Daily or monthly ibandronate prevents or restores deteriorations of bone mass, architecture, biomechanical properties and markers of bone turnover in androgen-deficient aged rats.

AIM: The aim of this study was to investigate the effects of the bisphosphonate ibandronate (IBN) in a male osteoporosis animal model. METHODS: Two studies were performed in 9-month-old orchidectomised (ORX) or sham-operated rats. In prevention study, subcutaneous IBN was administered daily (1 µg/kg) or monthly (28 µg/kg every 28 days) starting on day of surgery for 5 months. In treatment study, the same treatment started 6 months after ORX. After sacrifice, bone analyses by dual-energy X-ray absorptiometry, 3-dimensional micro-computed tomography, and 3-point bending were performed in femora or vertebrae. Serum tartrate-resistant acid phosphatase 5b (TRAP-5b) and aminoterminal propeptide of collagen I (PINP) were analysed for resorption and osteocalcin (BGP) for bone formation. RESULTS: In both studies, ORX resulted in significant femoral and vertebral bone loss and microarchitectural deterioration after 5 months of ORX, and became more pronounced after 11 months. Biomechanical strength was also decreased. Serum levels for TRAP-5b and BGP increased while PINP levels were reduced or unchanged. Both daily and monthly IBN prevented or even restored ORX-induced changes in both studies, with the intermittent regimen showing a improvement in efficacy with respect to many of the biomechanical parameters.

Inhibition of osteolytic bone metastasis of breast cancer by combined treatment with the bisphosphonate ibandronate and tissue inhibitor of the matrix metalloproteinase-2.

Multiple steps are involved in the metastasis of cancer cells from primary sites to distant organs. These steps should be considered in the design of pharmacologic approaches to prevent or inhibit the metastatic process. In the present study, we have compared the effects of inhibiting several steps involved in the bone metastatic process individually with inhibition of both together. The steps we chose were matrix metalloproteinase (MMP) secretion, likely involved in tumor cell invasion, and osteoclastic bone resorption, the final step in the process. We used an experimental model in which inoculation of human estrogen-independent breast cancer MDA-231 cells into the left cardiac ventricle of female nude mice causes osteolytic lesions in bone. To inhibit cancer invasiveness, the tissue inhibitor of the MMP-2 (TIMP-2), which is a natural inhibitor of MMPs, was overexpressed in MDA-231 cells. To inhibit bone resorption, a potent bisphosphonate, ibandronate (4 microg/mouse) was daily administered subcutaneously. Nude mice received either; (a) nontransfected MDA-231 cells; (b) nontransfected MDA231 cells and ibandronate; (c) TIMP-2-transfected MDA-231 cells; or (d) TIMP-2-transfected MDA-231 cells and ibandronate. In mice from group a, radiographs revealed multiple osteolytic lesions. However, in mice from group b or group c, osteolytic lesions were markedly decreased. Of particular note, in animals from group d receiving both ibandronate and TIMP-2-transfected MDA-231 cells, there were no radiologically detectable osteolytic lesions. Survival rate was increased in mice of groups c and d. There was no difference in local enlargement in the mammary fat pad between nontransfected and TIMP-2-transfected MDA-231 cells. These results suggest that inhibition of both MMPs and osteoclastic bone resorption are more efficacious treatment for prevention of osteolytic lesions than either alone, and suggest that when therapies are designed based on the uniqueness of the bone microenvironment and combined with several common steps in the metastatic process, osteolytic bone metastases can be more efficiently and selectively inhibited.

Effects of ibandronate on bone quality: preclinical studies.

