The effects of vanadium treatment on bone in diabetic and non-diabetic rats

Role of advanced glycation endproducts in bone fragility in type 1 diabetes

The excess fracture risk observed in adults with type 1 diabetes (T1D) is inexplicable in the presence of only modest reductions in areal bone mineral density (BMD). Accumulation of advanced glycation endproducts (AGEs) in bone has been invoked as one explanation for the increased bone fragility in diabetes. The evidence linking AGEs and fractures in individuals with T1D is sparse, although the association has been observed in individuals with type 2 diabetes. Recent data show that in T1D, AGEs as measured by skin intrinsic fluorescence, are a risk factor for lower BMD. Further research in T1D is needed to ascertain whether there is a causal relationship between fractures and AGEs. If confirmed, this would pave the way for finding interventions that can slow AGE accumulation and thus reduce fractures in T1D.

Vanadium-Doped Mesoporous Bioactive Glass Promotes Osteogenic Differentiation of rBMSCs via the WNT/β-Catenin Signaling Pathway

Pentavalent vanadium [V(V)] has been studied as bioactive ions to improve the bone defect repair; however, its osteogenic promotion mechanism is still not fully understood so far. In this study, a V-doped mesoporous bioactive glass (V-MBG) was prepared, and its effects on osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and potential signaling pathways were investigated. The physicochemical characterization revealed that the incorporation of V slightly reduced the specific surface area and increased the mesoporous pore size, and the abundant mesopores of V-MBG were beneficial to the sustained dissolution of V(V) ions as well as calcium, silicon, and phosphorus ions. Cell proliferation results indicated that the high dilution ratio (>16) V-MBG extract markedly promoted the proliferation of rBMSCs compared with the control group and the same dilution ratio MBG extract. Compared with the same dilution ratio MBG extract, diluted V-MBG extracts markedly promoted the secretion of alkaline phosphatase (ALP) and osteocalcin (OCN) protein at day 7 but insignificantly stimulated the runt-related transcription factor 2 (RUNX2) and vascular endothelial growth factor (VEGF) protein synthesis. In depth, the diluted V-MBG extracts remarkably up-regulated the expression of WNT/β-catenin pathway direct target genes, including WNT3a, β-catenin, and AXIN2 genes in contrast to the same dilution ratio MBG extracts, suggesting that the released V(V) ions might promote osteogenic differentiation of rBMSCs via the WNT/β-catenin signaling pathway.

Effects of Linagliptin and Pioglitazone on Fracture Healing in an Experimental Type 2 Diabetes Rat Model

AIM

Our study aimed to examine the effects of Linagliptin, Pioglitazone, and their combination on fracture healing in a diabetes rat femur fracture model.

MATERIAL AND METHODS

Type 2 diabetes mellitus (T2DM) induced rats were randomly divided into four groups: non-treated diabetes group (TD), Pioglitazone group (P), Linagliptin group (L), and Pioglitazone and Linagliptin group (PL). Daily oral dosage of pioglitazone (10 mg/kg/day), linagliptin (10 mg/kg/day), and their combination were administered. Femur fractures were stabilized intramedullary. At weeks 2 and 6, rats were sacrificed for evaluation radiologically, biomechanically, histopathologically, histomorphometrically, and immunohistochemically.

RESULTS

Flexural strength of the L and PL groups were significantly higher compared to the P group. The highest healing score was in the L group and lowest in the P group, while the highest inflammation score was in the P group and lowest in the L group. A cluster of differentiation (CD) CD 34 reactivity was highest in the L group and lowest in the PL group.

CONCLUSION

Linagliptin treatment significantly increased histological healing scores, callus volume, biomechanical strength, and vascularity, however, minimized the inflammatory process, which was increased by pioglitazone. The combination of linagliptin and pioglitazone restored BMD and increased biomechanical strength. Linagliptin monotherapy is rarely indicated; hence, T2DM patients with a high risk of bone fractures can be considered for combined therapy of pioglitazone and linagliptin.

The Effects of Chromium and Vanadium on Biomarkers of Carbohydrate and Lipid Metabolism in Workers Exposed to Coal Fly Ash

Chromium (Cr) and vanadium (V) are micronutrients playing a role in carbohydrate and lipid metabolism but can be toxic at high concentrations, especially in specific forms. The study documents the effect of Cr and V concentrations on glucose and lipid metabolism in workers exposed to coal fly ash. We quantified selected metals (Cr, V) in the blood and serum of workers from a thermal power plant in Kosovo and compared them with the reference biological values. We determined fasting serum glucose and lipid profiles using a biochemical analyzer Synchron CX7 (Beckman Coulter). We quantified blood and serum Cr and V by inductively coupled plasma mass spectrometry. We also evaluated the association between carbohydrate and lipid metabolism biomarkers (glucose, cholesterol, and triglycerides) and co-exposure to coal fly ash. Power plant workers had significantly higher blood Cr and V levels (p < 0.0001) and significantly lower serum Cr and V levels (p < 0.0001) than the controls. We also found statistically significant (p < 0.0001) correlations between high blood Cr levels and low glucose/blood Cr ratios as well as between high serum Cr levels and low glucose/serum Cr ratios. Finally, in power plant workers, high blood V levels significantly correlated with low triglycerides/blood V and cholesterol/blood V ratios (p < 0.0001), while high serum V levels correlated with low cholesterol/serum V ratios (p = 0.005). Based on these findings, we concluded that the glucose/Cr, triglycerides/V and cholesterol/V ratios should be considered when evaluating carbohydrate and lipid metabolism disorders in occupationally-exposed workers.

The Abundance of Trace Elements in Human Bone Relative to Bone Type and Bone Pathology

As the global population ages and the proportion of individuals afflicted with musculoskeletal disease spirals upward, there is an increasing interest in understanding and preventing bone-related diseases. Bone diseases, such as osteoporosis and osteoarthritis, are known to be influenced by a variety of factors including age, gender, nutrition, and genetics, but are also inherently linked to the human body's ability to produce biominerals of suitable quality. Because the crystal lattice structure and mineralogy of bone hydroxyapatite is surprisingly analogous to geological hydroxyapatite, trace element levels and exposure have long been proposed to influence the structure of biominerals as they do geological minerals (e.g., strontium substitution changes the crystal lattice of bone minerals, while toxic lead disrupt bone cellular processes leading to bone disease). Here, we explore the distribution of trace elements in human bones to evaluate the distribution of these elements with respect to bone type (cortical vs. trabecular) and bone disease (osteoarthritis vs. osteoporosis). We find higher concentrations of many metabolically active transition metals, as well as lead, in cortical bone compared to trabecular bone. When compared to patients who have osteoarthritis, and thus presumably normal bone minerals, osteoporosis patients have higher concentrations of scandium and chromium (Cr) in trabecular bone, and Cr and lead in cortical bone. Lower concentrations of barium and titanium are associated with osteoporotic trabecular bone. This survey is an exploratory cross-sectional geochemical examination of several trace element concentrations previously understudied in human bone minerals.

