Long-term oral bisphosphonates delay healing after tooth extraction: a single institutional prospective study.

Tooth extraction in patients receiving bisphosphonates is thought to be a risk factor for osteonecrosis of the jaw (ONJ); however, ONJ did not develop, even when tooth extraction was performed with continued oral bisphosphonate therapy. A drug holiday from bisphosphonates before tooth extraction may not be necessary. INTRODUCTION: It is controversial whether bisphosphonate withdrawal is necessary prior to invasive procedures such as tooth extraction in order to prevent bisphosphonate-related osteonecrosis of the jaw (BRONJ). This study aimed to evaluate the clinical safety of continuing oral bisphosphonate therapy in patients undergoing tooth extraction. METHODS: We prospectively enrolled 132 patients (20 men, 112 women) who were receiving oral bisphosphonates for the prevention or treatment of osteoporosis and required tooth extraction. All patients were managed using an identical protocol, which included preoperative antibiotic prophylaxis and did not necessarily require complete wound closure. The patients were classified into groups according to the duration of bisphosphonate administration: < 2 years (n = 51), 2-5 years (n = 41), 5-10 years (n = 28), and > 10 years (n = 12). The groups were compared regarding the time taken for the extraction socket to heal, and the occurrence of BRONJ. Follow-up duration was at least 3 months. RESULTS: A total of 274 teeth were removed. Long-term oral bisphosphonate therapy for > 5 years significantly delayed the healing of the extraction socket in comparison with administration for < 5 years; however, BRONJ did not develop in any group. There was no prolongation of wound healing due to systemic risk factors such as glucocorticoid administration and diabetes mellitus. There were no adverse skeletal events such as bone fracture. CONCLUSIONS: Patients who underwent tooth extraction with continued oral bisphosphonate therapy showed delayed healing of the extraction socket as the cumulative administration period prolonged, but BRONJ did not develop.

Time to onset of bisphosphonate-related osteonecrosis of the jaws: a multicentre retrospective cohort study.

OBJECTIVES: Osteonecrosis of the jaw (ONJ) is a potentially severe adverse effect of bisphosphonates (BP). Although the risk of ONJ increases with increasing duration of BP treatment, there are currently no reliable estimates of the ONJ time to onset (TTO). The objective of this study was to estimate the TTO and associated risk factors in BP-treated patients. SUBJECTS AND METHODS: Retrospective analysis of data from 22 secondary care centres in seven countries relevant to 349 patients who developed BP-related ONJ between 2004 and 2012. RESULTS: The median (95%CI) TTO was 6.0 years in patients treated with alendronate (n = 88) and 2.2 years in those treated with zoledronate (n = 218). Multivariable Cox regression showed that dentoalveolar surgery was inversely associated, and the use of antiangiogenics directly associated, with the TTO in patients with cancer treated with zoledronate. CONCLUSIONS: The incidence of ONJ increases with the duration of BP therapy, with notable differences observed with respect to BP type and potency, route of administration and underlying disease. When data are stratified by BP type, a time of 6.0 and 2.2 years of oral alendronate and intravenous zoledronate therapy, respectively, is required for 50% of patients to develop ONJ. After stratification by disease, a time of 5.3 and 2.2 years of BP therapy is required for 50% of patients with osteoporosis and cancer, respectively, to develop ONJ. These findings have significant implications for the design of future clinical studies and the development of risk-reduction strategies aimed at either assessing or modulating the risk of ONJ associated with BP.

Spectrum of clinical and genetic features of patients with inherited platelet disorder with suspected predisposition to hematological malignancies: a nationwide survey in Japan.

BACKGROUND: Inherited thrombocytopenia (IT) contains several forms of familial thrombocytopenia and some of them have propensity to hematological malignancies. The etiological and genetic features of this heterogeneous syndrome have not yet been elucidated. PATIENTS AND METHODS: We conducted a nationwide survey to collect clinical information and samples from patients with familial thrombocytopenia and/or hematological malignancies in order to obtain a comprehensive understanding of IT. RESULTS: Among the 43 pedigrees with clinical samples, RUNX1 mutations were identified in 8 pedigrees (18.6%). While MYH9 and ANKRD26 mutations were identified in 2 and 1 pedigrees, respectively, no gene mutations were detected in the remaining 32 pedigrees from a panel of previously reported pathogenetic mutations. Clinical data were comparable between FPD/AML and non-FPD/AML probands. CONCLUSIONS: Our study clarified that it is unexpectedly difficult to diagnose FPD/AML based on clinical information alone, and thus, genetic testing is strongly recommended. Our survey also identified some pedigrees with a strong family history of myelodysplastic syndromes of unknown origin. Additionally, there were 14 pedigrees in which three or more members were affected by immune thrombocytopenia (ITP), and a computer-aided simulation suggested that such a distribution almost never happens by coincidence, which implicates a genetic predisposition to ITP.