Osteoporosis is a skeletal disorder characterized by low bone mass and deterioration of bone microarchitecture resulting in bone fragility, which increases the risk of fracture. The clinical efficacy of bisphosphonates is evaluated through improvements in bone mineral density (BMD) and reductions in the risk for fracture. However, as bisphosphonates are administered long term, there is increasing interest in their effects on bone quality, which includes bone mass, strength and architecture. Ibandronate is a potent, nitrogen-containing bisphosphonate with significant antifracture efficacy when administered daily and in regimens with extended between-dose intervals. Clinical studies with ibandronate are supported by an extensive preclinical program that investigated the efficacy and bone safety of ibandronate in various animal models of osteoporosis. In preclinical studies, treatment with ibandronate maintained, or improved the quality, strength and architecture of bone. Intermittent and daily ibandronate regimens provided similar benefits. During ibandronate treatment, the bone retains its capacity for repair and bone mineralization is not adversely affected. Notably, positive relationships among BMD, bone strength and bone architecture have been demonstrated. This review describes the preclinical evidence for the preservation of bone quality with ibandronate, irrespective of the dosing regimen and even when administered at doses higher than those used therapeutically.

Ibandronate treatment reverses glucocorticoid-induced loss of bone mineral density and strength in minipigs.

The Göttingen minipig is one of the few large animal models that show glucocorticoid (GC)-induced bone loss. We investigated whether GC-induced loss of bone mineral density (BMD) and bone strength in minipigs can be recovered by treatment with the bisphosphonate ibandronate (IBN). 40 primiparous sows were allocated to 4 groups when they were 30 months old: GC treatment for 8 months (GC8), for 15 months (GC15), GC treatment for 15 months plus IBN treatment for months 8-15 (GC&IBN), and a control group without GC treatment. Prednisolone was given at a daily oral dose of 1 mg/kg body weight for 8 weeks and thereafter 0.5 mg/kg body weight. IBN was administered intramuscularly and intermittently with an integral dose of 2.0 mg/kg body weight. BMD of the lumbar spine (L1-3) was assessed in vivo by Quantitative Computed Tomography (QCT) at months 0, 8, and 15. Blood and urine samples were obtained every 2-3 months. After sacrificing the animals lumbar vertebrae L4 were tested mechanically (Young's modulus and ultimate stress). Histomorphometry was performed on L2 and mineral content determined in ashed specimens of T12 and L4. In the GC&IBN group, the GC associated losses in BMD of -10.5%+/-1.9% (mean+/-standard error of the mean, p<0.001) during the first 8 months were more than recovered during the following 7 months of IBN treatment (+14.8%+/-1.2%, p<0.0001). This increase was significantly larger (p<0.0001) than the insignificant +2.1%+/-1.2% change in group GC15. At month 15, the difference between groups GC&IBN and GC15 was 22% (p<0.01) for BMD, 48% (p<0.05) for Young's modulus, and 31% (p<0.14) for ultimate stress; bone-specific alkaline phosphatase showed trends to lower values (p<0.2) while deoxypyridinoline was comparable. This minipig study demonstrates that GC-induced impairment of bone strength can be effectively and consistently treated by IBN. GC&IBN associated alterations in BMD and bone turnover markers can be monitored in vivo using QCT of the spine and by biochemical analyses, reflecting the changes in bone strength.

The bisphosphonate ibandronate improves implant integration in osteopenic ovariectomized rats.

Osteoporosis is known to impair the process of implant osseointegration. Bisphosphonates are drugs that inhibit osteoclast-mediated bone resorption and normalize the high rate of bone turnover that characterizes this disease. Consequently, there is a rationale for using bisphosphonates to enhance the early stabilization of implants in subjects with low bone mass. In this study, 84 rats received titanium-only or hydroxyapatite (HA)-coated titanium femoral implants, 3 months after being ovariectomized (OVX) or sham operated. They were then treated for 4 weeks. The OVX rats were randomly assigned to daily subcutaneous injections of either saline or the bisphosphonate ibandronate (at a dose of 1 microg/kg or 25 microg/kg), while the sham-operated animals received saline throughout. The 1 microg/kg or 25 microg/kg ibandronate doses are considered translatable to doses used to treat osteoporosis and metastatic bone disease (MBD), respectively, in rats, and roughly reflect those used in humans. At the end of the treatment period, bone mineral density (BMD) at the lumbar spine increased in both of the ibandronate-treated groups when compared with the OVX control animals and to a level similar to that of the sham-operated control group. Osseointegration, determined by histomorphometric analysis and expressed as percentage of osseointegration implant surface (OIS), did not differ between groups for the titanium-only implants. For the HA-coated implants, however, OIS was 113.5% and 185% higher in the groups receiving 1 microg/kg or 25 microg/kg ibandronate, respectively, relative to the OVX controls. In turn, the OIS of the HA-coated implants was 56.5% lower in the OVX control group than in the sham control group. These findings clearly demonstrate that OVX-induced osteopenia impairs the osseointegration of HA-coated titanium implants and that ibandronate, administered at doses analogous to those used to clinically treat osteoporosis and MBD, counters this harmful effect. Ibandronate may, therefore, have a role in improving the osseointegration of implants in patients with osteoporosis and MBD.

