Anabolic effects of insulin on bone suggest a role for chromium picolinate in preservation of bone density

Chromium nanoparticles improve bone turnover regulation in rats fed a high-fat, low-fibre diet

The aim of the study was to investigate the effect of returning to a balanced diet combined with chromium picolinate (CrPic) or chromium nanoparticles (CrNPs) supplementation at a pharmacologically relevant dose of 0.3 mg/kg body weight on the expression level of selected genes and bone turnover markers in the blood and bones of rats fed an obese diet. The results of the study showed that chronic intake of a high-fat obesogenic diet negatively affects bone turnover by impairing processes of both synthesis and degradation of bones. The switch to a healthy diet proved insufficient to regulate bone metabolism disorders induced by an obesogenic diet, even when it was supplemented with chromium, irrespective of its form. Supplementation with CrPic with no change in diet stimulated bone metabolism only at the molecular level, towards increased osteoclastogenesis (bone resorption). In contrast, CrNPs added to the high-fat diet effectively regulated bone turnover by increasing both osteoblastogenesis and osteoclastogenesis, with these changes directed more towards bone formation. The results of the study suggest that unfavourable changes in bone metabolism induced by chronic intake of a high-fat diet can be mitigated by supplementation with CrNPs, whereas a change in eating habits fails to achieve a similar effect.

The Effect of Doping on the Electrical and Dielectric Properties of Hydroxyapatite for Medical Applications: From Powders to Thin Films

Recently, the favorable electrical properties of biomaterials have been acknowledged as crucial for various medical applications, including both bone healing and growth processes. This review will specifically concentrate on calcium phosphate (CaP)-based bioceramics, with a notable emphasis on hydroxyapatite (HA), among the diverse range of synthetic biomaterials. HA is currently the subject of extensive research in the medical field, particularly in dentistry and orthopedics. The existing literature encompasses numerous studies exploring the physical-chemical, mechanical, and biological properties of HA-based materials produced in various forms (i.e., powders, pellets, and/or thin films) using various physical and chemical vapor deposition techniques. In comparison, there is a relative scarcity of research on the electrical and dielectric properties of HA, which have been demonstrated to be essential for understanding dipole polarization and surface charge. It is noteworthy that these electrical and dielectric properties also offer valuable insights into the structure and functioning of biological tissues and cells. In this respect, electrical impedance studies on living tissues have been performed to assess the condition of cell membranes and estimate cell shape and size. The need to fill the gap and correlate the physical-chemical, mechanical, and biological characteristics with the electrical and dielectric properties could represent a step forward in providing new avenues for the development of the next-generation of high-performance HA-doped biomaterials for future top medical applications. Therefore, this review focuses on the electrical and dielectric properties of HA-based biomaterials, covering a range from powders and pellets to thin films, with a particular emphasis on the impact of the various dopants used. Therefore, it will be revealed that each dopant possesses unique properties capable of enhancing the overall characteristics of the produced structures. Considering that the electrical and dielectric properties of HA-based biomaterials have not been extensively explored thus far, the aim of this review is to compile and thoroughly discuss the latest research findings in the field, with special attention given to biomedical applications.

Effects of maternal calcium propionate supplementation on offspring productivity and meat metabolomic profile in sheep

This study determined the effect of dietary calcium propionate (CaPr) as a source of energy supplementation during the First Half of Gestation (FMG), the Second Half of Gestation (SMG), and during All Gestation (AG), on offspring post-weaning growth performance, meat quality, and meat metabolomic profile. Thirty-one pregnant ewes were assigned to one of four treatments: a) supplementation of 30 gd-1 of CaPr during the first half of gestation (day 1 to day 75, n = 8) (FMG); b) supplementation of 30 gd-1 of CaPr during the second half of gestation (day 76 to day 150, n = 8) (SMG); c) supplementation of 30 gd-1 of CaPr during all gestation (AG, n = 8); d) no CaPr supplementation (control; CS, n = 7). The ewes were ad libitum fed a basal diet based on oat hay and corn silage. Ewes were distributed in a completely randomized unbalanced design to four treatments. The FMG group had lower (P ≤ 0.05) birth weight and weaning weight than the CS group. However, the average daily gain was similar across all treatments. Empty body weight and FMG had lower values (P ≤ 0.05) than the other groups. Both FMG and AG had lower hot carcass weight (P ≤ 0.05) compared to CS, while CaPr treatments resulted in reduced hot carcass yield (P ≤ 0.05). Meat color and texture were similar among treatments. A principal component analysis between gestation stages showed a trend for separating CS and FMG from SMG and AG, and that was explained by 93.7% of the data variability (PC1 = 87.9% and PC2 = 5.8%). Regarding meat metabolomic profile, 23 compounds were positively correlated between all treatments. Only 2 were negatively correlated (eicosane and naphthalene 1,2,3); but tetradecanoic acid, hexadecane, undecane 5-methyl, (-)-alpha, hexadecenoic acid, octadecanoic acid, and octadecane had a highly significant correlation (P ≤ 0.05). Overall, dam supplementation with CaPr during different periods of gestation provoked changes in meat metabolites related to the biosynthesis of fatty acids in lambs without negative changes in lamb's growth performance and carcass quality.

