Vitamin K2 promotes bone healing in a rat femoral osteotomy model with or without glucocorticoid treatment

Concurrent Treatment with Vitamin K2 and D3 on Spine Fusion in Patients with Osteoporosis-Associated Lumbar Degenerative Disorders

STUDY DESIGN

A prospective and nonrandomized concurrent controlled trial.

OBJECTIVE

To address the early effects of concurrent treatment with vitamin K2 and vitamin D3 on fusion rates in patients who have undergone spinal surgery.

SUMMARY OF BACKGROUND DATA

Intervertebral pseudarthrosis has been reported after transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF), especially in patients with osteopenia or osteoporosis. No study has assessed the early effects of concurrent treatment with vitamin K2 and vitamin D3 on fusion rates.

METHODS

Patients with osteopenia or osteoporosis who underwent TLIF or PLIF in our department were included. Patients in the VK2+VD3 group received vitamin K2, vitamin D3, and calcium treatment, whereas subjects in the control group only received calcium and vitamin D3. Spine fusion was evaluated by computed tomography. The Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOA-BPEQ) and visual analog scale (VAS) were used to assess the clinical and neurological symptoms. Bone mineral density (BMD) and bone metabolism markers were measured for osteoporotic evaluation.

RESULTS

Seventy-eight patients were included, and nine patients subsequently discontinued because of 2019-nCoV. At six months postoperatively, complete fusion rates were significantly higher in the VK2+VD3 group than that in the control group (91.18% vs 71.43%, P = 0.036). At six months postoperatively, BMD was increased in the VK2+VD3 group and was higher than that in the control group, although there was no significant difference. At three months postoperatively, a significant increase in procollagen type I amino terminal propeptide (91.81%) and a slight decrease in C-terminal end peptide (8.06%) were observed in the VK2+VD3 group. In both groups, the JOA-BPEQ and VAS scores were significantly improved after spine surgery.

CONCLUSION

Administration of vitamin K2 and vitamin D3 can increase lumbar interbody fusion rates, improve clinical symptoms, promote bone information, and avoid further decline in BMD within six months after TLIF or PLIF.Level of Evidence: 3.

Vitamin K2 Can Rescue the Dexamethasone-Induced Downregulation of Osteoblast Autophagy and Mitophagy Thereby Restoring Osteoblast Function In Vitro and In Vivo

Chronic long-term glucocorticoids (GC) use is associated with glucocorticoid-induced osteoporosis (GIOP) by inhibiting the survival and impairing the functions of osteoblasts. Autophagy and mitophagy play key roles in osteoblast differentiation, mineralization and survival, and mounting evidence have implicated osteoblast autophagy and mitophagy as a novel mechanism in the pathogenesis of GIOP. Vitamin K2 (VK2) is an essential nutrient supplement that have been shown to exert protective effects against osteoporotic bone loss including GIOP. In this study, we showed that the glucocorticoid dexamethasone (Dex) deregulated osteoblast autophagy and mitophagy by downregulating the expression of autophagic and mitophagic markers LC3-II, PINK1, Parkin. This consequently led to inhibition of osteoblast differentiation and mineralization function in vitro. Interestingly, co-treatment with VK2 significantly attenuated the Dex-induced downregulation of LC3-II, PINK1, Parkin, thereby restoring autophagic and mitophagic processes and normal osteoblastic activity. In addition, using an established rat model of GIOP, we showed that VK2 administration can protect rats against the deleterious effects of Dex on bone by reinstating autophagic and mitophagic activities in bone tissues. Collectively, our results provide new insights into the role of osteoblast autophagy and mitophagy in GIOP. Additionally, the use of VK2 supplementation to augment osteoblast autophagy/mitophagy may significantly improve clinical outcomes of GIOP patients.