Impaired immune response to voluntary arm-crank ergometer exercise in patients with cervical spinal cord injury.

STUDY DESIGN: Non-randomized study. OBJECTIVE: The mechanism underlying exercise-induced argumentation of natural killer cell cytotoxic activity (NKCA) in humans remains unclear. To address this, NKCA responses were studied during and after exercise in persons with cervical spinal cord injury (CSCI) and dysfunctional sympathetic nervous system. SETTING: Kibikogen Rehabilitation Center for Employment Injuries. METHODS: We examined the NKCA responses to 20-min arm-crank ergometer exercise at 60% of maximum oxygen consumption in eight persons with CSCI (between C6 and C7) and six able-bodied subjects. NKCA, adrenaline, and cortisol were measured before, immediately after exercise, 1 h after exercise, and 2 h after exercise. RESULTS: In able-bodied subjects, NKCA increased immediately after exercise (P<0.01) and then decreased to below the pre-exercise level 1 h after exercise, before recovering to the baseline level at 2 h after exercise. Plasma adrenaline concentrations increased significantly immediately after exercise (P<0.01) and returned to the baseline level 1 h after exercise. The plasma cortisol level did not change throughout the study. In contrast, NKCA, plasma concentrations of adrenaline, and cortisol did not change throughout the study in subjects with CSCI. CONCLUSION: In subjects with CSCI, the lack of response in NKCA throughout the experiment is probably mainly due to a dysfunctional sympathetic nervous system.

Effect of daily oral minodronate on vertebral fractures in Japanese postmenopausal women with established osteoporosis: a randomized placebo-controlled double-blind study.

UNLABELLED: SUMMARY; A randomized placebo-controlled trial was conducted to examine the effect of daily oral 1 mg minodronate on vertebral fractures in 704 postmenopausal women with established osteoporosis for 24 months. Minodronate treatment reduced vertebral fractures by 59% without serious adverse events. Minodronate is a safe and effective bisphosphonate for osteoporosis treatment. INTRODUCTION: Minodronate increases bone mineral density (BMD) in postmenopausal osteoporotic patients. However, its efficacy in reducing osteoporotic fractures has not been tested. METHODS: To examine anti-fracture efficacy and safety of daily oral minodronate in postmenopausal women with established osteoporosis, a randomized, double-blind, placebo-controlled trial was conducted in 704 postmenopausal women (55 to 80 years) with one to five vertebral fractures and low BMD. Subjects were randomly assigned to receive daily oral 1 mg minodronate (n = 359) or placebo (n = 345) for 24 months, with daily supplements of 600 mg calcium and 200 IU vitamin D(3). RESULTS: Daily 1 mg minodronate for 24 months reduced the risk of vertebral fractures by 59% (95% CI, 36.6-73.3%). Furthermore, when fractures during the first 6 months were eliminated, the risk of vertebral fractures from 6 to 24 months was reduced by 74% in minodronate-treated group. Minodronate treatment also reduced height loss. Bone turnover markers were suppressed by about 50% after 6 months of minodronate treatment and remained suppressed thereafter. The overall safety profile including gastrointestinal safety was similar between the two groups. CONCLUSIONS: Daily oral minodronate is safe, well-tolerated, and is effective in reducing vertebral fracture risk in postmenopausal women with established osteoporosis.

External hip protectors are effective for the elderly with higher-than-average risk factors for hip fractures.