The Impact of Fetal Programming in Ewe Nutrition with Chromium Propionate or Calcium Salts of Palm Oil on the Meat Quality and Bone of the Progeny

This study aimed to evaluate the inclusion of chromium propionate or calcium salts of palm oil in ewes' diet during the final third of gestation and lactation on progeny performance, carcass characteristics, non-carcass components, and bone density. Forty-three ewe, Santa Inês and Dorper breed, three ± one-year-old, and body weight 57 ± 10 kg were used. The experimental design was in casual blocks in three treatments, CTL treatment (n = 15) with starch from corn; CR (n = 15) diet CTL plus chromium propionate; PF (n = 13) diet CTL plus calcium salts of palm oil. After weaning, 23 male lambs from these ewes were confined in individual stalls, with the same diet for 60 days, slaughtered. The data were analyzed using the SAS program, PROC GLM, and compared the means using Tukey's test at 5% probability. The maternal diet did not alter the dry matter intake, feeding efficiency, and average daily weight gain. Therefore, weights (weaning and slaughter) and carcass yield were higher for CR and PF groups than for CTL (P < 0.05). The treatment did not influence the loin eye area and fat thickness (P > 0.05). The spleen and the respiratory tract were smaller for PF and larger for CTL (P < 0.05). Leg weight was higher for CR. The perimeter and depth of the shank for the CR and PF lambs were higher, indicating an effect of maternal nutrition in this commercial cut. The CR group had a smaller epiphysis measurement and femur length than the CTL group. We concluded that the fetal programming effect in ewes fed with Cr propionate and Ca salts of palm oil benefited the progeny by increasing their body weight, better carcass yield, and a higher proportion of prime cuts.

The role of copper chromite nanoparticles on physical and bio properties of scaffolds based on poly(glycerol-azelaic acid) for application in tissue engineering fields

Tissue engineering combines suitable cells, engineering methods, and proper biochemical factors to develop functional and biological tissues and repair damaged tissues. In this study, we focused on synthesizing and characterizing a nanocomposite scaffold based on glycerol and azelaic acid (Gl-Az) combined with copper chromite (CuCr₂O₄) nanoparticles in order to increase the osteogenic differentiation efficiency of human adipose-derived stem cells (hADSCs) on fabricated scaffolds. The degradability and hydrophobicity properties as well as mechanical and thermal behaviors of nanocomposite scaffolds were investigated. Next, the cell toxicity of glycerol, azelaic acid and CuCr₂O₄ nanoparticles was studied by MTT assay test and acridine orange staining. Finally, the osteogenic differentiation of hADSCs on Gl-Az-CuCr₂O₄ scaffolds was examined using alkaline phosphatase activity (ALP) and calcium content. The obtained results demonstrated that Gl-Az-1%CuCr₂O₄ not only showed appropriate mechanical strength, biocompatibility and degradability but also influenced the capability of hADSCs to differentiate into osteogenic lineages. The hADSCs culture in Gl-Az-1%CuCr₂O₄ showed a significant increase in ALP activity levels and calcium biomineralization after 14 days of osteogenic differentiation. In conclusion, the Gl-Az-1%CuCr₂O₄ nanocomposite could be used as a biocompatible and degradable scaffold to induce the bone differentiation of hADSCs and it could be a promising scaffold in bone regenerative medicine.

Proportional relationship between periodontal inflamed surface area, clinical attachment loss, and glycated hemoglobin level in patients with type 2 diabetes mellitus on insulin therapy and on oral antidiabetic therapy

BACKGROUND

Treatment of diabetes includes oral antidiabetic drugs (OAD), insulin, or their combinations. Insulin can achieve faster glycemic control and have anabolic action on bone. This study was undertaken to assess the prevalence and severity of periodontitis, and to estimate the proportional relationship between periodontal inflamed surface area, clinical attachment loss, and glycated hemoglobin (HbA1c) level in patients with type 2 diabetes (T2DM) on OAD therapy and on insulin therapy.

METHODS

This cross-sectional study comprised 130 patients with T2DM on OAD therapy (OAD group) and 130 patients with T2DM on insulin therapy (INSULIN group). All patients were assessed for sociodemographic, behavioral characteristics, clinical history, periodontal parameters (bleeding on probing, probing depth, clinical attachment loss [Clinical AL], Oral Hygiene Index-simplified, plaque index, and periodontal inflamed surface area [PISA]), and biochemical variables (HbA1c, fasting plasma glucose, postprandial plasma glucose).

RESULTS

Prevalence, extent, and severity of periodontitis and PISA were lower in the INSULIN group as compared with the OAD group. A proportional relationship was observed between HbA1c and PISA and between HbA1c and Clinical AL. A unit increase in HbA1c is associated with an increase in PISA of 130.47 mm² and an increase in Clinical AL of 0.182 mm.

