Secondary osteoporosis

Recent advances in seafood bioactive peptides and their potential for managing osteoporosis

Marine biodiversity provides a range of diverse biological resources, including seafoods that are rich in protein and a well-balanced amino acid composition. Previous studies have shown that peptides can improve bone formation and/or inhibit bone resorption, suggesting the potential for seafood bioactive peptides (SBPs) in development of food and pharmaceuticals for management of osteoporosis. In this review, we provided an up-to-date overview of the anti-osteoporosis activity of SBPs and describe their underlying molecular mechanisms. We focus on SBPs' development, broadening the scope and depth of research, as well as strengthening in vivo and clinical research. In vitro cell cultures and in vivo animal osteoporosis models have demonstrated the potential for seafood-derived SBPs, including fish, mollusks, crustaceans, seaweed and microalgae, in preventing osteoporosis. These peptides may act by activating the signaling pathways, such as BMP/Smads, MAPK, OPG/RANKL/RANK, and NF-κB, which are associated with modulation bone health.

Vitamin K2 improves femoral bone strength without altering bone mineral density in gastrectomized rats

Gastrectomy (GX) induces osteopenia in rats. The present study examined the skeletal effects of vitamin K2 in GX rats. Thirty male Sprague-Dawley rats (12 wk old) were randomized by the stratified weight method into the following three groups of 10 animals each: sham operation (control) group; GX group; and GX+oral vitamin K2 (menatetrenone, 30 mg/kg, 5 d/wk) group. Treatment was initiated at 1 wk after surgery. After 6 wk of treatment, the bone mineral content (BMC), bone mineral density (BMD), and mechanical strength of the femoral diaphysis and distal metaphysis were determined by peripheral quantitative computed tomography and mechanical strength tests, respectively. GX induced decreases in the BMC, BMD, and ultimate force of the femoral diaphysis and distal metaphysis. Vitamin K2 did not significantly influence the BMC or BMD of the femoral diaphysis or distal metaphysis in GX rats, but attenuated the decrease in the ultimate force and increased the stiffness of the femoral diaphysis. The present study showed that administration of vitamin K2 to GX rats improved the bone strength of the femoral diaphysis without altering the BMC or BMD, suggesting effects of vitamin K2 on the cortical bone quality.

Diabetes mellitus, thyroid dysfunctions and osteoporosis: is there an association?

BACKGROUND

Osteoporosis is the most common metabolic bone disease with complicated, multifactorial and heterogenic nature that has no known pathological cause. As the role of Diabetes Mellitus (DM) and thyroid dysfunctions in the prevalence of osteoporosis is not exactly known, therefore this study was designed to evaluate the probable association between osteoporosis with DM and thyroid dysfunctions in Iranian patients.

METHODS

In this cross-sectional study, 300 subjects out of the total number of patients referring to Gorgan bone densitometry centers (3000subjects) were selected via random sampling method in 2009. Individual characteristics, DM, thyroid dysfunctions and densitometry results were collected from densitometry records. Data analysis was carried out by SPSS version 16 software and by using Chi square and T-test. The level of significance in all tests was considered 0.05.

RESULTS

The mean of T-score in lumbar and femoral areas of diabetic patients were -0.87 ± 1.08 and -1.94 ± 1.33 and in patient with thyroid dysfunctions was -0.80 ± 1.09 and -1.64 ± 1.24 respectively. The mean of BMD in lumbar and femoral areas of diabetic patients were 0.96 ± 0.19 and 0.75 ± 0.19 and in patient with thyroid dysfunctions were 0.96 ± 0.17 and 0.76 ±0.19 respectively. The mean of BMI in osteoporotic subjects in the lumbar and femoral areas were 25.94 ± 5.62 and 26.95 ± 5.20 respectively. The association between BMI and BMD in the lumbar and femoral areas were statistically significant, but the association between DM and thyroid dysfunctions with BMD and T-score in the femoral and lumbar areas was not statistically significant (P-value > 0.05).

CONCLUSION

The results of current study show that there is no association between DM and thyroid dysfunctions with osteoporosis.

Influence of gastrectomy on cortical and cancellous bones in rats

The aim of the present study was to examine the influence of gastrectomy (GX) on cortical and cancellous bones in rats. Twenty male Sprague-Dawley rats were randomized into the two groups of 10 animals each: a sham operation (control) group and a GX group. Seven weeks after surgery, the bone mineral content and density (BMC and BMD, resp.) and the mechanical strength of the femur were determined, and bone histomorphometric analyses were performed on the tibia. GX induced decreases in the BMC, BMD, ultimate force, work to failure, and stiffness of the femoral distal metaphysis and the BMC, BMD, and ultimate force of the femoral diaphysis. GX induced a decrease in cancellous bone mass, characterized by an increased osteoid thickness, osteoid surface, osteoid volume, and bone formation. GX also induced a decrease in cortical bone mass, characterized by increased endocortical bone resorption. The GX induced reductions in the bone mass and strength parameters were greater in cancellous bone than in cortical bone. The present study showed that the response of bone formation, resorption, and osteoid parameters to GX and the degree of GX-induced osteopenia and the deterioration of bone strength appeared to differ between cortical and cancellous bones in rats.

