an overview of the current evidence regarding the clinical use of biochemical markers of bone remodelling in bone disease, with an emphasis on osteoporosis.

Osteoporosis

Effective therapies are available for the patient who has arthritic osteoporosis. The approach is critical to ensure an optimal quality of life in these individuals who suffer with a disease that is clearly treatable.

New mechanisms and targets in the treatment of bone fragility

Bone modelling and remodelling are cell-mediated processes responsible for the construction and reconstruction of the skeleton throughout life. These processes are chiefly mediated by locally generated cytokines and growth factors that regulate the differentiation, activation, work and life span of osteoblasts and osteoclasts, the cells that co-ordinate the volumes of bone resorbed and formed. In this way, the material composition and structural design of bone is regulated in accordance with its loading requirements. Abnormalities in this regulatory system compromise the material and structural determinants of bone strength producing bone fragility. Understanding the intercellular control processes that regulate bone modelling and remodelling is essential in planning therapeutic approaches to prevention and treatment of bone fragility. A great deal has been learnt in the last decade. Clinical trials carried out exclusively with drugs that inhibit bone resorption have identified the importance of reducing the rate of bone remodelling and so the progression of bone fragility to achieved fracture reductions of approx. 50%. These trials have also identified limitations that should be placed upon interpretation of bone mineral density changes in relation to treatment. New resorption inhibitors are being developed, based on mechanisms of action that are different from existing drugs. Some of these might offer resorption inhibition without reducing bone formation. More recent research has provided the first effective anabolic therapy for bone reconstruction. Daily injections of PTH (parathyroid hormone)-(1–34) have been shown in preclinical studies and in a large clinical trial to increase bone tissue mass and reduce the risk of fractures. The action of PTH differs from that of the resorption inhibitors, but whether it is more effective in fracture reduction is not known. Understanding the cellular and molecular mechanisms of PTH action, particularly its interactions with other pathways in determining bone formation, is likely to lead to new therapeutic developments. The recent discovery through mouse genetics that PTHrP (PTH-related protein) is a crucial bone-derived paracrine regulator of remodelling offers new and interesting therapeutic targets.

Biochemical markers of bone turnover part II: clinical applications in the management of osteoporosis

With the ageing population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to every day clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis and follow-up of such pathologies have markedly grown. Together with clinical and imaging techniques, biochemical tests play an important role in the assessment and differential diagnosis of metabolic bone disease. These biochemical indices are non-invasive, comparatively inexpensive and, when applied and interpreted correctly, helpful tools in the diagnostic and therapeutic assessment of metabolic bone disease. This second part of the two part series reviews the current evidence regarding the clinical use of biochemical markers of bone remodelling in the management of osteoporosis.

The effect of bilateral oophorectomy on bone mineral density

The objective of this study is to investigate the effect of bilateral oophorectomy with total abdominal hysterectomy on bone loss, comparing the cases having surgery before and after the menopause. Bone mineral density (BMD) measurements were obtained from the lumbar spine and femoral neck of totally 127 cases. Out of 127, 105 had surgery before menopause and 22 cases were operated on postmenopausally. The results were compared with the USA normal values. The average age of surgical menopause (SM) cases was 48.45 years with a mean duration of menopause of 5.77 years. The average height and weight were 157.67 cm and 68.19 kg, respectively. The average age of cases having surgery after menopause (SAM) was 62.45 years with a mean duration of 5.59 years after the surgery (duration after menopause is 13.23 years). The average height and weight were 157.45 cm and 73.55 kg, respectively. The average of BMD measurements of lumbar spines L2-L4 was 1.04 gr/cm(2) (BMD = 85.65% and T score = -0.96) in the cases with SM. On the contrary, the average of the BMD measurements of lumbar spines L2-L4 was 1.05 gr/cm(2) (BMD = 101.14% and T score = 0.24) in the cases with SAM. The average of the BMD measurements of femoral neck was 0.85 gr/cm(2) (BMD = 91.39% and T score = -0.64) in the cases with SM. On the contrary, the average of the BMD measurements of femoral neck was 0.82 gr/cm(2) (BMD = 96.69% and T score = -0.31) in the cases with SAM. The bilateral oophorectomy as a surgical procedure is not a statistically significant factor for the acceleration of the bone loss. The main points are the age and the duration of menopause of the patient affecting the bone loss if the surgery is performed before menopause.

