Browsing by Author "Turner, Charles H."

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    CD44+/CD24- breast cancer cells exhibit enhanced invasive properties: an early step necessary for metastasis
    (BioMed Central, 2006-10-24) Sheridan, Carol; Kishimoto, Hiromitsu; Fuchs, Robyn K.; Mehrotra, Sanjana; Bhat-Nakshatri, Poornima; Turner, Charles H.; Goulet Jr., Robert; Badve, Sunil; Nakshatri, Harikrishna; Anatomy and Cell Biology, School of Medicine
    Introduction A subpopulation (CD44+/CD24-) of breast cancer cells has been reported to have stem/progenitor cell properties. The aim of this study was to investigate whether this subpopulation of cancer cells has the unique ability to invade, home, and proliferate at sites of metastasis. Methods CD44 and CD24 expression was determined by flow cytometry. Northern blotting was used to determine the expression of proinvasive and 'bone and lung metastasis signature' genes. A matrigel invasion assay and intracardiac inoculation into nude mice were used to evaluate invasion, and homing and proliferation at sites of metastasis, respectively. Results Five among 13 breast cancer cell lines examined (MDA-MB-231, MDA-MB-436, Hs578T, SUM1315, and HBL-100) contained a higher percentage (>30%) of CD44+/CD24- cells. Cell lines with high CD44+/CD24- cell numbers express basal/mesenchymal or myoepithelial but not luminal markers. Expression levels of proinvasive genes (IL-1α, IL-6, IL-8, and urokinase plasminogen activator [UPA]) were higher in cell lines with a significant CD44+/CD24- population than in other cell lines. Among the CD44+/CD24--positive cell lines, MDA-MB-231 has the unique property of expressing a broad range of genes that favor bone and lung metastasis. Consistent with previous studies in nude mice, cell lines with CD44+/CD24- subpopulation were more invasive than other cell lines. However, only a subset of CD44+/CD24--positive cell lines was able to home and proliferate in lungs. Conclusion Breast cancer cells with CD44+/CD24- subpopulation express higher levels of proinvasive genes and have highly invasive properties. However, this phenotype is not sufficient to predict capacity for pulmonary metastasis.
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    Control of bone mass and remodeling by PTH receptor signaling in osteocytes
    (2008-08-13) O'Brien, Charles A.; Plotkin, Lilian I.; Galli, Carlo; Goellner, Joseph J.; Gortazar, Arancha R.; Allen, Matthew R.; Robling, Alexander G.; Bouxsein, Mary; Schipani, Ernestina; Turner, Charles H.; Jilka, Robert L.; Weinstein, Robert S.; Manolagas, Stavros C.; Bellido, Teresita
    Osteocytes, former osteoblasts buried within bone, are thought to orchestrate skeletal adaptation to mechanical stimuli. However, it remains unknown whether hormones control skeletal homeostasis through actions on osteocytes. Parathyroid hormone (PTH) stimulates bone remodeling and may cause bone loss or bone gain depending on the balance between bone resorption and formation. Herein, we demonstrate that transgenic mice expressing a constitutively active PTH receptor exclusively in osteocytes exhibit increased bone mass and bone remodeling, as well as reduced expression of the osteocyte-derived Wnt antagonist sclerostin, increased Wnt signaling, increased osteoclast and osteoblast number, and decreased osteoblast apoptosis. Deletion of the Wnt co-receptor LDL related receptor 5 (LRP5) attenuates the high bone mass phenotype but not the increase in bone remodeling induced by the transgene. These findings demonstrate that PTH receptor signaling in osteocytes increases bone mass and the rate of bone remodeling through LRP5-dependent and -independent mechanisms, respectively.
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    The Effect of Alendronate and Risedronate on Bone Remodeling in the Canine Maxilla
    (1999) Callegari, Brent Joseph; Garetto, Lawrence P.; Hartsfield, James K., Jr.; Katona, Thomas R.; Turner, Charles H.; Shanks, James C.
