Bone Mineralization Rate Research Articles

Serum Human \(\beta\) Defensin (HBD-2) and Osteocalcin Levels in Menopausal Iraqi Women with Osteopenia

Background and Purpose: Osteopenia (OP) is a chronic and advanced condition that is often described by diminished bone mineral density (BMD), deteriorated bone tissue microarchitecture, and an elevated risk of fracture. The low molecular weight antimicrobial peptides known as Human Defensin (HBD-2) proteins are produced locally by keratinocytes in various tissues, including skin, mucosa, and bones. Osteocalcin, often called bone gamma-carboxyglutamic acid-containing protein (BGLAP), is a tiny (49 amino acids) noncollagenous protein hormone in bone and dentin. It was initially discovered to be a calcium-binding protein. Material and Methods: Prospective study to evaluate the osteoblast's ability to produce and release osteocalcin makes it a noncollagenous protein, and has primary physiological roles include calcium ion homeostasis, maintaining an average rate of bone mineralization, preventing the aberrant development of hydroxyapatite crystals, and participating in bone remodeling via a negative feedback loop. In menopausal women with osteopenia, this study evaluates the osteocalcin and human beta-defensin 2 for their diagnostic potential. A small amount of venous blood, about 5 ml, was added to the tube and centrifuged for five minutes at a speed of 3 \(\times\) 103 rpm. The serum was put into an Eppendorf tube and stored in a freezer at -20 \(^\circ\)C before being tested. With the help of the specified equation, the body mass index is determined. Findings and Conclusion: Increasing serum HBD 2, osteocalcin levels in postmenopausal women with osteopenia plays an essential role in developing osteopenia to osteoporosis. Differences in serum levels of alkaline phosphatase were seen among patients (as a sample) and controls; serum levels of HBD2 and osteocalcin were considerably lower in controls than in patients (p 0.01).

Rat Serum Osteocalcin Concentration Is Decreased by Restriction of Energy Intake

We studied the effects of energy restriction on serum osteocalcin concentration and bone formation rate in rats. The experiment was designed to achieve energy restriction by reducing the carbohydrate intake while providing identical quantities of protein, fat, vitamins and minerals. Energy intakes of three groups of post-weaning male rats were restricted by 20, 40 and 60% for 4 wk. Serum calclum, phosphorus, transthyretin, triiodothyronine (T3), thyroxine (T4), 1,25-dihydroxycholecalciferol, 25-hydroxycholecalciferol and immunoreactive parathyroid hormone (iPTH) concentrations were determined. Energy restriction (20, 40 and 60%) produced a significant and gradual drop of serum osteocalcin concentrations, although the serum concentrations of its key regulators, i.e., 1,25-dihydroxycholecalciferol and iPTH, were not significantly affected. On the contrary, serum concentrations of calcium, phosphorus, transthyretin, T3 and T4 were significantly lower in the energy-restricted groups. However, our results do not support their implication in the regulation of serum osteocalcin synthesis by energy intake. Serum osteocalcin concentration was positively correlated with bone mineral apposition (r = 0.50, P < 0.05) and bone mineralization (r = 0.50, P < 0.05) rates suggesting that its decrease resulted from a reduction of bone formation, and not from abnormal mineralization, because osteoid seam thickness was not modified. Energy intake seems to be an important determinant of serum osteocalcin concentration and bone formation; however, the exact mechanism underlying this regulation remains to be determined.

Imaging of joint response to exercise with MRI and PET.

Imaging of the joint in response to loading stress may provide additional measures of joint structure and function beyond conventional, static imaging studies. Exercise such as running, stair climbing, and squatting allows evaluation of the joint response to larger loading forces than during weight bearing. Quantitative MRI (qMRI) may assess properties of cartilage and meniscus hydration and organization in vivo that have been investigated to assess the functional response of these tissues to physiological stress. [18F]sodium fluoride ([18F]NaF) interrogates areas of newly mineralizing bone and provides an opportunity to study bone physiology, including perfusion and mineralization rate, as a measure of joint loading stress. In this review article, methods utilizing quantitative MRI, PET, and hybrid PET-MRI systems for assessment of the joint response to loading from exercise in vivo are examined. Both methodology and results of various studies performed are outlined and discussed. Lastly, the technical considerations, challenges, and future opportunities for these approaches are addressed.