Ablation of persephin receptor glial cell line-derived neurotrophic factor family receptor alpha4 impairs thyroid calcitonin production in young mice

Glial cell line-derived neurotrophic factor family receptor (GFRalpha) 4, the binding receptor for persephin, is coexpressed with the signaling Ret receptor tyrosine kinase predominantly in thyroid calcitonin-producing C cells. We show by in situ hybridization and immunohistochemistry that the functional, glycolipid-anchored form of GFRalpha4 is produced in mouse only in the C cells but not in parathyroid gland or in the brain. C cells expressed functional GFRalpha4 throughout postnatal development, whereas Ret expression in these cells decreased postnatally and was undetectable in adults. To understand the physiological role of GFRalpha4, we produced GFRalpha4-deficient [knockout (KO)] mice. No differences were observed between wild-type and GFRalpha4-KO littermate animals in growth, gross behavior, or viability. The number and morphology of the thyroid C cells were indistinguishable between the genotypes in both newborn and adult age. However, thyroid tissue calcitonin content was reduced by 60% in newborn and by 45% in 3-wk-old GFRalpha4-KO mice compared with wild-type controls. In contrast, thyroid calcitonin levels were similar in adult animals. Consistent with the reduced calcitonin levels, bone formation rate in juvenile GFRalpha4-KO mice was increased. In conclusion, this study indicates a novel role for endogenous GFRalpha4 signaling in regulating calcitonin production in thyroid C cells of young mice.

Pretreatment levels of bone turnover and the antifracture efficacy of alendronate: the fracture intervention trial

The influence of pretreatment bone turnover on alendronate efficacy is not known. In the FIT, we examined the effect of pretreatment bone turnover on the antifracture efficacy of daily alendronate given to postmenopausal women. The nonspine fracture efficacy of alendronate was significantly greater among both osteoporotic and nonosteoporotic women with higher baseline levels of the bone formation marker PINP.

INTRODUCTION

Previous trials have shown that high bone turnover is associated with greater increases in BMD among bisphosphonate-treated women. The influence of pretreatment bone turnover levels on antifracture efficacy has not been well studied.

MATERIALS AND METHODS

We randomized women 55-80 years of age with femoral neck BMD T scores < or = -1.6 to alendronate (ALN), 5-10 mg/day (n = 3105), or placebo (PBO; n = 3081). At baseline, 3495 women were osteoporotic (femoral neck BMD T score < or = -2.5 or prevalent vertebral fracture), and 2689 were not osteoporotic (BMD T score > -2.5 and no prevalent vertebral fracture). Pretreatment levels of bone-specific alkaline phosphatase (BSALP), N-terminal propeptide of type 1 collagen (PINP), and C-terminal cross-linked telopeptide of type 1 collagen (sCTx) were measured in all participants using archived serum (20% fasting). The risk of incident spine and nonspine fracture was compared in ALN- and PBO-treated subjects stratified into tertiles of baseline bone marker level.

RESULTS AND CONCLUSIONS

During a mean follow-up of 3.2 years, 492 nonspine and 294 morphometric vertebral fractures were documented. Compared with placebo, the reduction in nonspine fractures with ALN treatment differed significantly among those with low, intermediate, and high pretreatment levels of PINP levels (p = 0.03 for trend). For example, among osteoporotic women in the lowest tertile of pretreatment PINP (<41.6 ng/ml), the ALN versus PBO relative hazard for nonspine fracture was 0.88 (95% CI: 0.65, 1.21) compared with a relative hazard of 0.54 (95% CI: 0.39, 0.74) among those in the highest tertile of PINP (>56.8 ng/ml). Results were similar among women without osteoporosis at baseline. Although they did not reach statistical significance, similar trends were observed with baseline levels of BSALP. Conversely, spine fracture treatment efficacy among osteoporotic women did not differ significantly according to pretreatment marker levels. Spine fracture treatment efficacy among nonosteoporotic women was related to baseline BSALP (p = 0.05 for trend). In summary, alendronate nonspine fracture efficacy is greater among both osteoporotic and nonosteoporotic women with high pretreatment PINP. If confirmed in other studies, these findings suggest that bisphosphonate treatment may be most effective in women with elevated bone turnover.