UNLABELLED: In our cluster randomised controlled trial for efficacy of hip protector with 672 ambulatory elderly women, a hip protector was more effective for prevention of hip fractures in residents with fall history (n = 202; hazard ratio (HR), 0.375; 95%CI, 0.14-0.98; p = 0.05) and body-mass index (BMI) < or = 19.0 (n = 206; HR, 0.37; 95%CI, 0.14-0.95; p = 0.04) by a Cox proportional hazards regression model. INTRODUCTION: Hip fractures result from both osteoporosis and falling. A potentially cost-effective method of preventing hip fractures involves the use of hip protectors but recent studies have revealed the uncertain effectiveness of hip protectors even in institutional settings. METHODS: This study was a cluster randomised controlled trial with nursing homes. We randomly assigned 76 homes with 672 ambulatory but frail elderly women. Several risk factors were assessed at baseline and incorporated into a Cox proportional hazards regression model. UMIN Clinical Trials Registry number is UMIN000000467. Research period was between January 2004 and March 2006. RESULTS: In the intervention group, 19 hip fractures occurred (54.0/1,000 person-years), whereas 39 hip fractures occurred in the control group (78.8/1,000 person-years). Hazard ratio of hip fracture in the intervention group was 0.56 (95%CI, 0.31-1.03; p = 0.06) after adjusting for risk factors. In subgroup analysis, hip protectors were more effective for prevention of hip fractures in residents with fall history (n = 202; HR, 0.375; 95%CI, 0.14-0.98; p = 0.05) and BMI < or = 19.0 (n = 206; HR, 0.37; 95%CI, 0.14-0.95; p = 0.04). Overall compliance with use of hip protectors was 79.7%. CONCLUSION: Risk of hip fracture can be reduced by hip protectors among elderly women with fall history and low BMI.

A biodegradable polymer as a cytokine delivery system for inducing bone formation.

Bone morphogenetic proteins (BMPs) that have the potential to elicit new bone in vivo have been used in a tissue-engineering approach for the repair of bone injuries and bone defects. Although it is now possible to generate large amounts of recombinant human (rh) BMPs for medical use, the major challenge remains in the development of optimal local delivery systems for these proteins. Here we describe the development of a synthetic biodegradable polymer, poly-d,l-lactic acid-p-dioxanone-polyethylene glycol block copolymer (PLA-DX-PEG). This polymer exhibits promising degradation characteristics for BMP delivery systems and good biocompatibility under test conditions. PLA-DX-PEG/rhBMP-2 composite implants induced ectopic new bone formation effectively when tested in vivo, and can repair large bone defects orthotopically. This polymeric delivery system represents an advance in the technology for the enhancement of bone repair.

Usefulness of an accelerometer-based portable navigation system in total knee arthroplasty.

AIMS: The aim of this study was to evaluate the effects of using a portable, accelerometer-based surgical navigation system (KneeAlign2) in total knee arthroplasty (TKA) on the alignment of the femoral component, and blood loss. PATIENTS AND METHODS: A total of 241 consecutive patients with primary osteoarthritis of the knee were enrolled in this prospective, randomised controlled study. There were 207 women and 34 men. The mean age of the patients was 74.0 years (57 to 89). The KneeAlign2 system was used for distal femoral resection in 121 patients (KA2 group) and a conventional intramedullary femoral guide was used in 120 patients (IM group). RESULTS: One patient (0.8%) in the KA2 group and 19 in the IM group had an alignment which was > 3° away from the neutral mechanical axis (p < 0.01). The mean deviation from neutral alignment was 1.01° (standard deviation (sd) 1.0°) in the KA2 group and 1.93° (sd 1.7°) in the IM group (p < 0.01). Blood loss was significantly less in the KA2 group compared with the IM group (784 ml (sd 357) versus 1071 ml (sd 310), p < 0.001). CONCLUSION: The KneeAlign2 system provides a technically straightforward method for identifying the femoral head and performing an accurate distal femoral resection at TKA with significantly less blood loss compared with a conventional intramedullary guide. Cite this article: Bone Joint J 2017;99-B:1047-52.

Evaluation of the flexion gap by axial radiography of the distal femur.

The shape of the flexion gap in 20 normal knees was evaluated by axial radiography of the distal femur, and the results compared with those obtained in a previous study by MRI. The observed asymmetry was reduced by 29% using radiography, with a mean value of 3.6 degrees (1.5 degrees to 6.3 degrees) compared with that obtained by MRI of 5.1 degrees (2.6 degrees to 9.5 degrees), a mean discrepancy of 1.49 degrees. The results obtained by radiography and MRI showed a strong correlation (r = 0.78). Axial radiography is acceptable for the evaluation of the flexion gap and is less expensive and more comfortable to perform than MRI. Additionally, no metallic artefact occurs when the radiological method is used for assessment after arthroplasty.

Clinical outcome of extrasynovial steroid injection for trigger finger.