BM 21.0955, a potent new bisphosphonate to inhibit bone resorption.

A total of 300 new bisphosphonates were screened for their effect on bone resorption in the rat. Among these, 1-hydroxy-3-(methylpentylamino)propylidenebisphosphonate (BM 21.0955) was selected for detailed investigation. It inhibited arotinoid-stimulated bone resorption as assessed by calcemia in thyroparathyroidectomized rats at a SC dose as low as 0.001 mg P (0.016 mumol) per kg body weight per day. The compound was thus about 2, 10, 50, and 500 times more potent than risedronate, alendronate, pamidronate, and clodronate, respectively. Intravenous administration was as effective as subcutaneous, and oral administration was 100 times less effective. The effect after one administration decreased with time but was still measurable after 2 weeks. Nonstimulated bone resorption assayed by the urinary excretion of radiolabeled tetracycline from lifelong prelabeled animals was also inhibited. This effect started 3 days after a single dose and was still maximal after 7 days. Histomorphometric analysis of the tibial metaphysis in growing intact rats also showed an inhibition of bone resorption along with an increase in bone mass. The number of osteoclasts increased in animals treated with 0.01 and 0.1 mg P per kg (0.16 and 1.6 mumol/kg) body weight SC but decreased in animals given 1 mg P per kg (16.1 mumol/kg), showing that the inhibition of bone resorption was not due to an inhibition of osteoclast recruitment. No inhibition of mineralization occurred. This new bisphosphonate appears to have great potential for use in human bone disease.

A new bisphosphonate, BM 21.0955, prevents bone loss associated with cessation of ovarian function in experimental dogs.

We previously found that bone loss occurs as soon as 1 month after ovariohysterectomy (OHX) in beagle dogs. Indirect evidence pointed to an early dramatic increase in bone resorption. To verify this hypothesis and evaluate the effects of a newly developed bisphosphonate, BM 21.0955 (Boehringer Mannheim), 36 beagle dogs were subjected to OHX and 12 dogs were sham operated (Sham). OHX dogs were divided into six groups (n = 6 each) and received subcutaneous injections of vehicle or BM 21.0955 at various doses (0.1, 0.3, 1, 10, and 100 micrograms/kg/day) for 1 month. Sham dogs were given vehicle (n = 6) or BM 21.0955 (1 microgram/kg/day, n = 6). Iliac crest biopsies and blood drawings were done at baseline and at month 1. OHX dogs given vehicle exhibited a decrease in cancellous bone volume associated with an increase in erosion depth and a decrease in serum levels of 1,25-dihydroxyvitamin D. BM 21.0955 prevented the bone loss at a dose > or = 1 microgram/kg and the increase in erosion depth and the decrease in serum levels of 1,25-(OH)2D at a dose > or = 0.3 microgram/kg. No osteomalacia was observed at any dose of BM 21.0955. Bone turnover was reduced only when BM 21.0955 was administered at doses of 10 or 100 micrograms/kg. There were no changes in body weight or serum levels of calcium, phosphorus, creatinine, parathyroid hormone, or osteocalcin in all groups. The increase in erosion depth in OHX dogs given vehicle proves that the early rapid bone loss after cessation of ovarian function is related to an increase in osteoclastic activity. The antiosteoclastic activity of BM 21.0955 at a dose > or = 1 microgram/kg prevents this increase and preserves bone volume. The absence of any signs of osteomalacia at any dose confers a relatively wide therapeutic margin to BM 21.0955. BM 21.0955 at a dose > or = 10 micrograms/kg also acts as an inhibitor of bone turnover. This is not observed at a dose of 1 microgram/kg, at least after 1 month of administration.

