The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Taiji Adachi - One of the best experts on this subject based on the ideXlab platform.
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Residual Stress in Bone Structure: Experimental Observation and Model Study with Uniform Stress Hypothesis
Biomechanics, 1996Co-Authors: M. Tanaka, Taiji AdachiAbstract:In soft tissues, residual stress/strain have been observed experimentally and their role has been investigated from the point of view of stress/strain regulation or mechanical remodeling. In this chapter, the residual stress of bone structure is examined for the leporine tibiofibula bone and the bovine Coccygeal Vertebra. The fibula-cutting experiment for the leporine tibiofibula demonstrated that the axial strain induced in the tibia is distributed in the circumferential direction, suggesting that the residual stress is caused by statical indeterminacy. Numerical fibula cutting was studied for the remodeling equilibrium, which was simulated by the remodeling model considering residual stress and in which stress distribution is uniform under the working load. It was found that the strain induced by the real fibula cutting experiment coincides with that by the numerical experiments. For the bovine Coccygeal Vertebra, the end-plates and cancellous bone were removed sequentially, and positive strains were observed in the cephalocaudal and circumferential directions. The strain induced in the cephalocaudal direction was examined for the uniform stress state of the model of two-bar elements of the cortical and cancellous bone under working load, and the strain induced in the circumferential direction was for that of the model of two-cylinder elements as well. From these considerations, it was confirmed that the residual stress of bone structure suggested experimentally can be understood in the context of model studies based on the uniform stress hypothesis at remodeling equilibrium.
An‐chung Lin - One of the best experts on this subject based on the ideXlab platform.
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Vascularized autogenous canine Coccygeal bone transfer.
Microsurgery, 1991Co-Authors: Lih‐sen Yeh, Sheng‐mou Hou, An‐chung LinAbstract:Based on cadaver studies in dogs, the 8th, 9th, or 10th canine Coccygeal Vertebra with overlying skin was designed for free vascularized bone transfer. In six dogs the Coccygeal osteocutaneous flap was transferred to fill a defect of the tibia, anastomosing the median caudal artery and one of the two caudal veins to the tibial vessels. The overlying skin provided a reliable monitoring system for the transferred tissue. The behavior of the vascularized Coccygeal Vertebrae was then evaluated with radiographic and histologic examination and compared with control Vertebrae transferred without reconnection of the blood vessels. The results revealed that the canine Coccygeal bone graft is a reliable vascularized osteocutaneous flap, which can be applied either in clinical veterinary surgery or in orthopedic microsurgical research.
D. B. Coates - One of the best experts on this subject based on the ideXlab platform.
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Bone mineral density in the tail-bones of cattle: effect of dietary phosphorus status, liveweight, age and physiological status
Animal Production Science, 2018Co-Authors: D. B. Coates, Rob Dixon, R. J. Mayer, R. M. Murray, C. P. MillerAbstract:In three grazing experiments in the seasonally dry tropics of Australia, growing steers (Experiment 1), first-calf cows (Experiment 2) and mature breeder cows (Experiment 3), ingested diets for 12–17 months, which were either adequate or severely deficient in phosphorus (P) (Padeq and Pdefic, respectively). Bone mineral density (BMD) at the proximal end of the ninth Coccygeal Vertebra (Cy9) was measured at intervals using single photon absorptiometry (SPA). Liveweight (LW) and plasma inorganic phosphorus (PIP) concentrations were monitored at intervals and rib-bone cortical bone thickness (CBT) of biopsy samples was measured at the end of Experiments 1 and 3. Measurements of LW change, PIP concentrations and CBT confirmed that diet P intakes of cattle in the Padeq treatments were adequate whereas there was severe and chronic P deficiency in the Pdefic treatments. In Experiment 1 BMD in Padeq steers increased with LW and age from ~0.25–0.27 g/cc (8 months, 200 kg LW) to ~0.34 g/cc (32 months, 490 kg LW), whereas in Pdefic steers BMD decreased progressively to ~0.23–0.24 g/cc. Although BMD decreased in the Pdefic steers bone volume of Cy9 (calculated from tail-bone thickness) increased, and some net bone deposition in the Cy9 continued. Rib-bone CBT and tail-bone BMD at the end of Experiment 1 were closely correlated (r = 0.93). In Experiment 2 BMD was initially 0.33 g/cc (~25 months, 400 kg LW) and did not change through pregnancy and lactation in Padeq cows. However, in the Pdefic cows there was a gradual decline in BMD to ~0.25 g/cc. There was no change in dimensions of the Cy9 so the decreases in BMD involved net demineralisation of bone. In Experiment 3 BMD was less responsive to P deficiency than in Experiments 1 and 2. Only after ~11 months was BMD reduced (P < 0.05) in the Pdefic cows, and then only by 15%. In contrast, rib-bone CBT decreased by 30% due to P deficiency, and BMD was poorly correlated with CBT (r = 0.4). The effects of animal weight, age and maturity on tailbone BMD of P-adequate animals, and the different responses to P deficiency observed in young growing steers, first-calf cows and mature breeders are discussed in relation to the use of SPA measured tail-bone BMD to diagnose P deficiency in grazing cattle.