A prospective clinical study was performed to investigate the clinical results of extrasynovial (subcutaneous) steroid injection for trigger finger. One hundred and twenty-nine trigger fingers were investigated in 100 adult patients; 76 were women and 24 were men. Their mean age was 60 years (range: 17 to 88 years). We classified trigger fingers into three different grades according to clinical severity at a medical examination. All patients were injected with betamethasone mixed with lidocaine. Surgical release of the A1 pulley was performed at the patients' request if steroid injection therapy was not effective. Pain and snapping were relieved in 98% and 74% of cases, respectively. Recurrence occurred in about half our patients, but the same clinical benefit was obtained after re-injection. Surgery was performed for seven fingers. No complications of steroid injections were observed. This study suggests that extrasynovial steroid injection is a valuable conservative treatment for trigger finger and it is not necessary to try and inject into the tendon sheath to get a good result and markedly reduce the risk of causing damage to tendons and other structures.

Differentiation-dependent expression of I and sialyl I antigens in the developing lung of human embryos and in lung cancers.

The localization of two carbohydrate antigens, I and sialyl I antigens, in the lungs of developing human embryos was investigated using specific monoclonal antibodies and compared with the distribution patterns of the known embryonic antigen, stage-specific embryonic antigen-1 (Lex hapten). When the future bronchi were actively developing from the bronchial buds in the lungs of 50- to 53-day-old embryos, the immature bronchial bud cells were I-, Lex+, while the fully differentiated epithelial cells of the larger bronchus were I+, Lex-. When the bronchiolar bud cells matured into bronchiolar epithelial cells in the lung of a 12-week-old embryo, the immature bronchiolar bud cells were I-,Lex+, while the fully differentiated epithelial cells of the bronchioles were I+,Lex-. Sialylated forms of the antigens finally appeared in the lungs of 18-week-old embryos, when the terminal bud cells actively proliferated and underwent the differentiation process into epithelial cells of alveoli and alveolar ducts. The immature terminal bud cells at this stage were I-, sialyl I-, Lex+, sialyl Lex-i+, while the fully differentiated alveolar epithelial cells were I+, sialyl I+, Lex-, sialyl Lex-i-. After 8 months, the flattened mature alveolar epithelial cells were strongly positive for both I and sialyl I antigens, the strong expression of which continued after birth and even into the adult stage. These distribution patterns indicate that the I and sialyl I antigens are specific markers for the differentiated type cells in each stage of development, while Lex and related embryonic antigens were specific to the immature bud cells in every stage. The above-described differentiation-dependent expression patterns of these antigens seem to be reflected in the distribution of these antigens in human lung cancers, i.e., I and sialyl I antigens were expressed in lung cancer cells more weakly than in normal lung cells, while the Lex and sialyl Lex-i were expressed in cancer cells much more strongly than in normal lung cells. This was further reflected in the serum levels of these antigens in the patients with respiratory disorders. The distribution pattern of the serum levels of these antigens in patients with lung cancers showed sialyl Lex-i greater than sialyl I, indicating that these serum antigens originated from the lung cancer lesion where sialyl Lex-i is much more dominant than sialyl I antigen.(ABSTRACT TRUNCATED AT 400 WORDS)

Synthetic biodegradable polymers as drug delivery systems for bone morphogenetic proteins.

Bone morphogenetic proteins (BMP) induce bone formation in vivo, and clinical application in repair of bone fractures and defects is expected. However, appropriate systems to deliver BMP for clinical use need to be developed. We synthesized a new synthetic biodegradable polymer, poly-D,L-lactic acid-para-dioxanone-polyethylene glycol block copolymer (PLA-DX-PEG), to serve as a biocompatible, biodegradable polymer for recombinant human (rh) BMP-2 delivery systems. In animal experiments, new bone was efficiently formed and a large bone defect was repaired using PLA-DX-PEG/rhBMP-2 composites. In addition, this new polymer could be used as an injectable delivery system for rhBMP-2. The rhBMP-2/PLA-DX-PEG composites also could be combined with other materials such as hydroxyapatite or titanium. This new synthetic polymer might be used for rhBMP-2 delivery in various clinical situations involving repair of bone, leading to great changes in orthopedic treatment.

Blocking effect of verapamil on conduction over a catecholamine-sensitive bypass tract in exercise-induced Wolff-Parkinson-White syndrome.

By intravenous administration of isoproterenol, 0.5 micrograms/min, a catecholamine-sensitive bypass tract was confirmed in two patients with exercise-induced Wolff-Parkinson-White syndrome. In a 24 year old woman, an intravenous bolus injection of 5 mg of verapamil suddenly blocked conduction over a catecholamine-sensitive bypass tract. In a 62 year old man, the exercise-induced Wolff-Parkinson-White syndrome disappeared after 3 days of oral administration of verapamil (120 mg/day). These observations suggest that a slow inward calcium current plays an important role in conduction over a catecholamine-sensitive bypass tract in exercise-induced Wolff-Parkinson-White syndrome.