Comparison of the Anabolic Effects of Reported Osteogenic Compounds on Human Mesenchymal Progenitor-derived Osteoblasts

There is variability in the reported effects of compounds on osteoblasts arising from differences in experimental design and choice of cell type/origin. This makes it difficult to discern a compound's action outside its original study and compare efficacy between compounds. Here, we investigated five compounds frequently reported as anabolic for osteoblasts (17β-estradiol (oestrogen), icariin, lactoferrin, lithium chloride, and menaquinone-4 (MK-4)) on human mesenchymal progenitors to assess their potential for bone tissue engineering with the aim of identifying a potential alternative to expensive recombinant growth factors such as bone morphogenetic protein 2 (BMP-2). Experiments were performed using the same culture conditions to allow direct comparison. The concentrations of compounds spanned two orders of magnitude to encompass the reported efficacious range and were applied continuously for 22 days. The effects on the proliferation (resazurin reduction and DNA quantification), osteogenic differentiation (alkaline phosphatase (ALP) activity), and mineralised matrix deposition (calcium and collagen quantification) were assessed. Of these compounds, only 10 µM MK-4 stimulated a significant anabolic response with 50% greater calcium deposition. Oestrogen and icariin had no significant effects, with the exception of 1 µM icariin, which increased the metabolic activity on days 8 and 22. 1000 µg/mL of lactoferrin and 10 mM lithium chloride both significantly reduced the mineralised matrix deposition in comparison to the vehicle control, despite the ALP activity being higher in lithium chloride-treated cells at day 15. This demonstrates that MK-4 is the most powerful stimulant of bone formation in hES-MPs of the compounds investigated, highlighting its potential in bone tissue engineering as a method of promoting bone formation, as well as its prospective use as an osteoporosis treatment.

Optimal administration frequency and dose of teriparatide for acceleration of biomechanical healing of long-bone fracture in a mouse model

Despite preclinical studies demonstrating the effectiveness of teriparatide for skeletal repair in small animals, inconclusive data from clinical trials have raised questions regarding the optimal teriparatide dosing regimen for bone repair. To address this, we assessed the effect of teriparatide frequency and dose on long-bone healing using a mouse femur osteotomy/fracture model. Eight-week-old male ICR mice were subjected to open femur osteotomies, then randomized into following five groups (n = 8 per group): vehicle; low dose/high frequency: 3 μg/kg/dose, 3 times/day; low dose/low frequency: 9 μg/kg/dose, 1 time/day; high dose/high frequency: 9 μg/kg/dose, 3 times/day; high dose/low frequency: 27 μg/kg/dose, 1 time/day. Skeletal repair was assessed by microcomputed tomography, mechanical testing, and histology 4 weeks after surgery. High-dose and/or high-frequency teriparatide treatment increased callus bone volume but failed to have a significant impact on the biomechanical recovery of fractured femurs, possibly because of impaired cortical shell formation in fracture calluses. Meanwhile, low-dose/low-frequency teriparatide therapy enhanced callus bone formation without interfering with cortical shell formation despite a lesser increase in callus bone volume, leading to significant two and fourfold increases in ultimate load and stiffness, respectively. Our findings demonstrate that administering teriparatide at higher doses and/or higher frequencies raises fracture callus volume but does not always accelerate the biomechanical recovery of fractured bone, which points to the importance of finding the optimal teriparatide dosing regimen for accelerating skeletal repair.

Effects of combined menaquinone-4 and PTH1-34 treatment on osetogenesis and angiogenesis in calvarial defect in osteopenic rats

PURPOSE

The aim of this study was to evaluate the effect of combining human parathyroid hormone (1-34) (PTH_1-34; PTH) and menaquinone-4 (MK-4) on calvarial bone defect repair in osteopenic rats.

METHODS

Fourteen week olds were subject to craniotomy for the establishment of osteopenic animal models fed through a chronically low-protein diet. After that, critical calvarial defect model was established and all rats were randomly divided into four groups: sham, MK-4, PTH, and PTH + MK-4. The animals received MK-4 (30 mg/kg/day), PTH_1-34 (60 μg/kg, three times a week), or PTH_1-34 (60 μg/kg, three times a week) plus MK-4 (30 mg/kg/day) for 8 weeks, respectively. Serum γ-carboxylated osteocalcin (Gla-OC) levels, histological and immunofluorescent labeling were employed to evaluate the bone formation and mineralization in calvarial bone defect. In addition, Microfil perfusion, immunohistochemical, and micro-CT suggested enhanced angiogenesis and bone formation in calvarial bone healing.

RESULTS

In this study, treatment with either PTH_1-34 or MK-4 promoted bone formation and vascular formation in calvarial bone defects compared with the sham group. In addition, combined treatment of PTH_1-34 plus MK-4 increased serum level of Gla-OC, improved vascular number and vascular density, and enhanced bone formation in calvarial bone defect in osteopenic conditions as compared with monotherapy.