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Validation of single photon absorptiometry for on-farm measurement of density and mineral content of tail bone in cattle
Animal Production Science, 2016Co-Authors: D. B. Coates, Rob Dixon, R. J. Mayer, R. M. MurrayAbstract:A validation study examined the accuracy of a purpose-built single photon absorptiometry (SPA) instrument for making on-farm in vivo measurements of bone mineral density (BMD) in tail bones of cattle. In vivo measurements were made at the proximal end of the ninth Coccygeal Vertebra (Cy9) in steers of two age groups (each n = 10) in adequate or low phosphorus status. The tails of the steers were then resected and the BMD of the Cy9 bone was measured in the laboratory with SPA on the resected tails and then with established laboratory procedures on defleshed bone. Specific gravity and ash density were measured on the isolated Cy9 Vertebrae and on 5-mm2 dorso-ventral cores of bone cut from each defleshed Cy9. Calculated BMD determined by SPA required a measure of tail bone thickness and this was estimated as a fraction of total tail thickness. Actual tail bone thickness was also measured on the isolated Cy9 Vertebrae. The accuracy of measurement of BMD by SPA was evaluated by comparison with the ash density of the bone cores measured in the laboratory. In vivo SPA measurements of BMD were closely correlated with laboratory measurements of core ash density (r = 0.92). Ash density and specific gravity of cores, and all SPA measures of BMD, were affected by phosphorus status of the steers, but the effect of steer age was only significant (P < 0.05) for steers in adequate phosphorus status. The accuracy of SPA to determine BMD of tail bone may be improved by reducing error associated with in vivo estimation of tail bone thickness, and also by adjusting for displacement of soft tissue by bone mineral. In conclusion a purpose-built SPA instrument could be used to make on-farm sequential non-invasive in vivo measurements of the BMD of tailbone in cattle with accuracy acceptable for many animal studies.
R. M. Murray - One of the best experts on this subject based on the ideXlab platform.
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Bone mineral density in the tail-bones of cattle: effect of dietary phosphorus status, liveweight, age and physiological status
Animal Production Science, 2018Co-Authors: D. B. Coates, Rob Dixon, R. J. Mayer, R. M. Murray, C. P. MillerAbstract:In three grazing experiments in the seasonally dry tropics of Australia, growing steers (Experiment 1), first-calf cows (Experiment 2) and mature breeder cows (Experiment 3), ingested diets for 12–17 months, which were either adequate or severely deficient in phosphorus (P) (Padeq and Pdefic, respectively). Bone mineral density (BMD) at the proximal end of the ninth Coccygeal Vertebra (Cy9) was measured at intervals using single photon absorptiometry (SPA). Liveweight (LW) and plasma inorganic phosphorus (PIP) concentrations were monitored at intervals and rib-bone cortical bone thickness (CBT) of biopsy samples was measured at the end of Experiments 1 and 3. Measurements of LW change, PIP concentrations and CBT confirmed that diet P intakes of cattle in the Padeq treatments were adequate whereas there was severe and chronic P deficiency in the Pdefic treatments. In Experiment 1 BMD in Padeq steers increased with LW and age from ~0.25–0.27 g/cc (8 months, 200 kg LW) to ~0.34 g/cc (32 months, 490 kg LW), whereas in Pdefic steers BMD decreased progressively to ~0.23–0.24 g/cc. Although BMD decreased in the Pdefic steers bone volume of Cy9 (calculated from tail-bone thickness) increased, and some net bone deposition in the Cy9 continued. Rib-bone CBT and tail-bone BMD at the end of Experiment 1 were closely correlated (r = 0.93). In Experiment 2 BMD was initially 0.33 g/cc (~25 months, 400 kg LW) and did not change through pregnancy and lactation in Padeq cows. However, in the Pdefic cows there was a gradual decline in BMD to ~0.25 g/cc. There was no change in dimensions of the Cy9 so the decreases in BMD involved net demineralisation of bone. In Experiment 3 BMD was less responsive to P deficiency than in Experiments 1 and 2. Only after ~11 months was BMD reduced (P < 0.05) in the Pdefic cows, and then only by 15%. In contrast, rib-bone CBT decreased by 30% due to P deficiency, and BMD was poorly correlated with CBT (r = 0.4). The effects of animal weight, age and maturity on tailbone BMD of P-adequate animals, and the different responses to P deficiency observed in young growing steers, first-calf cows and mature breeders are discussed in relation to the use of SPA measured tail-bone BMD to diagnose P deficiency in grazing cattle.
