Characterization of bone mineral composition in the proximal tibia of cynomolgus monkeys: effect of ovariectomy and nandrolone decanoate treatment

Longitudinal alterations in bone morphometry, mechanical integrity and composition in Type-2 diabetes in a Zucker diabetic fatty (ZDF) rat

Individuals with Type-2 Diabetes (T2D) have an increased risk of bone fracture, without a reduction in bone mineral density. It is hypothesised that the hyperglycaemic state caused by T2D forms an excess of Advanced Glycated End-products (AGEs) in the organic matrix of bone, which are thought to stiffen the collagen network and lead to impaired mechanical properties. However, the mechanisms are not well understood. This study aimed to investigate the geometrical, structural and material properties of diabetic cortical bone during the development and progression of T2D in ZDF (fa/fa) rats at 12-, 26- and 46-weeks of age. Longitudinal bone growth was impaired as early as 12-weeks of age and by 46-weeks bone size was significantly reduced in ZDF (fa/fa) rats versus controls (fa/+). Diabetic rats had significant structural deficits, such as bending rigidity, ultimate moment and energy-to-failure measured via three-point bend testing. Tissue material properties, measured by taking bone geometry into account, were altered as the disease progressed, with significant reductions in yield and ultimate strength for ZDF (fa/fa) rats at 46-weeks. FTIR analysis on cortical bone powder demonstrated that the tissue material deficits coincided with changes in tissue composition, in ZDF (fa/fa) rats with long-term diabetes having a reduced carbonate:phosphate ratio and increased acid phosphate content when compared to age-matched controls, indicative of an altered bone turnover process. AGE accumulation, measured via fluorescent assays, was higher in the skin of ZDF (fa/fa) rats with long-term T2D, bone AGEs did not differ between strains and neither AGEs correlated with bone strength. In conclusion, bone fragility in the diabetic ZDF (fa/fa) rats likely occurs through a multifactorial mechanism influenced initially by impaired bone growth and development and proceeding to an altered bone turnover process that reduces bone quality and impairs biomechanical properties as the disease progresses.

Measures of Bone Mineral Carbonate Content and Mineral Maturity/Crystallinity for FT-IR and Raman Spectroscopic Imaging Differentially Relate to Physical-Chemical Properties of Carbonate-Substituted Hydroxyapatite

Bone mineral carbonate content assessed by vibrational spectroscopy relates to fracture incidence, and mineral maturity/ crystallinity (MMC) relates to tissue age. As FT-IR and Raman spectroscopy become more widely used to characterize the chemical composition of bone in pre-clinical and translational studies, their bone mineral outcomes require improved validation to inform interpretation of spectroscopic data. In this study, our objectives were (1) to relate Raman and FT-IR carbonate:phosphate ratios calculated through direct integration of peaks to gold-standard analytical measures of carbonate content and underlying subband ratios; (2) to relate Raman and FT-IR MMC measures to gold-standard analytical measures of crystal size in chemical standards and native bone powders. Raman and FT-IR direct integration carbonate:phosphate ratios increased with carbonate content (Raman: p < 0.01, R² = 0.87; FT-IR: p < 0.01, R² = 0.96) and Raman was more sensitive to carbonate content than the FT-IR (Raman slope + 95% vs FT-IR slope, p < 0.01). MMC increased with crystal size for both Raman and FT-IR (Raman: p < 0.01, R² = 0.76; FT-IR p < 0.01, R² = 0.73) and FT-IR was more sensitive to crystal size than Raman (c-axis length: slope FT-IR MMC + 111% vs Raman MMC, p < 0.01). Additionally, FT-IR but not Raman spectroscopy detected differences in the relationship between MMC and crystal size of carbonated hydroxyapatite (CHA) vs poorly crystalline hydroxyapatites (HA) (slope CHA + 87% vs HA, p < 0.01). Combined, these results contribute to the ability of future studies to elucidate the relationships between carbonate content and fracture and provide insight to the strengths and limitations of FT-IR and Raman spectroscopy of native bone mineral.

Effects of nandrolone decanoate on femur morphology. Experimental study

PURPOSE

To evaluate the immediate and late effects of nandrolone on femur morphology of rats.

METHODS

Twenty-eight animals with 20 weeks of age were divided into four groups: C28, control animals that were euthanized eight weeks after the experiment started; C40, control animals euthanized 20 weeks after the experiment started; T28, treated animals receiving nandrolone during eight weeks and euthanized immediately after the treatment period; and T40, animals treated during eight weeks and euthanized 12 weeks after the end of the treatment. Treated animals received nandrolone decanoate during eight weeks and control groups received peanut oil by intramuscular injection. After euthanasia, femurs were removed, dissected, weighted and measured by digital pachymeter.

RESULTS

The T40 group presented an increase on distal epiphysis diameter when compared to C40 group. There was no difference between treated and control groups in relation to body and femur absolute weight, relative weight and length of femur. There was also no difference in relation to diameter of proximal epiphysis and diameter of diaphysis among the groups.

CONCLUSIONS

Nandrolone decanoate does not produce significant effect on femur, exception on its distal extremity at late period. The effects of such drug may depend on the time after administration.

Raman and Fourier transform infrared imaging for characterization of bone material properties

As the application of Raman spectroscopy to study bone has grown over the past decade, making it a peer technology to FTIR spectroscopy, it has become critical to understand their complimentary roles. Recent technological advancements have allowed these techniques to collect grids of spectra in a spatially resolved fashion to generate compositional images. The advantage of imaging with these techniques is that it allows the heterogenous bone tissue composition to be resolved and quantified. In this review we compare, for non-experts in the field of vibrational spectroscopy, the instrumentation and underlying physical principles of FTIR imaging (FTIRI) and Raman imaging. Additionally, we discuss the strengths and limitations of FTIR and Raman spectroscopy, address sample preparation, and discuss outcomes to provide researchers insight into which techniques are best suited for a given research question. We then briefly discuss previous applications of FTIRI and Raman imaging to characterize bone tissue composition and relationships of compositional outcomes with mechanical performance. Finally, we discuss emerging technical developments in FTIRI and Raman imaging which provide new opportunities to identify changes in bone tissue composition with disease, age, and drug treatment.