Serum levels of insulin-like growth factor (IGF); IGF-binding proteins-3, -4, and -5; and their relationships to bone mineral density and the risk of vertebral fractures in postmenopausal women

We previously found that serum levels of insulin-like growth factor I (IGF-I) and IGF-binding protein (IGFBP)-3, but not IFGBP-2, were associated with bone mineral density (BMD) and the risk of vertebral fractures. The aim of the present study was to investigate the roles of IGFBP-4 and -5 in age-dependent bone loss and vertebral fracture risk in postmenopausal Japanese women and to compare them with those of IGF-I and IGFBP-3. One hundred and ninety-three Japanese women aged 46-88 years (mean 62.5) were enrolled in the cross-sectional study. BMD was measured at the lumbar spine, femoral neck, ultradistal radius (UDR), and total body by dual-energy X-ray absorptiometry. Serum levels of IGFBP-4 and -5 as well as IGF-I and IGFBP-3 were measured by radioimmunoassay. Serum levels of IGF-I, IGFBP-3, and IGFBP-5 declined with age, while serum IGFBP-4 increased with age. Multiple regression analysis was performed between BMD at each skeletal site and serum levels of IGF-I and IGFBPs adjusted for age, body weight, height, and serum creatinine. BMD at the UDR was significantly and positively correlated with all serum levels of IGF-I and IGFBPs measured (P < 0.01), while BMD at the femoral neck was correlated with none of them. Serum IGF-I level was significantly and positively correlated with BMD at all sites except the femoral neck (P < 0.01), while serum IGFBP-3 and -4 levels were significantly and positively correlated with only radial BMD (P < 0.01). Serum IGFBP-5 level was positively correlated with UDR BMD (P < 0.001) and negatively correlated with total BMD (P < 0.05). Serum IGF-I, IGFBP-3, and IFGBP-5 levels were significantly lower in women with vertebral fractures than in those without fractures (mean +/- SD: 97.1 +/- 32.1 vs. 143.9 +/- 40.9 ng/dl, P < 0.0001; 2.18 +/- 1.02 vs. 3.23 +/- 1.07 microg/ml, P < 0.0001; 223.6 +/- 63.3 vs. 246.5 +/- 71.5 ng/ml, P = 0.0330, respectively). When multivariate logistic regression analysis was performed with the presence of vertebral fractures as a dependent variable and serum levels of IGF-I and IGFBPs adjusted for age, body weight, height, serum creatinine, and serum alubumin as independent variables, IGF-I and IGFBP-3 were selected as indices affecting the presence of vertebral fractures [odds ratio (OR) = 0.29, 95% confidential interval (CI) 0.15-0.57 per SD increase, P = 0.0003 and OR = 0.31, 95% CI 0.16-0.61 per SD increase, P = 0.0007, respectively]. To compare the significance values, IGF-I, IGFBP-3, and age were simultaneously added as independent variables in the analysis. IGFBP-3 was more strongly associated with the presence of vertebral fractures than IGF-I and age (P = 0.0006, P = 0.0148, and P = 0.0013, respectively). Thus, after comprehensive measurements of serum levels of IGF-I and IGFBPs, it seems that serum IGF-I level is most efficiently associated with bone mass and that serum IGFBP-3 level is most strongly associated with the presence of vertebral fractures in postmenopausal women among the IGF system components examined.

Early changes in biochemical markers of bone turnover predict bone mineral density response to antiresorptive therapy in Korean postmenopausal women with osteoporosis