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Validation of single photon absorptiometry for on-farm measurement of density and mineral content of tail bone in cattle
Animal Production Science, 2016Co-Authors: D. B. Coates, Rob Dixon, R. J. Mayer, R. M. MurrayAbstract:A validation study examined the accuracy of a purpose-built single photon absorptiometry (SPA) instrument for making on-farm in vivo measurements of bone mineral density (BMD) in tail bones of cattle. In vivo measurements were made at the proximal end of the ninth Coccygeal Vertebra (Cy9) in steers of two age groups (each n = 10) in adequate or low phosphorus status. The tails of the steers were then resected and the BMD of the Cy9 bone was measured in the laboratory with SPA on the resected tails and then with established laboratory procedures on defleshed bone. Specific gravity and ash density were measured on the isolated Cy9 Vertebrae and on 5-mm2 dorso-ventral cores of bone cut from each defleshed Cy9. Calculated BMD determined by SPA required a measure of tail bone thickness and this was estimated as a fraction of total tail thickness. Actual tail bone thickness was also measured on the isolated Cy9 Vertebrae. The accuracy of measurement of BMD by SPA was evaluated by comparison with the ash density of the bone cores measured in the laboratory. In vivo SPA measurements of BMD were closely correlated with laboratory measurements of core ash density (r = 0.92). Ash density and specific gravity of cores, and all SPA measures of BMD, were affected by phosphorus status of the steers, but the effect of steer age was only significant (P < 0.05) for steers in adequate phosphorus status. The accuracy of SPA to determine BMD of tail bone may be improved by reducing error associated with in vivo estimation of tail bone thickness, and also by adjusting for displacement of soft tissue by bone mineral. In conclusion a purpose-built SPA instrument could be used to make on-farm sequential non-invasive in vivo measurements of the BMD of tailbone in cattle with accuracy acceptable for many animal studies.
James R. Strickland - One of the best experts on this subject based on the ideXlab platform.
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Vasoactivity and Vasoconstriction Changes in Cattle Related to Time off Toxic Endophyte-Infected Tall Fescue
MDPI AG, 2016Co-Authors: James L. Klotz, Glen E. Aiken, Jessica R. Bussard, Andrew P. Foote, David L. Harmon, Ben M. Goff, Neal F. Schrick, James R. StricklandAbstract:Previous research has indicated that serotonergic and α-adrenergic receptors in peripheral vasculature are affected by exposure of cattle grazing toxic endophyte-infected (E+; Epichlöe coenophialia) tall fescue (Lolium arundinaceum). The objective of this experiment was to determine the period of time necessary for the vascular effects of ergot alkaloids to subside. Two experiments were conducted to investigate changes in vascular contractile response and vasoconstriction over time relative to removal from an ergot alkaloid-containing E+ tall fescue pasture. In Experiment 1, lateral saphenous vein biopsies were conducted on 21 predominantly Angus steers (357 ± 3 kg body weight) at 0 (n = 6), 7 (n = 6), 14 (n = 5), or 28 days (n = 4) after removal from grazing pasture (3.0 ha; endpoint ergovaline + ergovalinine = 1.35 mg/kg DM) for 126 days. In Experiment 2, lateral saphenous veins were biopsied from 24 Angus-cross steers (361 ± 4 kg body weight) at 0, 21, 42, and 63 days (n = 6 per time point) following removal from grazing tall fescue pastures (3.0 ha; first 88 days endpoint ergovaline + ergovalinine = 0.15 mg/kg DM; last 18 days endpoint ergovaline + ergovalinine = 0.57 mg/kg DM) for 106 total days. Six steers (370 ± 18 kg body weight) off of bermudagrass pasture for the same time interval were also biopsied on Day 0 and Day 63 (n = 3 per time point). Additionally, in Experiment 2, cross-sectional ultrasound scans of caudal artery at the fourth Coccygeal Vertebra were taken on Days 0, 8, 15, 21, 29, 36, 42, and 45 to determine mean artery luminal area to evaluate vasoconstriction. In both experiments, steers were removed from pasture and housed in a dry lot and fed a corn silage diet for the duration of biopsies and ultrasound scans. Biopsied vessels used to evaluate vasoactivity were cleaned, incubated in a multimyograph, and exposed to increasing concentrations of 4-Bromo-3,6-dimethoxybenzocyclobuten-1-yl) methylamine hydrobromide (TCB2; 5HT2A agonist), guanfacine (GF; α2A-adrenergic agonist), and (R)-(+)-m-nitrobiphenyline oxalate (NBP; α2C-adrenergic agonist) in both experiments and ergovaline (ERV) and ergotamine (ERT) in Experiments 1 and 2, respectively. In Experiment 1, days off pasture × agonist concentration was not significant (p > 0.1) for all four compounds tested. In Experiment 2, GF, NBP, TCB2 and ERT were significant for days off pasture × agonist concentration interaction (p < 0.02) and vasoactivity increased over time. Vasoactivity to agonists was reduced (p < 0.05) when steers were initially removed from E+ tall fescue pasture compared to bermudagrass, but did not differ by Day 63 for any variable. Luminal areas of caudal arteries in steers grazed on E+ tall fescue relaxed and were similar to steers that had grazed bermudagrass for 36 days on non-toxic diet (p = 0.15). These data demonstrate changes in peripheral vasoactivity and recovery from vasoconstriction occur beyond five weeks off toxic pasture and 5HT2A receptors appear to be more dramatically affected in the lateral saphenous vein by grazing E+ tall fescue pasture than adrenergic receptors