Citations

Moderate physical exercise (PE) combined with metabolic treatment (MT) (antioxidants and l -arginine) are well known to reduce atherosclerotic lesion formation in hypercholesterolemic mice. However, the long-term beneficial effects on unstable atheroma remain poorly understood. We started early PE training in large groups of 6-week-old hypercholesterolemic mice (by graduated swimming) alone or in combination with nutritional supplementation (1.0% vitamin E added to the chow and 0.05% vitamin C and 6% l -arginine added to the drinking water). Inactive controls did not receive PE. The spontaneous development of atherosclerotic plaque rupture (associated with advanced atherosclerosis) and survival rates were evaluated. Moderate PE elicited an increase in plasma levels of nitric oxide. Early combined treatment with PE and MT in the hypercholesterolemic mice significantly reduced lesions (also detected noninvasively at 10 months) and spontaneous atherosclerotic plaque rupture and prolonged survival more effectively than each intervention alone. Thus, early concerted actions of MT and PE improve the natural history of atherosclerotic lesions and reduce the plaque instability in hypercholesterolemic mice.

Background The triceps tendon has been described as a single unit with contribution from each of the 3 heads of the muscle. An observation at the time of surgical repair of a triceps tendon injury led to an anatomical study to further define the anatomy of this tendon as it inserts on the olecranon. Hypothesis The medial head of the triceps has a tendon that is distinct from, and deep to, the common tendon of the long and lateral heads. Study Design Descriptive laboratory study and case report. Methods Eight cadaveric elbows were dissected to examine the triceps tendon. None of the specimens had any evidence of prior injury or surgery to the elbow. All specimens were fresh-frozen and stored at–4°C until they were thawed for use. Skin and subcutaneous tissue were removed, and the tendon of each head of the triceps was explored from the muscle to its bony insertion. Results In all 8 specimens, on gross inspection, the medial head had a separate insertion deep to the common insertion of the lateral and long heads. The muscle of the medial head extended further distally than did the long and lateral heads. The medial head was muscular to its deep insertion, with a small amount of tendon blended with the muscle distally. Histologic analysis demonstrated that the tendon of the medial head and that of the other 2 heads are confluent distally at their olecranon insertion. Conclusion The medial head of the triceps has a tendon that is distinct from, and deep to, the common tendon of the long and lateral heads on gross inspection. Histologic studies show the insertion of these 2 tendons is confluent. Clinical Relevance This anatomy has important implications for surgical repair of these tendon injuries. Rupture of the deep triceps insertion alone can occur and lead to weakness of elbow extension with the elbow flexed beyond 90°. Triceps strength should be tested with the elbow fully flexed when injury to the tendinous insertion is suspected.

Abstract To examine the functional role of membrane-bound SLF, we evaluated the growing skeletons of WT and SLF mutant (Sl/Sld) mice that do not produce this protein using DXA, bone histomorphometry, cell culture, and flow cytometry. Deletion of membrane-bound SLF delays bone growth, decreases bone mass and BMD, impairs osteoblast function, and increases osteoclast surface in young mice. Introduction: Mutations at the murine steel locus lead to a defect in the development of hematopoietic stem cells, mast cells, and germ cells. Two isoforms of steel factor (SLF), soluble and membrane-associated, have been reported. Soluble SLF increases osteoclast formation and activity in cell culture. The effects of deletion of membrane-bound SLF on bone metabolism in mice have yet to be determined and are the subject of this study. Materials and Methods: Five-, 7-, and 12-week-old male and 5-week-old female WCB6F1/J-KitlSl/KitlSl-d (Sl/Sld) mice and wildtype (WT) littermates were used. BMD and bone mass, growth, architecture, and turnover were evaluated by DXA (males and females) and histomorphometry (males only). Primary osteoblasts isolated from humeri of 5-week-old male WT and Sl/Sld mice were used to determine osteoblast function, and bone marrow cells from tibias and femurs of these mice were analyzed to determine cell surface expression of osteoclast precursors. Results and Conclusions: Young Sl/Sld mice grew more slowly, had a reduced bone mass, and had shorter bones than WT littermates. Male mutants had significantly decreased whole body BMD in all age groups, largely because of a reduction in BMC. Tibial cross-sectional, cortical, and marrow area of cortical bone and cancellous bone volume was reduced in the mutants at all ages. The osteopenia in Sl/Sld was caused by increased osteoclast surface at all ages and decreased osteoblast surface at 5 weeks of age. [3H]thymidine incorporation studies showed that proliferation of osteoblasts derived from mutant mice was significantly suppressed (56%). Moreover, a decrease in mineralization was observed in Sl/Sld osteoblast culture. Fluorescence-activated cell sorting analysis of bone marrow cells from Sl/Sld mice revealed a 65% increase in the percentage of c-Fms+CD11b+RANK+ cells compared with WT controls. These findings suggest that membrane-bound SLF/c-Kit signaling plays a role in the regulation of peak bone mass.