Abstract A031: Dissecting the role of the bone ecosystem and intrinsic resistance in the evolution of refractory multiple myeloma

Abstract Multiple myeloma (MM) is a largely incurable cancer characterized by the expansion of plasma cells in the bone marrow. A key component of MM growth involves the establishment of a “vicious cycle” of enhanced bone resorption and tumor growth, resulting in extensive bone destruction and osteolytic lesions. Although there are many approved therapies that contribute to the long-term survival of patients, MM ultimately become refractory to treatment. The evolution of resistance is in part due to the bone ecosystem, which protects MM cells during treatment through interactions between the tumor cells and mesenchymal stem cells and cytokines secreted during bone resorption. The acquisition of refractory disease has also been attributed to intrinsic drug resistance, which allows for MM clones with inherent resistance to become the dominant population due to treatment-imposed selective pressures. While both the protective bone microenvironment and intrinsic drug resistance contribute to refractory disease, the role of the bone microenvironment in the development of cell intrinsic resistance has not been established and remains difficult to assess using current in vitro and in vivo methods alone. However, integration of cancer and evolutionary biology with computational modeling allows a unique insight into the spatiotemporal aspects of myeloma evolution and how treatment impacts the evolutionary dynamics of the disease. To explore these evolutionary dynamics, we developed a hybrid agent-based model that incorporates key cellular species that drive normal bone remodeling and, in the context of cancer, create an environment that provides protection. We use published data as well as our own to calibrate parameters such as the bone mineralization rate and to compare cell population dynamics to model outputs. Furthermore, we incorporate spatial data from immunofluorescence imaging of bone to motivate model assumptions on the localization of dividing and dying MM cells. We show that our model captures two key features: normal bone homeostasis, and the myeloma-bone vicious cycle. We then examine how the bone ecosystem impacts the growth dynamics of MM cells and the degradation of bone under standard of care treatments such as bortezomib, an anticancer therapy. Specifically, we test how the spatial distribution of the cells and factors that provide protection, as well as the timing and dose of treatment, impacts treatment response. Our data demonstrates that resistant disease cannot develop without myeloma intrinsic mechanisms, however, protection from the bone microenvironment dramatically increases the likelihood of intrinsic resistance developing. This model provides a foundation to explore how ecological and evolutionary dynamics in the bone ecosystem and MM contribute to drug resistance and tumor growth which ultimately has the potential to help improve treatment strategies. Citation Format: Anna K. Miller, Ryan T. Bishop, Tao Li, Conor C. Lynch, David Basanta. Dissecting the role of the bone ecosystem and intrinsic resistance in the evolution of refractory multiple myeloma [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr A031.

BONE HEALTH AND GROWTH IN SPINAL MUSCULAR ATROPHY TYPE 2 AND 3

Objective: Spinal muscular atrophy is a lower motor neuron disease, but other parts of the body could be affected. This study compared bone mineral density with bone metabolism and physical growth rates in patients diagnosed with spinal muscular atrophy type 2 and type 3. Material and Methods: Twenty-six patients with spinal muscular atrophy were included in the study (15 patients for type 2 and 11 for type 3). Weights and heights of patients were measured, standard deviation scores were determined, and the body-mass index was calculated. Motor function and pubertal assessment were performed. Serum calcium, phosphorus, alkaline phosphatase, parathormone, and 25-hydroxyvitamin vitamin D levels were compared. Spine radiography for scoliosis and bone densitometry for bone mineral density were performed, and volumetric bone mineral density was calculated for age and sex. Results: Medians of height standard deviation scores were significantly lower in type 2 patients. There was no difference between the two groups in terms of serum calcium, phosphorus, alkaline phosphatase, parathormone, and 25-hydroxyvitamin D levels. The ratio of scoliosis was higher in type 2 patients as was its severity, but Z-scores of volumetric bone mineral density was lower in the same group. Conclusion: This study showed that bone mineralization and growth rates were significantly lower in spinal muscular atrophy, mainly in type 2. Further studies are needed to evaluate bone health in spinal muscular atrophy patients.