Raman spectroscopy investigation shows that mineral maturity is greater in CD-1 than in C57BL/6 mice distal femurs after sexual maturity

Purpose/Aim of the study mice are the most often used pre-clinical lab models for studying the pathologies of bone mineralization. However, recent evidence suggests that two of the most often used mice strains (C57BL/6J and CD-1) might show differences in the bone mineralization process. This study sought to investigate the main compositional properties of bone tissue between nonpathological C57BL/6J and CD-1 murine knee joints. Materials and Methods : to this end, medial and lateral condylar subchondral bones and the adjacent diaphyseal cortical bone of 13 murine femurs (n = 7 C57BL/6J and n = 6 CD-1 at eight weeks old, just after sexual maturation) were analyzed with ex vivo Raman spectroscopy. Results : regardless of the bone tissue analyzed, our results showed that CD-1 laboratory mice present a more mature mineral phase than C57BL/6J laboratory mice, but present no difference in maturity of the collagen phase. For both strains, the subchondral bone of the medial condylar and cortical bone from the diaphysis have similar compositional properties, and CD-1 presents less variation than C57BL/6J. Furthermore, we depict a novel parametric relationship between the crystallinity and carbonate-to-amide-I ratio that might help in deciphering the mineral maturation process that occurs during bone's mineralization. Conclusions : Our results suggest that the timing of bone maturation might be different between non-pathological C57BL/6J and CD-1 murine knee femurs.

Vibrational spectroscopic techniques to assess bone quality

Although musculoskeletal diseases such as osteoporosis are diagnosed and treatment outcome is evaluated based mainly on routine clinical outcomes of bone mineral density (BMD) by DXA and biochemical markers, it is recognized that these two indicators, as valuable as they have proven to be in the everyday clinical practice, do not fully account for manifested bone strength. Thus, the term bone quality was introduced, to complement considerations based on bone turnover rates and BMD. Bone quality is an "umbrella" term that incorporates the structural and material/compositional characteristics of bone tissue. Vibrational spectroscopic techniques such as Fourier transform infrared microspectroscopy (FTIRM) and imaging (FTIRI), and Raman spectroscopy, are suitable analytical tools for the determination of bone quality as they provide simultaneous, quantitative, and qualitative information on all main bone tissue components (mineral, organic matrix, tissue water), in a spatially resolved manner. Moreover, the results of such analyses may be readily combined with the outcomes of other techniques such as histology/histomorphometry, small angle X-ray scattering, quantitative backscattered electron imaging, and nanoindentation.

Effects of losartan treatment on the physicochemical properties of diabetic rat bone

Inhibitors of the renin-angiotensin system used to treat several diseases have also been shown to be effective on bone tissue, suggesting that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may reduce fracture risk. The present study investigated the effects of losartan on the physicochemical and biomechanical properties of diabetic rat bone. Losartan (5 mg/kg/day) was administered via oral gavage for 12 weeks. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Whole femurs were tested under tension to evaluate the biomechanical properties of bone. The physicochemical properties of bone were analyzed by Fourier transform infrared spectroscopy. Although losartan did not recover decreases in the BMD of diabetic bone, it recovered the physicochemical (mineral and collagen matrix) properties of diabetic rat bone. Furthermore, losartan also recovered ultimate tensile strength of diabetic rat femurs. Losartan, an angiotensin II type 1 receptor blocker, has a therapeutic effect on the physicochemical properties of diabetic bone resulting in improvement of bone strength at the material level. Therefore, specific inhibition of this pathway at the receptor level shows potential as a therapeutic target for diabetic patients suffering from bone diseases such as osteopenia.

Ovarian hormone depletion affects cortical bone quality differently on different skeletal envelopes

The physical properties of bone tissue are determined by the organic and mineral matrix, and are one aspect of bone quality. As such, the properties of mineral and matrix are a major contributor to bone strength, independent of bone mass. Cortical bone quality may differ regionally on the three skeletal envelopes that compose it. Each of these envelopes may be affected differently by ovarian hormone depletion. Identifying how these regions vary in their tissue adaptive response to ovarian hormones can inform our understanding of how tissue quality contributes to overall bone strength in postmenopausal women. We analyzed humeri from monkeys that were either SHAM-operated or ovariectomized. Raman microspectroscopic analysis was performed as a function of tissue age based on the presence of multiple fluorescent double labels, to determine whether bone compositional properties (mineral/matrix ratio, tissue water, glycosaminoglycan, lipid, and pyridinoline contents, and mineral maturity/crystallinity) are similar between periosteal, osteonal, and endosteal surfaces, as well as to determine the effects of ovarian hormone depletion on them. The results indicate that mineral and organic matrix characteristics, and kinetics of mineral and organic matrix modifications as a function of tissue age are different at periosteal vs. osteonal and endosteal surfaces. Ovarian hormone depletion affects the three cortical surfaces (periosteal, osteonal, endosteal) differently. While ovarian hormone depletion does not significantly affect the quality of either the osteoid or the most recently mineralized tissue, it significantly affects the rate of subsequent mineral accumulation, as well as the kinetics of organic matrix modifications, culminating in significant differences within interstitial bone. These results highlight the complexity of the cortical bone compartments, add to existing knowledge on the effects of ovarian hormone depletion on local cortical bone properties, and may contribute to a better understanding of the location specific action of drugs used in the management of postmenopausal osteoporosis.

Stanozolol Decreases Bone Turnover Markers, Increases Mineralization, and Alters Femoral Geometry in Male Rats

Stanozonol (ST) is a synthetic derivative of testosterone; it has anabolic/androgenic activity, increasing both the turnover of trabecular bone and the endocortical apposition of bone. The present study aimed to examine the effects of ST on bone status in rats by bone mineral content, markers of formation and resorption, bone density, and structural and microarchitectural parameters. Twenty male Wistar rats were randomly distributed into two experimental groups corresponding to placebo or ST administration, which consisted of weekly intramuscular injections of 10 mg/kg body weight of ST. Plasma parameters were analyzed by immunoassay. Bone mineral content was determined by spectrophotometry. Bone mineral density (BMD) and structural parameters were measured by peripheral quantitative computed tomography, and trabecular and cortical microarchitecture by micro-computed tomography. Plasma Ca, Mg, and alkaline phosphatase were higher, and urinary Ca excretion, corticosterone, and testosterone concentrations lower in the ST group. Femur Ca content was higher and P content was lower in the ST, whereas osteocalcin, aminoterminal propeptides of type I procollagen, and C-terminal telopeptides of type I collagen were lower. Total cross-sectional, trabecular, and cortical/subcortical areas were lower in the ST. No differences were observed on BMD and area parameters of the diaphysis as well as on trabecular and cortical microarchitecture. The use of ST increases bone mineralization, ash percentage, and Ca and Mg content in femur. In spite of an absence of changes in BMD, geometric metaphyseal changes were observed. We conclude that ST alters bone geometry, leads to low bone turnover, and thus may impair bone quality.