CONCLUSIONS

In summary, this study indicated that PTH_1-34 plus MK-4 combination therapy accelerated bone formation and angiogenesis in calvarial bone defects in presence of osteopenia.

Combined treatment with vitamin K2 and PTH enhanced bone formation in ovariectomized rats and increased differentiation of osteoblast in vitro

Osteoporosis is accompanied by insufficient osteogenic capacity. Several lines of evidence suggested that solutions to enhance osteoblastogenesis were important strategies for osteoporotic bone defect repair. This study investigated the effect of combined treatment with vitamin K2 and PTH on bone formation in calvarial bone defect in osteoporotic rats and its influence on osteoblast in vitro. Bilateral ovariectomy was used in SPF Sprague Dawley rats to generate an osteoporosis model. Subsequently, a calvarial defect model was established and all osteoporotic rats were randomly assigned to the following groups: control, VK (vitamin K2, 30 mg/kg everyday), PTH (recombinant human PTH (1-34), 60 μg/kg, three times a week) or VK + PTH (vitamin K2, 30 mg/kg everyday plus PTH, 60 μg/kg three times a week) for 8 weeks. In vitro, bone marrow-derived stem cells (BMSCs) were cultured and treated with vitamin K2, PTH or vitamin K2+PTH. ALP staining and western blot were performed to observe the influence of combined treatment on BMSCs. Bone formation within calvarial defect were assessed by serum γ-carboxylated osteocalcin (Gla-OC), micro-CT, histological and immunofluorescent labeling. In this study, combined treatment of PTH and vitamin K2 showed positive effects on preventing bone loss in femurs in OVX rats. Combined treatment increased serum Gla-OC and promoted bone formation in osteoporotic calvarial bone defects. Immunohistochemistry showed that OCN and RUNX2 were more highly expressed in the VK + PTH group than in the control groups. In vitro studies results suggested that combined treatment with PTH and vitamin K2 increased expression of ALP, BMP2 and RUNX2 in BMSCs. Our data suggested that the combination of vitamin K2 and PTH increased differentiation of osteoblast and had a synergistic effect on bone formation in osteoporotic calvarial bone defect.

Comparison of cortisol and inflammatory response between aged and middle-aged patients undergoing total hip arthroplasty: a prospective observational study

Background

To investigate the differences in the perioperative serum cortisol, C-reactive protein (CRP) and interleukin-6 (IL-6) levels between aged and middle-aged patients undergoing total hip arthroplasty (THA).

Methods

Sixty patients (30 aged and 30 middle-aged) undergoing THA for osteoarthritis between August 2016 and January 2017 participated in this study. Blood samples were collected preoperatively and at 6 hours, 24 hours and 3 days after surgery to measure the cortisol, CRP and IL-6 concentrations. The clinical outcomes were assessed using the visual analogue scale (VAS) pain score and Harris hip score (HHS).

Results

No significant differences were found between the two groups before the operation in the cortisol, IL-6 and CRP levels; the VAS score; or the HHS. Cortisol was significantly lower at 6 hours after surgery in the aged group than in the middle-aged group (P < 0.05). IL-6 at 6 and 24 hours after surgery, CRP at 3 days after surgery and the VAS score at 6 and 24 hours after surgery in the aged group were significantly higher than those in the middle-aged group (P < 0.05). In the aged group, weak correlations were found between the cortisol concentration 6 hours after THA and the IL-6 level 24 hours after THA (r = −0.37, P = 0.04) and between the IL-6 level 6 hours after THA and the VAS score 24 hours after THA (r = 0.42, P = 0.02).

Conclusion

Aged patients showed lower cortisol levels at 6 hours after surgery and higher IL-6 levels at 6 and 24 hours after surgery than middle-aged patients undergoing THA.

The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review

Vitamins D and K are both fat-soluble vitamins and play a central role in calcium metabolism. Vitamin D promotes the production of vitamin K-dependent proteins, which require vitamin K for carboxylation in order to function properly. The purpose of this review is to summarize available evidence of the synergistic interplay between vitamins D and K on bone and cardiovascular health. Animal and human studies suggest that optimal concentrations of both vitamin D and vitamin K are beneficial for bone and cardiovascular health as supported by genetic, molecular, cellular, and human studies. Most clinical trials studied vitamin D and K supplementation with bone health in postmenopausal women. Few intervention trials studied vitamin D and K supplementation with cardiovascular-related outcomes. These limited studies indicate that joint supplementation might be beneficial for cardiovascular health. Current evidence supports the notion that joint supplementation of vitamins D and K might be more effective than the consumption of either alone for bone and cardiovascular health. As more is discovered about the powerful combination of vitamins D and K, it gives a renewed reason to eat a healthy diet including a variety of foods such as vegetables and fermented dairy for bone and cardiovascular health.