Vanadium and diabetic dyslipidemia: A systematic review of animal studies

BACKGROUND

Diabetic dyslipidemia is caused by hyperglycemia and excessive mobilization of storage lipids, leading to increasing concentrations of triglycerides and total cholesterol. Due to the insulin-mimetic or insulin-enhancer features of vanadium, it has been recognized as a regulator of cell metabolism with hypoglycemic and hypolipidemic properties. The purpose of the current animal systematic review was to evaluate the effect of vanadium administration on diabetic dyslipidemia in diabetic animals.

METHODS

This is, to our knowledge, the first systematic review with the aim of investigating the relationship between vanadium and diabetic dyslipidemia among diabetes induced animals. Searches were performed in PubMed, Scopus, and web of science databases for animal studies examining the effect of vanadium on diabetic dyslipidemia in diabetic animals.

RESULTS

Of 124 full-text articles assessed, 48 animal studies were included in the present study with minor risk of bias. The majority of the studies confirmed the beneficial effects of different vanadium compounds in at least one of the parameters of lipid profile, especially regarding triglyceride and total cholesterol.

CONCLUSION

Current findings lend support to assess the long-term effects of different forms and doses of vanadium on lipid profile through well-designed clinical trials.

Dietary Soybean Oil Supplementation Affects Keel Bone Characters and Daily Feed Intake but Not Egg Production and Quality in Laying Hens Housed in Furnished Cages

To evaluate dietary soybean oil supplementation on production performance, egg quality, and keel bone health in laying hens. Two hundred and four laying hens at 20 weeks of age (WOA) were distributed into 12 cages containing 17 birds each. Birds were either fed a commercial diet (control group, CON) or a diet supplemented with 3% of soybean oil (SO group). Experiments lasted 17 weeks. Body weight, daily feed intake, production performance and egg quality were measured at 25, 29, 33, and 37 WOA. Birds were subsequently assessed for keel bone status by palpation, and keel was excised to measure bone length, microstructure, bone mineral density (BMD), elements contents, and the expression of osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), collagen type II alpha 1 (COL2α1), periostin (POSTN), and sclerostin (SOST). The results showed that dietary SO supplementation did not affect production performance and egg quality (P > 0.05), but improved body weight of hens at 29 and 37 WOA (P < 0.05), and decreased daily feed intake at 33 and 37 WOA (P < 0.05). Incidence of keel bone damage (especially fracture) was higher in hens of SO group. Keel bone length in birds of SO group was significantly decreased compared to CON (P < 0.05). Keel bone of supplemented hens showed increased trabecular separation at 29 WOA and higher levels of V, Mn, Fe, Se, and Ba at 33 WOA (P < 0.05). Moreover, decreased BMD, trabecular number and thickness were observed in keel bone of laying hens receiving supplementation at 29 and 37 WOA (P < 0.05); decreased levels of Li, Ca, Hg, and TI at 33 WOA and trabecular thickness at 37 WOA (P < 0.05) were also identified. mRNA levels of SOST and RANKL and the ratio of RANKL/OPG mRNA levels were increased in birds fed a SO-supplemented diet (P < 0.05); COL2α1, OPG, and POSTN were downregulated at all sampling points (P < 0.05). Taken together, results indicate that feeding laying hens a diet supplemented with soybean oil can decrease daily feed intake and impair keel bone health but not influence production performance and egg quality.

Vanadium coordination compounds loaded on graphene quantum dots (GQDs) exhibit improved pharmaceutical properties and enhanced anti-diabetic effects

Vanadium compounds are promising anti-diabetic agents, and graphene quantum dots (GQDs) are emerging as potential drug delivery systems to improve drug solubility in water and membrane transport. Using highly dispersible and water-soluble GQDs, we herein prepared a novel GQD-VO (p-dmada) complex, in which vanadium coordination compounds [VO(p-dmada)] were packed closely on one side of the GQD sheets possibly via the π-π stacking mechanism. The in vitro tests showed that GQD-VO(p-dmada) exhibited membrane permeability (Papp) as good as that of GQDs with reduced cytotoxicity. In vivo tests on type 2 diabetic mice demonstrated that GQD-VO(p-dmada) exhibited a delayed glucose lowering profile but more profound effects on insulin enhancement and β-cell protection after three-week treatment compared to VO(p-dmada) alone. In addition, GQD alone was observed for the first time to effectively lower the blood lipid levels of the db/db mice. Overall, GQD-VO(p-dmada) showed improved pharmacokinetic performance and hypoglycemic effects, and using GQD as a nanoplatform for drug delivery may provide vast opportunities for the further design of metal-based pharmaceutical agents.

Inorganic Biomaterials for Regenerative Medicine

Regenerative medicine leverages the innate potential of the human body to efficiently repair and regenerate damaged tissues using engineered biomaterials. By designing responsive biomaterials with the appropriate biophysical and biochemical characteristics, cellular response can be modulated to direct tissue healing. Recently, inorganic biomaterials have been shown to regulate cellular responses including cell-cell and cell-matrix interactions. Moreover, ions released from these mineral-based biomaterials play a vital role in defining cell identity, as well as driving tissue-specific functions. The intrinsic properties of inorganic biomaterials, such as the release of bioactive ions (e.g., Ca, Mg, Sr, Si, B, Fe, Cu, Zn, Cr, Co, Mo, Mn, Au, Ag, V, Eu, and La), can be leveraged to induce phenotypic changes in cells or modulate the immune microenvironment to direct tissue healing and regeneration. Biophysical characteristics of biomaterials, such as topography, charge, size, electrostatic interactions, and stiffness can be modulated by addition of inorganic micro- and nanoparticles to polymeric networks have also been shown to play an important role in their biological response. In this Review, we discuss the recent emergence of inorganic biomaterials to harness the innate regenerative potential of the body. Specifically, we will discuss various biophysical or biochemical effects of inorganic-based materials in directing cellular response for regenerative medicine applications.

Effects of Diabetes on Bone Material Properties

PURPOSE OF REVIEW

Individuals with type 1 and type 2 diabetes mellitus (T1DM, T2DM) have an increased risk of bone fracture compared to non-diabetic controls that is not explained by differences in BMD, BMI, or falls. Thus, bone tissue fracture resistance may be reduced in individuals with DM. The purpose of this review is to summarize work that analyzes the effects of T1DM and T2DM on bone tissue compositional and mechanical properties.

RECENT FINDINGS

Studies of clinical T2DM specimens revealed increased mineralization and advanced glycation endproduct (AGE) concentrations and significant relationships between mechanical performance and composition of cancellous bone. Specifically, in femoral cancellous tissue, compressive stiffness and strength increased with mineral content; and post-yield properties decreased with AGE concentration. In addition, cortical resistance to in vivo indentation (bone material strength index) was lower in patients with T2DM vs. age-matched non-diabetic controls, and this resistance decreased with worsening glycemic control. Recent studies on patients with T1DM and history of a prior fragility fracture found greater mineral content and concentrations of AGEs in iliac trabecular bone and correspondingly stiffer, harder bone at the nanosacle. Recent observational data showed greater AGE and mineral content in surgically retrieved bone from patients with T2DM vs. non-DM controls, consistent with reduced bone remodeling. Limited data on human T1DM bone tissue also showed higher mineral and AGE content in patients with prior fragility fractures compared to non-DM and non-fracture controls.