X-ray diffraction from bone employing annular and semi-annular beams

There is a compelling need for accurate, low cost diagnostics to identify osteo-tissues that are associated with a high risk of fracture within an individual. To satisfy this requirement the quantification of bone characteristics such as 'bone quality' need to exceed that provided currently by densitometry. Bone mineral chemistry and microstructure can be determined from coherent x-ray scatter signatures of bone specimens. Therefore, if these signatures can be measured, in vivo, to an appropriate accuracy it should be possible by extending terms within a fracture risk model to improve fracture risk prediction.In this preliminary study we present an examination of a new x-ray diffraction technique that employs hollow annular and semi-annular beams to measure aspects of 'bone quality'. We present diffractograms obtained with our approach from ex vivo bone specimens at Mo Kα and W Kα energies. Primary data is parameterized to provide estimates of bone characteristics and to indicate the precision with which these can be determined.

The effect of calcium and vitamin D supplementation on osteoporotic rabbit bones studied by vibrational spectroscopy

Fourier transform infrared spectroscopy is utilized to examine the effects of increased calcium, vitamin D, and combined calcium-vitamin D supplementation on osteoporotic rabbit bones with induced inflammation. The study includes different bone sites (femur, tibia, humerus, vertebral rib) in an effort to explore possible differences among the sites. We evaluate the following parameters: mineral-to-matrix ratio, carbonate content, and non-apatitic species (labile acid phosphate and labile carbonate) contribution to bone mineral. Results show that a relatively high dose of calcium or calcium with vitamin D supplementation increases the bone mineralization index significantly. On the other hand, vitamin D alone is not as effective in promoting mineralization even with high intake. Mature B-type apatite was detected for the group with calcium supplementation similar to that of aged bone. High vitamin D intake led to increased labile species concentration revealing bone formation. This is directly associated with the suppression of pro-inflammatory cytokines linked to induced inflammation. The latter is known to adversely alter bone metabolism, contributing to the aetiopathogenesis of osteoporosis. Thus, a high intake of vitamin D under inflammation-induced osteoporosis does not promote mineralization but suppresses bone resorption and restores metabolic balance.

Prostate cancer metastases alter bone mineral and matrix composition independent of effects on bone architecture in mice--a quantitative study using microCT and Raman spectroscopy

Prostate cancer is the most common primary tumor and the second leading cause of cancer-related deaths in men in the United States. Prostate cancer bone metastases are characterized by abnormal bone remodeling processes and result in a variety of skeletal morbidities. Prevention of skeletal complications is a crucial element in prostate cancer management. This study investigated prostate cancer-induced alterations in the molecular composition and morphological structure of metastasis-bearing bones in a mouse model of prostate cancer using Raman spectroscopy and micro-computed tomography (microCT). LNCaP C4-2B prostate cancer cells were injected into the right tibiae of 5-week old male SCID mice. Upon sacrifice at 8weeks post tumor inoculation, two out of the ten tumor-bearing tibiae showed only osteoblastic lesions in the radiographs, 4 osteolytic lesions only and 4 mixed with osteoblastic and osteolytic lesions. Carbonate substitution was significantly increased while there was a marked reduction in the level of collagen mineralization, mineral crystallinity, and carbonate:matrix ratio in the cortex of the intact tumor-bearing tibiae compared to contralateral controls. MicroCT analysis revealed a significant reduction in bone volume/total volume, trabecular number and trabecular thickness, as well as significant increase in bone surface/volume ratio in tibiae with osteolytic lesions, suggesting active bone remodeling and bone loss. None of the changes in bone compositional properties were correlated with lesion area from radiographs or the changes in bone architecture from microCT. This study indicates that LNCaP C4-2B prostate cancer metastases alter bone tissue composition independent of changes in architecture, and altered bone quality may be an important contributor to fracture risk in these patients. Raman spectroscopy may provide a new avenue of investigation into interactions between tumor and bone microenvironment.

Incidence and bone biopsy findings of atypical femoral fractures

Bisphosphonates are widely used in the treatment of osteoporosis. It has been suggested that bisphosphonate treatment may be associated with atypical femoral fractures (AFFs), severely suppressed bone turnover rate, and decreased mineralization. We studied bone properties using bone quantitative histomorphometry and Fourier transform infrared spectroscopic imaging (FTIRI) on patients with AFFs. Further, the incidence of AFFs was estimated. Patient records of Kuopio University Hospital, Finland from January 2007 to June 2009 were reviewed to identify all patients who had sustained and had been operated for AFF (n = 8). The incidence of AFFs among patients on bisphosphonates was 0.61 fractures/1,000 patients per year, compared to 0.0067/1,000 per year among untreated patients. The patients that underwent bone biopsy (n = 4) were postmenopausal women (aged 55.5-81.1 years) who had been treated with bisphosphonates for over 4 years. Histomorphometry revealed low trabecular bone volume. Bone formation and resorption parameters tended to be low. Trabecular bone single labels were detected in one patient in the region of interest. In the extended label search, trabecular bone double labels were found in two patients. Based on FTIRI results, higher phosphate-to-amide I ratio and collagen maturity were found compared to normal samples. The heterogeneity of phosphate-to-amide I ratio was low. Overall incidence of atypical femoral fractures is low. The poor fracture resistance in some patients on long-term bisphosphonate-therapy could be explained by low bone formation, and changes in bone composition, i.e., higher degree of mineralization, increased collagen maturity, and decreased heterogeneity of the degree of mineralization.

