Effects of various antihypertensive drugs on the function of osteoblast

Therapeutic Effect of Benidipine on Medication-Related Osteonecrosis of the Jaw

Medication-related osteonecrosis of the jaw (MRONJ) is an intractable disease that is typically observed in patients with osteoporosis or tumors that have been treated with either bisphosphonate (BP) or antiangiogenic medicine. The mechanism of MRONJ pathogenesis remains unclear, and no effective definitive treatment modalities have been reported to date. Previous reports have indicated that a single injection of benidipine, an antihypertensive calcium channel blocker, in the vicinity of a tooth extraction socket promotes wound healing in healthy rats. The present study was conducted to elucidate the possibility of using benidipine to promote the healing of MRONJ-like lesions. In this study, benidipine was administered near the site of MRONJ symptom onset in a model rat, which was then sacrificed two weeks after benidipine injection, and analyzed using histological sections and CT images. The analysis showed that in the benidipine groups, necrotic bone was reduced, and soft tissue continuity was recovered. Furthermore, the distance between epithelial edges, length of necrotic bone exposed in the oral cavity, necrotic bone area, and necrotic bone ratio were significantly smaller in the benidipine group. These results suggest that a single injection of benidipine in the vicinity of MRONJ-like lesions can promote osteonecrotic extraction socket healing.

Osteogenic effects of antihypertensive drug benidipine on mouse MC3T3-E1 cells in vitro

Hypertension is a prevalent systemic disease in the elderly, who can suffer from several pathological skeletal conditions simultaneously, including osteoporosis. Benidipine (BD), which is widely used to treat hypertension, has been proved to have a beneficial effect on bone metabolism. In order to confirm the osteogenic effects of BD, we investigated its osteogenic function using mouse MC3T3-E1 preosteoblast cells in vitro. The proliferative ability of MC3T3-E1 cells was significantly associated with the concentration of BD, as measured by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and cell cycle assay. With BD treatment, the osteogenic differentiation and maturation of MC3T3-E1 cells were increased, as established by the alkaline phosphatase (ALP) activity test, matrix mineralized nodules formation, osteogenic genetic test, and protein expression analyses. Moreover, our data showed that the BMP2/Smad pathway could be the partial mechanism for the promotion of osteogenesis by BD, while BD might suppress the possible function of osteoclasts through the OPG/RANKL/RANK (receptor activator of nuclear factor-κB (NF-κB)) pathway. The hypothesis that BD bears a considerable potential in further research on its dual therapeutic effect on hypertensive patients with poor skeletal conditions was proved within the limitations of the present study.

Potential risk factors for early and late dental implant failure: a retrospective clinical study on 9080 implants

Background

The aim of this study was to analyze potential risk factors for early and late dental implant failure (DIF) in a clinical cohort trial.

In a private practice, 9080 implants were inserted during a period of 10 years. In case of DIF, data were classified into early and late DIF and compared to each other in regard of gender, age, site of implantation, implant geometry, and patients’ systemic diseases.

Results

Three hundred fifty-one implants failed within the observation period (survival rate: 96.13%). Early DIF occurred in 293 implants (83.48%) compared to late DIF in 58 implants (16.52%). Significant earlier DIF was seen in the mandible (OR = 3.729, p < 0.001)—especially in the posterior area—and in younger patients (p = 0.017), whereas an increased likelihood of late DIF was associated with maxillary implants (OR = 3.729, p < 0.001) and older patients.

Conclusions

Early DIF is about twice as common as late DIF. Main risk factors for early DIF are implant location in the (posterior) mandible as well as younger age. On contrary, late DIF is rather associated with older patients, cancellous bone quality, and longer implants.