Abstract Alcohol is a risk factor for the development of osteoporosis, especially in men. Chronic alcohol abuse decreases bone mass, which contributes to the increased incidence of fractures. To better understand the mechanism of action of ethanol on bone metabolism, we have studied the dose-response effects of ethanol on conditionally immortalized human fetal osteoblasts (hFOB) in culture. Ethanol treatment had no significant effects on osteoblast number after 1 day or 7 days. Ethanol treatment did not reduce type I collagen protein levels at either time point at any dose but slightly reduced alkaline phosphatase activity after 7 days. The messenger RNA (mRNA) levels for alkaline phosphatase, type I collagen, and osteonectin were unaltered by 24 h of ethanol treatment but a high dose (200 mM) reduced mRNA levels for the two bone matrix proteins after 7 days. Ethanol treatment led to dose-dependent increases in transforming growth factor β1 (TGF-β1) mRNA levels and decreases in TGF-β2 mRNA levels. The concentration of ethanol in the medium decreased with time because of evaporation but there was little degradation caused by metabolism. These results, which show that cultured osteoblasts are less sensitive than osteoblasts in vivo, suggest that the pronounced inhibitory effects of ethanol on bone formation are not caused by direct cell toxicity.

Abstract Skeletal unloading decreases bone formation and osteoblast number in vivo and decreases the number and proliferation of bone marrow osteoprogenitor (BMOp) cells in vitro. We tested the ability of parathyroid hormone (PTH) to stimulate BMOp cells in vivo by treating Sprague Dawley rats (n = 32) with intermittent PTH(1–34) (1 h/day at 8 μ g/100 g of body weight), or with vehicle via osmotic minipumps during 7 days of normal weight bearing or hind limb unloading. Marrow cells were flushed from the femur and cultured at the same initial density for up to 21 days. PTH treatment of normally loaded rats caused a 2.5-fold increase in the number of BMOp cells, with similar increases in alkaline phosphatase (ALP) activity and mineralization, compared with cultures from vehicle-treated rats. PTH treatment of hind limb unloaded rats failed to stimulate BMOp cell number, ALP activity, or mineralization. Hind limb unloading had no significant effect on PTH receptor mRNA or protein levels in the tibia. Direct in vitro PTH challenge of BMOp cells isolated from normally loaded bone failed to stimulate their proliferation and inhibited their differentiation, suggesting that the in vivo anabolic effect of intermittent PTH on BMOp cells was mediated indirectly by a PTH-induced factor. We hypothesize that this factor is insulin-like growth factor-I (IGF-I), which stimulated the in vitro proliferation and differentiation of BMOp cells isolated from normally loaded bone, but not from unloaded bone. These results suggest that IGF-I mediates the ability of PTH to stimulate BMOp cell proliferation in normally loaded bone, and that BMOp cells in unloaded bone are resistant to the anabolic effect of intermittent PTH therapy due to their resistance to IGF-I.

Abstract We examined the time course effects of continuous PTH on cortical bone and mechanical properties. PTH increased cortical bone turnover and induced intracortical porosity with no deleterious effect on bone strength. Withdrawal of PTH increased maximum torque to failure and stiffness with no change in energy absorbed. Introduction: The skeletal response of cortical bone to parathyroid hormone (PTH) is complex and species dependent. Intermittent administration of PTH to rats increases periosteal and endocortical bone formation but has no known effects on intracortical bone turnover. The effects of continuous PTH on cortical bone are not clearly established. Materials and Methods: Eighty-four 6-month-old female Sprague-Dawley rats were divided into three control, six PTH, and two PTH withdrawal (WD) groups. They were subcutaneously implanted with osmotic pumps loaded with vehicle or 40 μg/kg BW/day human PTH(1-34) for 1, 3, 5, 7, 14, and 28 days. After 7 days, PTH was withdrawn from two groups of animals for 7 (7d-PTH/7d-WD) and 21 days (7d-PTH/21d-WD). Histomorphometry was performed on periosteal and endocortical surfaces of the tibial diaphysis in all groups. μCT of tibias and mechanical testing by torsion of femora were performed on 28d-PTH and 7d-PTH/21d-WD animals. Results and Conclusions: Continuous PTH increased periosteal and endocortical bone formation, endocortical osteoclast perimeter, and cortical porosity in a time-dependent manner, but did not change the mechanical properties of the femur, possibly because of addition of new bone onto periosteal and endocortical surfaces. Additionally, withdrawal of PTH restored normal cortical porosity and increased maximum torque to failure and stiffness. We conclude that continuous administration of PTH increased cortical porosity in rats without having a detrimental effect on bone mechanical properties.