Nonhealing, progressive stress fractures of the foot in a 13-year-old basketball player: is vitamin K deficiency a risk factor?

[Purpose] To report an adolescent male basketball player with nonhealing stress fractures of the foot and discuss the probable factors. [Subject and Methods] A 13-year-old basketball player presented with right foot pain. He had been playing basketball for three years and practicing 5 days/week. He denied any increase in daily training intensity. Magnetic resonance imaging confirmed stress fractures of the cuboid and cuneiform, with mild edema of the soft tissues between the tarsal bones and tenosynovitis of the flexor hallucis and flexor digitorum longi. The foot was immobilized for 4 weeks, with progressive weight bearing introduced at the fifth week. At the 6th week, while still restricted to partial weight bearing, he reported diffuse severe pain. The entire foot was painful with palpation, and new imaging showed stress fractures of the talus, cuboid, cuneiform, and proximal first metatarsal bones, and tenosynovitis of the flexor hallucis longus and flexor digitorum longus tendons with progression of the soft tissue edema around the tarsal bones. Acute phase reactants were elevated; vitamin K level was low. [Results] He started participating in games again at the 6th month post-injury. [Conclusion] Management of patients with stress fractures includes immobilization, physical therapy, and biomechanical arrangements. If the expected healing does not occur, a deficiency of vitamin K might be considered as a factor. Questioning on dietary habits of the patient and encouraging adequate intake of the deficient nutrient might assist in the healing process.

Protective effect of VK2 on glucocorticoid-treated MC3T3-E1 cells

Glucocorticoids (GCs) contribute to the increased incidence of secondary osteoporosis and osteonecrosis, and medications for the prevention and treatment of these complications have been investigated for many years. Vitamin K₂ (VK₂) has been proven to promote bone formation both in vitro and in vivo. In this study, we examined the effects of VK₂ on dexamethasone (DEX)-treated MC3T3-E1 osteoblastic cells. We observed that VK₂ promoted the proliferation and enhanced the survival of dexamethasone-treated MC3T3-E1 cells. In addition, VK₂ upregulated the expression levels of osteogenic marker proteins, such as Runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and osteocalcin, which were significantly inhibited by dexamethasone. On the whole, our findings indicate that VK₂ has the potential to antagonize the effects of GCs on MC3T3-E1 cells, and may thus prove to be a promising agent for the prevention and treatment of GC-induced osteoporosis and osteonecrosis.

A biomechanical, micro-computertomographic and histological analysis of the influence of diclofenac and prednisolone on fracture healing in vivo

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) have long been suspected of negatively affecting fracture healing, although numerous disputes still exist and little data are available regarding diclofenac. Glucocorticoids interfere in this process over a similar and even broader mechanism of action. As many previously conducted studies evaluated either morphological changes or biomechanical properties of treated bones, the conjunction of both structural measures is completely missing. Therefore, it was our aim to evaluate the effects of diclofenac and prednisolone on the fracture callus biomechanically, morphologically and by 3-dimensional (3D) microstructural analysis.

METHODS

Femura of diclofenac-, prednisolone- or placebo-treated rats were pinned and a closed transverse fracture was generated. After 21 days, biomechanics, micro-CT (μCT) and histology were examined.

RESULTS

The diclofenac group showed significantly impaired fracture healing compared with the control group by biomechanics and μCT (e.g. stiffness: 57.31 ± 31.11 N/mm vs. 122.44 ± 81.16 N/mm, p = 0.030; callus volume: 47.05 ± 15.67 mm3 vs. 67.19 ± 14.90 mm3, p = 0.037, trabecular thickness: 0.0937 mm ± 0.003 vs. 0.0983 mm ± 0.003, p = 0.023), as confirmed by histology. Biomechanics of the prednisolone group showed obviously lower absolute values than the control group. These alterations were confirmed in conjunction with μCT and histology.