Eldecalcitol effects on osteoblastic differentiation and function in the presence or absence of osteoclastic bone resorption

Eldecalcitol (ELD) is an active vitamin D3 analog, possesses anti-resorption properties and is an approved therapeutic drug for the treatment of osteoporosis in Japan. However, the effect of ELD on osteoblasts in a distinct cell microenvironment, including in the presence or absence of osteoclastic bone resorption, is undetermined. In the current study, the effect of bone resorption supernatant on the ELD-mediated regulation of viability, differentiation and receptor activator of ΝF-κB ligand/osteoprotegerin (RANKL/OPG) expression was assessed in MC3T3-E1 pre-osteoblast cells. The murine macrophage-like cell line RAW 264.7 was induced to differentiate into functional osteoblasts. Bone resorption supernatant was prepared by culturing osteoclast with a bovine cortical bone specimen. Mouse MC3T3-E1 cells were subsequently treated with ELD combined with differentiated osteoclast cell culture (OCS) or osteoclast bone resorption model supernatants. Cell counting kit-8, alkaline phosphatase (ALP) activity, reverse transcription-quantitative (RT-q) PCR and western blot analysis were used to assess cell viability, osteogenic activity and RANKL and OPG expression in MC3T3-E1 cells. The OCS and OCS + ELD treatment exhibited significantly increased MC3T3-E1 cell viability when compared with the control group. However, ELD, bone resorption culture supernatant (BRS) and ELD + BRS treatments significantly decreased MC3T3-E1 cell viability. The results of ALP activity analysis, RT-qPCR and western blot analysis demonstrated that ELD treatment and OCS decreased the osteogenic markers (ALP and RUNX2), however, BRS increased them. All treatments enhanced the expression of RANKL and RANKL/OPG ratio. The results of the current study revealed that ELD inhibits osteoblastic differentiation in vitro. However, in the presence of BRS, which mimics the local bone microenvironment in vivo, the net effect on osteogenesis was positive. Furthermore, osteoclasts and bone matrix-derived factors increased the RANKL/OPG ratio, thereby potentiating osteoclastic activity.

Effect of a Single Injection of Benidipine-Impregnated Biodegradable Microcarriers on Bone and Gingival Healing at the Tooth Extraction Socket

Objective: A dihydropyridine-type calcium channel blocker, benidipine (BD), is extensively used in hypertension therapy. In vitro study reported BD promoting bone metabolism. We evaluated the effect of sustained release of BD-loaded poly(lactic-co-glycolic acid) (PLGA) microcarriers on the promotion of bone and gingival healing at an extraction socket in vivo. In addition, the effect of BD on osteoblasts, osteocytes, fibroblasts, and epithelial cells was evaluated in vitro. Approach: The maxillary first molar of rats was extracted. Next, PLGA microcarriers containing BD were directly injected into the gingivobuccal fold as a single dose. After injection, bone and soft-tissue healing was histologically evaluated. Effect of BD on proliferation, migration, and gene expression of gingival and bone cell was also examined in vitro. Results: After tooth extraction, BD significantly augmented bone volume and density, and also epithelial wound healing. During in vitro studies, BD promoted significant proliferation and migration of fibroblasts and epithelial cells. Real-time RT-PCR revealed that BD upregulated messenger RNA expression of Ahsg (alpha 2-HS glycoprotein) and Csf2 (colony-stimulating factor 2) in osteoblasts. Innovation: The prevention of bone and soft-tissue reduction associated with tooth extraction has been eagerly anticipated in the field of dentistry. This study first reported the effect of BD on extraction socket healing. Conclusion: A single dose of topically administered BD-loaded PLGA microcarriers promoted bone and soft-tissue healing at the extraction site of tooth.

Benzofuran-dihydropyridine hybrids: A new class of potential bone anabolic agents

A series of novel benzofuran-dihydropyridine hybrids were designed by molecular hybridization approach and evaluated for bone anabolic activities. Among the screened library, ethyl 4-(7-(sec-butyl)-2-(4-methylbenzoyl)benzofuran-5-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate (compound 21) significantly enhanced the ALP production and mineralized nodule formation, which are primary requisites in the process of in vitro osteogenesis. Oral administration of compound 21 at 10 mg.kg^-1 day^-1 for two weeks led to restoration of trabecular bone microarchitecture in drill hole fracture model by significantly increasing BV/TV and Tb.N. Furthermore, histological and molecular studies showed compound 21 triggering the new bone regeneration in a drill hole defect site by increasing BMP expression. Furthermore, molecular modeling studies were performed to gain insight into the binding approach, which revealed that both benzofuran and dihydropyridine moieties are essential to show similar binding interactions to fit into the active site of BMP2 receptor, an important target of the osteogenic agents. Our results suggest that compound 21 stimulates BMP2 synthesis in osteoblast cells that promotes new bone formation (∼40%) at the fracture site which helps in shorten the healing period.

