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Roger S Seymour - One of the best experts on this subject based on the ideXlab platform.

  • femoral Bone perfusion through the nutrient foramen during growth and locomotor development of western grey kangaroos macropus fuliginosus
    The Journal of Experimental Biology, 2017
    Co-Authors: T J N Nelson, Edward P Snelling, Roger S Seymour
    Abstract:

    ABSTRACT The nutrient artery passes through the nutrient foramen on the shaft of the femur and supplies more than half of the total Blood Flow to the Bone. Assuming that the size of the nutrient foramen correlates with the size of the nutrient artery, an index of Blood Flow rate ( Q i ) can be calculated from nutrient foramen dimensions. Interspecific Q i is proportional to locomotor activity levels in adult mammals, birds and reptiles. However, no studies have yet estimated intraspecific Q i to test for the effects of growth and locomotor development on Bone Blood Flow requirements. In this study, we used micro-CT and medical CT scanning to measure femoral dimensions and foramen radius to calculate femoral Q i during the in-pouch and post-pouch life stages of western grey kangaroos ( Macropus fuliginosus ) weighing 5.7 g to 70.5 kg and representing a 12,350-fold range in body mass. A biphasic scaling relationship between Q i and body mass was observed (breakpoint at ca. 1–5 kg body mass right before permanent pouch exit), with a steep exponent of 0.96±0.09 (95% CI) during the in-pouch life stage and a statistically independent exponent of –0.59±0.90 during the post-pouch life stage. In-pouch joeys showed Q i values that were 50–100 times higher than those of adult diprotodont marsupials of the same body mass, but gradually converged with them as post-pouch adults. Bone modelling during growth appears to be the main determinant of femoral Bone Blood Flow during in-pouch development, whereas Bone remodelling for micro-fracture repair due to locomotion gradually becomes the main determinant when kangaroos leave the pouch and become more active.

Allen T Bishop - One of the best experts on this subject based on the ideXlab platform.

  • augmentation of surgical angiogenesis in vascularized Bone allotransplants with host derived a v bundle implantation fibroblast growth factor 2 and vascular endothelial growth factor administration
    Journal of Orthopaedic Research, 2010
    Co-Authors: Mikko Larsen, Wouter F Willems, M Pelzer, Patricia F Friedrich, Michael J Yaszemski, Allen T Bishop
    Abstract:

    We have previously shown experimental transplantation of living allogeneic Bone to be feasible without long-term immunosuppression by development of a recipient-derived neoangiogenic circulation within Bone. In this study, we examine the role of angiogenic cytokine delivery with biodegradable microspheres to enhance this process. Microsurgical femoral allotransplantation was performed from Dark Agouti to Piebald Virol Glaxo rats. Poly(D,L-lactide-co-glycolide) microspheres loaded with buffer, basic fibroblast growth factor (FGF), vascular endothelial growth factor (VEGF), or both, were inserted intramedullarly along with a recipient-derived arteriovenous (a/v) bundle. FK-506 was administered daily for 14 days, then discontinued. At 28 days, Bone Blood Flow was measured using hydrogen washout. Microangiography, histologic, and histomorphometric analyses were performed. Capillary density was greater in the FGF+VEGF group (35.1%) than control (13.9%) (p < 0.05), and a linear trend was found from control, FGF, VEGF, to FGF+VEGF (p < 0.005). Bone formation rates were greater with VEGF (p < 0.01) and FGF+VEGF (p < 0.05). VEGF or FGF alone increased Blood Flow more than when combined. Histology rejection grading was low in all grafts. Local administration of vascular and fibroblast growth factors augments angiogenesis, Bone formation, and Bone Blood Flow from implanted Blood vessels of donor origin in vascularized Bone allografts after removal of immunosuppression.