BONE HEALTH AND GROWTH IN SPINAL MUSCULAR ATROPHY TYPE 2 AND 3

Objective: Spinal muscular atrophy is a lower motor neuron disease, but other parts of the body could be affected. This study compared bone mineral density with bone metabolism and physical growth rates in patients diagnosed with spinal muscular atrophy type 2 and type 3. Material and Methods: Twenty-six patients with spinal muscular atrophy were included in the study (15 patients for type 2 and 11 for type 3). Weights and heights of patients were measured, standard deviation scores were determined, and the body-mass index was calculated. Motor function and pubertal assessment were performed. Serum calcium, phosphorus, alkaline phosphatase, parathormone, and 25-hydroxyvitamin vitamin D levels were compared. Spine radiography for scoliosis and bone densitometry for bone mineral density were performed, and volumetric bone mineral density was calculated for age and sex. Results: Medians of height standard deviation scores were significantly lower in type 2 patients. There was no difference between the two groups in terms of serum calcium, phosphorus, alkaline phosphatase, parathormone, and 25-hydroxyvitamin D levels. The ratio of scoliosis was higher in type 2 patients as was its severity, but Z-scores of volumetric bone mineral density was lower in the same group. Conclusion: This study showed that bone mineralization and growth rates were significantly lower in spinal muscular atrophy, mainly in type 2. Further studies are needed to evaluate bone health in spinal muscular atrophy patients.

Microarchitecture of titanium cylinders obtained by additive manufacturing does not influence osseointegration in the sheep.

Large bone defects are a challenge for orthopedic surgery. Natural (bone grafts) and synthetic biomaterials have been proposed but several problems arise such as biomechanical resistance or viral/bacterial safety. The use of metallic foams could be a solution to improve mechanical resistance and promote osseointegration of large porous metal devices. Titanium cylinders have been prepared by additive manufacturing (3D printing/rapid prototyping) with a geometric or trabecular microarchitecture. They were implanted in the femoral condyles of aged ewes; the animals were left in stabling for 90 and 270 days. A double calcein labeling was done before sacrifice; bones were analyzed by histomorphometry. Neither bone volume, bone/titanium interface nor mineralization rate were influenced by the cylinder’s microarchitecture; the morphometric parameters did not significantly increase over time. Bone anchoring occurred on the margins of the cylinders and some trabeculae extended in the core of the cylinders but the amount of bone inside the cylinders remained low. The rigid titanium cylinders preserved bone cells from strains in the core of the cylinders. Additive manufacturing is an interesting tool to prepare 3D metallic scaffolds, but microarchitecture does not seem as crucial as expected and anchoring seems limited to the first millimeters of the graft.

Large Animal Model of Osteoporotic Defect Healing: An Alternative to Metaphyseal Defect Model.

Osteoporosis is a common metabolic disorder diagnosed by lower bone density and higher risk of fracture. Fragility fractures because of osteoporosis are associated with high mortality rate. Deep understanding of fracture healing in osteoporosis is important for successful treatment. Therefore, the FDA approved the use of small and large animal models for preclinical testing. This study investigated the clinical relevance of a fracture defect model in the iliac crest of the osteoporotic sheep model and its several advantages over other models. The osteoporosis was achieved using ovariectomy (OVX) in combination with diet deficiency (OVXD) and steroid administration (OVXDS). Fluorochrome was injected to examine the rate of bone remodelling and bone mineralization. The defect areas were collected and embedded in paraffin and polymethyl metha acrylate (PMMA) for histological staining. OVXDS showed significantly lower bone mineral density (BMD) and bone mineral content (BMC) at all time points. Furthermore, variations in healing patterns were noticed, while the control, OVX and OVXD showed complete healing after 8 months. Bone quality was affected mostly in the OVXDS group showing irregular trabecular network, lower cortical bone thickness and higher cartilaginous tissue at 8 months. The mineral deposition rate showed a declining pattern in the control, OVX, and OVXD from 5 months to 8 months. One the contrary, the OVXDS group showed an incremental pattern from 5 months to 8 months. The defect zone in osteoporotic animals showed impaired healing and the control showed complete healing after 8 months. This unique established model serves as a dual-purpose model and has several advantages: no intraoperative and postoperative complications, no need for fixation methods for biomaterial testing, and reduction in animal numbers, which comply with 3R principles by using the same animal at two different time points.