Angiotensin II induces modulation of calcium channel currents in osteoblasts

Angiotensin II (Ang II) plays a major role in the maintenance of extracellular fluid volume and blood pressure. In addition to its well-established role in circulatory homeostasis, it has been implicated in the process of bone formation. Osteoblasts play a major role in bone formation, employing intracellular Ca(2+) as a second messenger to modulate hormonal responses and as a cofactor for mineralization. Voltage-dependent Ca(2+) channels (VDCCs) mediate the influx of Ca(2+) in response to membrane depolarization. The purpose of this study was to investigate the effects of Ang II on VDCC currents in osteoblasts using a patch-clamp recording method. To our knowledge, the data presented here demonstrate for the first time that Ang II facilitates VDCCs in osteoblasts.

Fracture healing: an appraisal of the effects of frequently prescribed medications

BACKGROUND

Recognizing the existence of adverse drug effects of frequently prescribed drugs can empower a clinician with knowledge to avoid dangerous adverse effects that may result in hazardous, negative patient outcomes on either fracture healing or bone health. Pharmacovigilance reports have described the influence of medications, allowing for bone health to be quite unpredictable.

METHODS

First, mechanisms found in the medical literature of potential drug adverse effects regarding fracture healing are presented. Second, the 100 most frequently prescribed medications in 2010 are reviewed regarding adverse effects on fracture healing. These reported adverse effects are evaluated for medical causation. Last, a data table describing the 100 reviewed medications and their reported effects on fracture healing is provided.

RESULTS

The actual number of different medications in the review was 72. Reported drug adverse effects on bone and fracture healing occurred with 59 of the 72 drugs (81.9%). These adverse effects are either described as a definitive statement or represented by postmarketing case reports. Thirteen of the 72 review drugs (18.1%) did not have any description of the possible effects on bone health. A total of 301 cases reports describing delayed union, malunion, and nonunion of fractures represent 31 of the 72 medications reviewed (43.1%).

CONCLUSIONS

This review offers the health-care provider information regarding potential adverse drug effects on bone health. Empowered with this information, clinicians may assist their patients in maximizing pharmacologic outcomes by avoiding these reported harmful adverse effects.

Effects of the antihypertensive drug benidipine on osteoblast function in vitro

The dihydropyridine-type calcium channel blocker, benidipine (BD) has been widely used in hypertension therapy. Previous studies have demonstrated that BD has a positive effect on bone metabolism. Inspired by this promoting phenomenon, the present study investigated the effects of BD on osteoblasts in vitro. Experiments were designed and performed, including an MTT assay, reverse transcription-polymerase chain reaction, western blot analysis, alkaline phosphatase activity measurements and alizarin red S staining. The results demonstrated that BD promoted osteoblast proliferation and osteogenic differentiation at concentrations from 1×10⁻⁶ to 1×10⁻⁹ M by upregulating Runx2, BMP2 and OCN gene expression levels. Overall, BD at appropriate concentrations has been demonstrated to have positive effects on osteoblast function in addition to its conventional clinical usage.

Effects of lercanidipine on bone density and bone repair in spontaneously hypertensive rats

PURPOSE

To evaluate the effects of the lercanidipine on bone healing (BH) and bone density (BD) in the tibiae of spontaneously hypertensive rats (SHR), using histometric and tartrate-resistant acid phosphatase (TRAP) expression analyses.

MATERIALS AND METHODS

Wistar and SHR were assigned to one of the following groups: normotensive rats (NTR) (n = 15), untreated SHR (n = 15), and lercanidipine-treated SHR (n = 15). The latter group was treated daily with lercanidipine for 6 weeks. Two weeks after the beginning of drug administration, a critical-sized surgical defect was created in the right tibia of all groups, whereas the contralateral tibia remained without defect. The animals were killed 30 days after the creation of the bone defect.