CONCLUSION

A proportional relationship was observed between PISA, clinical attachment loss, and HbA1c level in patients with type 2 diabetes mellitus on insulin therapy and OAD therapy. Despite comparable oral hygiene status and glycemic control between the two groups, the periodontal parameters were lesser in the INSULIN group as compared with the OAD group.

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.

Impact of Type 2 Diabetes Mellitus and Antidiabetic Medications on Bone Metabolism

PURPOSE OF REVIEW

This review focuses on the complex interactions between hyperglycemia and bone fragility and the effects of antidiabetic medications on bone metabolism.

RECENT FINDINGS

Type 2 diabetes (T2D) is associated with increased risk of bone fracture even in those with increased or normal bone mineral density (BMD). The pathophysiology of diabetic bone disease is not completely understood, but it is thought to be multifactorial and associated with complex cross talk among factors such as AGEs, IGF-1, enteric hormones, and pro-inflammatory cytokines. Treatment for T2D may have an impact on bone metabolism. Diabetic bone disease should be considered a serious complication of long-standing T2D.

Estimated intestinal absorption of phosphorus and its deposition in chosen tissues, bones and feathers of chickens receiving chromium picolinate or chromium nanoparticles in diet

The aim of the study was to determine whether the level and form of Cr in the diet of chickens influences its accumulation in tissues as well as intestinal absorption of P and its deposition in tissues. The experiment was carried out on 405 one-day-old male Ross 308 chickens that were randomly divided into five treatment groups. Control group was fed the diet without supplemental chromium; experimental groups were fed the diet with 3 or 6 mg/kg chromium picolinate (Cr-Pic) and with 3 or 6 mg/kg chromium nanoparticles (Cr-NP). Chromium was found to accumulate in the tissues of the ileum, liver, breast muscle, bones skin and in feathers of chickens. Chromium deposited in the ileum of chickens does not affect the ex vivo estimated intestinal absorption of P. The use of Cr in the diet of chickens carries the risk of lowering P levels in femur.

C-terminal telopeptide of type I collagen, osteocalcin, alkaline phosphatase, and parathyroid hormone in healthy and hospitalized foals

Hypocalcemia is a common finding in critically ill equine patients. Parathyroid hormone (PTH) helps to maintain calcium homeostasis in hypocalcemic patients by promoting renal calcium reabsorption and bone resorption. Increased serum PTH concentrations have been reported in critically ill people and animals, including horses and foals. It is unknown whether increased secretion of PTH is associated with markers of bone turnover in hospitalized foals. The goals of this study were to measure markers of bone resorption (C-terminal telopeptide of type I collagen [CTX-I]) and bone formation (osteocalcin [OCN]; alkaline phosphatase [ALP]) and to determine their association with PTH concentrations, disease severity, and mortality in hospitalized foals. This prospective, multicenter, cross-sectional study was conducted on 75 newborn foals ≤3 d old divided into hospitalized (n = 65; 41 septic; 24 sick nonseptic) and healthy (n = 10) groups. Blood samples were collected on admission to measure serum CTX-I, OCN, and PTH concentrations and ALP activity. Data were analyzed by nonparametric methods and univariate logistic regression. Serum CTX-I and PTH concentrations were significantly higher, whereas OCN concentrations were lower, in septic compared with healthy foals (P < 0.05). Serum ALP activity was not different between groups; however, it was lower in hospitalized and septic foals with low OCN concentrations (P < 0.05). In hospitalized foals, PTH concentrations were positively correlated with CTX-I concentrations and inversely associated with ALP activity (P < 0.05). High CTX-I and low OCN concentrations were associated with disease severity (P < 0.05). Hospitalized nonsurviving foals had significantly lower OCN concentrations compared with survivors (P < 0.05), but CTX-I concentrations were not associated with survival. Hospitalized foals with PTH concentrations >12.4 pmol/L were more likely to die (OR = 1.5; 95% CI = 1.1-4.16; P < 0.05). Elevated PTH and CTX-I together with reduced OCN concentrations and ALP activity in sick foals indicates that bone resorption is increased during critical illness, which may be a compensatory mechanism to correct hypocalcemia or reflect a response to systemic inflammation and metabolic imbalances. Bone resorption could negatively impact skeletal development in the growing foal. Low OCN and high PTH concentrations were predictors of nonsurvival in hospitalized foals.

Negative impact of polycystic ovary syndrome on bone health: a systematic review and meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) has reproductive and metabolic aspects that may affect bone health. Controversial results from different studies regarding the risk of fractures, bone mineral density (BMD) or bone markers led to uncertainty whether PCOS might improve or deteriorate bone health.

OBJECTIVE AND RATIONALE

This study aimed to investigate the impact of PCOS on bone markers, BMD and fracture risk.