Casting More Light on Pediatric Fractures.

* Abbreviation: BMD — : bone mineral density By 16 years of age, up to 40% of otherwise healthy girls and 64% of boys will have experienced ≥1 broken bone, with a peak incidence in the peri-pubertal years.1 Is this just because youth are active or risk takers? An alternative explanation is that the fastest rate of bone mineralization occurs several months after the most rapid gains in bone size during adolescence.2 The incidence of childhood fractures appears to be on the rise in both the United States and Scandinavia, raising concerns about unhealthy lifestyle trends.1 Addressing this public health problem requires an understanding of which children are fracturing bones and why. In the population-based retrospective study of emergency department visits from Ontario, Canada, in this issue of Pediatrics , Escott et al3 suggest the risk of a broken bone is not equal for all. The study compared the fracture incidence for those with or without a baseline fracture over a 7-year follow-up period. To focus on healthy youth (<16 years of age), children with osteogenesis imperfecta, low bone density, juvenile arthropathy, pathologic fracture, or a history of child abuse or neglect were excluded from … Address correspondence to Laura K. Bachrach, MD, Division of Pediatric Endocrinology, Stanford University School of Medicine, 300 Pasteur Dr, Stanford, CA 94305-5208. E-mail: lkbach{at}stanford.edu

Effects of long-term treatment of denosumab on bone mineral density: insights from an in-silico model of bone mineralization.

Denosumab is one of the most commonly prescribed anti-resorptive drugs for the treatment of postmenopausal osteoporosis. The therapeutic effect of denosumab is to inhibit osteoclast differentiation and consequently bone resorption. Gains in bone mineral density (BMD) are achieved based on the ability of the bone matrix to undergo secondary mineralization. Experimental data show that the increase of BMD after commencing denosumab treatment are bone site specific. In this paper, we developed a comprehensive mechanistic pharmacokinetic-pharmacodymamic (PK-PD) model of the effect of denosumab on bone remodeling in postmenopausal osteoporosis (PMO). The PD model is based on a bone cell population model describing the bone remodeling process at the tissue scale. The conceptual model of the bone mineralization process, originally proposed by Boivin and Meunier, is quantitatively incorporated using a FIFO (First-In-First-Out) queue algorithm. The latter takes into account the balance of mineral within bone tissue due to the mineralization process, distinguishing the primary and secondary phases and removal of bone matrix due to bone resorption. The numerical simulations show that the model is able to predict the bone-site specific increase in BMD as was observed in the experimental data of Bone et al. 2008 for a typical denosumab administration pattern of 60 mg every 6 months. At the hip a 5 % increase in BMD was observed, while at the lumbar spine a 7.5 % increase of BMD was achieved after a 2 year treatment period. The difference in BMD is due to the fact that bone turnover at the hip is lower compared to lumbar spine and consequently has less potential for secondary mineralization. Parametric studies revealed that the rate of bone mineralization is an essential parameter regulating BMD gains. If mineralization is neglected only minimal increases in BMD are observed.