  • role of conventional and vascularized Bone grafts in scaphoid nonunion with avascular necrosis a canine experimental study
    Journal of Hand Surgery (European Volume), 2000
    Co-Authors: Toru Sunagawa, Allen T Bishop, Keiichi Muramatsu
    Abstract:

    The effectiveness of vascularized and conventional Bone grafts in the treatment of carpal fracture nonunion with avascular necrosis was evaluated in 12 adult dogs. The proximal third of the radiocarpal Bone was removed bilaterally and frozen in liquid nitrogen. Its replacement, leaving a 4-mm gap, simulated a scaphoid fracture nonunion with avascular necrosis. A dorsal radius inlay graft was placed across the gap. The graft was nonvascularized, or conventional on one side, and vascularized with a reverse-Flow arteriovenous pedicle on the other. Following a healing period, quantitative assessment of Bone Blood Flow, fracture healing, and Bone remodeling was conducted. Seventy-three percent of the vascularized grafts and none of the conventional grafts healed. At 6 weeks, Bone Blood Flow in the proximal pole was significantly higher on the side of the vascularized graft. Quantitative histomorphometry of the avascular proximal segment demonstrated significantly higher levels of fluorochrome-labeled osteoid- and osteoblast-covered trabecular surfaces on the vascularized graft side. These experimental data support the potential clinical application of pedicled reverse-Flow vascularized grafts in the treatment of carpal fracture nonunions with avascular necrosis, including proximal pole scaphoid nonunions.

  • experimental carpal reverse Flow pedicle vascularized Bone grafts part ii Bone Blood Flow measurement by radioactive labeled microspheres in a canine model
    Journal of Hand Surgery (European Volume), 2000
    Co-Authors: Yuan Kun Tu, Allen T Bishop, Teiji Kato, Mary L Adams, Michael B Wood
    Abstract:

    Abstract Reverse-Flow pedicle vascularized Bone grafts (VBGs) from the radius, commonly used for carpal nonunion and avascular necrosis, provide superior clinical results. In this experimental study Bone Blood Flow in canine distal radius VBGs was measured to determine the status of the Bone circulation immediately after elevation (group 1) and 2 weeks later (group 2). Immediate VBG Flow (group 1) was substantial, but significantly less than the contralateral undisturbed distal radius (8.42 mL/min/100 g and 16.53 mL/min/100 g, respectively). At 2 weeks after surgery (group 2) VBG Flow was compared with nonvascularized control grafts. Vascularized Bone graft Flow was significantly higher than group 1 (mean, 33.72 mL/min/100 g). Minimal Flow was seen in the conventional graft control (0.62 mL/min/100 g). This study demonstrates that reverse-Flow pedicle radius VBG maintain enhanced Bone circulation long-term. Given the similarity of human and canine distal radius vascular anatomy, these data support the clinical use of reverse-Flow VBG for carpal pathology. (J Hand Surg 2000;25A:46–54. Copyright © 2000 by the American Society for Surgery of the Hand.)

T J N Nelson - One of the best experts on this subject based on the ideXlab platform.

  • femoral Bone perfusion through the nutrient foramen during growth and locomotor development of western grey kangaroos macropus fuliginosus
    The Journal of Experimental Biology, 2017
    Co-Authors: T J N Nelson, Edward P Snelling, Roger S Seymour
    Abstract:

    ABSTRACT The nutrient artery passes through the nutrient foramen on the shaft of the femur and supplies more than half of the total Blood Flow to the Bone. Assuming that the size of the nutrient foramen correlates with the size of the nutrient artery, an index of Blood Flow rate ( Q i ) can be calculated from nutrient foramen dimensions. Interspecific Q i is proportional to locomotor activity levels in adult mammals, birds and reptiles. However, no studies have yet estimated intraspecific Q i to test for the effects of growth and locomotor development on Bone Blood Flow requirements. In this study, we used micro-CT and medical CT scanning to measure femoral dimensions and foramen radius to calculate femoral Q i during the in-pouch and post-pouch life stages of western grey kangaroos ( Macropus fuliginosus ) weighing 5.7 g to 70.5 kg and representing a 12,350-fold range in body mass. A biphasic scaling relationship between Q i and body mass was observed (breakpoint at ca. 1–5 kg body mass right before permanent pouch exit), with a steep exponent of 0.96±0.09 (95% CI) during the in-pouch life stage and a statistically independent exponent of –0.59±0.90 during the post-pouch life stage. In-pouch joeys showed Q i values that were 50–100 times higher than those of adult diprotodont marsupials of the same body mass, but gradually converged with them as post-pouch adults. Bone modelling during growth appears to be the main determinant of femoral Bone Blood Flow during in-pouch development, whereas Bone remodelling for micro-fracture repair due to locomotion gradually becomes the main determinant when kangaroos leave the pouch and become more active.