SEARCH METHODS

A systematic review and a meta-analysis were carried out. PubMed, EMBASE and Cochrane databases were searched for eligible studies from 1st of January of 1990 to 9th of October of 2018. Eligible studies enrolled women older than 18 years with PCOS, which should be diagnosed according to the Rotterdam Consensus, the Androgen Excess Society, the National Institutes of Health Consensus or the International Classification of Diseases. The studies were grouped according to patient mean BMI: <27 kg/m2 or ≥27 kg/m2. The results were polled as mean difference (MD), standardized MD (SMD) and hazard ratio (HR).

OUTCOMES

Overall, 921 studies were retrieved, and 31 duplicated studies were removed. After screening the titles and abstracts, 80 studies were eligible for full text reading. Of those, 23 studies remained for qualitative synthesis. With the exception of one study, all studies were considered high quality based on the Newcastle-Ottawa scale (NOS; score ≥6). Meta-analysis was performed in 21 studies, with a total of 31 383 women with PCOS and 102 797 controls. Women with PCOS with BMI <27 kg/m2 had lower BMD of the total femur (MD, -0.04; 95% CI, -0.07 to 0.00; I2 = 31%; P = 0.22) and spine (MD, -0.07; 95% CI, -0.13 to -0.01; I2 = 70%; P < 0.01) when compared with the control group, whereas for women with BMI ≥27 kg/m2 no difference was observed (femur: MD, 0.02; 95% CI, -0.02 to 0.05; I2 = 20%, P = 0.29; spine: MD, 0.02; 95% CI, -0.06 to 0.05; I2 = 0%; P = 0.84). Osteocalcin was remarkably reduced in women with PCOS with BMI <27 kg/m2 (SMD, -2.68; 95% CI, -4.70 to -0.67; I2 = 98%; P < 0.01), but in women with BMI ≥27 kg/m2, there were no differences between PCOS and controls. Few studies (n = 3) addressed the incidence of bone fractures in women with PCOS. The HR for total bone fractures did not identify differences between women with PCOS and controls.

WIDER IMPLICATIONS

On the basis of the available evidence, it is possible to assume that PCOS in women with BMI <27 kg/m2 is associated with reduced BMD in the spine and femur, and decreased bone formation, as manifested by lower levels of circulating osteocalcin. These findings suggest that bone parameters in PCOS may be linked, to some extent, to adiposity. These studies included premenopausal women, who have already achieved peak bone mass. Hence, further prospective studies are necessary to clarify the existence of increased risk of fractures in women with PCOS.

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.

Type 1 Diabetes and Bone Fragility: Links and Risks

Type 1 diabetes (T1D) is associated with an increased fracture risk, which is present at young and old age. Reductions in bone mineral density do not explain the increased fracture risk. Novel scanning modalities suggest that structural deficits may contribute to the increased fracture risk. Furthermore, T1D may due to insulinopenia be a state of low bone turnover. However, diabetes complications and comorbidities may influence fracture risk. Patients with T1D are fearful of falls. The diabetes related complications, hypoglycemic events, and antihypertensive treatment may all lead to falls. Thus, the increased fracture risk in T1D seems to be multifactorial, and earlier intervention with antiosteoporotic medication and focus on fall prevention is needed. This systematic review addresses the epidemiology of fractures and osteoporosis in patients with T1D and the factors that influence fracture risk.

Analysis of the Content of Chromium in Certain Parts of the Human Knee Joint

Chromium is an essential microelement in the human body. It exerts an effect on bones by modulating their biochemical parameters: alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP). With considerable accumulation of chromium in the skeleton, the activity of alkaline phosphatase was found to decrease, which affected bone formation rate. The study objective was to analyze chromium content in the knee tissues. Tissues for analysis were obtained during endoprosthesoplasty of the knee joint and included tibia, femur, and meniscus tissues. Samples were collected from 50 patients, including 36 women and 14 men. The analysis was performed using the inductively coupled plasma atomic emission spectroscopy (ICP-AES) method, by means of a Varian 710-ES apparatus. The results revealed no significant differences in the content of chromium in the knee joint tissues between women and men. The highest level of chromium was found in the femoral bone of the knee joint, then in the meniscus, and was lowest in the tibia, although the differences were statistically insignificant. Chromium content increased with age.

The effect of insulin on bone mineral density among women with type 2 diabetes: a SWAN Pharmacoepidemiology study

This was a longitudinal study examining the effects of insulin use on bone mineral density loss. Insulin use was found to be associated with greater bone mineral density loss at the femoral neck among women with diabetes mellitus.

INTRODUCTION

Women with diabetes mellitus (DM) have higher bone mineral density (BMD) and experience slower BMD loss but have an increased risk of fracture. The data regarding the effect of insulin treatment on BMD remains conflicted. We examined the impact of insulin initiation on BMD.