Abstract Studies were performed to determine if the nonsteroidal anti-inflammatory drug ibuprofen alters bone and mineral metabolism in female rats. In experiment 1, four groups of growing rats underwent either sham operation or ovariectomy (OVX). One week later, controlled-release pellets with ibuprofen or placebo were implanted subcutaneously at the back of the neck. Following 3 weeks of treatment, rats were sacrificed and blood and bone samples were removed for serum assays and histomorphometric analysis. Body growth rate and the static cortical bone measurements made at the tibial diaphysis did not change in response to OVX. OVX, however, did increase radial bone growth, lowered serum 17β-estradiol, reduced uterine weight, and decreased the cancellous bone area of the tibial metaphysis in the rats. Ibuprofen did not alter serum 17β-estradiol or uterine weight but reduced radial bone growth as well as cancellous bone area of the tibial metaphysis in both sham-operated and OVX animals. In experiments 2 and 3, we tested the influence of ibuprofen on the effects of the tissue-selective estrogen agonist tamoxifen and of exogenous 17β-estradiol in the OVX rat. Ibuprofen completely blocked the effects of tamoxifen and partially blocked the effects of 17β-estradiol to prevent cancellous osteopenia. In contrast, ibuprofen did not influence the effects of tamoxifen and 17β-estradiol to reduce radial bone growth. Besides the skeletal effects, ibuprofen suppressed estrogen-induced uterine growth. Our data suggest that ibuprofen blocks selective estrogen receptor-mediated activities in the rat.

Abstract IGF-I and their binding proteins are important in bone health. Examination of BMD, osteoblast proliferation, and markers of bone resorption in transgenic mice that constitutively overexpress IGFBP-3 indicates that overexpression of IGFBP-3 increases osteoclast number and bone resorption, impairs osteoblast proliferation, and has a significant negative effect on bone formation. Introduction: Low serum insulin-like growth factor I (IGF-I) levels correlate with an increased risk of osteoporotic fractures. Serum IGF-I is largely bound to IGF-binding protein-3 (IGFBP-3), which can inhibit IGF-I action and enhance delivery of IGF-I to tissues. Its role in bone biology is unclear. Methods: Bone mineral density (BMD), osteoblast proliferation, and markers of bone resorption were examined in transgenic (Tg) mice that constitutively overexpressed human IGFBP-3 cDNA driven by either the cytomegalovirus (CMV) or phosphoglycerate kinase (PGK) promoter. Results: Cultured calvarial osteoblasts from Tg mice expressed the transgene and grew more slowly than cells from wild-type (Wt) mice, and the mitogenic response to IGF-I was attenuated in osteoblasts from Tg mice. Total volumetric BMD and cortical BMD, measured in the femur using peripheral quantitative computed tomography (pQCT) were significantly reduced in both Tg mouse strains compared with Wt mice. PGKBP-3 Tg mice showed the most marked reduction in bone density. Osteocalcin levels were similar in Wt and CMVBP-3 Tg mice but were significantly reduced in PGKBP-3 Tg mice. Urinary deoxypyridinoline and osteoclast perimeter, markers of bone resorption, were significantly increased in both Tg mouse strains compared with Wt mice. Using double labeling with tetracycline, we demonstrated that pericortical and endocortical mineral apposition rate was significantly reduced in PGKBP-3 Tg mice compared with Wt mice. Conclusions: These data show that overexpression of IGFBP-3 increases osteoclast number and bone resorption, impairs osteoblast proliferation, and has a significant negative effect on bone formation.

Abstract Purpose: MV-CEA is an oncolytic measles virus currently being tested in patients with ovarian cancer and whose propagation can be monitored by measuring blood carcinoembryonic antigen (CEA) levels. MV-NIS is an oncolytic measles virus coding for the thyroidal sodium iodide symporter (NIS) whose propagation can be mapped by serial radioiodine imaging. Expression of both CEA and NIS genes from a single virus would combine sensitive, quantitative expression monitoring (CEA) with radioisotopic expression mapping (NIS). Because of the unfavorable replication kinetics of measles viruses expressing both CEA and NIS, we explored the feasibility of combining MV-CEA with MV-NIS for comprehensive virotherapy monitoring in ovarian cancer. Experimental Design and Results: Mice implanted with i.p. SKOV3ip.1 ovarian cancer xenografts received MV-CEA alone, MV-NIS alone, or a combination of MV-CEA plus MV-NIS. Viral gene expression was monitored by measuring blood CEA levels, and the location of virus-infected cells was monitored by gamma camera imaging. Surprisingly, mice receiving the combination of MV-CEA plus MV-NIS showed greatly superior responses to therapy, but this was associated with 10-fold lower plasma levels of CEA compared with mice treated with MV-CEA alone. In vitro studies showed superior replication kinetics of MV-NIS relative to MV-CEA. The gamma camera scans were considerably less sensitive than the plasma CEA marker for monitoring virus infection. Conclusions: Dual therapy with MV-CEA and MV-NIS is superior to treatment with either virus alone, and it allows noninvasive monitoring of virotherapy via soluble marker peptide and gamma camera imaging. This has important implications for the clinical development of oncolytic measles viruses.