Composition and microarchitecture of human trabecular bone change with age and differ between anatomical locations

The microarchitecture of trabecular bone adapts to its mechanical loading environment according to Wolff's law and alters with age. Trabecular bone is a metabolically active tissue, thus, its molecular composition and microarchitecture may vary between anatomical locations as a result of the local mechanical loading environment. No comprehensive comparison of composition and microarchitecture of trabecular bone in different anatomical locations has been conducted. Therefore, the objective of this study was to compare the molecular composition and microarchitecture, evaluated with Fourier transform infrared (FTIR) microspectroscopy and micro-computed tomography (μCT), respectively, in the femoral neck, greater trochanter and calcaneus of human cadavers. Specimens were harvested from 20 male human cadavers (aged 17-82 years) with no known metabolic bone diseases. Significant differences were found in composition and microarchitecture of trabecular bone between the anatomical locations. Compositional differences were primarily observed between the calcaneus and the proximal femur sites. Mineralization was higher in the greater trochanter than in the calcaneus (+2%, p<0.05) and crystallinity was lowest in the calcaneus (-24%, p<0.05 as compared to the femoral neck). Variation in the composition of trabecular bone within different parts of the proximal femur was only minor. Collagen maturity was significantly lower in greater trochanter than in femoral neck (-8%, p<0.01) and calcaneus (-5%, p<0.05). The greater trochanter possessed a less dense trabecular bone microarchitecture compared to femoral neck or calcaneus. Age related changes were mainly found in the greater trochanter. Significant correlations were found between the composition and microarchitecture of trabecular bone in the greater trochanter and calcaneus, indicating that both composition and microarchitecture alter similarly. This study provides new information about composition and microarchitecture of trabecular bone in different anatomical locations and their alterations with age with respect to the anatomical loading environments.

Fourier transform infrared spectroscopic imaging parameters describing acid phosphate substitution in biologic hydroxyapatite

Acid phosphate substitution into mineralized tissues is an important determinant of their mechanical properties and their response to treatment. This study identifies and validates Fourier transform infrared spectroscopic imaging (FTIRI) spectral parameters that provide information on the acid phosphate (HPO4) substitution into hydroxyapatite in developing mineralized tissues. Curve fitting and Fourier self-deconvolution were used to identify subband positions in model compounds (with and without HPO4). The intensity of subbands at 1127 and 1110 cm(-1) correlated with the acid phosphate content in these models. Peak height ratios of these subbands to the ν3 vibration at 1096 cm(-1) found in stoichiometric apatite were evaluated in the model compounds and mixtures thereof. FTIRI spectra of bones and teeth at different developmental ages were analyzed using these spectral parameters. Factor analysis (a chemometric technique) was also conducted on the tissue samples and resulted in factor loadings with spectral features corresponding to the HPO4 vibrations described above. Images of both factor correlation coefficients and the peak height ratios 1127/1096 and 1112/1096 cm(-1) demonstrated higher acid phosphate content in younger vs. more mature regions in the same specimen. Maps of the distribution of acid phosphate content will be useful for characterizing the extent of new bone formation, the areas of potential decreased strength, and the effects of therapies such as those used in metabolic bone diseases (osteoporosis, chronic kidney disease) on mineral composition. Because of the wider range of values obtained with the 1127/1096 cm(-1) parameter compared to the 1110/1096 cm(-1) parameter and the smaller scatter in the slope, it is suggested that this ratio should be the parameter of choice.

Infrared spectroscopic assessment of the inflammation-mediated osteoporosis (IMO) model applied to rabbit bone

A model of osteoporosis based on induced inflammation (IMO) was applied on rabbit bones. The structural heterogeneity and molecular complexity of bone significantly affect bone mechanical properties. A tool like Fourier transform infrared spectroscopy, able to analyze both the inorganic and organic phase simultaneously, could provide compositional information regarding cortical and trabecular sections under normal and osteoporotic conditions. In this study, we assessed the mineral/matrix ratio, carbonate and phosphate content and labile (i.e., non-apatitic) species contribution to bone mineral and collagen cross-linking patterns. Clear differences were observed between cortical and trabecular bone regarding mineral and carbonate content. Induced inflammation lowers the mineral/matrix ratio and increases the overall carbonate accumulation. Elevated concentrations of labile species were detected in osteoporotic samples, especially in the trabecular sections. Collagen cross-linking patterns were indirectly observed through the 1660/1690 cm⁻¹ ratio in the amide I band and a positive correlation was found with the mineralization index. Principal component analysis (PCA) applied to female samples successfully clustered trabecular and osteoporotic cases. The important role played by the phosphate ions was confirmed by corresponding loadings plots. The results suggest that the application of the IMO model to rabbit bones effectively alters bone remodeling and forms an osteoporotic bone matrix with a dissimilar composition compared to the normal one.

Pharmacological evaluation of LiuWei Zhuanggu Granules in rats

Many commonly consumed foods, herbs and spices contain a complex array of naturally occurring bioactive molecules called phytochemicals, which may confer health benefits. In this study, the impact of LiuWei Zhuanggu Granules (LWZGG) on mineral metabolism in osteopenia development was evaluated. Results showed that serum estrogen, bone gla protein (BGP), and calcitonin (CT) levels, bone Ca, Zn and Cu levels, femur, lumbar vertebrae and trabecular bone density, tibia maximum stress and maximum bending strength were increased, and serum parathyroid hormone (PTH), serum and urine Ca, Zn and Cu levels were decreased in rat bone. It can be concluded that LWZGG is useful to improve bone quality in ovariectomized (OVX) rats.

Synchrotron Radiation Spectroscopic Techniques as Tools for the Medicinal Chemist: Microprobe X-Ray Fluorescence Imaging, X-Ray Absorption Spectroscopy, and Infrared Microspectroscopy

This review updates the recent advances and applications of three prominent synchrotron radiation techniques, microprobe X-ray fluorescence spectroscopy/imaging, X-ray absorption spectroscopy, and infrared microspectroscopy, and highlights how these tools are useful to the medicinal chemist. A brief description of the principles of the techniques is given with emphasis on the advantages of using synchrotron radiation-based instrumentation rather than instruments using typical laboratory radiation sources. This review focuses on several recent applications of these techniques to solve inorganic medicinal chemistry problems, focusing on studies of cellular uptake, distribution, and biotransformation of established and potential therapeutic agents. The importance of using these synchrotron-based techniques to assist the development of, or validate the chemistry behind, drug design is discussed.

