Christopher P. Jerome

Teriparatide (PTH(1-34)) Strengthens the Proximal Femur of Ovariectomized Nonhuman Primates Despite Increasing Porosity

OVX monkeys treated for 18 months with 1 or 5 μg/kg/d teriparatide [PTH (1–34)] had significantly stronger proximal femora relative to ovariectomized controls. Teriparatide enhancement of cortical area, cortical width, and trabecular bone volume seemed to more than compensate for the dose‐dependent increase in cortical porosity. Beneficial effects of teriparatide treatment on the proximal femur persisted beyond the treatment period and may extend to the marrow.

Effect of treatment for 3 months with human parathyroid hormone 1–34 peptide in ovariectomized cynomolgus monkeys (Macaca fascicularis).

A potential negative side effect of intermittent parathyroid hormone (PTH) therapy to treat osteoporosis is the loss of cortical bone concomitant with increased cancellous bone mass. We addressed this issue by studying the effects of PTH on whole-body, axial, and appendicular bone mass in an animal model with haversian cortical bone remodeling. Ovariectomized, young adult female cynomolgus monkeys were assigned to placebo (n = 9) or PTH groups (n = 10). The PTH group received 10 microg/kg synthetic human PTH(1-34) peptide by subcutaneous injection, 3 days/week for 6 months, and the placebo group received vehicle. Multiple endpoints of bone mass, strength, and turnover in the axial and appendicular skeleton were assessed, including dual-energy X-ray absorptiometry (DEXA), quantitative computed tomography (qCT), analysis of serum (calcium, phosphorus, alkaline phosphatase, osteocalcin, and tartrate-resistant acid phosphatase) and urinary (calcium and creatinine) biomarkers, histomorphometry, and biomechanical testing. Compared with placebo-treated animals, PTH-treated monkeys had no change in whole-body bone mass, but a 6.7% increase in spinal areal bone mineral density (aBMD) was observed. Cortical bone mass measured by qCT at appendicular sites was not affected by PTH treatment, but there were significant increases in cancellous bone mass in the proximal tibia, and a similar trend in the distal radius. Small, transient increases in serum and urinary calcium were observed, but there were no treatment-related effects on other biochemical endpoints. Increased bone formation rate (BFR/BV) in the midradius and midfemur was accompanied by a nonsignificant increase in midfemur porosity. Increased vertebral cancellous bone volume (BV/TV) was associated with greater trabecular and interstitial thickness with no effect on wall thickness. Increases in bone strength were observed in both axial (vertebral maximum stress and load at fracture) and appendicular (femoral neck fracture load) skeleton. Together, these results indicate that PTH therapy in the cynomolgus monkey results in a net gain of spinal and appendicular cancellous bone mass with no adverse effect on cortical bone.

Bone mass in female cynomolgus macaques: a cross-sectional and longitudinal study by age.

A cross-sectional study by age was designed to evaluate and describe the bone mineral content (BMC, g) and density (BMD, g/cm2) in a population of female cynomolgus macaques (Macaca fascicularis). Dual-energy X-ray absorptiometry was used to measure, in segments L2-L4 of the lumbar spine, the BMC (BMCs), BMD (BMDs), length, and total-body BMC (BMCTB) in 171 female monkeys ranging in age between 3.7 and 22.0 years. The animals were divided into three age groups: (1) young (<6.5 years, n=51); (2) adult (>6.5 years and <10.5 years, n=63); and (3) mature (>10.5 years, n=57). Young animals had a significantly lower (P<0.05) body weight and shorter trunk length than adult or mature animals. Young animals also had significantly less (P<0.05) BMCS, BMDS, and BMCTB than adult or mature animals, and had significantly shorter (P<0.05) lumbar spine vertebral segments than the other two groups. Longitudinally, 63 animals had repeated lumbar spine scans to examine changes over time. Young animals showed a positive and significant change (P<0.05) in BMCS and BMDS through time, whereas these parameters did not change in adult animals, and mature animals had a trend towards bone loss through time. Densitometric results suggested that peak bone mass in the lumbar spine was achieved by 9 years of age. Radiographic and dental criteria were developed to identify animals that had reached peak bone mass, and the combined radiographic and dental scoring system reliably identified animals 9 years and older. Female cynomolgus macaques 9 years old or older are recommended for investigations of bone remodeling and associated conditions, such as osteoporosis.