Intermittent and continuous administration of the bisphosphonate ibandronate in ovariohysterectomized beagle dogs: effects on bone morphometry and mineral properties.

Bisphosphonates have emerged as a valuable treatment for postmenopausal osteoporosis. Bisphosphonate treatment is usually accompanied by a 3-6% gain in bone mineral density (BMD) during the first year of treatment and by a decrease in bone turnover. Despite low bone turnover, BMD continues to increase slowly beyond the first year of treatment. There is evidence that bisphosphonates not only increase bone volume but also enhance secondary mineralization. The present study was conducted to address this issue and to compare the effects of continuous and intermittent bisphosphonate therapy on static and dynamic parameters of bone structure, formation, and resorption and on mineral properties of bone. Sixty dogs were ovariohysterectomized (OHX) and 10 animals were sham-operated (Sham). Four months after surgery, OHX dogs were divided in six groups (n = 10 each). They received for 1 year ibandronate daily (5 out of 7 days) at a dose of 0, 0.8, 1.2, 4.1, and 14 microg/kg/day or intermittently (65 microg/kg/day, 2 weeks on, 11 weeks off). Sham dogs received vehicle daily. At month 4, there was a significant decrease in bone volume in OHX animals (p < 0.05). Doses of ibandronate >/= 4.1 microg/kg/day stopped or completely reversed bone loss. Bone turnover (activation frequency) was significantly depressed in OHX dogs given ibandronate at the dose of 14 microg/kg/day. This was accompanied by significantly higher crystal size, a higher mineral-to-matrix ratio, and a more uniformly mineralized bone matrix than in control dogs. This finding lends support to the hypothesis that an increase in secondary mineralization plays a role in gain in BMD associated with bisphosphonate treatment. Moreover, intermittent and continuous therapies had a similar effect on bone volume. However, intermittent therapy was more sparing on bone turnover and bone mineral properties. Intermittent therapy could therefore represent an attractive alternative approach to continuous therapy.

Inhibition of bone resorption by the bisphosphonate BM 21.0955 is not associated with an alteration of the renal handling of calcium in rats infused with parathyroid hormone-related protein.

Hypercalcaemia of malignancy is determined by an increase of bone resorption and/or renal tubular reabsorption of calcium (Ca). However, this latter component has been found to vary in certain patients during therapy with bone resorption inhibitors such as bisphosphonates. We investigated the possible effects of the highly potent bisphosphonate BM 21.0955 on the renal handling of Ca in thyroparathyroidectomized rats made hypercalcaemic by the stimulation of both bone resorption and renal tubular reabsorption of Ca induced by the chronic infusion of parathyroid hormone-related protein (PTHrP). Dose-dependent inhibition of bone resorption by BM 21.0955, as indicated by the decrease in fasting urinary Ca excretion from 64.0 +/- 7.3 to 6.7 +/- 3.1 nmol/ml GFR, was associated with a change in plasma Ca from 2.97 +/- 0.10 to 2.63 +/- 0.16 mmol/l. However, the relationship between urinary Ca excretion and plasma Ca was not altered, either at endogenous plasma Ca concentration or during the acute infusion of Ca. Similarly, an index of renal tubular reabsorption of Ca calculated from the slope of the linear portion of the relationship between urinary Ca and plasma Ca, which was increased by PTHrP administration, was not influenced by BM 21.0955 therapy (2.59 +/- 0.15 vs. 2.55 +/- 0.11 mmol/l GFR). These results indicate that BM 21.0955, which is one of the most potent bisphosphonates inhibiting bone resorption, did not affect the renal tubular reabsorption of Ca enhanced by PTHrP.

Association between histomorphometry and biochemical markers of bone turnover in a longitudinal rat model of parathyroid hormone-related peptide (PTHrP)-mediated tumor osteolysis.