TNF-alpha and IL-1beta suppress N-cadherin expression in MC3T3-E1 cells.

Excessive production of tumor necrosis factor (TNF) and interleukin-1 (IL-1) secondary to estrogen deficiency have been implicated as the cause of osteoporosis in postmenopausal woman. These cytokines appear to stimulate osteoclast precursor proliferation and activate mature osteoclast formation directly and possibly indirectly via osteoblasts. To investigate the other possible roles that these cytokines may play in stimulating the bone resorption process, we examined the effect of TNF-alpha and IL-1beta on cell-cell adhesion molecules, cadherins, in osteoblastic MC3T3-E1 cells. In this study, we investigated cadherin expression and the effect of TNF-alpha, IL-1beta, and parathyroid hormone (PTH) on the expression of cadherins in MC3T3-E1 cells. Confluent cultures of MC3T3-E1 cells were challenged with recombinant human TNF-alpha (1-100 U/ml), recombinant human IL-1beta (1-100 ng/ml) and human PTH(1-34) (1-100 ng/ml), respectively. The results show that MC3T3-E1 cells express functional cadherin molecules, N-cadherin and OB-cadherin. TNF-alpha (10-100 U/ml) and IL-1beta (10-100 ng/ml) suppressed N-cadherin without changing OB-cadherin expression, while PTH (1-100 ng/ml) had no effect on cadherin expression. These results raise the possibility that TNF-alpha and IL-1beta may compromise the cell-cell adhesion of osteoblasts which cover the bone surface. The ensuing compromised cell-cell adhesion of osteoblasts may in turn facilitate the direct adhesion of osteoclasts on the calcified bone matrix surface. These results implicate an indirect role for osteoblasts in the promotion of bone resorption by TNF-alpha and IL-1beta.

Bone mineral density in the proximal femur and hip fracture type in the elderly.

Bone mineral density (BMD) in the contralateral proximal femur in 100 female elderly patients with hip fracture and the 35 controls without hip fracture were investigated using dual-photon absorptiometry. The hip fracture patients were divided into intracapsular fracture (n = 53) and extracapsular fracture (n = 47) groups, and these two groups were further divided into five subgroups according to fracture site: intracapsular fracture type 1 (transcervical fracture, n = 29) and type 2 (subcapital fracture, n = 24); extracapsular fracture type 1 (intertrochanteric line fracture, n = 13), type 2 (pertrochanteric fracture, n = 28), and type 3 (combined type of pertrochanteric and subtrochanteric fracture, n = 6). The intracapsular fracture group showed BMD values similar to those of controls; the extracapsular fracture group showed significantly lower BMD values than controls. When these two were subclassified into five subgroups, different results were seen in terms of BMD value in the proximal femur and fracture types; intracapsular fracture type 1 showed BMD values equivalent to those of controls; on the other hand, type 2 showed significantly lower BMD value than controls, and the BMD distribution in the proximal femur among the extracapsular fracture subgroups 1-3 differed, although all of them showed significantly lower BMD values than controls. The degree of trauma causing the fractures was also assessed according to available anamnestic data, but no significant difference was found in trauma tendency between the intra- and the extracapsular fracture group or among the subgroups in each group.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone morphogenetic protein 2 stimulates osteogenesis but does not affect chondrogenesis in osteochondrogenic differentiation of periosteum-derived cells.

The effects of recombinant human bone morphogenetic protein 2 (rhBMP-2) on osteochondrogenesis were examined in high-density cultures of periosteum-derived cells, which have the potential to differentiate into bone and hypertrophic cartilage in vitro. Proliferation of these cells was inhibited by treatment with rhBMP-2. The time course for alkaline phosphatase (ALP) expression was shortened and the mineralization of the culture was increased by supplementation with rhBMP-2. These stimulatory effects of rhBMP-2 were observed at doses of 10-100 ng/m. Bone Gla protein (BGP) was immunocytochemically detectable earlier in the culture treated with rhBMP-2, and the BGP-positive layer of the rhBMP-2-treated cultures was thicker than that of the control cultures. On the other hand, there was no difference in uronic acid content or the time course of alpha 1(II) collagen mRNA expression between the rhBMP-2-treated and the control cultures. These results indicate that rhBMP-2 shortens the time course of osteogenesis and increases the amount of bone formation, whereas chondrogenesis remains unaffected.