CONCLUSIONS

The inhibiting effects of both substances were not only mediated by absolute parameters (e.g. breaking load, BV), but we have shown, for the first time, that additional changes occurred in the microstructural bony network. Especially in patients at risk for delayed bone healing (arteriosclerosis, diabetes mellitus, smoking), the administration of these drugs should be weighed carefully.

Vitamin K2 Ameliorates Damage of Blood Vessels by Glucocorticoid: a Potential Mechanism for Its Protective Effects in Glucocorticoid-induced Osteonecrosis of the Femoral Head in a Rat Model

Glucocorticoid has been reported to decrease blood vessel number and harm the blood supply in the femoral head, which is recognized to be an important mechanism of glucocorticoid-induced osteonecrosis of the femoral head (ONFH). To prevent glucocorticoid-induced ONFH, medication that promotes both bone formation and angiogenesis would be ideal. Vitamin K2 has been revealed to play an important role in bone metabolism; however, few studies have focused on the effect of Vitamin K2 on new vascular formation. Thus, this study aimed to investigate whether Vitamin K2 promoted new blood vessel formation in the presence of glucocorticoids, both in vitro and in vivo. The effect of Vitamin K2 on viability, migration, in vitro tube formation, and VEGF, vWF, CD31, KDR, Flt and PDGFB in EAhy926 incubated with or without dexamethasone were elucidated. VEGF, TGF-β and BMP-2, angiogenesis-related proteins secreted by osteoblasts, were also detected in the osteoblast-like cell line of MG63. In addition, blood vessels of the femoral head in rats administered with or without methylprednisolone and Vitamin K2 were evaluated using angiography and CD31 staining. In vitro studies showed that Vitamin K2 significantly protected endothelial cells from dexamethasone-induced apoptosis, promoted endothelial cell migration and in vitro tube formation. Angiogenesis-related proteins both in EAhy926 and MG63 were also upregulated by Vitamin K2 when cotreated with dexamethasone. In vivo studies showed enhanced blood vessel volume and CD31-positive staining cells in rats cotreated with VK2 and methylprednisolone compared to rats treated with methylprednisolone only. Collectively, Vitamin K2 has the ability to promote angiogenesis in vitro and to ameliorate vessels of the femoral head in glucocorticoid-treated rats in vivo, indicating that Vitamin K2 is a promising drug that may be used to prevent steroid-induced ONFH.

Vitamin D in Foot and Ankle Fracture Healing: A Literature Review and Research Design

Vitamin D is a generic name for a group of essential vitamins, or secosteroids, important in calcium homeostasis and bone metabolism. Specifically, efficacy of vitamin D with regard to bone healing is in question. A literature review was performed, finding mostly large studies involving vitamin D effects on prevention of fractures and randomized animal model studies consisting of controlled fractures with vitamin D interventions. The prevention articles generally focus on at-risk populations, including menopausal women and osteoporotic patients, and also most often include calcium in the treatment group. Few studies look at vitamin D specifically. The animal model studies often focus more on vitamin D supplementation; however the results are still largely inconclusive. While recent case reports appear promising, the ambiguity of results on the topic of fracture healing suggests a need for more, higher level research. A novel study design is proposed to help determine the efficacy on vitamin D in fracture healing.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Systematic Review.

Copaiba oil effect on experimental jaw defect in Wistar rats

PURPOSE

To evaluate the effects of copaiba oil on jaw defects repair in Wistar rats treated with bioglass or adipose tissue.

METHODS

A jaw defect was randomly created in forty-two rats and filled with bioglass or adipose tissue. The two groups (Gbio and Gcell) were subdivided in three subgroups with seven animals each according to gavage administration: control (distillated water), oil (copaiba oil) and melox (meloxicam). Euthanasia was performed after forty post-operative days. The bone formation was analyzed regarding the histological aspects.

RESULTS

The osteoclasts activity was observed only in four subgroups (p=0.78). Regarding the osteoblasts presence, it was very similar between the subgroups, the difference was due to Gcell-melox (p=0.009) that presented less osteoblastic activity. The inflammatory cells were more evident in Gcell-melox subgroup, however, there was no difference in comparison with the other subgroups (p=0.52). Bone formation was observed in all subgroups, just two animals showed no bone formation even after 40 days. More than 50% of bone matrix mineralization was observed in 56% (23 animals) of the analyzed areas. The bone matrix mineralization was not different between subgroups (p=0.60).