Advanced tumor osteopathy is characterized by abnormal bone turnover. Using a rat model of parathyroid hormone-related peptide (PTHrP)-mediated tumor osteolysis, the aim of the present study was to define the sequential changes in, and the association between, biochemical and histomorphometric indices of bone metabolism during the early stages of developing tumor osteopathy. Eight-month-old Wistar rats (n = 48) were subcutaneously inoculated with either 2 x 10(6) cells of the Walker carcinosarcoma 256, or saline on day 0, and treated with either saline or the bisphosphonate ibandronate until killing on day 8. Serum calcium (sCa), alkaline phosphatase (sTAP), and osteocalcin (sOC) and urinary calcium (uCa), deoxypyridinoline (uDPD), and pyridinoline (uPYD) were measured daily. In a second semilongitudinal experiment (n = 70), the number of osteoclasts and osteoblasts (N.Oc, N.Ob), trabecular bone volume (BV/TV), and osteoid volume (O.Ar) were assessed by histomorphometry. In untreated tumor-bearing animals, osteoclast numbers increased by 74% on day 3 (5.4 +/- 2.4 vs. 3.1 +/- 1.5/mm(2), p < 0.05), and trabecular bone volume fell by 24% on day 4 (12.5 +/- 2.0 vs. 15.8 +/- 1.2%, p < 0.05). Both time course and magnitude of these changes were closely reflected by an increase in uDPD (0.46 +/- 0.14 vs. 0. 31 +/- 0.15 nmol/12 h, p < 0.05) and uPYD on day 4 (1.44 +/- 0.25 vs. 1.03 +/- 0.3 nmol/12 h, p < 0.05), sCa (3.8 +/- 0.52 vs. 3.0 +/- 0. 13 mmol/L, p < 0.01), and uCa (0.13 +/- 0.08 vs. 0.03 +/- 0.01 mmol/12 h, p < 0.001) on day 6, and sTAP (254 +/- 127 vs. 120 +/- 40 U/L, p < 0.001) on day 7 (mean +/- SD), whereas sOC remained unchanged until day 8. When combining the results of the two experiments, a high correlation was found between the number of osteoclasts and the urinary excretion of PYD (r = 0.91) and DPD (r = 0.89). Treatment with ibandronate delayed hypercalcemia, abolished hypercalciuria, and accelerated bone resorption. We conclude that osteoclast activation is an early event in PTHrP-mediated osteolysis, which is closely reflected by the renal excretion of pyridinium cross-links of type I collagen. Therefore, specific biochemical markers of collagen breakdown may be useful as early indicators of developing tumor osteopathy.

Intermittent intravenous administration of the bisphosphonate ibandronate prevents bone loss and maintains bone strength and quality in ovariectomized cynomolgus monkeys.

Using a clinically relevant regimen, this study investigated the effects of treatment with ibandronate, a highly potent nitrogen-containing bisphosphonate, on bone loss, biochemical markers of bone turnover, densitometry, histomorphometry, biomechanical properties, and bone concentration in aged ovariectomized monkeys. Sixty-six female cynomolgus monkeys, aged 9 years and older, were ovariectomized (OVX) or sham operated. Intravenous (iv) bolus injections of ibandronate at 10, 30, or 150 microg/kg or placebo were administered at 30-day intervals (corresponding to intervals of 3 months in humans), starting at OVX, for 16 months. OVX significantly decreased bone mass at the lumbar spine, proximal femur, femoral neck, and radius and increased bone turnover in a time-dependent manner, as assessed by dual energy X-ray absorptiometry, peripheral quantitative computed tomography, or histomorphometry. Ibandronate iv bolus injections administered at 30 microg/kg every 30 days prevented osteopenia induced by estrogen depletion. OVX-induced increases in bone turnover (as determined by activation frequency, bone formation rate, and biochemical markers of bone turnover, including urinary N-telopeptide and deoxypyridinoline excretion and serum values for osteocalcin and bone-specific alkaline phosphatase) were suppressed on treatment, and bone mass, architecture, and strength were preserved at clinically relevant sites. Treatment with high-dose (150 microg/kg/dose) iv bolus injections of ibandronate further increased bone mass and improved bone strength at both the spine and femoral neck, without adversely affecting bone quality. In contrast, treatment with a 10 microg/kg/dose only partially prevented the OVX-induced effects. These data support the potential for the long-term administration of ibandronate by intermittent iv bolus injections in humans to prevent osteoporosis and improve bone quality at clinically relevant sites.