Synchrotron FTIR Microspectroscopy Study of the Striatum in 6-Hydroxydopamine Rat Model of Parkinson's Disease

In the present study, synchrotron-based Fourier transform-infrared (FTIR) microspectroscopy is used to analyze the biochemical composition of the striatal neurons in normal and Parkinson's disease (PD) rat brain tissues. The rat model of Parkinson's disease is established by destroying the nigrostriatal pathway with 6-hydroxydopamine (6-OHDA). The detailed spectral analyses show the significant changes of cellular compositions such as lipids, and proteins in the striatal neurons of 6-OHDA-lesioned PD rats with respect to control neurons. As a result, the intensities of spectral absorption assigned to lipid of the striatal neurons in PD rats are higher than in control animals. Furthermore, the unsaturation levels of phospholipids decrease in PD neurons with respect to control neurons, indicating a high level of lipid peroxidation. The analysis of protein secondary structure shows the significantly higher ratio ofβ-sheet in PD neurons compared to that of control neurons, suggesting that the abnormal protein structure occurs before their morphological appearances in the striatal neurons. These findings suggest that the biochemical changes in neurons could be involved in the pathogenesis of Parkinson's disease.

5α-Estrane-3β,17β-diol and 5β-estrane-3α,17β-diol: definitive screening biomarkers to sign nandrolone abuse in cattle?

17β-Nandrolone (17β-NT) is one of the most frequently misused anabolic steroids in meat producing animals. As a result of its extensive metabolism combined with the possibility of interferences with other endogenous compounds, detection of its illegal use often turns out to be a difficult issue. In recent years, proving the illegal administration of 17β-NT became even more challenging since the presence of endogenous presence of 17β-NT or some of its metabolite in different species was demonstrated. In bovines, 17α-NT can occur naturally in the urine of pregnant cows and recent findings reported that both forms can be detected in injured animals. Because efficient control must both take into account metabolic patterns and associated kinetics of elimination, the purpose of the present study was to investigate further some estranediols (5α-estrane-3β,17β-diol (abb), 5β-estrane-3α,17β-diol (bab), 5α-estrane-3β,17α-diol (aba), 5α-estrane-3α,17β-diol (aab) and 5β-estrane-3α,17α-diol (baa)) as particular metabolites of 17β-NT on a large number of injured (n=65) or pregnant (n=40) bovines. Whereas the metabolites abb, bab, aba and baa have previously been detected in urine up to several days after 17β-NT administration, the present study showed that some of the isomers abb (5α-estrane-3β,17β-diol) and bab (5β-estrane-3α,17β-diol) could not be detected in injured or pregnant animals, even at very low levels. This result may open a new way for the screening of anabolic steroid administration considering these 2 estranediols as biomarkers to indicate nandrolone abuse in cattle.

Altered bone composition in children with vertebral fracture

Primary osteoporosis in children often leads to vertebral fractures, but it remains unknown whether these fractures associate with changes in bone composition. This study aimed to determine the differences in bone composition in fracture-prone children with and without vertebral fractures, as assessed by Fourier transform infrared spectroscopic imaging (FTIRI) and bone histomorphometry. Iliac crest bone biopsies (n = 24) were obtained from children who were suspected of primary osteoporosis based on evidence from the fracture history and/or low bone mineral density (BMD) by dual-energy X-ray absorptiometry. Vertebral morphology was determined by radiography. Bone biopsies were analyzed using histomorphometry and FTIRI. Phosphate-to-amide I, carbonate-to-phosphate, carbonate-to-amide I, and cross-link ratio (collagen maturity) were calculated. Children with (n = 14) and without (n = 10) vertebral fracture were compared. Low cancellous bone volume (BV/TV) was detected by histomorphometry in 36% of the children with vertebral fracture, and bone turnover rate was abnormal in 64% of them. Children with vertebral fractures had lower carbonate-to-phosphate ratios (p < .05) and higher collagen maturity (p < .05) than children without vertebral fracture. The children with low BV/TV in biopsy showed lower carbonate-to-amide I ratios (p < .05) than the children with normal bone volume. This study showed changes in bone composition among fracture-prone children who had sustained a vertebral fracture. The observed changes in bone composition in these children may contribute to their greater propensity to sustain vertebral fractures.

Infrared assessment of bone quality: a review

BACKGROUND

Bone strength depends on both bone quantity and quality. The former is routinely estimated in clinical settings through bone mineral density measurements but not the latter. Bone quality encompasses the structural and material properties of bone. Although its importance is appreciated, its contribution in determining bone strength has been difficult to precisely quantify partly because it is multifactorial and requires investigation of all bone hierarchical levels. Fourier transform infrared spectroscopy provides one way to explore these levels.

QUESTIONS/PURPOSES

The purposes of our review were to (1) provide a brief overview of Fourier transform infrared spectroscopy as a way to establish bone quality, (2) review the major bone material parameters determined from Fourier transform infrared spectroscopy, and (3) review the role of Fourier transform infrared microspectroscopic analysis in establishing bone quality.

METHODS

We used the ISI Web of Knowledge database initially to identify articles containing the Boolean term "infrared" AND "bone." We then focused on articles on infrared spectroscopy in bone-related journals.

RESULTS

Infrared spectroscopy provides information on bone material properties. Their microspectroscopic versions allow one to establish these properties as a function of anatomic location, mineralization extent, and bone metabolic activity. It provides answers pertaining to the contribution of mineral to matrix ratio, mineral maturity, mineral carbonate substitution, and collagen crosslinks to bone strength. Alterations of bone material properties have been identified in disease (especially osteoporosis) not attainable by other techniques.

CONCLUSIONS

Infrared spectroscopic analysis is a powerful tool for establishing the important material properties contributing to bone strength and thus has helped better understand changes in fragile bone.

Bone loss caused by iron overload in a murine model: importance of oxidative stress

Osteoporosis is a frequent problem in disorders characterized by iron overload, such as the thalassemias and hereditary hemochromatosis. The exact role of iron in the development of osteoporosis in these disorders is not established. To define the effect of iron excess in bone, we generated an iron-overloaded mouse by injecting iron dextran at 2 doses into C57/BL6 mice for 2 months. Compared with the placebo group, iron-overloaded mice exhibited dose-dependent increased tissue iron content, changes in bone composition, and trabecular and cortical thinning of bone accompanied by increased bone resorption. Iron-overloaded mice had increased reactive oxygen species and elevated serum tumor necrosis factor-α and interleukin-6 concentrations that correlated with severity of iron overload. Treatment of iron-overloaded mice with the antioxidant N-acetyl-L-cysteine prevented the development of trabecular but not cortical bone abnormalities. This is the first study to demonstrate that iron overload in mice results in increased bone resorption and oxidative stress, leading to changes in bone microarchitecture and material properties and thus bone loss.