    Bisphosphonates, effective inhibitors of bone resorption, are used in the treatment of postmenopausal osteoporosis. At present, the effects of bisphosphonate therapy on the maxilla have not been quantitatively studied. As part of the masticatory system, dentate alveolar bone is exposed to a unique pattern of loading. As such, data obtained from bisphosphonate studies of other bones may not be applicable to the cortical bone of the dentate maxilla. The objective of this study is to histomorphometrically quantify the effects of alendronate and risedronate therapy on alveolar bone of the dog maxilla (MX) and to determine if this site is affected differently than the cortical bone in the rib (R) from these same animals. Twenty-two female dogs were divided into three treatment groups of 1 mg/kg/day alendronate, 0.5 mg/kg/day risedronate, and a saline vehicle control. Fluorochrome labels were used to mark sites of bone formation. Maxillary and rib specimens from each dog were prepared for analysis of static and dynamic histomorphometric parameters. MX cortical bone surrounding the third premolar was further analyzed by side (buccal vs. lingual) and region (coronal vs. apical). Mineralizing surface (MS/BS) and bone formation rate (BFR) in the coronal maxilla of the control group is significantly (p < 0.05) higher than that of the bisphosphonate groups. In bisphosphonate treated animals, MS/BS, BFR, and activation frequency (AcF) were significantly (p < 0.05) higher in the R than in the MX. In all treatment groups, very little osteoid was detected, and no significant difference in the mineral apposition rate (MAR) was noted. These results indicate that: (1) bisphosphonate dosages used in this study effectively inhibited remodeling within the dog maxilla; (2) alveolar bone remodeling was decreased more than remodeling in rib cortical bone; (3) within the dentate maxilla, alveolar bone remodeling was decreased more in the coronal than in the apical region, and (4) none of the groups appears to show inhibition of mineralization.
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    The Effects of Instrument-Assisted Cross Fiber Massage on Ligament Healing
    (2010-05) Loghmani, Mary T.; Warden, Stuart J.; Burr, David B.; Robling, Alex G.; Seifert, Mark Frederick; Turner, Charles H.
    Ligament injury is one of the most prevalent musculoskeletal disorders that may lead to disability or disease, such as osteoarthritis. Conservative interventions which accelerate or augment ligament healing are needed to enhance therapeutic outcomes. The purpose of this research agenda was to investigate the tissue level effects of a type of manual therapy, cross fiber massage (CFM), in particular instrument-assisted CFM (IACFM), on ligament healing. Bilateral knee medial collateral ligament (MCL) injuries were created using an established rodent model where one MCL received IACFM treatment and the other untreated MCL served as a within subjects control. The short and long term effects of IACFM on the biomechanical and histological properties of repairing ligaments were investigated. Tensile mechanical testing was performed to determine ligament mechanical properties. Ligament histology was examined under light microscopy and scanning electron microscopy. IACFM was found to accelerate early ligament healing (4 weeks post-injury), possibly via favorable effects on collagen formation and organization, but minimal improvement was demonstrated in later healing (12 weeks post-injury). Regional blood flow and angiogenesis were investigated as possible mechanisms underlying the accelerated healing found in IACFM-treated ligaments. Laser Doppler perfusion imaging was used to investigate vascular function. Micro-computed tomography was used to determine vascular structural parameters. Compared to untreated contralateral injured controls, IACFM-treated injured knees demonstrated a delayed increase in blood flow and altered microvascular structure, possibly suggesting angiogenesis. Mechanotransduction is discussed as a mechanism for the beneficial effects of CFM in that application of a mechanical force was found to enhance biomechanical and histological properties as well as vascular function and structure acutely in healing ligaments. Although this thesis focused on IACFM treatment of injured knee ligaments, it is plausible for concepts to apply to other manual modalities that offer conservative alternatives to invasive procedures or pharmaceuticals in the treatment of soft tissue injuries.
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    Estrogen receptor-β regulates mechanical signaling in primary osteoblasts
    (American Physiological Society (APS), 2014-04-15) Castillo, Alesha B.; Triplett, Jason W.; Pavalko, Fredrick M.; Turner, Charles H.; Department of Cellular & Integrative Physiology, IU School of Medicine
    Mechanical loading is an important regulator in skeletal growth, maintenance, and aging. Estrogen receptors have a regulatory role in mechanically induced bone adaptation. Estrogen receptor-α (ERα) is known to enhance load-induced bone formation, whereas ERβ negatively regulates this process. We hypothesized that ERβ regulates mechanical signaling in osteoblasts. We tested this hypothesis by subjecting primary calvarial cells isolated from wild-type and ERβ-knockout mice (BERKO) to oscillatory fluid flow in the absence or presence of estradiol (E2). We found that the known responses to fluid shear stress, i.e., phosphorylation of the mitogen-activated protein kinase ERK and upregulation of COX-2 expression, were inhibited in BERKO cells in the absence of E2. Flow-induced increase in prostaglandin E2 (PGE2) release was not altered in BERKO cells in the absence of E2, but was increased when E2 was present. Additionally, immunofluorescence analysis and estrogen response element luciferase assays revealed increased ERα expression and flow- and ligand-induced nuclear translocation as well as transcriptional activity in BERKO cells in both the presence and absence of E2. Taken together, these data suggest that ERβ plays both ligand-dependent and ligand-independent roles in mechanical signaling in osteoblasts. Furthermore, our data suggest that one mechanism by which ERβ regulates mechanotransduction in osteoblasts may result from its inhibitory effect on ERα expression and function. Targeting estrogen receptors (e.g., inhibiting ERβ) may represent an effective approach for prevention and treatment of age-related bone loss.