Biochemical markers of bone turnover have been suggested to be useful in monitoring the efficacy of antiresorptive therapy. In this study, we investigated the predictive value of bone turnover markers to determine short-term response in bone mineral density (BMD) and to identify nonresponders in 138 postmenopausal women (mean age 58 years) with osteoporosis given with either hormone thearpy (HT) or alendronate. Urinary type I collagen N-telopeptide (NTx) and serum osteocalcin (OC) at baseline, 3, and 6 months after treatment as well as spine and femoral neck BMD at baseline and 12 months were measured. Significant decreases in both NTx and OC were evident in women on treatment with antiresorptive agents as early as 3 months (p<0.01). Percent change of NTx at 3 months correlated with the percent change of spinal BMD at 12 months of treatment. When bone turnover markers were stratified by tertiles, the average rate of lumbar spine BMD gain increased significantly with increasing tertiles of baseline value (p<0.05) and percent change (p<0.05) of urinary NTx at 3 month of treatment. In terms of BMD response, urinary NTx at 3 months decreased significantly more in BMD responders group than in nonresponders group. Logistic regression analysis demonstrated that percent change of NTx at 3 months is an independent predictor to identify BMD nonresponders, defined as those whose BMD gain remained within the precision error range of dual energy X-ray absorptiometer (DXA). We conclude that biochemical markers of bone turnover, especially percent change in urinary NTx levels, can be used to determine BMD response to antiresorptive therapy in Korean postmenopausal women with osteoporosis.

Osteoporosis

Bone is a complex organ which contains an organic matrix which serves as scaffolding, includes mineral as calcium distributed in a pattern providing structure and serves as an ion reservoir for the body. Throughout life it dynamically changes in response to changes in activity, body mass, and weight bearing. It is important to define patients at risk for bone loss, since accrued bone loss leading to osteoporosis in the older population of both men and women is unacceptable. There are many different therapies including biphosphonates which can decrease loss of bone and decrease fracture risk in patients who already have had sustained a fracture. Newer therapies such as parathyroid hormone may improve the fracture risk even more than biphosphonates over a shorter period of time.

The efficacy and tolerability of risedronate on bone mineral density and bone turnover markers in osteoporotic Chinese women: a randomized placebo-controlled study

Osteoporosis has become an important health problem in postmenopausal Asian populations as the prevalence of hip and vertebral fractures in some Asian countries has risen to approach that of Caucasian populations. Risedronate, a pyridinyl-bisphosphonate agent, is a potent inhibitor of bone resorption. Risedronate increases bone mineral density (BMD), reduces markers of bone turnover, and reduces the risk of fractures in Caucasian postmenopausal women. To determine the efficacy and tolerability of risedronate in Chinese, a multicenter, randomized, double blind, placebo controlled study was performed in Hong Kong. Sixty-five (65) postmenopausal osteoporotic Southern Chinese women, aged 67+/-6 years, were randomly assigned to receive either risedronate 5 mg daily (n=31) or placebo (n=34) for 12 months. All women received calcium carbonate 500 mg daily and vitamin D 400 IU daily. Mean baseline BMD T-score at the spine and total hip was -3.4 and -2.6, respectively. A significant increase in spine BMD was already evident at month 3 of risedronate treatment (P<0.001). Risedronate significantly increased BMD and reduced bone turnover markers as compared with placebo. The risedronate group had significant increase in BMD at 12 months at both the spine and hip when compared with the placebo group (L1-4 6.6% vs. 0.4%, P<0.001; total hip 2.7% vs. 0.3, P<0.0001; femoral neck 1.8% vs. 1.1%, P<0.02; trochanter 4% vs. 1.1%, P<0.0001, respectively). Significant changes in urine N-telopeptide (NTx) and serum osteocalcin were evident as early as 1 and 3 months, respectively, with risedronate treatment. No significant changes were seen in both BMD and bone markers in the placebo group. Risedronate was well tolerated without major adverse effects. We conclude that risedronate is an effective and well-tolerated agent for the treatment of postmenopausal osteoporosis in Asian population.

Effect of intermittent administration of 200 IU intranasal salmon calcitonin and low doses of 1α(OH) vitamin D3 on bone mineral density of the lumbar spine and hip region and biochemical bone markers in women with postmenopausal osteoporosis: a pilot study