Decreased Bone Mass and Strength in Ovariectomized Cynomolgus Monkeys ( Macaca fascicularis )

Agents for prevention or treatment of osteoporosis must now be tested in a large animal species that exhibits bone remodeling. Ovariectomized, nonhuman primates provide one such model, and they consistently develop osteopenia accompanied by high bone turnover rates. The goal of this study was to further characterize this model, and particularly to determine the effect of ovariectomy on bone strength in vertebrae and femoral necks. Longitudinal evaluations of spinal bone mass and serum markers of bone turnover were performed in 19 sham-ovariectomized (SHAM) and 18 ovariectomized (OVX), domestically reared cynomolgus monkeys, aged >9 years. OVX monkeys lost bone relative to both baseline values and SHAM controls. Serum markers of bone turnover were increased by OVX. After 72 weeks, both vertebral bone compressive strength and femoral neck breaking strength were significantly decreased in OVX animals compared with SHAM. Ovariectomized cynomolgus monkeys, like postmenopausal women, develop accelerated bone loss, increased bone turnover, and reduced bone strength, and provide a suitable large animal model for efficacy studies with agents for prevention or treatment of osteoporosis.

Effects of shock waves on the structure and growth of the immature rat epiphysis.

The left proximal tibia of eighteen five week old male Sprague-Dawley rats was exposed to 1500 shock waves at 20 kV in a Dornier XL-1 experimental lithotripter. Six of these rats, and six age-matched controls, were sacrificed two, four and ten weeks later. Eight of 18 (44%) of treated animals had lesions of focal growth plate dysplasia attributable to treatment. In the absence of extensive lesions, no significant difference was identified in the growth plate thickness of shocked versus unshocked limbs. In the group sacrificed at ten weeks, two of six (33%) treated animals had extensive dysplastic lesions which were associated with marked shortening of the shocked limb. In the absence of extensive lesions, there was no significant shortening of shocked limbs. Shock wave exposure of the rat epiphysis can affect subsequent bone growth.

Effects of ovariectomy on iliac trabecular bone in baboons (Papio anubis)

SummaryBiopsies were collected from the left iliac crest of six adult female baboons, after which three of the animals were ovariectomized. Biopsies were collected from the right iliac crest six months later. Histomorphometric evaluation of the biopsies revealed consistent increases in fractional forming surface, appositional rate, and volume-based bone formation rate after ovariectomy. The data indicate that bone turnover is increased following ovariectomy in the baboon.

Oral contraceptive treatment inhibits the normal acquisition of bone mineral in skeletally immature young adult female monkeys

The purpose of the present study was to determine the effects of oral contraceptive therapy on bone density and serum markers of bone metabolism in a prospective, longitudinal study of young adult female cynomolgus monkeys. Two hundred and seven intact cynomolgus monkeys were randomized to two groups, and fed an atherogenic diet containing either no drug (Control) or a triphasic oral contraceptive regimen (Contraceptive). Measurements of bone density were carried out by dual-energy X-ray absorptiometry at 10-month intervals (0, 10, and 20 months) and serum bone biomarkers were determined at 5-month intervals over the 20-month time course. No significant differences in these variables were observed prior to treatment. Both groups of animals gained bone mineral during the study, indicating that peak bone mass had not been reached at baseline. Contraceptive-treated animals gained less spinal (lumbar vertebrae 2–4) bone mineral content and density and less whole-body bone mineral content than Controls over the course of the study. Significant depressive effects of contraceptive treatment on gains in BMC and BMD were observed during each 10-month interval of the study. Bone metabolism was inhibited in the Contraceptive group, as reflected by marked reductions (∼ 40%) in serum osteocalcin and alkaline phosphatase levels along with moderate reductions in serum acid phosphatase and calcium. The results suggest that triphasic oral contraceptive treatment of young adult female monkeys that have not reached peak bone mass inhibits net bone accretion and/or growth by reducing bone metabolism. Thus, prolonged continuous oral contraceptive use in skeletally immature females may lead to a lower peak bone mass — an effect which could increase the risk of fractures in later life.