Infrared spectroscopy indicates altered bone turnover and remodeling activity in renal osteodystrophy

Renal osteodystrophy alters metabolic activity and remodeling rate of bone and also may lead to different bone composition. The objective of this study was to characterize the composition of bone in high-turnover renal osteodystrophy patients by means of Fourier transform infrared spectroscopic imaging (FTIRI). Iliac crest biopsies from healthy bone (n = 11) and patients with renal osteodystrophy (ROD, n = 11) were used in this study. The ROD samples were from patients with hyperparathyroid disease. By using FTIRI, phosphate-to-amide I ratio (mineral-to-matrix ratio), carbonate-to-phosphate ratio, and carbonate-to-amide I ratio (turnover rate/remodeling activity), as well as the collagen cross-link ratio (collagen maturity), were quantified. Histomorphometric analyses were conducted for comparison. The ROD samples showed significantly lower carbonate-to-phosphate (p < .01) and carbonate-to-amide I (p < .001) ratios. The spatial variation across the trabeculae highlighted a significantly lower degree of mineralization (p < .05) at the edges of the trabeculae in the ROD samples than in normal bone. Statistically significant linear correlations were found between histomorphometric parameters related to bone-remodeling activity and number of bone cells and FTIRI-calculated parameters based on carbonate-to-phosphate and carbonate-to-amide I ratios. Hence the results suggested that FTIRI parameters related to carbonate may be indicative of turnover and remodeling rate of bone.

Ablation of cathepsin k activity in the young mouse causes hypermineralization of long bone and growth plates

Cathepsin K deficiency in humans causes pycnodysostosis, which is characterized by dwarfism and osteosclerosis. Earlier studies of 10-week-old male cathepsin K-deficient (knockout, KO) mice showed their bones were mechanically more brittle, while histomorphometry showed that both osteoclasts and osteoblasts had impaired activity relative to the wild type (WT). Here, we report detailed mineral and matrix analyses of the tibia of these animals based on Fourier transform infrared microspectroscopy and imaging. At 10 weeks, there was significant hypercalcification of the calcified cartilage and cortices in the KO. Carbonate content was elevated in the KO calcified cartilage as well as cortical and cancellous bone areas. These data suggest that cathepsin K does not affect mineral deposition but has a significant effect on mineralized tissue remodeling. Since growth plate abnormalities were extensive despite reported low levels of cathepsin K expression in the calcified cartilage, we used a differentiating chick limb-bud mesenchymal cell system that mimics endochondral ossification but does not contain osteoclasts, to show that cathepsin K inhibition during initial stages of mineral deposition retards the mineralization process while general inhibition of cathepsins can increase mineralization. These data suggest that the hypercalcification of the cathepsin K-deficient growth plate is due to persistence of calcified cartilage and point to a role of cathepsin K in bone tissue development as well as skeletal remodeling.

Effect of human trabecular bone composition on its electrical properties

Mechanical properties of bone are determined not only by bone mineral density (BMD), but also by tissue trabecular structure and organic composition. Impedance spectroscopy has shown potential to diagnose trabecular bone BMD and strength, however, the relationships between organic composition and electrical and dielectric properties have not been systematically investigated. To investigate these issues organic composition of 26 human trabecular bone samples harvested from the distal femur and proximal tibia was determined and compared with relative permittivity, loss factor, conductivity, phase angle, specific impedance and dissipation factor measured at wide range (50 Hz to 5 MHz) of frequencies. A strong linear correlation was found between the relative permittivity at 1.2 MHz and trabecular bone fat content (r = -0.85, p<0.01, n=26). On the other hand, relative permittivity measured at 200 Hz served as a good predictor of water content (r = 0.83). Phase angle, specific impedance and especially conductivity were strongly related to the trabecular bone dry density and water content (|r| > or = 0.69). Variation in bone tissue collagen content was strongly related to the relative permittivity measured at 1.2 MHz (r = 0.64), but only moderately to other parameters. Glycosaminoglycan content showed no significant relations with any investigated electrical parameters. The present study indicates that if the trabecular bone composition is known, the relationships presented in this study could facilitate calculation of current field distribution, e.g. during electrical stimulation of osteogenesis. On the other hand, our results suggest that permittivity measured at low (<1 kHz) or high (>100 kHz) frequencies could be used, e.g. during implant surgery, for prediction of trabecular bone water or fat contents, respectively.

In situ examination of the time-course for secondary mineralization of Haversian bone using synchrotron Fourier transform infrared microspectroscopy

At the tissue level it is well established that the rate of remodeling is related to the degree of mineralization. However, it is unknown how long it takes for an individual bone structural unit (BSU) to become fully mineralized during secondary mineralization. Using synchrotron Fourier transform infrared microspectroscopy (FTIRM) we examined the time required for newly formed bone matrix to reach a physiological mineralization limit. Twenty-six, four-month old female New Zealand white rabbits were administered up to four different fluorochrome labels at specific time points to evaluate the chemical composition of labeled osteons from the tibial diaphysis that had mineralized for 1, 8, 18, 35, 70, 105, 140, 175, 210, 245, 280, 315, 350, and 385 days. Interstitial bone from 505 day old rabbits was used as a reference value for the physiological limit to which bone mineralizes. Using synchrotron FTIRM, area integrations were carried out on protein (Amide I: 1688-1623 cm(-1)), carbonate (v(2)CO(3)(2-): 905-825 cm(-1)), and phosphate (v(4)PO(4)(3-): 650-500 cm(-1)) IR bands. IR spectral data are presented as ratios of phosphate/protein (overall matrix mineralization) and carbonate/protein. The rate of mineralization of osteonal bone proceeded rapidly between day 1 and 18, reaching 67% of interstitial bone levels. This was followed by a slower, more progressive accumulation of mineral up to day 350. By 350 days the rate of increase plateaued. The ratio of carbonate/protein also increased rapidly during the first 18 days, reaching 73% of interstitial bone levels. The ratio of carbonate/protein plateaued by day 315, reaching levels not significantly different to interstitial bone levels. In conclusion, our data demonstrate that bone accumulates mineral rapidly during the first 18 days (primary mineralization), followed by a more gradual increase in the accumulation of mineral (secondary mineralization) which we found to be completed in 350 days.