RESULTS

There were no significant differences among the groups for BH, trabecular BD, and the number of TRAP+ cells in the newly formed cortical bone (P > 0.05). SHR presented significantly lower cortical BD and increased cortical levels of TRAP+ cells, when compared with NTR and lercanidipine-treated SHR (P < 0.05).

CONCLUSION

SHR presented a lower cortical BD and increased levels of TRAP+ cells. In addition, the treatment of SHR with lercanidipine during 6 weeks was able to revert the deleterious effects of hypertension on cortical BD and on the number of TRAP+ cells in the tibia of SHR.

L-type calcium channels play a crucial role in the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells

L-type voltage-dependent Ca(2+) channels (VDCC(L)) play an important role in the maintenance of intracellular calcium homeostasis, and influence multiple cellular processes. They have been confirmed to contribute to the functional activities of osteoblasts. Recently, VDCC(L) expression was reported in mesenchymal stem cells (MSCs), but the role of VDCC(L) in MSCs is still undetermined. The aim of this study was to determine whether VDCC(L) may be regarded as a new regulator in the proliferation and osteogenic differentiation of rat MSC (rMSCs). In this study, we examined functional Ca(2+) currents (I(Ca)) and mRNA expression of VDCC(L) in rMSCs, and then suppressed VDCC(L) using nifedipine (Nif), a VDCC(L) blocker, to investigate its role in rMSCs. The proliferation and osteogenic differentiation of MSCs were analyzed by MTT, flow cytometry, alkaline phosphatase (ALP), Alizarin Red S staining, RT-PCR, and real-time PCR assays. We found that Nif exerts antiproliferative and apoptosis-inducing effects on rMSCs. ALP activity and mineralized nodules were significantly decreased after Nif treatment. Moreover, the mRNA levels of the osteogenic markers, osteocalcin (OCN), bone sialoprotein (BSP), and runt-related transcription factor 2 (Runx2), were also down-regulated. In addition, we transfected α1C-siRNA into the cells to further confirm the role of VDCC(L) in rMSCs, and a similar effect on osteogenesis was found. These results suggest that VDCC(L) plays a crucial role in the proliferation and osteogenic differentiation of rMSCs.

Effects of amlodipine on bone metabolism in male albino Wistar rats

Amlodipine (dihydropyridine-type calcium channel blocker) is a widely used agent for the treatment of hypertension in human and veterinary medicine but detailed information about its effects on bone metabolism are missing. Therefore, the aim of our study was to investigate the effect of amlodipine on bone metabolism in male albino Wistar rats. Amlodipine (0.3 mg/100 g body weight; gavage) was administered to 8 rats for 8 weeks. Control group (n = 8) received aqua pro inj. (0.2 ml/100 g body weight; gavage). Bone marker concentrations of carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I) and aminoterminal propeptide of procollagen type I in serum, and of bone alkaline phosphatase (BALP) in both serum and bone homogenate were measured by enzyme immunoassay. We investigated the expression of bone morphogenetic protein 2 (BMP-2) in proximal tibia using Western blotting, and bone mineral density was measured by Dual-energy X-ray Absorptiometry in lumbar and caudal vertebrae and in femoral areas. Mechanical properties of the femurs were measured by three-point bending of the shaft and compression testing of the femoral neck. After 8 weeks of amlodipine administration there was a significant decrease in serum concentrations of BALP (p= 0.0009) and CTX-I (p= 0.003), and the content of BALP in bone homogenate (p= 0.026) compared to the control. In addition, Western blot analysis indicated increased BMP-2 protein concentration after amlodipine administration. Our findings suggest that amlodipine has a retarding influence on bone metabolism in rats by decreasing bone turnover, which probably in consequence increases expression of BMP-2.

Protective effect of amlodipine on rat bone tissue after orchidectomy

AIM

Our study aimed to investigate the effect of amlodipine on bone metabolism in orchidectomized rats.