Perspectives on osteoporosis research: Its focus and some insights from a new paradigm

Conclusion(1) Could future osteoporosis research begin to account for the things described in this editorial? (2) Could agencies that give grants to support that research begin to encourage that accounting? (3) Since the FDA guidelines have great influence on what osteoporosis research is done and not done, mitht revisions of the 1994 guidelines try to acknowledge those things?

Effects of raloxifene on bone density, biomarkers, and histomorphometric and biomechanical measures in ovariectomized cynomolgus monkeys.

ObjectiveThe purpose of this study was to determine the effect of raloxifene on bone density, strength, metabolism, and histomorphometric characteristics in ovariectomized cynomolgus monkeys. DesignA prospective, longitudinal study was designed to examine the effects of conjugated equine estrogens (0.04 mg/kg, CEE) and raloxifene (1 or 5 mg/kg, R1 and R5, respectively) on bone density, biomarkers, histomorphometry, and strength. Control groups included ovariectomized and sham-operated monkeys. Treatment was initiated the day after ovariectomy and continued for 24 months. Bone biomarker data were collected at baseline and every 3 months after surgery. Bone mass was determined at baseline and every 6 months after ovariectomy. Iliac biopsies were collected at baseline and 16 months postovariectomy, and the second lumbar vertebra and left midshaft femur collected at necropsy were examined histomorphometrically. Bone biomechanical properties were determined for the right femur and vertebrae. ResultsCompared with the placebo-treated ovariectomized monkeys, the high-dose raloxifene group had lower levels of alkaline phosphatase, tartrate-resistant acid phosphatase, urinary CrossLaps (collagen degradation products), and greater bone mass in the lumbar vertebrae. In the endocortical compartment, the high-dose raloxifene group had significantly lower mineralizing surface, mineral apposition rate, and bone formation rate in the iliac biopsy collected at 16 months and lower bone formation rate in the second lumbar vertebra. Within the midshaft femur, low-dose raloxifene significantly decreased the osteonal and total bone formation rates and also prevented the decrease in Youngs modulus induced by ovariectomy in the midshaft femur. ConclusionsHigh-dose raloxifene prevented the development of osteopenia in the ovariectomized monkey by reducing bone turnover, albeit to a lesser extent than CEE. Histomorphometric and biomarker data suggest that mechanisms underlying the effect of raloxifene differ somewhat from that of CEE.

Development of osteopenia in ovariectomized cynomolgus monkeys (Macaca fascicularis)

Spinal osteopenia that is due in part to failure to gain bone has previously been reported in ovariectomized nonhuman primates. In these studies, development of osteopenia over one year was followed by dual-energy x-ray absorptiometry in both domestically-reared and feral ovariectomized (OVX) and sham-ovariectomized (SHAM) cynomolgus monkeys. To promote development of absolute osteopenia, the domestically-reared animals were all older than nine years and were fed a diet containing 0.14% calcium for most of the experimental period. Both SHAM and OVX feral animals fed 0.6% calcium gained bone mass, with significantly lower rates of gain in SHAM monkeys. OVX domestically-reared monkeys lost bone during one year, while SHAM domestically-reared animals showed no significant change from baseline. Thus, relative osteopenia developed in both experiments, but only the domestically-reared animals developed absolute osteopenia. Nonhuman primates are the only animal model shown to develop absolute osteopenia after ovariectomy. These data suggest that absolute osteopenia develops after ovariectomy in monkeys with stable pre-ovariectomy bone mass which are fed a level of calcium comparable to that consumed by American women.