A 1-year prospective, open, randomized, controlled trial was conducted as a pilot study to examine the effect of intermittent administration of 200 IU intranasal salmon calcitonin and 1alpha(OH) vitamin D3 [1alpha(OH)D3] on bone mineral density (BMD) of the lumbar spine and hip as well as on the markers of bone metabolism in women with postmenopausal osteoporosis. A total of 102 randomly recruited women received either 200 IU intranasal salmon calcitonin (Miacalcic nasal 200, Novartis, Basel, Switzerland) daily, 1 month on-1 month off, 0.25 mug 1alpha(OH)D3, and 500 mg elemental calcium continuously (n=57 women) or only 0.25 mug 1alpha(OH)D3 and 500 mg calcium (n=45 women) for a period of 1 year. BMD of the lumbar spine and hip plus biochemical markers reflecting calcium (Ca) metabolism and bone turnover [serum Ca, serum phosphorus, intact parathormone (iPTH), total and bone-specific alkaline phosphatase, osteocalcin levels, 24-h urinary Ca, morning fasting urinary Ca/creatinine, and Pyrilinks-D/creatinine ratio] were measured at the beginning of the study before treatment and after 6 and 12 months of treatment. Baseline characteristics of participants, including age, body mass index, lumbar and hip BMD, and biochemical markers were similar between the two groups. A total of 91 patients completed the study (50 in the salmon calcitonin nasal spray group and 41 in the other group). Lumbar BMD increased significantly in the salmon calcitonin group from baseline (3.0%, p=0.005) and in comparison to the non-calcitonin-treated group (p=0.009). The salmon calcitonin group also had a significant increase in femoral neck BMD compared with baseline values (3.1%, p=0.0005) and in comparison to the non-calcitonin-treated group (p=0.0005) in Ward's triangle BMD (2.9% from baseline values, p=0.009) and in comparison to the non-calcitonin-treated group (p=0.005) in trochanteric BMD (3.4% from baseline values, p=0.007) and in comparison to the non-calcitonin-treated group (P=0.01). Urinary Ca/creatinine and Pyrilinks-D/creatinine levels were significantly decreased from baseline in the salmon calcitonin-treated group (-6.1 and -6.3%, respectively, p=0.001). Bone-specific alkaline phosphatase levels were also significantly decreased from baseline in the salmon calcitonin-treated group (-3.6%, p=0.003). In the same group, a significant decrease in iPTH serum levels compared to baseline values (-2.5%, p=0.005) and in comparison to the non-calcitonin-treated group (p=0.005) was noted. In conclusion, in this pilot study, 1-year intermittent treatment with 200 IU intranasal salmon calcitonin and low doses of 1alpha(OH)D3 produced a significant effect on bone turnover and BMD in postmenopausal women with osteoporosis.

Femoral neck trabecular microstructure in ovariectomized ewes treated with calcitonin: MRI microscopic evaluation

Ovariectomy induces deterioration of the trabecular structure in the femoral neck of ewes, as depicted by MR microscopic imaging. This structural deterioration is prevented by salmon calcitonin treatment.

INTRODUCTION

This study evaluated the trabecular (Tb) microarchitecture of an ovariectomy (OVX)-induced osteoporotic model in ewes and determined the effects of salmon calcitonin (sCT), an osteoclast inhibitor, on the Tb structure. This is the first report of OVX-induced changes in the Tb structure in the femoral neck in the ewes and effect of sCT on the microarchitecture.

MATERIALS AND METHODS

Ewes (5-8 years old, n = 28) were equally allocated into sham (Sham), OVX injected with vehicle, or OVX injected with sCT at 50 or 100 IU, three injections per week. They were killed 6 months after OVX. The femoral neck was examined with an MR imager at 9.4 T in axial, coronal, and sagittal planes. An internal calibration procedure as a means of standardizing image analysis was used to adjust the segmentation threshold. Data from all three planes were averaged.

RESULTS AND CONCLUSIONS

Compared with Sham, OVX induced significant changes (p < 0.0125) in the MRI-derived femoral neck Tb structure: Tb bone volume fraction (BV/TV), -18%; Tb number, -20%; Tb separation, +23%; number of free ends, +28%; number of nodes, -39%; number of Tb branches, -23%; mean length of Tb branches, -19%. Compared with OVX, treatment of sCT at 100 IU significantly improved all the Tb structural parameters to the Sham level (p < 0.0001 approximately p = 0.0281), whereas 50 IU significantly increased the Tb number and the mean length of the Tb branches. BV/TV explained 74% of the variation of compressive stress of the trabecular cylinder cores of the femoral neck. Combining all structural parameters in a multivariate regression analysis significantly improved the explanation to 84%, and adding BMD further improved the predictive ability of the model to 92%. We conclude that OVX induces deterioration of the MRI-derived Tb microstructure in the femoral neck of ewes. sCT treatment prevents OVX-induced changes. The femoral neck microarchitecture significantly correlates with its biomechanical properties. Combining microstructural parameters with BMD further improves the prediction of bone biomechanical properties. The effects of sCT on OVX ewes may help explain reduced fracture risk in postmenopausal osteoporotic women treated with sCT.