Ibandronate treatment decreases the effects of tumor-associated lesions on bone density and strength in the rat.

Bisphosphonate treatment is beneficial against symptoms of metastatic bone disease, although less is known about the effect of preventative treatment schedules. We investigated the effect of various treatment regimens of the bisphosphonate, ibandronate (IB), on the preservation of bone quality in a rat model of tumor-induced osteolysis. Osteolytic Walker 256 (W256) carcinosarcoma cells were implanted into the left femur of female Sprague-Dawley rats, resulting in a 10% reduction in bone mineral density (BMD), a 16% reduction in bone density (BD), and a 26% reduction in failure load compared with the right femur 28 days after implantation. IB was administered subcutaneously in five different treatment schedules: (1) IB PRE-POST received IB for 26 days, prior to implantation of W256 cells in the medullary canal of the femur, and for 28 additional days after surgery; (2) IB PRE-POST SHAM received the same IB administration, but with a sham operation; (3) IB PRE received IB injections before W256 cell insertion only; (4) IB PRE-0 received IB injections for 26 days and was then killed to serve as a time zero control; and (5) IB POST received sham injection with saline before W256 cell insertion, and then received IB injections for 28 days until killing. Controls (TUMOR ONLY) received sham injections with saline prior to W256 cell insertion, and then for 28 additional days until killing. We used dual-energy X-ray absorptiometry (DXA) to measure distal femur BMD and bone mineral content (BMC), peripheral quantitative computed tomography (pQCT) to measure distal femur BD, and torsion testing to obtain torsional failure load. Combined preventative and interventional IB treatment best preserved bone mass and strength, although all treatment schedules resulted in significant improvement compared with untreated controls (TUMOR ONLY). The possibility of reducing or even preventing skeletal morbidity in cancer patients with a high risk of developing metastatic spreading to bone is exciting, and warrants further exploration.

Effects of estrogen on the concentration of insulin-like growth factor-I in rat bone matrix.

Insulin-like growth factor-I (IGF-I) plays an important role in bone metabolism, but data on the regulation of IGF-I in bone tissue in vivo are still limited. In the present study, we examined the effects of ovariectomy (ovx) and estrogen replacement on the skeletal concentration of IGF-I in the femur shaft of 6-10 week-old female rats. Ovx had no consistent effect on bone matrix IGF-I concentration regardless of animal age at ovx. In contrast, administration of estradiol in doses that exceeded physiological replacement (50 and 150 nmol/kg per day, subcutaneously) significantly increased the bone matrix IGF-I concentration. These are the first in vivo data which demonstrate that estrogens are capable of increasing the concentration of IGF-I in bone tissue. However, this stimulatory effect appears to be limited to supraphysiological estrogen concentrations.

The complex of recombinant human insulin-like growth factor-I (rhIGF-I) and its binding protein-5 (IGFBP-5) induces local bone formation in murine calvariae and in rat cortical bone after local or systemic administration.