Vanadium in Biosphere and Its Role in Biological Processes

Ultra-trace elements or occasionally beneficial elements (OBE) are the new categories of minerals including vanadium (V). The importance of V is attributed due to its multifaceted biological roles, i.e., glucose and lipid metabolism as an insulin-mimetic, antilipemic and a potent stress alleviating agent in diabetes when vanadium is administered at lower doses. It competes with iron for transferrin (binding site for transportation) and with lactoferrin as it is secreted in milk also. The intracellular enzyme protein tyrosine phosphatase, causing the dephosphorylation at beta subunit of the insulin receptor, is inhibited by vanadium, thus facilitating the uptake of glucose inside the cell but only in the presence of insulin. Vanadium could be useful as a potential immune-stimulating agent and also as an antiinflammatory therapeutic metallodrug targeting various diseases. Physiological state and dose of vanadium compounds hold importance in causing toxicity also. Research has been carried out mostly on laboratory animals but evidence for vanadium importance as a therapeutic agent are available in humans and large animals also. This review examines the potential biochemical and molecular role, possible kinetics and distribution, essentiality, immunity, and toxicity-related study of vanadium in a biological system.

Influence of Feeding Inorganic Vanadium on Growth Performance, Endocrine Variables and Biomarkers of Bone Health in Crossbred Calves

The nutritional essentialities of transition element vanadium (V) as micro-nutrient in farm animals have not yet been established, though in rat model, vanadium as vanadate has been reported to exert insulin-mimetic effect and shown to be needed for proper development of bones. The objective of this study was to determine the effect of V supplementation on growth performance, plasma hormones and bone health status in calves. Twenty-four crossbred calves (body weight 72.83 ± 2.5 kg; age 3-9 months) were blocked in four groups and randomly assigned to four treatment groups (n = 6) on body weight and age basis. Experimental animals were kept on similar feeding regimen except that different groups were supplemented with either 0, 3, 6 or 9 ppm inorganic V/kg DM. Effect of supplementation during 150-day experimental period was observed on feed intake, body weight gain, feed efficiency, body measures, endocrine variables, plasma glucose and biomarkers of bone health status. Supplementation of V did not change average daily gain (ADG), dry matter intake (DMI), feed efficiency and body measures during the experimental period. During the post-V supplementation period plasma insulin-like growth factor-1 (IGF-1), triiodothyronine (T₃) and thyroxin (T₄) concentrations were increased and observed highest in 9 mg V/kg DM fed calves; however, levels of insulin, glucose, parathyroid hormone (PTH) and calcitonin hormones remained similar among calves fed on basal or V-supplemented diets. Bone alkaline phosphatase (Bone-ALP) concentration was increased (P < 0.05); however, plasma protein tyrosine phosphatase (PTP) level decreased (P < 0.05) in 6 and 9 mg V/kg DM supplemented groups. Plasma hydroxyproline (Hyp) and tartrate-resistant acid phosphatase (TRAP) concentration were unchanged by V supplementation. Blood V concentration showed positive correlation with supplemental V levels. These results suggest that V may play a role in modulation of the action of certain endocrine variables and biomarkers of bone health status in growing crossbred calves.

Nano vanadium dioxide films deposited on biomedical titanium: a novel approach for simultaneously enhanced osteogenic and antibacterial effects

Vanadium is a trace element in the human body, and vanadium compounds have a promising future in biological and medical applications due to their various biological activities and low toxicity. Herein, a novel pure vanadium dioxide (VO₂) nanofilm was deposited on a substrate of biomedical titanium by magnetron sputtering. The antibacterial effect of VO₂ against the methicillin-resistant Staphylococcus aureus (MRSA) was validated in vitro and in vivo. Moreover, the biocompatibility of VO₂ and its osteogenic effects were systematically illustrated. A possible osteogenic mechanism involving the amelioration of highly reactive oxygen species (ROS) levels were investigated. According to the results of our present and previous studies, the simultaneous antibacterial and osteogenic effects of VO₂ are attributed to its differential regulation of ROS levels in rat bone marrow mesenchymal stem cells (rBMSCs) and bacteria. This study is the first to report the simultaneous effects of VO₂ on bactericidal and osteogenic activities through its differential modification of ROS activity in eukaryotic (rBMSCs) and prokaryotic (MRSA) cells. The findings in this work may yield a deeper understanding of the biological activities of vanadium compounds while also paving the way for the further investigation and application of VO₂ in biological and medical materials.

Moderate-intensity 4mT static magnetic fields prevent bone architectural deterioration and strength reduction by stimulating bone formation in streptozotocin-treated diabetic rats

Type 1 diabetes mellitus (T1DM) has been associated with deterioration of bone microarchitecture and strength, resulting in increased fracture risk. Substantial studies have revealed the capacity of moderate-intensity static magnetic fields (SMF) on promoting osteoblastogenesis in vitro and stimulating bone growth and bone regeneration in vivo, whereas it is unknown whether SMF can resist T1DM-associated osteopenia/osteoporosis. We herein investigated the potential effects of whole-body SMF exposure with 4mT on bone loss in streptozotocin-induced T1DM rats. We found that SMF exposure for 16weeks inhibited architectural deterioration of trabecular bone and cortical bone and mechanical strength reduction in T1DM rats, as evidenced by the MicroCT and 3-point bending findings. Our serum biochemical, bone histomorphometric and PCR results revealed that SMF induced higher serum osteocalcin, mineral apposition rate and osteoblast number of trabecular bone, and higher skeletal osteocalcin, BMP2 and Runx2 gene expression in T1DM rats, whereas SMF showed no significant alteration in serum CTX, skeletal osteoclast number, or osteoclastogenesis-related RANKL-RANK signaling gene expression. Together, our findings suggest that moderate SMF prevented bone architectural deterioration and strength reduction by inhibiting the reduction of bone formation in T1DM rats, and indicate that SMF might become a promising biophysical countermeasure for T1DM-related osteopenia/osteoporosis.

Effect of vanadium on calcium homeostasis, osteopontin mRNA expression, and bone microarchitecture in diabetic rats

The aim of this study was to examine whether alterations caused by diabetes in calcium homeostasis, expression of osteopontin and the microarchitecture of bone are corrected by exposure to vanadium. Four study groups were examined over a period of five weeks: control (C), diabetic (DM), diabetic treated with 1 mg V per d (DMV), and diabetic treated with 3 mg V per d (DMVH). Vanadium was supplied in drinking water as bis(maltolato)oxovanadium(iv). Calcium was measured in the food, faeces, urine, serum, kidneys, liver, muscles, and femur. Osteopontin gene expression was determined in the liver, and the bone microarchitecture was studied with the aid of micro-computed tomography. In the DM group, food intake as well as calcium absorbed and retained and liver osteopontin mRNA increased, while Ca in the serum and femur decreased, and the bone microarchitecture worsened, in comparison with the control. In the DMV group, the amount of Ca absorbed and retained was similar to DM rats. Although the Ca content in the femur increased and osteopontin mRNA decreased, there were no significant changes in the bone microarchitecture, in comparison to the DM rats. In the DMVH group, the amount of Ca absorbed and retained, and the serum and femur content were equivalent to the control. The levels of osteopontin mRNA decreased and bone mineralization improved, compared to the DM group. We conclude that treatment with 3 mg V per d of the glucose lowering agent bis(maltolato)oxovanadium(iv) causes a decrease in osteopontin mRNA, which could favour the normalization of changes in Ca homeostasis and bone microarchitecture, both at the cortical and trabecular levels, caused by diabetes.