CONCLUSIONS

The subgroups that received copaiba oil showed bone repair, although not statistically significant in comparison to subgroups treated with meloxicam or controls. Copaiba oil administered by gavage had no effect on bone repair in this experimental model.

Therapeutic effects of systemic vitamin k2 and vitamin d3 on gingival inflammation and alveolar bone in rats with experimentally induced periodontitis

BACKGROUND

The synergistic effects of vitamin D3 and vitamin K2 on bone loss prevention have been reported. This study evaluates the effects of vitamin D3 and vitamin K2 supplementation in conjunction with conventional periodontal therapy (scaling and root planing [SRP]) on gingival interleukin (IL)-1β and IL-10, serum bone alkaline phosphatase (B-ALP) and tartrate-resistant acid phosphatase 5b (TRAP-5b), and calcium and alveolar bone levels in rats with experimentally induced periodontitis.

METHODS

Seventy-two rats were divided into the following groups: 1) healthy; 2) periodontitis; 3) SRP; 4) SRP + vitamin D3; 5) SRP + vitamin K2; and 6) SRP + vitamins K2 and D3. Periodontitis was induced by ligature placement for 7 days, and vitamin K2 (30 mg/kg) and/or vitamin D3 (2 μg/kg) were administered for 10 days in the SRP + vitamin D3, SRP + vitamin K2, and SRP + vitamins K2 and D3 groups by oral gavage. On day 18, the animals were sacrificed, serum B-ALP, TRAP-5b, and calcium levels were measured, gingiva specimens were extracted for IL-1β and IL-10 analysis, and distances between the cemento-enamel junction and alveolar bone crest were evaluated.

RESULTS

Alveolar bone levels in the periodontitis group were significantly greater than those in the other five groups. No significant differences were found in gingival IL-1β and IL-10, serum B-ALP and TRAP-5b, and calcium and alveolar bone levels between the groups receiving SRP and vitamins and the group receiving SRP alone.

CONCLUSION

Within the limitations of this study, vitamin D3 and K2 alone or in combination did not affect gingival IL-1β and IL-10, serum B-ALP and TRAP-5b levels, or alveolar bone compared with conventional periodontal therapy alone.

Vitamin K-dependent carboxylation of osteocalcin affects the efficacy of teriparatide (PTH(1-34)) for skeletal repair

Teriparatide (PTH1-34) promotes skeletal repair and increases bone mass. Vitamin K is involved in bone mineralization as a coenzyme of γ-carboxylase for Gla proteins, and therefore vitamin K insufficiency caused by malnutrition or therapeutic intake of the vitamin K antagonist warfarin could affect the efficacy of PTH1-34 therapy for bone repair. In the present study, we investigated whether vitamin K influences the efficacy of PTH1-34 therapy for bone repair in a rat osteotomy model. Female 12-week-old Sprague-Dawley rats were subjected to a closed midshaft osteotomy of the femur and randomized into four groups (n=10 per group): vehicle, PTH1-34 (daily 30 μg/kg/day subcutaneous injection)+solvent (orally, three times a week), PTH1-34+warfarin (0.4 mg/kg/day orally, three times a week), and PTH1-34+vitamin K2 (menatetrenone, 30 mg/kg/day orally, three times a week). Serum γ-carboxylated and uncarboxylated osteocalcin (Gla-OC and Glu-OC) levels and radiographic healing were monitored every 2 weeks. Skeletal repair was assessed by micro-computed tomography, mechanical testing, and histology at 8weeks after surgery. PTH1-34 amplified the osteotomy-induced increase in Gla-OC and improved the mechanical properties as well as the volumetric bone mineral tissue density of the fracture callus. Concurrent use of warfarin decreased the response to PTH1-34 therapy in terms of mechanical recovery, probably by impairing mineralization due to the lack of Gla-OC. Although the effects of combination therapy with PTH1-34 and vitamin K2 on bone repair did not significantly exceed those of PTH1-34 monotherapy in rats fed sufficient dietary vitamin K, postoperative Gla-OC levels were correlated with the mechanical properties of the osteotomized femur in PTH1-34-treated rats regardless of the use of warfarin or vitamin K2. These findings suggest the importance of vitamin K dependent γ-carboxylation of OC for realizing the full effects of PTH1-34 on skeletal repair.