The influence of recombinant human insulin-like growth factor-I (rhIGF-I), its binding protein-5 (IGFBP-5) or their equimolar complexes on calvarial osteogenesis was investigated by quantitative radiography and histomorphometry after local administration to adult mice or mature rats. The systemic effects of these proteins were investigated in aged Sprague-Dawley rats with regard to their ability to prevent or restore bone mass in ovariectomy induced osteopenia as assessed by radiography, dual-energy X-ray absorptiometry (DEXA) analyses, peripheral computerized tomography (pQCT) and mineral analyses after daily s.c. administration for 3 or 8 weeks following a bone depletion period of 8 weeks. Bone mass of murine calvariae was significantly increased in a dose-dependent manner by the complex 7 days after discontinuation of local administration for 19 days in mice, whereas IGF-I alone expressed only weak effects. IGFBP-5 alone was ineffective in this respect. In the same model, only the complex had a weak osteogenetic potential in 7 week or 5 month old rats. Systemic long-term treatment with the complex of rhIGF-I/IGFBP-5 (2.0/7.6 mg/kg/day, s.c.) for 8 weeks resulted in significantly increased cortical thickness, area and mineral density in femoral midshaft or tibial metaphysis suggesting periosteal bone formation. This was obviously related to increased muscle strength since these effects were parallelled by increased body weight. No effect on trabecular bone occurred as demonstrated by site-specific analyses (vertebrae, proximal tibia) using DEXA, pQCT and radiography. This selective action of rhIGF-I/IGFBP-5 on periosteal bone formation is unique for an IGFBP. Femoral ash and calcium content, both corrected for tissue volume, increased slightly. However, when the increase in cortical thickness and bone mass was corrected for bone size, the effects are nearly abolished, suggesting an additional effect of bone growth. This potential deserves further evaluation in order to differentiate between effects on cortical bone via muscle strength and lack of efficacy on trabecular bone balance.

Short-term administration of the bisphosphonate ibandronate increases bone volume and prevents hyperparathyroid bone changes in mild experimental renal failure.

BACKGROUND: Bisphosphonates (BP) are potent antiresorptive agents that have been used successfully in several bone diseases associated with hyperresorption. Hyperresorption, hypercalcemia, and osteoporosis are frequent findings in patients with renal failure or after renal transplantation. The present study was carried out to determine the effects of a new BP, ibandronate, on bone in a state of normal vs. moderately impaired renal function. MATERIAL AND METHODS: Forty 90-day-old female rats were either 2/3 nephrectomized (Nx, n = 20) or sham-operated (Sham, n = 20). Half of the Nx and Sham rats received either ibandronate (1.25 microg/rat s.c.) or vehicle once weekly for three weeks. Before euthanasia, blood drawings were performed and 24-hr urine was collected. Femurs were analyzed by bone histomorphometry. RESULTS: Serum creatinine, parathyroid hormone, and osteocalcin levels were equally higher in Nx rats given ibandronate or vehicle than in Sham rats. There was no difference in serum calcium, phosphorus, alkaline phosphatase, and urinary creatinine among the groups. Ibandronate-treated rats had lower urinary calcium and deoxypyridinoline crosslink levels than their Sham counterparts. Ibandronate-treated rats had higher bone volume than vehicle-treated animals. Ibandronate prevented the increase in erosion depth and bone turnover in Nx rats. CONCLUSIONS: BPs such as ibandronate represent potentially useful tools in the treatment of certain facets of renal bone disease. Indications for BP therapy may include treatment of osteoporosis, hypercalcemia, and/or extraosseous calcifications. Optimal dose and frequency of BP administration need to be determined in these patients.

Treatment with ibandronate preserves bone in experimental tumour-induced bone loss.

Cancer-induced bone diseases are often associated with increased bone resorption and pathological fractures. In recent years, osteoprotective agents such as bisphosphonates have been studied extensively and have been shown to inhibit cancer-related bone resorption in experimental and clinical studies. The third-generation bisphosphonate, ibandronate (BM 21.0955), is a potent compound for controlling tumour osteolysis and hypercalcaemia in rats bearing Walker 256 carcinosarcoma. We have studied the effect of ibandronate given as an interventional treatment on bone strength and bone loss after the onset of tumour growth in bone. Our results suggest that it is capable of preserving bone quality in rats bearing Walker 256 carcinosarcoma cells. Since other bisphosphonates have produced comparable results in man after their success in the Walker 256 animal models our findings suggest that ibandronate may be a powerful treatment for maintaining skeletal integrity in patients with metastatic bone disease.

[Improved osseointegration and periprosthetic bone volume around cementless metal implants under bisphosphonate treatment]. / Verbesserung von Osteointegration und periprothetischem Knochenanteil zementfreier metallischer Implantate unter Bisphosphonatgabe.