Effects of local vanadium delivery on diabetic fracture healing

This study evaluated the effect of local vanadyl acetylacetonate (VAC), an insulin mimetic agent, upon the early and late parameters of fracture healing in rats using a standard femur fracture model. Mechanical testing, and radiographic scoring were performed, as well as histomorphometry, including percent bone, percent cartilage, and osteoclast numbers. Fractures treated with local 1.5 mg/kg VAC possessed significantly increased mechanical properties compared to controls at 6 weeks post-fracture, including increased torque to failure (15%; p = 0.046), shear modulus (89%; p = 0.043), and shear stress (81%; p = 0.009). The radiographic scoring analysis showed increased cortical bridging at 4 weeks and 6 weeks (119%; p = 0.036 and 209%; p = 0.002) in 1.5 mg/kg VAC treated groups. Histomorphometry of the fracture callus at days 10 and 14 showed increased percent cartilage (121%; p = 0.009 and 45%; p = 0.035) and percent mineralized tissue (66%; p = 0.035 and 58%; p = 0.006) with local VAC treated groups compared to control. Additionally, fewer osteoclasts were observed in the local VAC treated animals as compared to controls at day 14 (0.45% ± 0.29% vs. 0.83% ± 0.36% of callus area; p = 0.032). The results suggest local administration of VAC acts to modulate osteoclast activity and increase percentage of early callus cartilage, ultimately enhancing mechanical properties comparably to non-diabetic animals treated with local VAC. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2174-2180, 2017.

Design of a multifunctional vanadium pentoxide/polymer biocomposite for implant-coating applications

In this study we designed a multifunctional implant coating by exploiting the properties of V₂O₅, i.e. the antibacterial activity via myeloperoxidase-like catalytic activity and the bioactivity of low concentrations of vanadate ions.

Environmental remediation of heavy metal ions from aqueous solution through hydrogel adsorption: a critical review

Heavy metal ions such as Cd(2+), Pb(2+), Cu(2+), Mg(2+), and Hg(2+) from industrial waste water constitute a major cause of pollution for ground water sources. These ions are toxic to man and aquatic life as well, and should be removed from wastewater before disposal. Various treatment technologies have been reported to remediate the potential toxic elements from aqueous media, such as adsorption, precipitation and coagulation. Most of these technologies are associated with some shortcomings, and challenges in terms of applicability, effectiveness and cost. However, adsorption techniques have the capability of effectively removing heavy metals at very low concentration (1-100 mg/L). Various adsorbents have been reported in the literature for this purpose, including, to a lesser extent, the use of hydrogel adsorbents for heavy metal removal in aqueous phase. Here, we provide an in-depth perspective on the design, application and efficiency of hydrogel systems as adsorbents.

Stable Incretin Mimetics Counter Rapid Deterioration of Bone Quality in Type 1 Diabetes Mellitus

Type 1 diabetes mellitus is associated with a high risk for bone fractures. Although bone mass is reduced, bone quality is also dramatically altered in this disorder. However, recent evidences suggest a beneficial effect of the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) pathways on bone quality. The aims of the present study were to conduct a comprehensive investigation of bone strength at the organ and tissue level; and to ascertain whether enzyme resistant GIP or GLP-1 mimetic could be beneficial in preventing bone fragility in type 1 diabetes mellitus. Streptozotocin-treated mice were used as a model of type 1 diabetes mellitus. Control and streptozotocin-diabetic animals were treated for 21 days with an enzymatic-resistant GIP peptide ([D-Ala(2) ]GIP) or with liraglutide (each at 25 nmol/kg bw, ip). Bone quality was assessed at the organ and tissue level by microCT, qXRI, 3-point bending, qBEI, nanoindentation, and Fourier-transform infrared microspectroscopy. [D-Ala2]GIP and liraglutide treatment did prevent loss of whole bone strength and cortical microstructure in the STZ-injected mice. However, tissue material properties were significantly improved in STZ-injected animals following treatment with [D-Ala2]GIP or liraglutide. Treatment of STZ-diabetic mice with [D-Ala(2) ]GIP or liraglutide was capable of significantly preventing deterioration of the quality of the bone matrix. Further studies are required to further elucidate the molecular mechanisms involved and to validate whether these findings can be translated to human patients.

Effects of thirty elements on bone metabolism

The human skeleton, made of 206 bones, plays vital roles including supporting the body, protecting organs, enabling movement, and storing minerals. Bones are made of organic structures, intimately connected with an inorganic matrix produced by bone cells. Many elements are ubiquitous in our environment, and many impact bone metabolism. Most elements have antagonistic actions depending on concentration. Indeed, some elements are essential, others are deleterious, and many can be both. Several pathways mediate effects of element deficiencies or excesses on bone metabolism. This paper aims to identify all elements that impact bone health and explore the mechanisms by which they act. To date, this is the first time that the effects of thirty minerals on bone metabolism have been summarized.

Alteration of the bone tissue material properties in type 1 diabetes mellitus: A Fourier transform infrared microspectroscopy study

Type 1 diabetes mellitus (T1DM) is a severe disorder characterized by hyperglycemia and hypoinsulinemia. A higher occurrence of bone fractures has been reported in T1DM, and although bone mineral density is reduced in this disorder, it is also thought that bone quality may be altered in this chronic pathology. Vibrational microscopies such as Fourier transform infrared microspectroscopy (FTIRM) represent an interesting approach to study bone quality as they allow investigation of the collagen and mineral compartment of the extracellular matrix in a specific bone location. However, as spectral feature arising from the mineral may overlap with those of the organic component, the demineralization of bone sections should be performed for a full investigation of the organic matrix. The aims of the present study were to (i) develop a new approach, based on the demineralization of thin bone tissue section to allow a better characterization of the bone organic component by FTIRM, (ii) to validate collagen glycation and collagen integrity in bone tissue and (iii) to better understand what alterations of tissue material properties in newly forming bone occur in T1DM. The streptozotocin-injected mouse (150 mg/kg body weight, injected at 8 weeks old) was used as T1DM model. Animals were randomly allocated to control (n = 8) or diabetic (n = 10) groups and were sacrificed 4 weeks post-STZ injection. Bones were collected at necropsy, embedded in polymethylmethacrylate and sectioned prior to examination by FTIRM. FTIRM collagen parameters were collagen maturity (area ratio between 1660 and 1690 cm(-1) subbands), collagen glycation (area ratio between the 1032 cm(-1) subband and amide I) and collagen integrity (area ratio between the 1338 cm(-1) subband and amide II). No significant differences in the mineral compartment of the bone matrix could be observed between controls and STZ-injected animals. On the other hand, as compared with controls, STZ-injected animals presented with significant higher value for collagen maturity (17%, p = 0.0048) and collagen glycation (99%, p = 0.0121), while collagen integrity was significantly lower by 170% (p = 0.0121). This study demonstrated the profound effect of early T1DM on the organic compartment of the bone matrix in newly forming bone. Further studies in humans are required to ascertain whether T1DM also lead to similar effect on the quality of the bone matrix.