Dissociation between global markers of bone formation and direct measurement of spinal bone formation in osteoporosis

Regional bone metabolism measured using 18F-fluoride PET was assessed in 72 postmenopausal women classified as normal, osteopenic, or osteoporotic. Lower values of regional bone formation activity at the lumbar spine were seen in osteoporotic women, whereas global markers of bone formation were significantly increased.

INTRODUCTION

Evaluations of global bone remodeling have revealed that increased bone turnover is a feature of patients with osteoporosis. The noninvasive functional imaging technique of 18F-fluoride positron emission tomography (PET) allows the direct quantitative assessment of bone metabolism at specific sites in the skeleton, including the clinically important site of the lumbar spine.

MATERIALS AND METHODS

The aim of this study was to compare regional skeletal kinetics in 72 postmenopausal women (mean age, 61 years) classified as normal, osteopenic, or osteoporotic according to their BMD T score at the lumbar spine. Each woman had a dynamic PET scan of the lumbar spine after injection of 90 MBq 18F-fluoride ion and measurements of biochemical markers of bone formation and resorption. The arterial plasma input function was derived using aorta arterial activity from the PET image. Time-activity curves were obtained by placing regions of interest over the lumbar vertebrae. A three-compartmental model was used to calculate bone blood flow (K1) and the net plasma clearance of tracer to bone mineral (Ki), reflecting regional osteoblastic activity (ml/minutes/ml). Rate constants k2, k3, and k4, which describe transport between plasma, the extracellular fluid (ECF) compartment, and the bone mineral compartment, were also measured.

RESULTS

The net uptake of fluoride to the bone mineral compartment (Ki) was significantly lower in the osteoporotic group compared with both the osteopenic and normal groups, with a mean difference of 0.005 ml/minutes/ml (16.7%). The fraction of the tracer in the extravascular tissue space that underwent specific binding to bone mineral (k3/k2 + k3) was also significantly reduced in the women classified as osteoporotic. In contrast, levels of bone-specific alkaline phosphatase (BSALP) were significantly higher in the osteoporotic group compared with the normal and osteopenic groups by 35% and 27%, respectively. A significant negative correlation (r = -0.41) was observed between levels of BSALP and the fraction of the tracer that underwent specific binding to bone mineral.

CONCLUSION

Lower values of Ki, a measurement of regional bone formation activity, were seen in women classified as osteoporotic, whereas levels of BSALP, a measure of global bone formation, were significantly increased. These findings are suggestive of increased global skeletal bone turnover in women with postmenopausal osteoporosis but with relatively reduced regional bone formation at the predominantly trabecular site of the lumbar spine.

RETRACTED: Comparative efficacy of hormone replacement therapy, etidronate, calcitonin, alfacalcidol, and vitamin K in postmenopausal women with osteoporosis: The Yamaguchi Osteoporosis Prevention Study

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor in Chief because of the stated concerns listed below. This article was accepted for publication by a previous editor and editorial board, at a time when submissions and documentation were in paper form, prior to the transition of The American Journal of Medicine to a digital submission and review process. These records are no longer extant and consequently we are unable to review the comments of the reviewers and editors involved at that time. We have attempted to contact the authors regarding these concerns and received no response. We are therefore retracting this article since the evidence presented below strongly argues for scientific misconduct. The integrity of these publications is severely compromised by wide-ranging and serious concerns about governance, ethics, authorship, implausible study conduct, implausible workload, discrepant participant numbers and treatment groups, impossible data, implausible data, implausible outcome data, and discrepant methodology.