AIM: The effects of a systemic treatment with the bisphosphonate ibandronate on osseointegration of uncoated and hydroxyapatite-coated titanium implants and on periprosthetic bone volume have been evaluated and the dosage of medication had to be defined. METHOD: We used an animal model of the rat, the animals were assigned to three treatment groups receiving 1 microg, 5 microg and 25 microg/kg body weight and one control group receiving NaCl 0.9%. An uncoated and a hydroxyapatite-coated titanium rod were inserted into the medullary canal of the femur. After 28 days the specimens were harvested and histomorphometric evaluation revealed extend of osseointegrated implant surface and changes of periprosthetic bone volume. RESULTS: Treatment groups receiving 5 microg and 25 microg ibandronate showed significant improvement of osseointegrated implant surface compared to the control group. Enhancement of periprosthetic bone volume was revealed in all treatment groups but only application of 25 microg ibandronate was significantly improved compared to the control group. CONCLUSION: A minor dose of 1 microg ibandronate is not effective to improve osseointegration. A high dosed bisphosphonate treatment with 5 microg or 25 microg ibandronate is potent to improve osseointegrated implant surface significantly compared to an untreated control in both uncoated and hydroxyapatite-coated titanium implants and to enhance periprosthetic bone volume. By that, improved secondary stability and prolonged survival time of cementless metal implants can be expected.

Tumor necrosis factor: a cytokine involved in toxic effects of endotoxin.

Endotoxin-induced tumor necrosis has been shown to be mediated by a factor termed tumor necrosis factor (TNF). The biochemical nature, source, and mode of induction of TNF have been clarified. TNF is a mediator of activated macrophages that is released into the supernatant by these cells after their stimulation with endotoxin. A number of biologic functions of TNF other than its tumoricidal activity have been demonstrated. In vivo, TNF induces reactions similar to those induced by endotoxin. Hypothermia, elevated hematocrit and plasma lactate levels, and reduced plasma glucose levels have been measured in mice injected with TNF. These reactions typically occur soon after endotoxin injection and are induced with purified recombinant TNF in mice that exhibit a low response to endotoxin. No TNF-induced production of interleukin 1 (which can induce similar effects) was detected in macrophage/monocyte cultures. Therefore, TNF appears to mediate endotoxin effects directly.

Tumor necrosis factor mediates endotoxic effects in mice.

Endotoxic reactions induced in mice by recombinant human tumor necrosis factor (TNF) were examined. Mice showed a dose-dependent hypothermia after intravenous TNF injection which was similar to a reaction to lipopolysaccharide injection. Plasma glucose levels were decreased, and plasma lactate levels were increased. Blood hematocrit levels were increased after TNF injection. No interleukin-1 activity was detected in the plasma of TNF-treated animals. The number of leukocytes was reduced 30 min after TNF injection and returned to normal within 24 h. Thus, the data demonstrate that the pathophysiological effects induced by TNF were similar to the effects induced by bacterial endotoxin. Since lipopolysaccharide is a very potent agent for eliciting TNF release from activated macrophages, these results suggest that TNF could act as an endogenous mediator of endotoxin effects.

[Anti-osteolytic therapy preserves trabecular structure and mechanical properties of bone in tumor osteolysis]. / Eine antiosteolytische Therapie bewahrt die Trabekelstruktur und die mechanischen Eigenschaften des Knochens in Tumorosteolysen.

PURPOSE OF THE STUDY: Little is known about the effect of a tumor on the trabecular architecture, therefore we employed an animal model for the assessment of bone quality in tumor osteolysis to determine the alterations of the trabecular architecture in tumor osteolysis and after an interventional treatment with a bisphosphonate. METHODS: To assess the bone mass and the micro-architecture of the trabecular bone in tumor osteolysis we employed a micro-computed tomography system. For the assessment of the mechanical properties of the treated and non-treated tumor-bearing bones we used a torsion test. RESULTS: The presence of a tumor in bone resulted in a reduction of bone mass, stability and architectural parameters. An interventional treatment of the animals with a bisphosphonate increased the bone mineral content, mechanical and architectural parameters compared to the non-treated, tumor-bearing animals. CONCLUSIONS: These results clearly show a beneficial effect of an anti-osteolytic treatment with a bisphosphonate in regard of bone quality in tumor-induced osteolysis.