Effects of vanadium (V) and magnesium (Mg) on rat bone tissue: mineral status and micromorphology. Consequences of V-Mg interactions

The extent to which the 12 week separate and combined administration of vanadium (as sodium metavanadate--SMV, 0.125 mg V per ml) and magnesium (as magnesium sulphate--MS, 0.06 mg Mg per ml) affects bone mineral status and micromorphology as well as the alkaline phosphatase (ALP) activity in femoral diaphysis (FD) was examined in male rats. The bone chemical composition of SMV-exposed rats was also investigated. SMV alone or in combination with MS (as SMV-MS) reduced the levels of MgFD (by 21% and 20%) and PFD (by 12% and 9%), lowered the CaFD content (by 7% and 10%), and caused a rise of the FeFD concentration (by 22.5% and 17%), compared with the control; SMV alone also reduced and enhanced the KFD and ZnFD concentrations (by 19% and 15%, respectively) but remained without significant effect on the femoral bone surface roughness (FBSR), whereas MS alone lowered the VFD, PFD, and CuFD levels (by 42%, 10%, and 20.6%), reduced FBSR, and created the regular femoral bone surface shape. The SMV-MS combination also induced a decline and rise in the levels of CuFD (by 30%) and NaFD (by 15%), respectively, compared with the control and the MS-supplemented rats; elevated ALPFD activity (by 24%, 35%, and 40%), compared with the control, SMV-exposed, and MS-supplemented animals; and increased FBSR. Relationships between the root mean square roughness (Sq) and skewness (Ssk): Sq [MS < SMV < Control < SMV-MS] ⇔ Ssk [SMV-MS > Control > SMV > MS], ALPFD and Sq: ALPFD⇔ Sq [SMV-MS > Control > SMV > MS], and between other variables were demonstrated. A partial limitation of the drop in the PFD and KFD levels and normalization of the ZnFD concentration were a consequence of the V-Mg antagonistic interaction whereas a consequence of the V-Mg synergistic interaction was the increase in the NaFD level, ALPFD activity, and FBSR. Ca10(PO4)5(SiO4)(OH) was part of the inorganic component of the bone of the SMV-exposed rats.

Local vanadium release from a calcium sulfate carrier accelerates fracture healing

This study evaluated the efficacy of using calcium sulfate (CaSO4 ) as a carrier for intramedullary delivery of an organic vanadium salt, vanadyl acetylacetonate (VAC) after femoral fracture. VAC can act as an insulin-mimetic and can be used to accelerate fracture healing in rats. A heterogenous mixture of VAC and CaSO4 was delivered to the fracture site of BB Wistar rats, and mechanical testing, histomorphometry, micro-computed tomography (micro-CT) were performed to measure healing. At 4 weeks after fracture, maximum torque to failure, effective shear modulus, and effective shear stress were all significantly higher (p < 0.05) in rats treated with 0.25 mg/kg VAC-CaSO4 as compared to carrier control rats. Histomorphometry found a 71% increase in percent cartilage matrix (p < 0.05) and a 64% decrease in percent mineralized tissue (p < 0.05) at 2 weeks after fracture in rats treated with 0.25 mg/kg of VAC-CaSO4 . Micro-CT analyses at 4 weeks found a more organized callus structure and higher trending maximum connected z-ray. fraction for VAC-CaSO4 groups. Evaluation of radiographs and serial histological sections at 12 weeks did not show any evidence of ectopic bone formation. As compared to previous studies, CaSO4 was an effective carrier for reducing the dose of VAC required to accelerate femoral fracture healing in rats.

Role of ERK/NFκB in vanadium (IV) oxide mediated osteoblast differentiation in C3H10t1/2 cells

Vanadium (V) compounds are reported to have insulin mimicking action, which render them to show excellent osteogenic activity. In the current study we investigated the effect of various vanadium compounds on osteoblast differentiation of mouse mesenchymal stem cells, C3H10t1/2 cells, and analyzed the underlying mechanism of vanadium for this action. Our data showed that treatment of C3H10t1/2 cells with V (IV) oxide complex (at 7-25 μM concentrations) induced osteoblast differentiation maximally as compared to V2O5. On the other hand, ammonium vanadate was found to dampen the osteoblast differentiation process. Based on this data, V (IV) oxide was investigated further to analyze its probable mode of action as an osteoblastic agent. The key factors implicated in osteoblast differentiation i.e., NFκB, ERK ½, AP1 and CRE were examined in response to V (IV) oxide exposure. Exposure to V (IV) oxide caused 2- and 5-folds induction of luciferase activities in cells transfected with SRE-luc and NFκB-luc reporter vectors respectively (p < 0.05). Further, exposure to V (IV) oxide enhanced the phosphorylation of ERK ½, IκB and NFκBp65 proteins. In addition, RT-PCR analysis, alizarin red staining and immunoblot analysis showed that inhibition of osteoblast differentiation in presence of PD98059 and parthenolide (inhibitors of ERK and NFκB pathways respectively) was rescued in presence of V (IV) oxide. These results suggest that V (IV) oxide up regulates osteoblast differentiation through ERK and NFκB pathways and hence could be utilized as an agent for bone formation after further analysis and validation.

Biomechanical characteristics of bone in streptozotocin-induced diabetic rats: An in-vivo randomized controlled experimental study

AIM: To investigate the in vivo effects of type I diabetes on the mechanical strength of tibial bone in a rodent model.

METHODS: The biomechanical effect of diabetes on the structural integrity of the tibia in streptozotocin induced diabetic Wistar rats was analysed. Induction of diabetes was achieved by an intra-peritoneal injection and confirmed by measuring serial blood glucose levels (> 150 mg/dL). After 8 wk the tibiae were harvested and compared to a control group. Biomechanical analysis of harvested tibiae was performed using a three-point bending technique on a servo hydraulic MTS 858 MiniBionix frame. Maximum force applied to failure (N), stiffness (N × mm) and energy absorbed (N/mm) were recorded and plotted on load displacement curves. A displacement control loading mode of 1 mm/min was selected to simulate quasi-static loading conditions. Measurements from load-displacement curves were directly compared between groups.

RESULTS: Fourteen streptozotocin induced diabetic Wistar rats were compared against nineteen non-diabetic controls. An average increase of 155.2 g in body weight was observed in the control group compared with only 5 g in the diabetic group during the experimental study period. Levels of blood glucose increased to 440.25 mg/dL in the diabetic group compared to 116.62 mg/dL in the control group.The biomechanical results demonstrate a highly significant reduction in the maximum load to failure from 69.5 N to 58 N in diabetic group compared to control (P = 0.011). Energy absorption to fracture was reduced from 28.2 N in the control group to 23.5 N in the diabetic group (P = 0.082). No significant differences were observed between the groups for bending stiffness.

CONCLUSION: Streptozotocin-induced diabetes in rodents reduces the maximum force and energy absorption to failure of bone, suggesting a predisposition for fracture risk.