METHODS

Eight-week-old rats were divided into three groups. The sham-operated control group (SHAM) and the control group after orchidectomy (ORX) received the standard laboratory diet (SLD). The experimental group after orchidectomy (ORX+AML) received SLD enriched with amlodipine for 12 weeks. Bone marker concentrations in serum of PINP, OPG and IGF-1, and the levels of CTX-I, BAP and BMP-2 in a bone homogenate were measured using enzyme-linked immunosorbent assay. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The femurs were used for biomechanical testing.

RESULTS

Bone markers (CTX-I, BAP, BMP-2) in ORX were higher versus SHAM. In ORX+AML there was a decrease in PINP, CTX-I, BAP, BMP-2 and OPG versus ORX. IGF-1 was decreased in ORX versus SHAM. In ORX+AML it was increased versus ORX. In ORX, a decrease was demonstrated versus SHAM in BMD of the whole body, in the lumbar vertebrae and in both femurs. In ORX+AML there was an increase in BMD of the whole body versus ORX. Three-point bending test revealed a decrease in maximal load values in ORX versus SHAM. After amlodipine administration there was an increase in the left femur versus ORX.

CONCLUSIONS

Amlodipine is capable of mitigating the negative effects of orchidectomy and could be a good prevention of osteoporosis.

Reciprocal roles of angiotensin II and Angiotensin II Receptors Blockade (ARB) in regulating Cbfa1/RANKL via cAMP signaling pathway: possible mechanism for hypertension-related osteoporosis and antagonistic effect of ARB on hypertension-related osteoporosis

Hypertension is a risk factor for osteoporosis. Animal and epidemiological studies demonstrate that high blood pressure is associated with increased calcium loss, elevated parathyroid hormone, and increased calcium movement from bone. However, the mechanism responsible for hypertension-related osteoporosis remains elusive. Recent epidemiological studies indicate the benefits of Angiotensin II Receptors Blockade (ARB) on decreasing fracture risks. Since receptors for angiotensin II, the targets of ARB, are expressed in both osteoblasts and osteoclasts, we postulated that angiotensin II plays an important role in hypertension-related osteoporosis. Cbfa1 and RANKL, the important factors for maintaining bone homeostasis and key mediators in controlling osteoblast and osteoclast differentiation, are both regulated by cAMP-dependent signaling. Angiotensin II along with factors such as LDL, HDL, NO and homocysteine that are commonly altered both in hypertension and osteoporosis, can down-regulate the expression of Cbfa1 but up-regulate RANKL expression via the cAMP signaling pathway. We thus hypothesized that, by altering the ratio of Cbfa1/RANKL expression via the cAMP-dependent pathway, angiotensin II differently regulates osteoblast and osteoclast differentiation leading to enhanced bone resorption and reduced bone formation. Since ARB can antagonize the adverse effect of angiotensin II on bone by lowering cAMP levels and modifying other downstream targets, including LDL, HDL, NO and Cbfa1/RANKL, we propose the hypothesis that the antagonistic effects of ARB may also be exerted via cAMP signaling pathway.

Hypertension may affect tooth-supporting alveolar bone quality: a study in rats

BACKGROUND

This study evaluates the ligature-induced bone loss (BL) and quality of tooth-supporting alveolar bone in spontaneously hypertensive rats (SHRs) by histometric, histochemical, and immunohistochemical analyses and assesses the effects of lercanidipine on these parameters.

METHODS

Wistar rats and SHRs were assigned to one of the following groups: normotensive rats (n = 15), untreated SHRs (n = 15), and treated SHRs (n = 15). The latter group was treated daily with lercanidipine for 45 days. Two weeks after the beginning of drug administration, the first right mandibular molar received a cotton ligature, whereas the contralateral tooth was left unligated. The following parameters were analyzed in the furcation area of decalcified histologic sections: BL, bone density (BD), number of positive cells for tartrate-resistant acid phosphatase (TRAP+), and expression of receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG).