METHODS

We investigated the annual changes in BMD associated with the new use of insulin among women with DM in the Study of Women's Health Across the Nation (SWAN). Propensity score (PS) matching, which is a statistical method that helps balance the baseline characteristics of women who did and did not initiate insulin, was used. Covariates with a potential impact on bone health were included in all models. Mixed model regression was used to test the change in BMD between the two groups. Median follow-up time was 5.4 years.

RESULTS

The cohort consisted of 110 women, mean age, 53.6 years; 49% white and 51% black. Women using insulin (n = 55) were similar on most relevant characteristics to the 55 not using insulin. Median diabetes duration for the user group was 10 vs. 5.0 years for the non-user group. There was a greater loss of BMD at the femoral neck among insulin users (- 1.1%) vs non-users (- 0.77%) (p = 0.04). There were no differences in BMD loss at the spine - 0.30% vs - 0.32% (p = 0.85) or at the total hip - 0.31% vs - 0.25 (p = 0.71), respectively.

CONCLUSIONS

Women with T2DM who initiated insulin experienced a more rapid BMD loss at the femoral neck as compared to women who did use insulin.

Hormonal alterations in PCOS and its influence on bone metabolism

According to the World Health Organization (WHO) polycystic ovary syndrome (PCOS) occurs in 4-8% of women worldwide. The prevalence of PCOS in Indian adolescents is 12.2% according to the Indian Council of Medical Research (ICMR). The National Institute of Health has documented that it affects approximately 5 million women of reproductive age in the United States. Hormonal imbalance is the characteristic of many women with polycystic ovarian syndrome (PCOS). The influence of various endocrine changes in PCOS women and their relevance to bone remains to be documented. Hormones, which include gonadotrophin-releasing hormone (GnRH), insulin, the leutinizing/follicle-stimulating hormone (LH/FSH) ratio, androgens, estrogens, growth hormones (GH), cortisol, parathyroid hormone (PTH) and calcitonin are disturbed in PCOS women. These hormones influence bone metabolism in human subjects directly as well as indirectly. The imbalance in these hormones results in increased prevalence of osteoporosis in PCOS women. Limited evidence suggests that the drugs taken during the treatment of PCOS increase the risk of bone fracture in PCOS patients through endocrine disruption. This review is aimed at the identification of the relationship between bone mineral density and hormonal changes in PCOS subjects and identifies potential areas to study bone-related disorders in PCOS women.

Differences in biochemical bone markers by diabetes type and the impact of glucose

BACKGROUND

Diabetes mellitus is associated with an increased fracture risk, however the fracture risk is 7 fold increased in patients with type 1 diabetes (T1D) and 1.4 fold increased in patients with type 2 diabetes (T2D) with decreased and increased bone mineral density, respectively. Oral ingestion of glucose causes an acute decrease in bone turnover markers, and thus glucose levels may affect bone turnover in diabetes.

OBJECTIVE

The aim was to examine disparities in bone turnover markers between patients with T1D and T2D and evaluate the effect of glucose on bone turnover.

METHODS

A cross-sectional study was conducted. Patients diagnosed with T1D (n=98) or T2D (n=96) were included from the outpatient clinics at two University Hospitals. All individuals had normal renal function. Glucose and bone turnover markers were measured in non-fasting blood samples.

RESULTS

P-procollagen type 1 amino terminal propeptide (P1NP), p-osteocalcin (OC), and s-Receptor Activator of Nuclear factor Kappa beta Ligand (RANKL) were lower in patients with T2D compared to T1D, and s-osteoprotegerin (OPG) was higher in T2D. P-C-terminal cross-linked telopeptide of type-I collagen (CTX), p-fibroblast growth factor-23 (FGF-23), p-sclerostin, and p-undercarboxylated osteocalcin (ucOC) were similar in between the two groups of patients. Increasing non-fasting glucose levels were inversely related to p-CTX, p-P1NP, p-OC, and p-ucOC and directly related to s-OPG in simple linear and multiple linear regressions adjusted for factors influencing bone turnover markers including HbA1c.

CONCLUSION

Bone turnover markers were lower in patients with T2D compared to T1D. Acute blood glucose alterations may change bone turnover mediated by OPG and have detrimental effects on bone health in diabetes.

TRIAL REGISTRATION NUMBER

ClinicalTrials.govNCT01870557.

Effects of exposure to dietary chromium on tissue mineral contents in rats fed diets with fiber

This study evaluated the effects of diets with fiber (cellulose and/or pectin) supplemented with chromium(III) on homeostasis of selected minerals in femurs, thigh muscles, livers, and kidneys of rats. For 6 weeks, male rats were fed experimental diets: a fiber-free diet (FF), a diet containing 5% cellulose (CEL), 5% pectin (PEC), or 2.5% cellulose and 2.5% pectin (CEL+PEC). These diets had 2.53 or 0.164 mg Cr/kg diet. The tissue levels of Ca, Mg, Zn, Fe, and Cr were determined by using atomic absorption spectrometry. Supplementing diets with Cr resulted in significantly higher Cr levels in the femurs of rats fed the CEL diet and significantly higher Cr and Fe levels in the rats fed the CEL+PEC diet compared to the rats fed FF diet. Muscle Ca content was significantly lower in the rats fed the CEL+PEC+Cr diet compared to the rats fed FF+Cr diet. The rats consuming the PEC+Cr diet had the highest liver Cr content. The highest kidney Zn content was observed in the rats fed diets containing Cr and one type of fiber. These results indicate that diets containing chromium at elevated dose and fiber have a significant effect on the mineral balance in rat tissues.