Effect of esculetin on bone metabolism in ovariectomized rats

OBJECTIVETo determine the effect of an esculetin formulation (at 97.4% purity) on osteoporosis, and to investigate the potential underlying molecular mechanism(s). METHODSSixty specific pathogen free-grade female Wistar rats were randomly assigned to three groups: blank control (n = 12), sham (n = 12), and model (n = 36). The model group were bilaterally ovariectomized. The sham group had the tissue surrounding the ovaries removed, while the ovaries were retained. After 3 months, the model group was randomly divided into three subgroups: OVX (n = 12), positive control (n = 12), and esculetin (n = 12). The positive control group and the esculetin group were intragastrically administered diethylstilbestrol (0.046 mg • kg−1 • d−1) or esculetin (384 mg • kg−1 • d−1), respectively, once per day for 6 consecutive days; medication administration was then stopped for 1 d, before being administered for another 6 consecutive days. All rats were treated for 3 months. Samples were collected at the end of the treatment period. An Osteocore3 Digital 2D bone densitometer was used to test the bone mineral density, and histomorphometric analysis was performed to measure bone mass, bone formation, and bone resorption. Enzyme-linked immunosorbent assay analysis was used to measure the serum concentrations of interleukin-6 (IL-6), osteoprotegerin (OPG), and receptor activator of nuclear factor-kappa B ligand (RANKL). Immunohistochemistry and in situ hybridization were performed to detect the protein and mRNA expressions of OPG and RANKL in osteoblasts and bone marrow stromal cells. RESULTSCompared with the OVX group, the esculetin group had significantly greater femoral bone mineral density and tibial trabecular bone volume, and significantly smaller trabecular resorption surface. The percentage of trabecular formation surface, average osteoid width, trabecular bone mineralization rate, and cortical bone mineralization rate did not significantly differ between groups. Compared with the sham group, the esculetin group had significantly decreased serum levels of IL-6 and RANKL, and significant downregulation of RANKL protein and mRNA expression levels in osteoblasts and bone marrow stromal cells; however, there was no significant difference between groups in OPG. CONCLUSIONEsculetin can increase bone mass by upregulating RANKL expression in osteoblasts and bone marrow stromal cells, and decreasing serum IL-6 concentration. This indicates that the therapeutic effect of esculetin on osteoporosis occurs via decreased bone resorption.

Substance P modulates bone remodeling properties of murine osteoblasts and osteoclasts

Clinical observations suggest neuronal control of bone remodeling. Sensory nerve fibers innervating bone, bone marrow and periosteum signal via neurotransmitters including substance P (SP). In previous studies we observed impaired biomechanical and structural bone parameters in tachykinin (Tac) 1-deficient mice lacking SP. Here, we aim to specify effects of SP on metabolic parameters of bone marrow macrophage (BMM)/osteoclast cultures and osteoblasts isolated from Tac1-deficient and wildtype (WT) mice. We demonstrated endogenous SP production and secretion in WT bone cells. Absence of SP reduced bone resorption rate, as we found reduced numbers of precursor cells (BMM) and multinucleated osteoclasts and measured reduced cathepsin K activity in Tac1−/− BMM/osteoclast cultures. However, this might partly be compensated by reduced apoptosis rate and increased fusion potential of Tac1−/− precursor cells to enlarged “super” osteoclasts. Contrarily, increased ALP enzyme activity and apoptosis rate during early osteoblast differentiation accelerated osteogenesis and cell death in the absence of SP together with reduced ALP activity of Tac1−/− osteoblasts during late osteogenic differentiation resulting in reduced bone formation at later stages. Therefore, we suggest that absence of SP presumably results in a slight reduction of bone resorption rate but concomitantly in a critical reduction of bone formation and mineralization rate.

The effect of vitamin D and calcium supplementation in pediatric steroid-sensitive nephrotic syndrome.