Influence of estradiol on vascular endothelial growth factor expression in bone: a study in Göttingen miniature pigs and human osteoblasts

Ovariectomy (OVX) in animal models is an accepted method to simulate postmenopausal osteoprosis. Vascular endothelial growth factor (VEGF) has been recently shown to play an important role during endochondral bone formation, hypertrophic cartilage remodeling, ossification, and angiogenesis. We hypothesized that reduced VEGF expression in bone contributes to OVX-induced bone loss and tested it in a miniature pig model and in vitro using human osteoblasts. Seventeen primiparous sows (Göttingen miniature pigs) were allocated to two experimental groups when they were 30 months old: a control group (n = 9) and an OVX group (n = 8). After 15 months, VEGF levels in lumbar vertebrae were measured by enzyme-linked immunosorbent assay and verified by Western blot analysis. VEGF and its receptor (VEGFR) were localized by immunohistochemistry. Expression of VEGF mRNA was analyzed by real-time reverse-transcription polymerase chain reaction. Differently sulfated glycosaminoglycans were localized in subchondral bone histochemically. Osteoblasts were immunopositive for VEGF. VEGF concentration in the vertebra was 27% lower in OVX miniature pigs. VEGFR-2 could be immunostained on osteoblasts. VEGF mRNA and protein were detectable in the lumbar vertebrae of all animals. In subchondral trabecular bone of OVX animals, significantly more islands of mineralized cartilage containing chondroitin 4- and 6-sulfate or keratan sulfate occurred compared to the control group. The occurrence of remnants of mineralized cartilage in subchondral bone of the OVX group may be caused by a delayed bone turnover due to low VEGF levels. In vitro experiments revealed an increase of VEGF in the supernatant of osteoblasts after incubation with estradiol. In conclusion, estrogen seems to be a key factor for regulation of VEGF expression in bone. Loss of VEGF due to menopause may be a reason for reduction of bone density.

A new sample substrate for imaging and correlating organic and trace metal composition in biological cells and tissues

Many disease processes involve alterations in the chemical makeup of tissue. Synchrotron-based infrared (IR) and X-ray fluorescence (XRF) microscopes are becoming increasingly popular tools for imaging the organic and trace metal compositions of biological materials, respectively, without the need for extrinsic labels or stains. Fourier transform infrared microspectroscopy (FTIRM) provides chemical information on the organic components of a material at a diffraction-limited spatial resolution of 2-10 microm in the mid-infrared region. The synchrotron X-ray fluorescence (SXRF) microprobe is a complementary technique used to probe trace element content in the same systems with a similar spatial resolution. However to be most beneficial, it is important to combine the results from both imaging techniques on a single sample, which requires precise overlap of the IR and X-ray images. In this work, we have developed a sample substrate containing a gold grid pattern on its surface, which can be imaged with both the IR and X-ray microscopes. The substrate consists of a low trace element glass slide that has a gold grid patterned on its surface, where the major and minor parts of the grid contain 25 and 12 nm gold, respectively. This grid pattern can be imaged with the IR microscope because the reflectivity of gold differs as a function of thickness. The pattern can also be imaged with the SXRF microprobe because the Au fluorescence intensity changes with gold thickness. The tissue sample is placed on top of the patterned substrate. The grid pattern's IR reflectivity image and the gold SXRF image are used as fiducial markers for spatially overlapping the IR and SXRF images from the tissue. Results show that IR and X-ray images can be correlated precisely, with a spatial resolution of less than one pixel (i.e., 2-3 microns). The development of this new tool will be presented along with applications to paraffin-embedded metalloprotein crystals, Alzheimer's disease, and hair composition.

Chemical makeup of microdamaged bone differs from undamaged bone

Microdamage naturally occurs in bone tissue as a result of cyclic loading placed on the body from normal daily activities. While it is usually repaired through the bone turnover process, accumulation of microdamage may result in reduced bone quality and increased fracture risk. It is unclear whether certain areas of bone are more susceptible to microdamage than others due to compositional differences. This study examines whether areas of microdamaged bone are chemically different than undamaged areas of bone. Bone samples (L3 vertebrae) were harvested from 15 dogs. Samples were stained with basic fuchsin, embedded in poly-methylmethacrylate, and cut into 5-microm-thick sections. Fuchsin staining was used to identify regions of microdamage, and synchrotron infrared microspectroscopic imaging was used to determine the local bone composition. Results showed that microdamaged areas of bone were chemically different than the surrounding undamaged areas. Specifically, the mineral stoichiometry was altered in microdamaged bone, where the carbonate/protein ratio and carbonate/phosphate ratio were significantly lower in areas of microdamage, and the acid phosphate content was higher. No differences were observed in tissue mineralization (phosphate/protein ratio) or crystallinity between the microdamaged and undamaged bone, indicating that the microdamaged regions of bone were not over-mineralized. The collagen cross-linking structure was also significantly different in microdamaged areas of bone, consistent with ruptured cross-links and reduced fracture resistance. All differences in composition had well-defined boundaries in the microcrack region, strongly suggesting that they occurred after microcrack formation. Even so, because microdamage results in an altered bone composition, an accumulation of microdamage might result in a long-term reduction in bone quality.

Chemical imaging of biological tissue with synchrotron infrared light

Fourier transform infrared micro-spectroscopy (FTIRM) and imaging (FTIRI) have become valuable techniques for examining the chemical makeup of biological materials by probing their vibrational motions on a microscopic scale. Synchrotron infrared (S-IR) light is an ideal source for FTIRM and FTIRI due to the combination of its high brightness (i.e., flux density), also called brilliance, and broadband nature. Through a 10-microm pinhole, the brightness of a synchrotron source is 100-1000 times higher than a conventional thermal (globar) source. Accordingly, the improvement in spatial resolution and in spectral quality to the diffraction limit has led to a plethora of applications that is just being realized. In this review, we describe the development of synchrotron-based FTIRM, illustrate its advantages in many applications to biological systems, and propose some potential future directions for the technique.