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    Fluoride and Cortical Bone: A Histomorphometric Study in Rabbits
    (1997) Acon-Ng, Patricia; Garetto, Lawrence P.; Dunipace, Ann J.; Katona, Thomas R.; Shanks, James C.; Turner, Charles H.
    Fluoride has been used in the treatment of osteoporosis because of its apparent ability to directly initiate bone formation. However, fluoride's therapeutic efficacy is controversial. Clinical trials in the range of 50 to 75 mg/day demonstrated severe side effects and a lack of consistent therapeutic benefits. Animal studies have not fully proven a positive effect of fluoride on bone strength. The objective of this study was to determine the histomorphometric changes in the cortical bone of rabbits caused by high doses of fluoride. The hypothesis was that high-dose fluoride intake enhances bone modeling and inhibits bone remodeling. Twenty-four young adult (four months old) female, Dutch Belted rabbits were randomly divided in two groups. The control group received no fluoride in their drinking water, while the experimental group received 100-ppm fluoride. Both groups received approximately 12-ppm fluoride in their food. A pair of tetracycline labels was given two weeks apart before initiation of the experiment. Fluoride treatment was given for six months. A terminal pair of calcein green labels was given before the animals were euthanized. Histomorphometric measurements were made using stereological point-hit and linear-intercept methods. The histomorphometric findings were correlated with fluoride serum and bone levels and also with strength tests. The study demonstrated that fluoride increases bone modeling by increasing periosteal bone apposition and endosteal bone resorption. The net effect of fluoride was an enlargement of the cortical bone and bone marrow and, therefore, the total tissue cross-section. However, the observed increase in bone mass produced by fluoride did not have a positive effect on the mechanical properties of bone. Fluoride did not produce a change in the primary histomorphometric parameters of osteoid surface (OS/BS%) or mineralizing surface (MS/BS%). Fluoride treatment produced an increase in the cortical periosteal modified mineral apposition rate (CPMAR). The remaining dynamic indices (i.e. endosteal MAR, remodeling MAR, cortical endosteal BFR and total BFR, activation frequency and formation period) were not affected by fluoride. The study failed to show an inhibitory effect of fluoride on bone remodeling.
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    Fluoride and the Rabbit Mandibular Condyle: A Strength and Histomorphometric Study
    (1997) Kizior, John William; Garetto, Lawrence P.; Dunipace, Ann J.; Chen, Jie; Shanks, James C.; Turner, Charles H.
    The specific aims of the project were to assess the histomorphometric and strength changes that occurred in the fluoride treated trabecular and subchondral bone of the mandibular condyle. This project represented a specific part of a larger experiment recently conducted by the Indiana University Oral Health Research Institute. We tested the hypothesis that fluoride treatment inhibits bone remodeling activity, enhances bone modeling activity, and decreases bone strength. The rabbit mandibular condyle, because it is composed of trabecular and subchondral bone and has a high rate of remodeling activity, was used as a model for human trabecular and subchondral bone. The six-month study involved 24 young adult (four months old) female, Dutch Belted rabbits. The rabbits were randomly divided into two groups based on body weight and plasma fluoride levels. The control group received no fluoride in their drinking water while the experimental group received 100-ppm fluoride. Both groups of rabbits received approximately 12-ppm fluoride in their food. A pair of tetracycline labels (10 mg/kg i.m.) was given two weeks before the initiation of the fluoride treatment. A pair of calcein green labels (5mg/kg i.m., bid), administered one week apart, was initiated two weeks before the end of the experiment. The animals were euthanized three days after the final label injection. Histomorphometric measurements were made at X125 magnification on a Nikon FXA epifluorescent microscope utilizing stereological point-point hit (volume-related parameters) and linear intercept (surface related parameters) methods. The fluoride treatment resulted in a significant increase in the percentage of osteoid surface, but no increase in osteoid thickness. The bone formation rate showed a trend toward an increased formation rate in the fluoride treatment group. The observation that the mineralized surface and osteoid thickness showed no change suggests a normal rate of mineralization. However, more surfaces were covered with osteoid. Mechanical testing showed no change in stiffness and a weak trend toward a decrease in ultimate strength in the fluoride group. The data suggest that the influence of fluoride treatment had a minimal affect on the trabecular bone of the rabbit mandibular condyle. The results from the vertebra study in the same animals showed a similar pattern of change following fluoride treatment. It is speculated the limited variability between the vertebra and the condyle could be due to altered functional mechanical loading or regional characteristics.