Metal-on-metal hip prostheses and systemic health: a cross-sectional association study 8 years after implantation

There is public concern over the long term systemic health effects of metal released from hip replacement prostheses that use large-diameter metal-on-metal bearings. However, to date there has been no systematic study to determine which organs may be at risk, or the magnitude of any effect. We undertook a detailed cross-sectional health screen at a mean of 8 years after surgery in 35 asymptomatic patients who had previously received a metal-on-metal hip resurfacing (MoMHR) versus 35 individually age and sex matched asymptomatic patients who had received a conventional hip replacement. Total body bone mineral density was 5% higher (mean difference 0.05 g/cm², P = 0.02) and bone turnover was 14% lower (TRAP 5b, mean difference −0.56IU/L, P = 0.006; osteocalcin, mean difference −3.08 ng/mL, P = 0.03) in the hip resurfacing versus conventional hip replacement group. Cardiac ejection fraction was 7% lower (mean absolute difference −5%, P = 0.04) and left ventricular end-diastolic diameter was 6% larger (mean difference 2.7 mm, P = 0.007) in the hip resurfacing group versus those patients who received a conventional hip replacement. The urinary fractional excretion of metal was low (cobalt 5%, chromium 1.5%) in patients with MoMHR, but creatinine clearance was normal. Diuretic prescription was associated with a 40% increase in the fractional excretion of chromium (mean difference 0.5%, P = 0.03). There was no evidence of difference in neuropsychological, renal tubular, hepatic or endocrine function between groups (P>0.05). Our findings of differences in bone and cardiac function between patient groups suggest that chronic exposure to low elevated metal concentrations in patients with well-functioning MoMHR prostheses may have systemic effects. Long-term epidemiological studies in patients with well-functioning metal on metal hip prostheses should include musculoskeletal and cardiac endpoints to quantitate the risk of clinical disease.

Chromium levels in insulin-sensitive tissues and the thigh bone are modulated by prednisolone and high-fat diets in mice

Glucocorticoids (GCs) are often prescribed in clinics but many adverse effects are also attributed to GCs. It is important to determine the role of GCs in the development of those adverse effects. Here, we investigated the impact of GCs on trivalent chromium (Cr) distribution in animals. Cr has been proposed to be important for proper insulin sensitivity, and deficits may lead to disruption of metabolism. For comparison, the effect of a high-fat diet on Cr modulation was also evaluated. C57BL/6JNarl mice were fed regular or high-fat diets for 12 weeks and further grouped for treatment with prednisolone or saline. Cr levels in tissues were determined 12 h after the treatments. Interestingly, prednisolone treatment led to significantly reduced Cr levels in fat tissue in mice fed regular diets; compared to the high-fat diet alone, prednisolone plus the high-fat diet led to a further reduction in Cr levels in the liver, muscle, and fat. Notably, a single dose of prednisolone was linked with elevated Cr levels in the thigh bones of mice fed by either regular or high-fat diets. In conclusion, this report has provided evidence that prednisolone in combination with a high-fat diet effects modulation of Cr levels in selected tissues.

Synergistic actions of insulin-sensitive and Sirt1-mediated pathways in the differentiation of mouse embryonic stem cells to osteoblast

Murine embryonic stem cells (mESCs) have the potential to differentiate into almost any type of cell, and hence, represent a useful biological resource for tissue engineering. The differentiation of mESCs into osteoblasts in vitro is usually dampened by simultaneous differentiation of adipocytes. Insulin exerts a profound effect on bone development through increased differentiation of osteoblasts and concurrent formation of adipocytes. Comparatively, Sirt1, which plays a crucial role in osteoblast differentiation, has been reported to down regulate adipocyte formation during osteoblast differentiation. This study analyzed the combined effects of insulin and Sirt1 on the differentiation of osteoblasts. Osteoblast differentiation was quantified by estimating the accumulation of mineralized matrix and expression of osteogenic genes. The present data show that the simultaneous action of the insulin and Sirt1-mediated pathways increased the efficiency of osteoblast differentiation. When the cells were tested for ALP activity and Alizarin red staining, there was a respective increase of ~180% and ~166% (P<0.05) compared to the control. Furthermore, the mRNA expression patterns of osteoprotegerin, osterix, runx2, and osteopontin were increased by 3.6, 2.3, 1.8, and 1.7-fold, respectively, with a concomitant decrease in the mRNA expression levels of adipocyte marker genes. Interestingly, blocking the effects of both Sirt1 and insulin resulted in decreased osteoblastogenesis (60%) and subsequent increased adipocyte differentiation (195%) (P<0.05). Moreover, immunoblotting analysis demonstrated that this activation was via an Akt-dependent pathway. In conclusion, the present data suggests an enhanced process of osteoblast differentiation that can be exploited further to improve mESC differentiation.