Role of vanadium (V) in the differentiation of C3H10t1/2 cells towards osteoblast lineage: a comparative analysis with other trace elements

In recent time, vanadium compounds are being used as antidiabetic drug and in orthopedic implants. However, the exact role of this incorporated vanadium in improving the quality of bone structure and morphology is not known. The impact of vanadium ion was studied and compared to other trace metal ions with respect to the proliferation and osteoblast differentiation of C3H10t1/2 cells. Toxicity profile of these trace metal ions revealed a descending toxicity trend of Fe(2+) > Zn(2+) > Cu(2+) > Co(2+) > Mn(2+) > V(5+) > Cr(2+). The effect of vanadium and other trace metal ions on osteoblast differentiation was evaluated by culturing the cells for 10 days in osteoblastic medium supplemented with different trace ions at concentrations lower than their cytotoxic doses. The results indicated that vanadium has maximum impact on the induction of osteoblast differentiation by upregulating alkaline phosphatase activity and mineralization by up to 145 and 150 %, respectively (p < 0.05), over control. Cu(2+) and Zn(2+) had a mild inhibitory effect, while Mn(2+), Fe(2+), and Co(2+) demonstrated a clear decrease in osteoblast differentiation when compared to the control. The data as presented here demonstrate that orthopedic implants, if supplemented with trace metals like vanadium, may provide a source of better model for bone formation and its turnover.

Systemic treatment with vanadium absorbed by Coprinus comatus promotes femoral fracture healing in streptozotocin-diabetic rats

The purpose of this study was to analyze the impact of vanadium absorbed by Coprinus comatus (VACC) on fracture healing in streptozotocin-diabetic rats. Forty-five male Wistar rats used were divided into three groups: normal rats (control), diabetic rats, and diabetic rats treated with VACC. A standardized fracture-healing model with a stable plate fixation was established for the rat femoral fracture. After a 4-week stable fixation, callus quality was assessed by microcomputerized tomography and histological and biomechanical examinations. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. Compared with the diabetic group, vanadium treatment significantly increased bone mineral content and biomechanical strength and improved microstructural properties of the callus. The ultimate load was increased by 29.1 % (P<0.05), and the total bone volume of callus enhanced by 11.2 % (P<0.05) at 4 weeks post fracture. Vanadium also promoted callus bone formation, which caused a 35.5 % increase in the total area of callus. However, VACC did not accelerate the fracture repair process in histological analysis. In conclusion, the current study suggests that systemic treatment with vanadium could promote fracture healing in streptozotocin-diabetic rats.

The effects of local vanadium treatment on angiogenesis and chondrogenesis during fracture healing

This study quantified the effects of local intramedullary delivery of an organic vanadium salt, which may act as an insulin-mimetic on fracture healing. Using a BB Wistar rat femoral fracture model, local vanadyl acetylacetonate (VAC) was delivered to the fracture site and histomorphometry, mechanical testing, and immunohistochemistry were performed. Callus percent cartilage was 200% higher at day 7 (p < 0.05) and 88% higher at day 10 (p < 0.05) in the animals treated with 1.5 mg/kg of VAC. Callus percent mineralized tissue was 37% higher at day 14 (p < 0.05) and 31% higher at day 21 (p < 0.05) in the animals treated with 1.5 mg/kg of VAC. Maximum torque to failure was 104% and 154% higher at 4 weeks post-fracture (p < 0.05) for the healing femurs from the VAC-treated (1.5 and 3.0 mg/kg) animals. Animals treated with other VAC doses demonstrated increased mechanical parameters at 4 weeks (p < 0.05). Immunohistochemistry detected 62% more proliferating cells at days 7 (p < 0.05) and 94% more at day 10 (p < 0.05) in the animals treated with 1.5 mg/kg VAC. Results showed 100% more vascular endothelial growth factor-C (VEGF-C) positive cells and 80% more blood vessels at day 7 (p < 0.05) within the callus subperiosteal region of VAC-treated animals (1.5 mg/kg) compared to controls. The results suggest that local VAC treatment affects chondrogenesis and angiogenesis within the first 7-10 days post-fracture, which leads to enhanced mineralized tissue formation and accelerated fracture repair as early as 3-4 weeks post-fracture.

Effect of bis(maltolato)oxovanadium (IV) (BMOV) on selenium nutritional status in diabetic streptozotocin rats

The role of V as a micronutrient, and its hypoglycaemic and toxicological activity, have yet to be completely established. The present study focuses on changes in the bioavailability and tissue distribution of Se in diabetic streptozotocin rats following treatment with V. The following four study groups were examined: control; diabetic (DM); diabetic treated with 1 mg V/d (DMV); diabetic treated with 3 mg V/d (DMVH). V was supplied in the drinking water as bis(maltolato)oxovanadium (IV). The experiment had a duration of 5 weeks. Se was measured in food, faeces, urine, serum, muscle, kidney, liver and spleen. Glucose and insulin serum were studied, together with glutathione peroxidase (GSH-Px), glutathione reductase (GR), glutathione transferase (GST) activity and malondialdehyde (MDA) levels in the liver. In the DM group, we recorded higher levels of food intake, Se absorbed, Se retained, Se content in the kidney, liver and spleen, GSH-Px and GST activity, in comparison with the control rats. In the DMV group, there was a significant decrease in food intake, Se absorbed, Se retained and Se content in the liver and spleen, and in GSH-Px and GST activity, while fasting glycaemia and MDA remained unchanged, in comparison with the DM group. In the DMVH group, there was a significant decrease in food intake, glycaemia, Se absorbed, Se retained, Se content in the kidney, liver and spleen, and in GSH-Px and GST activity, and increased MDA, in comparison with the DM and DMV groups. We conclude that under the experimental conditions described, the treatment with 3 mg V/d caused a tissue depletion of Se that compromised Se nutritional status and antioxidant defences in the tissues.

The effects of vanadium (V) absorbed by Coprinus comatus on bone in streptozotocin-induced diabetic rats

The purpose of this study was to evaluate the effects of vanadium absorbed by Coprinus comatus (VACC) treatment on bone in streptozotocin (STZ)-induced diabetic rats. Forty-five Wistar female rats used were divided into three groups: (1) normal rats (control), (2) diabetic rats, and (3) diabetic rats treated with VACC. Normal and diabetic rats were given physiological saline, and VACC-treated rats were administered VACC intragastrically at doses of 0.18 mg vanadium/kg body weight once daily. Treatments were performed over a 12-week period. At sacrifice, one tibia and one femur were removed, subjected to micro computed tomography (micro-CT) for determination of trabecular bone structure, and then processed for histomorphometry to assess bone turnover. Another femoral was used for mechanical testing. In addition, bone samples were collected to evaluate the content of mineral substances in bones. Treatment with VACC increased trabecular bone volume fraction in diabetic rats. Vanadium-treated animals had significant increases in ultimate load, trabecular thickness, and osteoblast surface. However, vanadium treatment did not seem to affect bone stiffness, bone energy absorption, trabecular separation, and osteoclast number. P levels in the femurs of diabetic rats treated with VACC were significantly higher than those of diabetic animals. Ca levels in diabetic and diabetic rats treated with vanadium showed no obvious changes. In conclusion, our results provide an important proof of concept that VACC may represent a powerful approach to treating or reversing diabetic osteopathy in humans.