Edward P Snelling - One of the best experts on this subject based on the ideXlab platform.

  • femoral Bone perfusion through the nutrient foramen during growth and locomotor development of western grey kangaroos macropus fuliginosus
    The Journal of Experimental Biology, 2017
    Co-Authors: T J N Nelson, Edward P Snelling, Roger S Seymour
    Abstract:

    ABSTRACT The nutrient artery passes through the nutrient foramen on the shaft of the femur and supplies more than half of the total Blood Flow to the Bone. Assuming that the size of the nutrient foramen correlates with the size of the nutrient artery, an index of Blood Flow rate ( Q i ) can be calculated from nutrient foramen dimensions. Interspecific Q i is proportional to locomotor activity levels in adult mammals, birds and reptiles. However, no studies have yet estimated intraspecific Q i to test for the effects of growth and locomotor development on Bone Blood Flow requirements. In this study, we used micro-CT and medical CT scanning to measure femoral dimensions and foramen radius to calculate femoral Q i during the in-pouch and post-pouch life stages of western grey kangaroos ( Macropus fuliginosus ) weighing 5.7 g to 70.5 kg and representing a 12,350-fold range in body mass. A biphasic scaling relationship between Q i and body mass was observed (breakpoint at ca. 1–5 kg body mass right before permanent pouch exit), with a steep exponent of 0.96±0.09 (95% CI) during the in-pouch life stage and a statistically independent exponent of –0.59±0.90 during the post-pouch life stage. In-pouch joeys showed Q i values that were 50–100 times higher than those of adult diprotodont marsupials of the same body mass, but gradually converged with them as post-pouch adults. Bone modelling during growth appears to be the main determinant of femoral Bone Blood Flow during in-pouch development, whereas Bone remodelling for micro-fracture repair due to locomotion gradually becomes the main determinant when kangaroos leave the pouch and become more active.

John A. Frangos - One of the best experts on this subject based on the ideXlab platform.

  • Bone tissue engineering the role of interstitial fluid Flow
    Biotechnology and Bioengineering, 1994
    Co-Authors: M V Hillsley, John A. Frangos
    Abstract:

    It is well established that vascularization is required for effective Bone healing. This implies that Blood Flow and interstitial fluid (ISF) Flow are required for healing and maintenance of Bone. The fact that changes in Bone Blood Flow and ISF Flow are associated with changes in Bone remodeling and formation support this theory. ISF Flow in Bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter Flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of Bone during exercise. These conditions also induce changes in Bone remodeling. Previously, we hypothesized that interstitial fluid Flow in Bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF Flow results in the Bone loss observed in disuse and microgravity. The purpose of this article is to review ISF Flow in Bone and its role in osteogenesis.

  • Bone tissue engineering the role of interstitial fluid Flow
    Biotechnology and Bioengineering, 1994
    Co-Authors: M V Hillsley, John A. Frangos
    Abstract:

    It is well established that vascularization is required for effective Bone healing. This implies that Blood Flow and interstitial fluid (ISF) Flow are required for healing and maintenance of Bone. The fact that changes in Bone Blood Flow and ISF Flow are associated with changes in Bone remodeling and formation support this theory. ISF Flow in Bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter Flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of Bone during exercise. These conditions also induce changes in Bone remodeling. Previously, we hypothesized that interstitial fluid Flow in Bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF Flow results in the Bone loss observed in disuse and microgravity. The purpose of this article is to review ISF Flow in Bone and its role in osteogenesis. © 1994 John Wiley & Sons, Inc.