Bone formation within alumina tubes: effect of calcium, manganese, and chromium dopants

Alumina tubes (1.3mm outer diameter, 0.6mm inner diameter, 15 mm length) doped with Ca, Mn, or Cr at nominal concentrations of 0.5 and 5.0 mol% were implanted into femoral medullary canals of female rats for 16 weeks. Tissue formation within tubes was determined by histology and histomorphometry. Addition of Ca to alumina promoted hypertrophic bone formation at the advancing tissue fronts and tube entrances, and appeared to retard angiogenesis by limiting ongoing cellular migration into the tube. It is speculated that the presence of a secondary phase of calcium hexaluminate, probably having a solubility greater than that of alumina, possibly increased the level of extracellular Ca and, consequently, stimulated osteoclastic activity at the bone-ceramic interface. Addition of Mn significantly enhanced osteogenesis within the tubes. However, it is not possible to determine whether phase composition or microstructure of the ceramic was responsible for this because both were significantly altered by Mn addition. Addition of Cr to the alumina apparently stimulated bone remodelling as indicated by increased cellular activity and bone resorption at the tissue-implant interface. Cr was incorporated into the alumina as a solid solution and the tissue response was speculated to be an effect of surface chemistry rather than microstructure. The work demonstrates that doping a bioinert ceramic with small amounts of specific elements can significantly alter tissue ingrowth, differentiation, and osteogenesis within a porous implant.

Effect of silicon doping on bone formation within alumina porous domains

The effect of doping a porous bioinert bioceramic with silicon (Si) on tissue ingrowth, differentiation, and osteogenesis was studied using a rat intramedullary model. Alumina tubes (1.3-mm outer diameter, 0.6-mm inner diameter, 15-mm length) doped with Si at nominal concentrations of 0.5 and 5.0 mol % were implanted into femoral medullary canals of female rats for 16 weeks. Tissue formation within the tubes was determined by histology and histomorphometry. Addition of 0.5 mol % Si to alumina stimulated cellular activity at the bone-ceramic interface and impaired osteogenic maturation within the tubes. In contrast, osteogenesis was enhanced in the 5.0 mol % Si-doped alumina tubes. It is considered that effect of Si is related to surface chemistry rather than microstructure. This work demonstrates that doping a bioinert ceramic with small amounts of Si can significantly alter tissue ingrowth, differentiation, and osteogenesis within a porous implant.

Physiologic regulators of bone turnover in young women with anorexia nervosa

OBJECTIVE

To clarify the role of physiologic regulators of bone turnover in patients with anorexia nervosa (AN).

STUDY DESIGN

Adolescent girls with AN (n = 61) had anthropometric, nutrition, and exercise data acquired, and bone mineral density (BMD) and body composition measured by dual energy x-ray absorptiometry. Serum samples were obtained for hormones, proresorptive cytokines, and bone formation markers, and urine for bone resorption markers.

RESULTS

In bivariate correlation analyses, significant (P <.05) predictors of lumbar BMD included height, weight, and exercise. In multiple regression models, these significant relationships held, even after controlling for the duration of amenorrhea and AN. For total body BMD, the same positive predictors were found and percentage of body fat was a negative correlate. For hip BMD, exercise and weight were found to be positive predictors. Dehydroepiandrosterone sulfate (DHEAS) was inversely correlated with N-telopeptides (NTx), and insulin-like growth factor I (IGF-I) was directly correlated with osteocalcin. Proresorptive cytokine levels were low or undetectable.

CONCLUSIONS

Exercise and weight were positive predictors of BMD. These data are the first to suggest a relationship between DHEAS and increased bone resorption in AN. IGF-I was correlated with bone formation indices. Low cytokine levels suggest that these factors do not mediate the increased bone resorption of AN.

Beneficial effects of hormonal replacement therapy on chromium status and glucose and lipid metabolism in postmenopausal women

OBJECTIVES

Postmenopausal women exhibit an increased incidence of cardiovascular diseases, and type 2 diabetes mellitus compared with younger women. However, women receiving hormonal replacement therapy (HRT) seem to be protected. Since chromium (Cr) functions in glucose, lipid and corticosteroid metabolism and these variables, as well as Cr status, decline with age, Cr status may be a contributing factor in the effects of hormone replacement therapy. Therefore, the objective of this study was to determine the effects of hormonal replacement therapy (HRT) on serum and urinary Cr, plasma lipids, glucose, fructosamine and the related hormonal variables, estradiol, insulin, leptin, cortisol, and DHEA-sulfate.