Time to reevaluate the therapeutic use of calcitonin and biological role attributable to parafollicular (C) cells

There is rich anecdotal evidence that calcitonin significantly increases bone mineral density and reduces fracture risk. However, observation in a previous study of an increased bone formation in calcitonin-deficient mice has led us to reevaluate the therapeutic use of calcitonin and to investigate the primary role of parafollicular (C) cells of the thyroid gland. We found that C cells are involved mainly in the regulation of follicular cell activity in a paracrine manner and in doing so they may regulate the growth rate in newborn by affecting the thyroid hormone levels in the early postnatal period. In the light of reports that showed thyroid physiology is different between populations and it is affected by environmental factors we suggested that C cells may be involved in population differences in thyroid physiology and environmental adaptation. We conclude that C cells may facilitate the adaptation of the follicular cells to environmental changes, enabling more effective coordinated functions of the body and producing variations between populations.

Relationship between pretreatment bone resorption and vertebral fracture incidence in postmenopausal osteoporotic women treated with risedronate

It is unclear whether the antifracture efficacy of bisphosphonates depends on pretreatment bone turnover. We analyzed the risedronate phase III clinical programs using the urinary excretion of deoxypyridinoline (uDPD) as an index of pretreatment bone resorption rates. Risedronate reduced incident vertebral fractures in women with postmenopausal osteoporosis independent from pretreatment bone resorption.

INTRODUCTION

Earlier studies on postmenopausal osteoporosis have suggested that the therapeutic efficacy of antiresorptive therapies might be influenced by pretreatment bone turnover. Because all of these studies have used bone mineral density (BMD) as the primary endpoint, it remains unclear whether this association holds true for incident fractures.

MATERIALS AND METHODS

This study aims to answer this question in a post hoc analysis of a subset of the risedronate phase III clinical programs, using the urinary excretion of deoxypyridinoline (uDPD) as an index of pretreatment bone resorption (PBR). A total of 1593 women with postmenopausal osteoporosis that had baseline uDPD values and paired spinal radiographs available were pooled, in similar proportions, from the risedronate multinational and North American VERT, and from the risedronate HIP trials. Patients from treatment and placebo groups were stratified by the uDPD premenopausal normative median. The four resulting groups were balanced for age, years since menopause, body mass index, baseline femoral neck BMD, and number of prevalent fractures, but baseline lumbar spine BMD was significantly higher in patients with low PBR rates.

RESULTS

In all groups, the proportion of patients with new vertebral fractures was higher in patients with baseline uDPD levels above the normative median. The incidence of vertebral fracture was significantly lower in groups assigned to risedronate compared with placebo. This effect was independent of PBR: in patients with high PBR, the relative risk (RR) of vertebral fracture after 1 year of risedronate was 0.28 (p = 0.03 compared with controls, absolute risk reduction 7.1%). In patients with low PBR, the RR of fracture after 1 year was 0.33 (p < 0.001, absolute risk reduction 4%). After 3 years, the RR of fracture was 0.52 (p = 0.042, absolute risk reduction 8.3%) in patients with high PBR, and 0.54 (p = 0.002, absolute risk reduction 7.1%) in patients with low PBR. Results were similar after adjusting for age, baseline lumbar spine BMD, and prevalent fractures. The number needed to treat to avoid one vertebral fracture at 12 months was 15 in the group of patients with high PBR and 25 in patients with low PBR. Risedronate significantly increased lumbar spine BMD. During the first year of treatment, women with high PBR gained lumbar spine BMD at a faster rate than patients with low PBR. Treatment-by-PBR status interactions were not significantly different over time.

CONCLUSION

The efficacy of risedronate to reduce incident vertebral fractures in women with postmenopausal osteoporosis is largely independent of pretreatment bone resorption rates.

Biochemical markers of bone metabolism in animals: uses and limitations

Routine assessment of the skeleton's response to disease and injury traditionally has consisted of plain-film radiography supplemented with advanced imaging techniques, such as computed tomography, magnetic resonance imaging, nuclear scintigraphy, and bone densitometry. Although these techniques provide increased sensitivity as compared with radiography, they still are limited by the fact that they can only document the net results of past skeletal activity. In contrast, serum and urinary biomarkers of bone formation and resorption provide near real-time information about bone cell activity. In this review, I describe the scientific rationale behind the use of these markers in humans and detail the efforts that have been made to adapt this technology to veterinary medicine and animal research. Commercial assay kits that are applicable to different animal species are described, and the potential limitations of the technology are discussed. The goal of this review is to provide clinical pathologists and researchers with the information needed to decide whether the use of bone markers is likely to be helpful and to select the most appropriate marker (or panel of markers) to answer a particular question.