RESULTS

In ligated teeth, no significant differences among groups were found regarding BL, TRAP+ cells, and the ratio of RANKL/OPG+ cells (P >0.05), although the expression of RANKL was decreased in the treated SHR group (P <0.05). Increased BL and decreased BD were observed around unligated teeth of the untreated and treated SHR groups (P <0.05). In the furcation area of the unligated teeth, the untreated SHR group presented a higher number of TRAP+ cells and higher ratio of RANKL/OPG+ cells compared to the other groups.

CONCLUSIONS

SHRs present harmful alterations in the quality of tooth-supporting bone, independently of inflammation. In addition, the administration of lercanidipine for 45 days decreased the expression of bone-resorption markers.

Adverse effects of the amlodipine on bone healing of the mandibular fracture: an experimental study in rats

BACKGROUND

Calcium channel blockers are effective antihypertensive agents, but they may affect many metabolic processes, including bone metabolism.

PURPOSE

The aim of this study was to evaluate by radiographic, histologic, and biochemical analyses the effects of amlodipine on bone healing of a defect simulating a fracture in mandibular ramus of rats.

METHODS

Fifty male Wistar rats were submitted to the same unilateral surgical procedure simulating a mandibular fracture. Experimental group received oral doses of amlodipine 0.04 mg/rat/day starting 12 days before procedure, while control group received water. Animals were sacrificed at 1, 7, 14, 30, and 90 days postoperatively. Numerical values were submitted to statistical analyses.

RESULTS

Radiographic analysis showed larger radiolucent area into bone defect to the experimental group at the periods of 14 (p = 0.016), 30 (p = 0.009), and 90 (p = 0.028) days. In the histological analysis, the experimental group had a slight delay in the chronology of the repair process. In the histomorphometric analysis, the experimental group presented significant lowering of newly formed bone volume at 7 and 14 days periods (p = 0.049). There was a significant decrease of alkaline phosphatase levels in experimental group in the initial periods (p = 0.049).

CONCLUSIONS

It was concluded that chronic use of amlodipine compromised bone neoformation in the repairing process of surgical defect in the mandibular ramus of rats, but no precluded occurrence of fracture consolidation.

Distinct effects of amlodipine treatment on vascular elastocalcinosis and stiffness in a rat model of isolated systolic hypertension

OBJECTIVE

Medial elastocalcinosis (MEC) contributes to the development of large artery stiffness and isolated systolic hypertension. Since endothelin receptor antagonists can prevent and regress elastocalcinosis, our aim was to determine whether amlodipine, a calcium channel blocker that inhibits endothelin signaling, could likewise influence MEC, or reduce pressure mainly through its vasorelaxing properties.

METHODS

Control male Wistar rats were compared with rats receiving warfarin (20 mg/kg per day) with vitamin K1 (15 mg/kg per day) alone (WVK) or in association with amlodipine (15 mg/kg per day) for 4 weeks or during the last week or last 4 weeks of an 8-week WVK treatment (two regression groups).

RESULTS

Inactivation of matrix Gla protein by WVK for 4 or 8 weeks increased the calcium content 10-fold in the aorta, inducing a significant elevation of pulse wave velocity and pulse pressure by selective augmentation of systolic blood pressure. Amlodipine prevented aortic MEC, pulse wave velocity and pulse pressure elevation, but reversed only MEC and pulse pressure when administered for 4 weeks. One week of amlodipine administered after 7 weeks of WVK partially decreased pulse pressure without modifying aortic MEC. Amlodipine did not reduce the fibrosis associated with calcified areas in the WVK model during the regression protocols.

CONCLUSION

The clinical efficacy of amlodipine in improving hemodynamic variables and reducing cardiovascular events in isolated systolic hypertension could be explained by its beneficial effect on vascular calcification. Amlodipine's lack of effect on pulse wave velocity and collagen deposition, however, suggests that it may reduce pulse pressure by means other than improving arterial stiffness.

Treatment with beta-blockers, ACE inhibitors, and calcium-channel blockers is associated with a reduced fracture risk: a nationwide case–control study

BACKGROUND

Cardiovascular diseases are associated with disturbances in calcium metabolism, including increased urinary calcium, vitamin D insufficiency, and decreased bone mineral density. Antihypertensive drugs may increase the risk of falling. However, risk of fracture in patients treated with non-diuretic cardiovascular drugs is largely unknown.