Low serum levels of total 25-hydroxycholecalciferol (25(OH)D) occur in nephrotic syndrome (NS). We aimed to assess the effects of vitamin D3 and calcium supplementation on 25(OH)D levels, bone mineralization, and NS relapse rate in children with steroid-sensitive NS. A randomized controlled trial (RCT) was performed in children with steroid-sensitive NS. The treatment group received vitamin D3 (60,000IU orally, weekly for 4weeks) and calcium supplements (500 to 1,000mg/day for 3months) after achieving NS remission. Blood samples for bone biochemistry were taken during relapse (T0), after 6weeks (T1) and 6months (T2) of randomization, whereas a lumbar DXA scan was performed at T0 and T2. Renal ultrasound was performed after study completion in the treatment group and in all patients with hypercalciuria. Of the 48 initial recruits, 43 patients completed the study. Post-intervention, 25(OH)D levels showed significant improvements in the treatment group compared with controls at T1 (p<0.001) and T2 (p<0.001). However, this was not associated with differences in bone mineral content (BMC) (p=0.44) or bone mineral density (BMD) (p=0.64) between the groups. Additionally, there was no reduction in relapse number in treated patients (p=0.54). Documented hypercalciuria occurred in 52% of patients in the treatment group, but was not associated with nephrocalcinosis. Although supplementation with calcium and vitamin D improved 25(OH)D levels significantly, there was no effect on BMC, BMD or relapse rate over a 6-month follow-up. Occurrence of hypercalciuria mandates caution and appropriate monitoring if using such therapy. Appropriate dosage of vitamin D3 remains uncertain and studies examining biologically active vitamin D may provide answers.

Symptoms of Sternal Nonunion Late after Cardiac Surgery.

Background A cohort of patients having symptoms of sternal nonunion late after sternotomy was studied to find out whether the complaints were related to true sternal nonunion or decreased bone density. Methods A survey was mailed to 2,053 cardiac surgical patients operated in our institution between July 2007 and June 2010. The patients were requested about symptoms referring to sternal instability. A group of symptomatic individuals as well as 1:1 age- and time-matched asymptomatic controls were examined with sternal palpation, ultrasound during standardized sternal pressure provocation, and computed tomography (CT). Results The number of patients replied in the survey was 1,918 (93.4%); 2.3% (44 patients) reported sensation of movement or clicking in sternum during body movements and during coughing. Symptomatic patients living within 200 km to the hospital (21) and their asymptomatic controls (21) were selected for further clinical and imaging studies. Mean period between the initial operation and the examinations was 36 (22-56) months. Sternal palpation pain was significantly associated with reported symptoms suggestive of sternal nonunion (odds ratio [OR] 22.0; 95% confidence interval [CI] 2.5-195); however, none of the patients had clinically unstable sternum or nonunion in the sternal imaging. The symptoms of sternal instability were more frequent in patients whose bone mineralization rate (as measured with T-scores) was higher. Conclusion Symptoms suggestive of sternal nonunion were experienced by 2.3%. However, their symptoms did not correlate with CT scans or provocation ultrasound although palpation pain was evident. Thus the pain is derived from nonmechanical etiologies. Higher bone mineralization rate correlated with abnormal symptoms of sternal wound.

Strontium coating by electrochemical deposition improves implant osseointegration in osteopenic models.

Osteopenia, a preclinical state of osteoporosis, restricts the application of adult orthodontic implant anchorage and tooth implantation. Strontium (Sr) is able to promote bone formation and inhibit bone absorption. The aim of the present study was to evaluate a new method for improving the success rate of dental implantation. In this study, an electrochemical deposition (ECD) method was used to prepare a Sr coating on a titanium implant. The coating composition was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction, and the surface morphology of the coating was studied using scanning electron microscopy. A total of 24 Sprague-Dawley rats received bilateral ovariectomy (OVX) and an additional 12 rats underwent a sham surgery. All rats were then implanted in the bilateral tibiae with titanium mini-implants with or without a Sr coating. The results of histological examination and a fluorescence double labeling assay showed strong new bone formation with a wider zone between the double labels, a higher rate of bone mineralization and better osseointegration in the OVX rats that received Sr-coated implants compared with the OVX rats that received uncoated implants. The study indicates that Sr coatings are easily applied by an ECD method, and that Sr coatings have a promoting effect on implant osseointegration in animals with osteopenia.