METHODS

Forty-four healthy postmenopausal women 50-60 years old participated in the study. Eighteen were treated by combined oral hormonal replacement therapy (estradiol 2 mg per day during days 1-25 and 10 mg of dydrogesterone on days 10-25) for at least 2 years, and 26 were untreated.

RESULTS

Serum Cr concentrations were significantly lower in untreated postmenopausal women than in women receiving HRT (0.070+/-0.008 vs. 0.100+/-0.008 ng/ml) whereas urinary Cr excretion was increased (0.14+/-0.02 vs. 0.07+/-0.01 ng of Cr/mg creatinine). The urinary losses of Cr were inversely correlated with plasma estradiol. Median value of urinary Cr was higher in postmenopausal women exhibiting endogenous estradiol levels below 250 pmol/l, whereas women with estradiol levels >250 pmol/l, exhibited lower Cr values. Plasma fructosamine, total and LDL cholesterol and TC/HDL ratio, which are all decreased by improved Cr nutrition, were also improved in the women receiving HRT. There were also nonsignificant decreasing trends in DHEA-sulfate (P<0.06) and cortisol (0.07).

CONCLUSIONS

Chromium status, based upon blood and urinary analyses, and glucose, insulin and lipid variables were improved in postmenopausal women receiving HRT. Additional studies are needed to determine if improved Cr status due to supplemental Cr can elicit effects consistent with those of hormone replacement therapy.

Adrenal and gonadal steroids inhibit IL-6 secretion by human marrow cells

Adrenal and gonadal steroids have protective effects on the skeleton that may be conferred partly by their ability to inhibit bone resorptive cytokines such as interleukin 6 (IL-6). We tested the hypothesis that IL-6 secretion by human marrow cells and a line of marrow stromal cells (KM101) is inhibited by dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT) and 17beta-oestradiol (E(2)). We also examined whether the estrogen status of the donor influenced the steroids' effects on IL-6 secretion. Femoral bone marrow was obtained from 19 postmenopausal women undergoing hip arthroplasty, and from seven subjects receiving oestrogen replacement therapy (ERT) at the time of surgery. Low-density mononuclear cells were isolated and cultured in IL-1beta-supplemented media, with or without DHEA, DHT or E(2). DHEA suppressed IL-6 more consistently than DHT or E(2): DHEA significantly suppressed IL-6 in 84% of cultures, DHT suppressed IL-6 in 58%, and E(2)did so in 50%. The magnitude of IL-6 inhibition was also greater for DHEA (group mean, treated/control of 62%) compared to DHT (81%) and E(2)(76%). In cultures from subjects receiving ERT, DHEA and DHT suppressed IL-6 in some, whereas E(2)did not suppress IL-6 secretion. Each steroid also significantly inhibited IL-6 secretion by KM101 cells. In summary, in marrow cultured from postmenopausal women, DHEA suppressed IL-6 secretion more consistently and to a greater degree than did DHT and E(2). Second, the inhibitory effect of E(2)was abrogated in marrow from women receiving ERT.

Aluminum, Iron, Lead, Cadmium, Copper, Zinc, Chromium, Magnesium, Strontium, and Calcium Content in Bone of End-Stage Renal Failure Patients

Background: Little is known about trace metal alterations in the bones of dialysis patients or whether particular types of renal osteodystrophy are associated with either increased or decreased skeletal concentrations of trace elements. Because these patients are at risk for alterations of trace elements as well as for morbidity from skeletal disorders, we measured trace elements in bone of patients with end-stage renal disease.

Methods: We analyzed bone biopsies of 100 end-stage renal failure patients enrolled in a hemodialysis program. The trace metal contents of bone biopsies with histological features of either osteomalacia, adynamic bone disease, mixed lesion, normal histology, or hyperparathyroidism were compared with each other and with the trace metal contents of bone of subjects with normal renal function. Trace metals were measured by atomic absorption spectrometry.

Results: The concentrations of aluminum, chromium, and cadmium were increased in bone of end-stage renal failure patients. Comparing the trace metal/calcium ratio, significantly higher values were found for the bone chromium/calcium, aluminum/calcium, zinc/calcium, magnesium/calcium, and strontium/calcium ratios. Among types of renal osteodystrophy, increased bone aluminum, lead, and strontium concentrations and strontium/calcium and aluminum/calcium ratios were found in dialysis patients with osteomalacia vs the other types of renal osteodystrophy considered as one group. Moreover, the concentrations of several trace elements in bone were significantly correlated with each other. Bone aluminum was correlated with the time on dialysis, whereas bone iron, aluminum, magnesium, and strontium tended to be associated with patient age. Bone trace metal concentrations did not depend on vitamin D intake nor on the patients’ gender.

Conclusions: The concentration of several trace elements in bone of end-stage renal failure patients is disturbed, and some of the trace metals under study might share pathways of absorption, distribution, and accumulation. The clinical significance of the increased/decreased concentrations of several trace elements other than aluminum in bone of dialysis patients deserves further investigation.