AIM

We investigated associations between fracture risk and treatment with commonly used cardiovascular drugs: beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and calcium-channel blockers.

DESIGN

A population-based pharmaco-epidemiological case-control study with fracture in year 2000 as outcome and drug use during the previous 5 years as exposure. We used nationwide computerized registers to assess individual use of drugs and related these data to individual fracture records and information on socio-economic and health-related confounders.

RESULTS

We included 124,655 cases that sustained a fracture and 373,962 age and gender-matched controls. After adjustment for potential confounders, risk of any fracture was reduced by 9% [odds ratio (OR) 0.91; 95% confidence interval (CI), 0.88-0.93] in users of beta-blockers, by 6% (OR, 0.94; 95%CI, 0.91-0.96) in users of calcium-channel blockers, and by 7% (OR, 0.93; 95%CI, 0.90-0.96) in users of ACE inhibitors. Moreover, risk of hip fractures was reduced significantly by 7-14% in users of the three groups of drugs. No major differences were found between men and women or in subjects younger or older than 70 years of age. Sub-analyses indicated differences between groups of calcium-channel blockers, as use of non-dihydropyridine drugs was associated with a larger risk reduction than use of dihydropyridine drugs.

CONCLUSION

Treatment with beta-blockers, ACE inhibitors, and calcium-channel blockers is associated with a small but significantly reduced risk of fracture.

Pharmacological, Pharmacokinetic, and Clinical Properties of Benidipine Hydrochloride, a Novel, Long-Acting Calcium Channel Blocker

Benidipine is a dihydropyridine-derived calcium channel blocker developed in Japan, with several unique mechanisms of action, that is, triple calcium channels (L, N, and T) blocking action with a membrane approach. Benidipine has relatively high vascular selectivity and is expected to show protective effects on vascular endothelial cells. Renal protective effects of benidipine also have been shown in several basic and clinical studies. Moreover, anti-oxidative action and enhancing nitric oxide production have been noted with this drug, following its cardio-protective effects in patients with ischemic heart diseases. In fact, benidipine exerted a better prognostic effect than other calcium channel blockers in the therapy for patients with vasospastic angina. In addition, benidipine showed reliable antihypertensive, renoprotective effects if used in combination with angiotensin II type 1 receptor blockers (ARBs) when adequate anti-hypertensive effects are not achieved by ARBs alone, indicating that benidipine is an useful calcium channel blocker in combination therapy for hypertension. Benidipine was launched on the Japanese market 14 years ago, but few severe side effects have been reported, suggesting that this is a drug with established safety and long-acting pharmacological effects.

Molecular and functional expression of voltage-operated calcium channels during osteogenic differentiation of human mesenchymal stem cells

We used the patch-clamp technique and RT-PCR to study the molecular and functional expression of VOCCs in undifferentiated hMSCs and in cells undergoing osteogenic differentiation. L-type Ca2+ channel blocker nifedipine did not influence alkaline phosphatase activity, calcium, and phosphate accumulation of hMSCs during osteogenic differentiation. This study suggests that osteogenic differentiation of hMSCs does not require L-type Ca2+ channel function.

INTRODUCTION

During osteogenic differentiation, mesenchymal stem cells from human bone marrow (hMSCs) must adopt the calcium handling of terminally differentiated osteoblasts. There is evidence that voltage-operated calcium channels (VOCCs), including L-type calcium channels, are involved in regulation of osteoblast function. We therefore studied whether VOCCs play a critical role during osteogenic differentiation of hMSCs.

MATERIALS AND METHODS

Osteogenic differentiation was induced in hMSCs cultured in maintenance medium (MM) by addition of ascorbate, beta-glycerophosphate, and dexamethasone (ODM) and was assessed by measuring alkaline phosphatase activity, expression of osteopontin, osteoprotegerin, RANKL, and mineralization. Expression of Ca2+ channel alpha1 subunits was shown by semiquantitative or single cell RT-PCR. Voltage-activated calcium currents of hMSCs were measured with the whole cell voltage-clamp technique.