The preventive effects of pulsed electromagnetic fields on diabetic bone loss in streptozotocin-treated rats

The present study was the first report demonstrating that pulsed electromagnetic field (PEMF) could partially prevent bone strength and architecture deterioration and improve the impaired bone formation in streptozotocin-induced diabetic rats. The findings indicated that PEMF might become a potential additive method for inhibiting diabetic osteopenia or osteoporosis.

INTRODUCTION

Diabetes mellitus (DM) can cause various musculoskeletal abnormalities. Optimal therapeutic methods for diabetic bone complication are still lacking. It is essential to develop more effective and safe therapeutic methods for diabetic bone disorders. Pulsed electromagnetic field (PEMF) as an alternative noninvasive method has proven to be effective for treating fracture healing and osteoporosis in non-diabetic conditions. However, the issue about the therapeutic effects of PEMF on diabetic bone complication has not been previously investigated.

METHODS

We herein systematically evaluated the preventive effects of PEMF on diabetic bone loss in streptozotocin-treated rats. Two similar experiments were conducted. In each experiment, 16 diabetic and eight non-diabetic rats were equally assigned to the control, DM, and DM + PEMF group. DM + PEMF group was subjected to daily 8-h PEMF exposure for 8 weeks.

RESULTS

In experiment 1, three-point bending test suggested that PEMF improved the biomechanical quality of diabetic bone tissues, evidenced by increased maximum load, stiffness, and energy absorption. Microcomputed tomography analysis demonstrated that DM-induced bone architecture deterioration was partially reversed by PEMF, evidenced by increased Tb.N, Tb.Th, BV/TV, and Conn.D and reduced Tb.Sp and SMI. Serum OC analysis indicated that PEMF partially prevented DM-induced decrease in bone formation. In experiment 2, no significant difference in the bone resorption marker TRACP5b was observed. These biochemical findings were further supported by the dynamic bone histomorphometric parameters BFR/BS and Oc.N/BS.

CONCLUSIONS

The results demonstrated that PEMF could partially prevent DM-induced bone strength and architecture deterioration and improve the impaired bone formation. PEMF might become a potential additive method for inhibiting diabetic osteoporosis.

Increasing duration of type 1 diabetes perturbs the strength-structure relationship and increases brittleness of bone

Type 1 diabetes (T1DM) increases the likelihood of a fracture. Despite serious complications in the healing of fractures among those with diabetes, the underlying causes are not delineated for the effect of diabetes on the fracture resistance of bone. Therefore, in a mouse model of T1DM, we have investigated the possibility that a prolonged state of diabetes perturbs the relationship between bone strength and structure (i.e., affects tissue properties). At 10, 15, and 18 weeks following injection of streptozotocin to induce diabetes, diabetic male mice and age-matched controls were examined for measures of skeletal integrity. We assessed 1) the moment of inertia (I(MIN)) of the cortical bone within diaphysis, trabecular bone architecture of the metaphysis, and mineralization density of the tissue (TMD) for each compartment of the femur by micro-computed tomography and 2) biomechanical properties by three-point bending test (femur) and nanoindentation (tibia). In the metaphysis, a significant decrease in trabecular bone volume fraction and trabecular TMD was apparent after 10 weeks of diabetes. For cortical bone, type 1 diabetes was associated with decreased cortical TMD, I(MIN), rigidity, and peak moment as well as a lack of normal age-related increases in the biomechanical properties. However, there were only modest differences in material properties between diabetic and normal mice at both whole bone and tissue-levels. As the duration of diabetes increased, bone toughness decreased relative to control. If the sole effect of diabetes on bone strength was due to a reduction in bone size, then I(MIN) would be the only significant variable explaining the variance in the maximum moment. However, general linear modeling found that the relationship between peak moment and I(MIN) depended on whether the bone was from a diabetic mouse and the duration of diabetes. Thus, these findings suggest that the elevated fracture risk among diabetics is impacted by complex changes in tissue properties that ultimately reduce the fracture resistance of bone.

Vitamin K₂ prevents hyperglycemia and cancellous osteopenia in rats with streptozotocin-induced type 1 diabetes

The purpose of the present study was to examine the effect of vitamin K₂ on cancellous and cortical bone mass in rats with streptozotocin (STZ)-induced type 1 diabetes. Twenty-seven male Sprague-Dawley rats aged 12 weeks were randomized by the weight-stratified method into the following three groups: age-matched control group, STZ + vehicle group, and STZ + vitamin K₂ group. STZ (40 + 50 mg/kg) was administered intravenously twice during the initial 1-week period. Vitamin K₂ (menatetrenone, 30 mg/kg) was administered orally 5 days a week. After 12 weeks of treatment, the serum glucose concentration and femoral length and weight were measured and histomorphometric analysis was performed on the cancellous and cortical bone of the distal femoral metaphysis and femoral diaphysis, respectively. STZ administration induced hyperglycemia and a decrease in femoral weight. The STZ + vehicle group also showed cancellous osteopenia due to a decrease in the number of osteoblasts/bone surface (N.Ob/BS) and the osteoblast surface (ObS)/BS without any significant changes in bone-resorption parameters, but it did not have a significant decrease in cortical bone mass. Administration of vitamin K₂ to STZ-treated rats prevented the development of hyperglycemia and a decrease in femoral weight. Vitamin K₂ also prevented cancellous osteopenia by inhibiting the decrease in N.Ob/BS and ObS/BS without significantly affecting bone-resorption parameters, but it did not significantly increase cortical bone mass. These results suggest that vitamin K₂ has beneficial effects on glucose concentration and cancellous bone mass in rats with STZ-induced type 1 diabetes.

Antioxidant enzyme activity and lipid peroxidation in the blood of rats co-treated with vanadium (V(+5)) and chromium (Cr (+3))

Selected biochemical parameters were studied in the blood of outbred, male Wistar rats which daily received to drink deionized water (Group I, control) or solutions of: sodium metavanadate (SMV; 0.100 mg V/mL)-Group II; chromium chloride (CC; 0.004 mg Cr/mL)-Group III; and SMV-CC (0.100 mg V and 0.004 mg Cr/mL)-Group IV for a 12-week period. The diet and fluid intake, body weight gain, and food efficiency ratio (FER) diminished significantly in the rats of Groups II and IV, compared with Groups I and III. The plasma total antioxidant status (TAS) as well as the MDA and the L: -ascorbic acid level in the erythrocytes (RBCs) remained unchanged in all the groups, whereas the plasma L: -ascorbic acid concentration decreased markedly in Group II, compared with Group III. The activities of Cu,Zn-superoxide dismutase (Cu,Zn-SOD), catalase (CAT), cellular glutathione peroxidase (cGSH-Px), and glutathione reductase (GR) in RBCs remained unaltered in all the treated rats. However, the activity of glutathione S-transferase (GST) and the content of reduced glutathione (GSH) in RBCs decreased and increased, respectively, in Groups II, III, and IV, compared with Group I. A vanadium-chromium interaction which affected the GST activity was also found. To summarize, SMV and CC administered separately or in combination in drinking water for 12 weeks did not alter either lipid peroxidation (LPO) or the activities of Cu,Zn-SOD, CAT, cGSH-Px, and GR, which allows a conclusion that both metals in the doses ingested did not reveal their pro-oxidant potential on RBCs.