Collagen type-I leads to in vivo matrix mineralization and secondary stabilization of Mg–Zr–Ca alloy implants

Biodegradable magnesium–zirconia–calcium (Mg–Zr–Ca) alloy implants were coated with Collagen type-I (Coll-I) and assessed for their rate and efficacy of bone mineralization and implant stabilization. The phases, microstructure and mechanical properties of these alloys were analyzed using X-ray diffraction (XRD), optical microscopy and compression test, respectively, and the corrosion behavior was established by their hydrogen production rate in simulated body fluid (SBF). Coll-I extracted from rat tail, and characterized using fourier transform infrared (FT-IR) spectroscopy, was used for dip-coating the Mg-based alloys. The coated alloys were implanted into the femur bones of male New Zealand white rabbits. In vivo bone formation around the implants was quantified by measuring the bone mineral content/density (BMC/BMD) using dual-energy X-ray absorptiometry (DXA). Osseointegration of the implant and new bone mineralization was visualized by histological and immunohistochemical analysis. Upon surface coating with Coll-I, these alloys demonstrated high surface energy showing enhanced performance as an implant material that is suitable for rapid and efficient new bone tissue induction with optimal mineral content and cellular properties. The results demonstrate that Coll-I coated Mg–Zr–Ca alloys have a tendency to form superior trabecular bone structure with better osteoinduction around the implants and higher implant secondary stabilization, through the phenomenon of contact osteogenesis, compared to the control and uncoated ones in shorter periods of implantation. Hence, Coll-I surface coating of Mg–Zr–Ca alloys is a promising method for expediting new bone formation in vivo and enhancing osseointegration in load bearing implant applications.

Evaluation of Serum Osteocalcin Level in Iraqi Postmenopausal Women with Primary Osteoporosis

Background: Osteoporosis (OP) is a chronic and a progressive disease characterized by low bone mass and micro-architectural deterioration of bone tissue, resulting in an increased risk of fracture. Osteocalcin is a non-collagenous protein synthesized and secreted by osteoblasts. Its main physiological functions are calcium ion homeostasis, maintain the normal bone mineralization rate, inhibit the abnormal formation of hydroxyapatite crystal, and to be involved in bone remodeling through a negative feedback mechanism.Objective: This study was planned to evaluate serum level of bone formation marker osteocalcin (OC) in postmenopausal women with and without primary osteoporosis; and study the correlation between serum osteocalcin level with women’s age.Subjects and Methods: Forty four (44) postmenopausal women were included in this study with age range (51-68 years). Subjects were divided into two groups: group A: twenty three (23) women with primary osteoporosis and group B: twenty one (21) women without primary osteoporosis (serve as controls). Patients were diagnosed as osteoporosis and controls as normal by measuring bone mineral density (BMD), using dual energy x-ray absorptiometry (DXA). In addition, serum calcium, phosphorous and alkaline phosphatase measured by spectrophotometer, while serum osteocalcin measured by enzyme linked immuno sorbent assay (ELISA).Results: Mean serum osteocalcin level in postmenopausal women with primary osteoporosis was significantly higher than controls (P&lt;0.0001) Moreover, a positive correlation between serum osteocalcin level with age for both patients (r=0.86, P&lt;0.0001) and controls (r=0.71, P&lt;0.001).Conclusion: Increasing serum osteocalcin level in postmenopausal women with osteoporosis plays an important role in development of primary osteoporosis.

Preparation and properties of α-calcium sulphate hemihydrate and β-tricalcium phosphate bone substitute

Autogenous bone graft carries the risk of complications. In contrast, artificial bone graft provides initial strength and allows new bone ingrowth. In this study, we examined methods of preparation of α-calcium sulphate hemihydrate (α-CSH) and β-tricalcium phosphate (β-TCP), and a composite of the two materials. Characterization of the materials was determined with X-ray diffraction, differential thermal analysis (DTA), scanning electron microscopy (SEM), and porosity analysis. β-TCP exhibited the spatial structure and porosity of normal bone with a macropore size of 50-400 μm and some 1 μm micropores. α-CSH exhibited a regular crystal structure. A combined material was prepared in a 1:1 weight ratio, and in a rabbit model, the rate of new bone mineralization was similar to that of autogenous bone graft. The combined material of β-TCP and α-CSH in this study may provide similar efficacy as autogenous bone graft.