RESULTS

mRNA for the pore-forming alpha1C and alpha1G subunits of the L-type and T-type Ca2+ channels, respectively, was found in comparable amounts in cells cultured in MM or ODM. The limitation of L-type Ca2+ currents to a subpopulation of hMSCs was confirmed by single cell RT-PCR, where mRNA for the alpha1C subunits was detectable in only 50% of the cells cultured in MM. Dihydropyridine-sensitive L-type Ca2+ currents were found in 13% of cells cultured in MM and in 12% of the cells cultured in ODM. Under MM and ODM culture conditions, the cells positive for L-type Ca2+ currents were significantly larger than cells without Ca2+ currents as deduced from membrane capacitance; thus, current densities were comparable. Addition of the L-type Ca2+ channel blocker nifedipine to the culture media did not influence alkaline phosphatase activity and the extent of mineralization.

CONCLUSION

These results suggest that, in the majority of hMSCs, Ca2+ entry through the plasma membrane is mediated by some channels other than VOCCs, and blockade of the L-type Ca2+ channels does not affect early osteogenic differentiation of hMSCs.

Effects of Lactobacillus helveticus fermented milk on bone cells in vitro

Milk fermented with Lactobacillus helveticus (L. helveticus) contains small peptides such as isoleucyl-prolyl-proline (IPP) and valyl-prolyl-proline (VPP), which inhibit the angiotensin converting enzyme (ACE). We investigated the effects of L. helveticus fermented milk whey (Lh-whey) and its components, sour milk whey, calcium and IPP and VPP peptides, on bone cells in vitro. An osteoblast assay was performed by determining the amount of deposited calcium as an index of bone formation in cultures of mouse osteoblasts formed from bone marrow-derived osteoblast precursor cells. An osteoclast assay was performed by determining the activity of tartrate-resistant acid phosphatase released into the culture medium in cultures of mouse osteoclasts formed from bone marrow-derived osteoclast precursor cells. The Lh-whey increased bone formation 1.3-1.4 times with the 1 x 10(-5), 1 x 10(-4) and 1 x 10(-3) solutions. The IPP and VPP peptides also demonstrated a significant 5-fold activation of bone formation in in vitro osteoblast cultures, whereas the sour milk whey and calcium had no effect. No significant effects were observed on osteoclasts in vitro with any of the study products. L. helveticus fermented milk whey contains bioactive components that increase osteoblastic bone formation in vitro. The effect may be due to the ACE-inhibitory IPP and VPP peptides, which showed a similar effect to that of the L. helveticus fermented milk whey.

Protective effect of benidipine against sodium azide-induced cell death in cultured neonatal rat cardiac myocytes

We investigated the effect of benidipine, a calcium antagonist, against sodium azide (NaN(3))-induced cell death in cultured neonatal rat cardiac myocytes with increase of LDH release, depletion of cellular ATP contents, and collapse of mitochondrial membrane potential (DeltaPsi) as indicators. Cells were treated with 1 mmol/L NaN(3) for 18 h. Benidipine concentration-dependently inhibited NaN(3)-induced cell death. The protective effect of benidipine was compared with those of amlodipine, nifedipine, candesartan, and captopril. Calcium antagonists exhibited a protective effect and the IC(50) values of benidipine, amlodipine, and nifedipine were 0.65, 90, and 65 nmol/L, respectively. NaN(3)-induced cell death was inhibited completely with the calpain inhibitor. It was considered that the sustained elevation of [Ca(2+)](i) might be implicated in NaN(3)-induced cell death. Benidipine, moreover, concentration-dependently preserved cellular ATP contents and maintained DeltaPsi the extent of the control level. In conclusion, benidipine exhibited the protective effect at an approximately 100-fold lower concentration than those of amlodipine and nifedipine in the NaN(3)-induced cardiac cell death model. It was considered that both the inhibition of Ca(2+) influx and the preservation of cellular ATP contents might play an important role in the protective effect of benidipine.