Vanadate complexes in serum: a speciation modeling study

The speciations of two drug candidate ligands, 2-hydroxypyridine-N-oxide (Hhpno) and 2-mercaptopyridine-N-oxide (Hmpno), with vanadate (V(V)) were determined at 25.0 degrees C and 0.20 mol dm(-3) KCl by pH-metric and (51)V-NMR methods. At pH 7.4, the two predominant compounds with both ligands are the VO(2)L(2) and VO(2)L(OH). NH(4)[VO(2)(hpno)(2)] x 3 H(2)O was prepared in solid form, and its crystal structure was determined by X-ray diffraction. The stabilities of the complexes VO(2)L(2) of five drug candidate ligands were compared at pH 7.4. In view of the stability sequence hpno > maltol approximately hdp (Hhdp: 3-hydroxy-1,2-dimethyl-4-pyridinone) >> mpno > picolinic acid, the first two of these ligands were chosen for equilibrium studies with apotransferrin (apoTf) competition. The V(V)-apoTf stability constants (log K(1) = 6.03 +/- 0.10; log K(2) = 5.46 +/- 0.18) determined by (51)V-NMR spectroscopy were confirmed by ultrafiltration. Both methods proved that there seems to be no hydrogencarbonate-vanadate competition for the apoTf anion-binding positions. The other potential high molecular mass V(V) binder in the serum is human serum albumin (HSA). As no interaction was detected by (51)V-NMR spectroscopy or fluorimetry, the binding properties of HSA were quantified on the basis of literature data. As a final conclusion, speciation modeling calculations suggest that, under serum conditions, apoTf is probably the primary metal ion binder, even in the presence of the most stable V(V) carrier ligands hpno and maltol and HSA plays a negligible role in V(V) binding.

Measuring and interpreting age-related loss of vertebral bone mineral density in a medieval population

This study investigates the age- and sex-related patterns in vertebral bone mineral density (BMD) and the relationship between BMD and vertebral osteophytosis (VO), using a specialized peripheral densitometer in a skeletal sample excavated from the British medieval village Wharram Percy. A total of 58 individuals were divided by sex into three broad age categories (18-29, 30-49, 50+ years.). Each fourth intact vertebral centra was scored for VO and 5-mm thick coronal sections scanned in a specialized peripheral densitometer (GE Lunar Piximus DXA). Changes in BMD associated with age, sex, and VO severity were examined in the whole vertebral section, a strictly trabecular region, and a primarily cortical region of bone separately. Significant change in vertebral BMD was found to occur by middle age with little or no statistical change in BMD between middle and old age. Females appear to suffer greater bone loss at an earlier age with no change in BMD between middle and old age, whereas males show a more steady loss of BMD across the age groups. The bone mineral content and BMD of the cortical region is higher in individuals with pronounced/severe osteophytosis. The unusual age- and sex-related patterns of change in vertebral BMD at Wharram Percy are compared with the patterns of age-related change from recent longitudinal population-based studies. The results emphasize the different pattern of bone loss in young adulthood seen in trabecular regions of the skeleton and highlight the importance of consideration of degenerative joint disease in BMD studies. The influence of lifestyle factors on vertebral BMD in this medieval population is also discussed.

Measurement of the toughness of bone: a tutorial with special reference to small animal studies

Quantitative assessment of the strength and toughness of bone has become an integral part of many biological and bioengineering studies on the structural properties of bone and their degradation due to aging, disease and therapeutic treatment. Whereas the biomechanical techniques for characterizing bone strength are well documented, few studies have focused on the theory, methodology, and various experimental procedures for evaluating the fracture toughness of bone, i.e., its resistance to fracture, with particular reference to whole bone testing in small animal studies. In this tutorial, we consider the many techniques for evaluating toughness and assess their specific relevance and application to the mechanical testing of small animal bones. Parallel experimental studies on wild-type rat and mouse femurs are used to evaluate the utility of these techniques and specifically to determine the coefficient of variation of the measured toughness values.

Calorimetric studies of the interaction between the insulin-enhancing drug candidate bis(maltolato)oxovanadium(IV) (BMOV) and human serum apo-transferrin

Bis(maltolato)oxovanadium(IV) (BMOV), and its ethylmaltol analog, bis(ethylmaltolato)oxovanadium(IV) (BEOV), are candidate insulin-enhancing agents for the treatment of type 2 diabetes mellitus; in mid-2008, BEOV advanced to phase II clinical testing. The interactions of BMOV and its inorganic congener, vanadyl sulfate (VOSO(4)), with human serum apo-transferrin (hTf) were investigated using differential scanning calorimetry (DSC). Addition of BMOV or VOSO(4) to apo-hTf resulted in an increase in thermal stability of both the C- and N-lobes of transferrin as a result of binding to either vanadyl compound. A series of DSC thermograms of hTf solutions containing different molar ratios of BMOV and VOSO(4) were used to determine binding constants; at 25 degrees C the binding constants of BMOV to the C- and N-lobes of apo-hTf were found to be 3 (+/-1)x10(5) and 1.8 (+/-0.7)x10(5)M(-1), respectively. The corresponding values for VOSO(4) were 1.7 (+/-0.3)x10(5) and 7 (+/-2)x10(4)M(-1). The results show that the vanadium species initially presented as either BMOV or VOSO(4) had similar affinities for human serum transferrin due to oxidation of solvated vanadyl(IV) prior to complexation to transferrin. Binding of metavanadate (VO(3)(-)) was confirmed by DSC and isothermal titration calorimetry (ITC) experiments of the interaction between sodium metavanadate (NaVO(3)) and hTf.

Element analysis in femur of diabetic osteoporosis model by SRXRF microprobe

Diabetes mellitus affects bone metabolism and leads to osteopenia and osteoporosis, but its pathogenic mechanism remains unknown. To address this problem, mineral element of bone was analyzed in experimental diabetic osteoporosis model. Male Wistar rats were randomly divided into streptozotocin (STZ)-induced diabetic group (n=5) and control group (n=5). The experiment lasted 68 days and at the end of the experiment, femoral bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry and element content in femur of animals was determined by synchrotron radiation X-ray fluorescence (SRXRF) microprobe analysis technique. Results showed that femoral BMD in diabetic group was significantly lower than that in control (P<0.01). Relative mineral content of calcium (Ca), phosphorus (P) and zinc (Zn) in diabetic femurs decreased significantly compared to controls. And strontium (Sr) in diabetics reduced 11% (P=0.09). Relative content of sulfur (S) in average was statistically higher (P<0.01) in diabetics than that in controls. But no obvious difference was observed in relative content of chromium (Cr), iron (Fe), copper (Cu), and lead (Pb) between the two groups. Statistical analysis revealed that Ca correlated positively with P (R=0.85 and P<0.001), with Sr (R=0.38 and P<0.05) and with Zn (R=0.37 and P<0.05). Whereas, Zn correlated negatively with S (R=-0.40 and P<0.05). Our results reveal that loss of minerals accounts for the BMD reduction in diabetics.