Metabolic and clinical consequences of hyperthyroidism on bone density

In 1891, Von Recklinghausen first established the association between the development of osteoporosis in the presence of overt hyperthyroidism. Subsequent reports have demonstrated that BMD loss is common in frank hyperthyroidism, and, to a lesser extent, in subclinical presentations. With the introduction of antithyroid medication in the 1940s to control biochemical hyperthyroidism, the accompanying bone disease became less clinically apparent as hyperthyroidism was more successfully treated medically. Consequently, the impact of the above normal thyroid hormones in the pathogenesis of osteoporosis may be presently underrecognized due to the widespread effective treatments. This review aims to present the current knowledge of the consequences of hyperthyroidism on bone metabolism. The vast number of recent papers touching on this topic highlights the recognized impact of this common medical condition on bone health. Our focus in this review was to search for answers to the following questions. What is the mechanisms of action of thyroid hormones on bone metabolism? What are the clinical consequences of hyperthyroidism on BMD and fracture risk? What differences are there between men and women with thyroid disease and how does menopause change the clinical outcomes? Lastly, we report how different treatments for hyperthyroidism benefit thyroid hormone-induced osteoporosis.

Osteoporosis and fracture risk in people with schizophrenia

PURPOSE OF REVIEW

Excessive bone mineral density (BMD) loss has been associated with schizophrenia, but its mechanisms and clinical implications are less clear. The aim of this review was to summarize the risk of osteoporosis and bone fractures in schizophrenia patients. Moreover, we aimed to examine the impact of antipsychotic-induced hyperprolactinemia on bone metabolism.

RECENT FINDINGS

Fifteen of 16 studies (93.8%) reported lower BMD or higher prevalence of osteoporosis in at least one region, or in at least one subgroup of schizophrenia patients compared with controls, but results were inconsistent across measured areas. Higher fracture risk was associated with schizophrenia in 2/2 studies (independently: n = 1), and 3/4 studies with antipsychotics. Reasons for this difference include insufficient exercise, poor nutrition, smoking, alcohol use, and low vitamin D levels. Altogether, 9/15 (60.0%) studies examining the relationship between antipsychotic-induced hyperprolactinemia and BMD loss found some effects of hyperprolactinemia. However, results were mixed, samples and effects were small, and only two studies were prospective.

SUMMARY

Schizophrenia is associated with reduced BMD and fracture risk. Prevention, early detection, and intervention are required. The relative contributions of antipsychotic-related hyperprolactinemia and unhealthy lifestyle behaviors remain unclear, needing to be assessed in well designed, prospective studies, including bone turnover markers as intermediary endpoints.

Decreased bone density in men on methadone maintenance therapy

AIMS

Opioid use may impact adversely upon skeletal health. Participants in methadone maintenance programmes commonly have prolonged exposure to opioids. We sought to determine whether participants in a methadone maintenance programme have evidence of altered bone mineral density (BMD) and bone turnover.

DESIGN

Cross-sectional study of people taking methadone maintenance therapy (MMT).

SETTING

Clinical research centre.

PARTICIPANTS

Eighty-three people (48 men, 35 women) who had taken MMT for a median (interquartile range) of 11 (6-16) years. Comparison data were from both a normative database and control subjects recruited and assessed at the same location as the participants taking MMT.

MEASUREMENTS

BMD at lumbar spine, total hip and total body; biochemical markers of bone turnover.

FINDINGS

In men taking MMT, BMD was lower than normal at each skeletal site [mean, 95% confidence interval Z-score -1.1 (-1.6 to -0.7) at the lumbar spine, -1.0 (-1.3 to -0.7) at the total hip, and -1.1 (-1.4 to -0.8) at the total body, P < 0.001 at each site]. BMD in the women taking MMT was not different from control values. Bone turnover was within the normal range in both genders. Serum testosterone was lower in the men taking MMT than in controls.

CONCLUSIONS

BMD is lower than normal throughout the skeleton in men, but not women, taking MMT. Assessment of skeletal health, including estimation of absolute fracture risk, should be undertaken in men participating in methadone maintenance programmes.