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.

Risk factors contributing to type 2 diabetes and recent advances in the treatment and prevention

Type 2 diabetes is a serious and common chronic disease resulting from a complex inheritance-environment interaction along with other risk factors such as obesity and sedentary lifestyle. Type 2 diabetes and its complications constitute a major worldwide public health problem, affecting almost all populations in both developed and developing countries with high rates of diabetes-related morbidity and mortality. The prevalence of type 2 diabetes has been increasing exponentially, and a high prevalence rate has been observed in developing countries and in populations undergoing "westernization" or modernization. Multiple risk factors of diabetes, delayed diagnosis until micro- and macro-vascular complications arise, life-threatening complications, failure of the current therapies, and financial costs for the treatment of this disease, make it necessary to develop new efficient therapy strategies and appropriate prevention measures for the control of type 2 diabetes. Herein, we summarize our current understanding about the epidemiology of type 2 diabetes, the roles of genes, lifestyle and other factors contributing to rapid increase in the incidence of type 2 diabetes. The core aims are to bring forward the new therapy strategies and cost-effective intervention trials of type 2 diabetes.

Vitamin K(2) improves renal function and increases femoral bone strength in rats with renal insufficiency

Renal insufficiency induces cortical bone loss in rats. The present study examined the influence of vitamin K(2) on renal function, cortical bone mass, and bone strength in rats with renal insufficiency. Thirty male Sprague-Dawley rats (8 weeks old) were randomized by the stratified weight method to the following three groups of 10 animals each: sham operation (control), 5/6 nephrectomy, and 5/6 nephrectomy + oral vitamin K(2) (menaquinone-4, menatetrenone, 30 mg/kg, 5 days/week). Treatment was initiated 10 days after surgery. After 6 weeks of treatment, samples of serum, urine, and bone (femur and tibia) were obtained. Renal function was evaluated, bone histomorphometric analysis was performed on the tibial diaphysis, and the bone mineral density (BMD) and mechanical strength of the femoral diaphysis were determined by peripheral quantitative computed tomography and a three-point bending test, respectively. Nephrectomy induced renal dysfunction, as indicated by increased levels of serum creatinine and urea nitrogen along with a decrease of creatinine clearance; and it also decreased BMD without significantly affecting bone strength at the femoral diaphysis. Vitamin K(2) improved renal function parameters but did not significantly influence BMD at the femoral diaphysis. However, vitamin K(2) decreased the bone marrow area of the tibial diaphysis and increased the stiffness of the femoral diaphysis. These findings suggest that administration of vitamin K(2) improves renal function and increases cortical bone strength without altering BMD in rats with renal insufficiency.

Effect of vitamin K2 on cortical and cancellous bone mass and hepatic lipids in rats with combined methionine-choline deficiency

The present study examined changes of cancellous and cortical bone in rats with combined methionine-choline deficiency (MCD). In addition, the effects of vitamin K2 on cortical and cancellous bone mass and hepatic lipids were investigated in rats with MCD. Six-week-old male Sprague-Dawley rats were randomized into three groups of ten, including an age-matched control (standard diet) group, an MCD diet group, and an MCD diet+vitamin K2 (menatetrenone at 30mg/kg/d orally, 5 times a week) group. After the one-month experimental period, histomorphometric analysis was performed on cortical and cancellous bone from the tibial diaphysis and proximal metaphysis, respectively, while histological examination of the liver was performed after staining with hematoxylin and eosin and Oil Red O. MCD rats displayed weight loss, diffuse and centrilobular fatty changes of the liver, and a decrease of the cancellous bone volume per tissue volume (BV/TV) and percent cortical area (Ct Ar) as a result of decreased trabecular, periosteal, and endocortical bone formation along with increased trabecular and endocortical bone resorption. Administration of vitamin K2 to rats with MCD attenuated weight loss, accelerated the decrease of cancellous BV/TV due to an increase of bone remodeling, and ameliorated the decrease of percent Ct Ar by increasing periosteal and endocortical bone formation. Vitamin K2 administration also prevented MCD-induced diffuse fatty change of the liver. These findings suggest a beneficial effect of vitamin K2 on cortical bone mass and hepatic lipid metabolism in rats with MCD. The loss of cancellous bone mass could possibly have been due to re-distribution of minerals to cortical bone.