Colocalization of noggin and bone morphogenetic protein-4 during fracture healing.

The regulation of callus formation during fracture repair involves the coordinate expression of growth factors and their receptors. This article describes the temporal and spatial expression of noggin gene, an antagonist to bone morphogenetic protein (BMP), during the fracture repair process. Noggin expression was examined by means of Northern blotting and in situ hybridization and compared with the expression pattern of BMP-4 in a model of fracture repair in adult mice. Expression levels of noggin messenger RNA (mRNA) were enhanced in the early phase of fracture callus formation. The localization of the noggin mRNA was similar to that of BMP-4 mRNA. Distinct noggin mRNA signals were located predominantly in cells lining the periosteum and the cortical endosteum near the fracture site at 2 days after fracture. At 5, 10, and 21 days after fracture, noggin mRNA was detected in the chondrocytes and osteoblasts in the newly formed callus. The pattern of localization was indistinguishable from that of BMP-4. These results suggest that the noggin/BMP-4 balance could be an important factor in the regulation of callus formation during fracture healing.

Transient and localized expression of bone morphogenetic protein 4 messenger RNA during fracture healing.

Temporal and spatial distribution of a gene encoding murine bone morphogenetic protein 4 (mBMP-4) during fracture repair were investigated in mice by RT-PCR and in situ hybridization. For in situ hybridization, fractured ribs and surrounding tissues were decalcified and hybridized with a mBMP-4-specific complementary RNA probe labeled with digoxigenin-11 UTP. mBMP-4 messenger RNA (mRNA) was not detected in ribs without fracture, whereas it was detected only in the early phase of fracture from 12 to 72 h after the onset of fracture before new cartilage or bone formation. The mBMP-4 mRNAs were present in cells distributed in three distinct regions, namely, the proliferating periosteum, the medullary cavity, and the muscles near the fracture site. These BMP-4-positive cells did not express bone gla protein mRNA, which is a marker of the mature osteogenic cell. RT-PCR also showed a transient increase in the level of BMP-4 mRNA in the early phase of fracture repair. The findings provide us with some new information. (1) The BMP-4 gene is produced by less differentiated osteoprogenitor cells, not by differentiated osteoblasts. (2) The BMP-4 gene is enhanced by the impact of fracture and localized in callus-forming tissue before callus formation. Together with the activities of BMP-4, as was previously described, our results suggest that newly produced BMP-4 gene product is one of the local contributing factors in callus formation in the early phase of fracture healing.

23(S),25(R)-1,25-dihydroxyvitamin D3-26,23-lactone stimulates murine bone formation in vivo.

23(S),25(R)-1,25-Dihydroxyvitamin D3-26,23-lactone (1,25-lactone) has been shown to have unique actions different from those of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. In contrast to 1,25-(OH)2D3, 1,25-lactone causes a significant reduction in the serum Ca2+ level, stimulates collagen production in an osteoblastic cell line, and inhibits bone resorption induced by 1,25-(OH)2D3. A possible effect of 1,25-lactone on bone formation was examined in experiments on ectopic bone formation using a bone-inducing factor derived from Dunn osteosarcomas. 1,25-Lactone, a metabolite of 1,25-(OH)2D3, increased [3H]proline uptake at the stage of chondrogenesis and 85Sr uptake during bone formation. Significantly enlarged bone was also induced by this compound 3 weeks after implantation. These results suggest that the 1,25-lactone may be able to stimulate bone formation under in vivo conditions.

Acid solutions enhance bone-inducing activity of a murine osteosarcoma.

Heterotopic osteogenesis induced by lyophilized powder of a murine osteosarcoma was greatly enhanced by treating the powder with the following acids: 0.01 N HCl (pH 2.0), 0.1 N HCl (pH 1.7), 1 N HCl (pH 1.2), 0.5 M acetic acid (pH 2.8), 0.5 M lactic acid (pH 2.0), and 0.5 M citric acid (pH 1.8). The acid-treated preparations were neutralized before implantation into back muscles of ddY mice. Acid treatment resulted in almost a fivefold increase in the amount of new bone formation, as measured by uptake of strontium-85 into the implants. In addition bone-inducing activity was increased by longer exposure to 0.01 N HCl up to 24 h. These findings suggest that the bone-inducing activity of the osteosarcoma is enhanced by various acids below pH 2.8. A possible role for hydrogen ion concentration in the regulation of osteogenesis is discussed.