Effects of lanthanum on composition, crystal size, and lattice structure of femur bone mineral of Wistar rats

The application of lanthanum (La) in industry, medicine, and agriculture may cause accumulation of the element in human body. This article examines the effects of La on the femur bone mineral of male Wistar rats after administration of La(NO3)3 by gavage at the dose of 2.0 mg La(NO3)3.kg(-1).day(-1) over a 6-month period. Chemical analysis confirmed La accumulation in bone and loss in bone mineral. Thermogravimetric analysis showed a decrease in the mineral-to-matrix ratio and an increase in carbonate content. Fourier-transform infrared spectrometry revealed elevation in the contents of labile carbonate and acidic phosphate. The synchrotron radiation small-angle X-ray scattering study presented a smaller mean thickness of the mineral crystals in the bone of La-treated rats. The synchrotron radiation-extended X-ray absorption fine structure analysis indicated that the La treatment resulted in a lowered disorder in the crystals. The smaller size, more adsorbed labile carbonate, and more acidic phosphate made the bone mineral easier to dissolve, as revealed in the kinetic measurement of bone demineralization. These findings suggest that La retards bone maturation of rats.

Mineral changes in osteoporosis: a review

Bone mineral composition, crystallinity, and bone mineral content of osteoporotic patients are different from those of normal subjects. We review the evidence that these mineralization parameters contribute to the strength (fracture resistance) of bone and the methods that have been used to examine them. A specific example is provided from analysis of biopsies from the Multiple Outcomes in Raloxifene Evaluation trial. For the analyses, randomly selected biopsies from placebo, low-dose, and high-dose groups (n = 5 per group) obtained at time zero and 2 years after treatment were examined by infrared imaging spectroscopy. In all cases, comparable increases in mineral content were found, but there were no significant variations in mineral crystallinity.

Infrared analysis of bone in health and disease

Infrared spectroscopy, microspectroscopy, and microspectroscopic imaging have been used to probe the composition and physicochemical status of mineral and matrix of bone in normal and diseased tissues using a series of validated parameters that reflect quantitative and qualitative properties. In this review, emphasis is placed on changes in bone's composition and physiochemical status during osteoporosis and the impact of currently used therapeutics on these parameters, although the impact of infrared microscopy in other pathological states is briefly discussed.

Alterations in mineral composition observed in osteoarthritic joints of cynomolgus monkeys

Osteoarthritis (OA) is a prevalent joint disease that affects more than 40 million Americans and is characterized by degeneration of the articular cartilage and thickening of the underlying subchondral bone. Although subchondral bone thickening has been implicated in articular cartilage degeneration, very little is known about the composition of subchondral bone in OA. In the present study, infrared microspectroscopy (IRMS) was used to determine the chemical composition of the calcified cartilage-subchondral bone plate in a monkey model of OA. Specifically, the levels of mineralization (mineral/protein ratio), carbonate accumulation (carbonate/protein ratio), crystallinity, and collagen structure were determined as a function of animal age and OA severity. OA severity was assessed using a grading scheme that included scores or measurements for several histomorphometric parameters including articular cartilage fibrillation or clefting, subchondral bone thickness, and numbers of tidemarks and chondrocyte clones. Individual scores and measurements were summarized using principal components (factor) analysis. Results demonstrated that the level of mineralization and carbonate content increased as a function of animal age. In addition, bone mineralization level increased as subchondral bone thickness increased. Dramatic increases in the mineralization level and carbonate accumulation were also observed as a function of the number of tidemarks. The presence of multiple tidemarks indicates the occurrence of one or more additional phases of cartilage calcification, suggesting that the observed compositional changes are due to cartilage mineralization. Our results support a reactivation of endochondral ossification that occurs with age, which is more pronounced in OA. No relationships were observed between mineral crystallinity and collagen cross-linking as a function of age or OA severity. In summary, compositional analysis of the mineralized plate beneath the articular cartilage in OA is characterized by thickened, overmineralized calcified cartilage or subchondral bone, which likely puts added mechanical stress on the joint, contributing to the progression of OA.

In situ chemistry of osteoporosis revealed by synchrotron infrared microspectroscopy

Reduced bone density is a well-known feature of osteoporosis, yet little is known about the changes in the chemical composition of bone or the impact of such chemical changes on fracture risks. Using ovariectomized cynomolgus monkeys (Macaca fascicularis) as a model for the menopausal onset of osteoporosis, we examined the microscopic chemical changes of bone measured by synchrotron infrared microspectroscopy as a function of time after ovariectomy. The results demonstrate that cortical bone formed 1 or 2 years after ovariectomy, as identified by fluorochrome labeling, has a higher phosphate content (PO4(3-)/matrix ratio), a lower carbonate content (CO3(2-)/matrix ratio), and more mature collagen cross-links (nonreducible cross-link/reducible cross-link ratio) than that formed in sham-operated controls. Trabecular bone after ovariectomy shows no changes in phosphate content, a lower carbonate content, and immature collagen cross-linking. Treatment with a bone turnover suppressor, (nandrolone decanoate) reverses most of the ovariectomy-induced chemical changes in the cortical bone to the levels of the ovary-intact controls, but has little effect on the trabecular bone. These results demonstrate that bone newly synthesized after ovariectomy is chemically different from healthy bone within specific bone regions, which may contribute to reduced bone quality in osteoporosis.

Combining high-resolution micro-computed tomography with material composition to define the quality of bone tissue

Atraumatic fractures of the skeleton in osteoporotic patients are directly related to a deterioration of bone strength. However, the failure of the bone tissue to withstand functional load bearing cannot be explained as a simple decrease in bone mineral density (quantity); strength is also significantly dependent upon bone quality. While a formal definition of bone quality is somewhat elusive, at the very least, it incorporates architectural, physical, and biologic factors that are critical to bone strength. Such factors include bone morphology (ie, trabecular connectivity, cross-sectional geometry, longitudinal curvature); the tissue's material properties (eg, stiffness, strength); its chemical composition and architecture (eg, ratio of calcium to other components of the organic and/or inorganic phase, collagen orientation, porosity, permeability); and the viability of the tissue (eg, responsivity of the bone cell population). Combining high-resolution structural indices of bone, as determined by micro-computed tomography; material properties determined by nanoindentation; and the chemical make-up of bone, as determined by infrared spectroscopy, helps to provide critical information toward a more comprehensive assessment of the interdependence of bone quality, quantity, and fracture risk.