Matrix Metalloproteinase-9 Expression in Alveolar Extraction Sockets of Zoledronic Acid–Treated Rats

The use of nitrogen-containing bisphosphonates (n-bis) is associated with necrosis of the jaws, also known as bisphosphonate-related osteonecrosis of the jaws (BRONJ); however, the pathophysiology is unknown. Matrix metalloproteinase-9 (MMP-9) expression is essential for normal bone healing and is also required for angiogenesis. N-bis alters MMP-9 expression in vitro and in vivo; therefore, we hypothesized that n-bis alters MMP-9 expression during oral wound healing after tooth extraction. A total accumulated dose of 2.25 mg/kg (n = 20) of Zoledronic acid (ZA) Zometa or saline (control, n = 20) was administered to Sprague-Dawley male rats. Next, both groups had maxillary molar teeth extracted. Rats were sacrificed at postoperative day 1, 3, 7, or 21. Western blotting or multiplex ELISA was used to evaluate proteins of interest. Real-time polymerase chain reaction was used to assess the relative quantities of target gene mRNA. MMP-9 enzymatic activity was assessed by zymography. The ZA group showed a statistically significant reduction in bone mineralization rate 21 days after tooth extraction compared with the control group (Student t test, P = .005). Moreover, ZA-treated animals showed a statistically significant increase in MMP-9-specific mRNA at postoperative days 3 (P = .003), 7 (P < .0001), and 21 (P < .0001) and protein on postoperative days 3 (P = .005) and 7 (P < .0001). MMP-9 enzymatic activity was also increased in ZA-treated rats compared with control animals (Student t test, P = .014). We also evaluated the extraction sockets for the presence of tissue inhibitor of MMP-1 (TIMP1), which is an inhibitor of MMP-9 enzymatic activity. TIMP1-specific mRNA and protein were not significantly altered by ZA treatment at the times tested (P > .05). Receptor of NF-κB ligand (RANKL) is known to regulate the expression of MMP-9; we therefore assessed the RANKL expression in our experimental oral wound-healing model. The ZA-treated animals had significantly increased RANKL mRNA at postoperative days 3 (P = .02) and 21 (P = .004), while the protein expression was significantly increased at postoperative days 1 (P < .0001), 7 (P = .02), and 21 (P = .03) compared with the control group. ZA reduced bone mineralization within tooth extraction sockets, suggesting aberrant bone healing. ZA increases the amount and enzymatic activity of MMP-9, while apparently not altering the amount of TIMP1 within extraction sockets. RANKL is increased in ZA-treated rats, which suggests that increased MMP-9 expression is due, in part, to augmented RANKL expression.

Preparation of combined β-TCP/α-CSH artificial bone graft and its performance in a spinal fusion model

To evaluate α-calcium sulfate hemihydrate (α-CSH)/β-tricalcium phosphate (β-TCP) combined artificial bone graft (COB) in an animal model of posterolateral spinal fusion, α-CSH and β-TCP were combined in a 3 : 7 weight ratio. A rabbit model of posterolateral spinal fusion was produced (N = 36); one side was implanted with the COB, and the other with local autogenous bone. Rabbits were killed on the 4th, 8th, or 12th week after surgery and fusion, COB degradation, mineralization, and new bone formation were evaluated. Scanning electron microscopy revealed that the COB retained the porous spatial structure of β-TCP and α-CSH crystals were adhered to the surface and pores of β-TCP. At the 12th week after surgery, the fusion rate was 75.0% on the 12th week after the operation, which was higher than the fusion rate of 54.4% the autogenous bone side (p = 0.073). Bone volume fraction of the COB was 0.49 ± 0.08 for the 4th week and 0.16 ± 0.05 for the 12th week after surgery. The mineralization rate of the new bone was greater on the side implanted with autogenous bone than on the side implanted with COB at all the three time points after surgery. At each time point after surgery, the difference in mineralization rate between the autogenous bone side and the COB side was statistically significant (p < 0.001); α-CSH/β-TCP in a 3 : 7 weight ratio was as effective as local autogenous bone in producing spinal fusion in a rabbit model. Used in this ratio, the speed of material degradation and new bone formation are relatively equivalent, and the rate of new bone mineralization is similar to that of autogenous bone graft.