Progress 03/01/01 to 12/31/05
Outputs
Components of bone matrix that appear in the blood are commonly used as biomarkers of bone metabolism. These biomarkers can represent synthetic gene products that "escape" into blood or degradation products derived from bone resorption. In the laying hen, medullary bone differs from cortical bone by virtue of a high content of the glycosaminoglycan keratan sulfate (KS). We have demonstrated that KS is present in laying hen plasma under various physiological situations. Previous research with restricted ovulator (RO) hens suggested that plasma KS reflects medullary bone formation rather than degradation. This research was extended to investigate the variation in plasma during the egg laying cycle. Unexpectedly, the peak in plasma KS coincided with peak eggshell calcification. These results are consistent with reports that medullary bone matrix synthesis is very active during this time during the egg cycle. This creates an enigma since this is the time of maximum calcium
release from medullary bone. In addition to KS we have identified other bone matrix proteins in laying hen plasma. These include bone sialoprotein, dental matrix protein, osteopontin and osteocalcin. Further studies are needed in order to determine which protein would best reflect cortical bone metabolism.
Impacts
Diseases related to skeletal metabolism represent a serious economic loss to the poultry industry. Eggshell breakage and bone fragility are two examples of skeletal related problems. Medullary bone is an important source of calcium, the major component of eggshell. Cortical bone fractures occur during the handling and processing of carcasses and render the meat unsuitable for human consumption. At the present time there are no non-invasive techniques available for monitoring bone metabolism in the laying hen. The results of this research indicate that plasma keratan sulfate is a useful biomarker for avian medullary bone metabolism. Other potential markers are being investigated as indicators of structural (cortical) bone metabolism.
Publications
- Wang, X., Ford, B. C., Praul, C. A. and Leach, R. M., Jr. 2005. Characterization of the non-collagenous proteins in avian cortical and medullary bone. Comp. Biochem. Physiology Part B 140:665-672.
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Progress 01/01/04 to 12/31/04
Outputs
Components of bone matrix that appear in the blood are commonly used as biomarkers of bone metabolism. These biomarkers can represent synthetic gene products that escape into blood or degradation products derived from bone resorption. In the laying hen, medullary bone differs from cortical bone by virtue of a high content of keratan sulfate (KS), a glycosaminoglycan. We have demonstrated that KS is present in laying hen plasma under various physiological situations. Previous research with restricted ovulator (RO) hens suggested that plasma KS reflects medullary bone formation rather than degradation. This research was extended to investigate the variation in plasma during the egg laying cycle. Unexpectedly, the peak in plasma KS coincided with peak eggshell calcification. However, these results are consistent with reports that medullary bone matrix synthesis is very active during this time during the egg cycle. This creates an enigma since this is the time of maximum
calcium release from medullary bone. In addition to KS, we have identified other bone matrix proteins in laying hen plasma. These include bone sialoprotein, dental matrix protein, osteopontin and osteocalcin. Studies are underway to determine which protein would best reflect cortical bone metabolism.
Impacts
Diseases related to skeletal metabolism represent a serious economic loss to the poultry industry. Eggshell breakage and bone fragility are two examples of skeletal related problems. Medullary bone is an important source of calcium, the major component of eggshell. Cortical bone fractures occur during the handling and processing of carcasses and render the meat unsuitable for human consumption. At the present time there are no non-invasive techniques available for monitoring bone metabolism in the laying hen. The results of this research indicate that plasma keratan sulfate is a useful biomarker for avian medullary bone metabolism. Other potential markers are being investigated as indicators of structural (cortical) bone metabolism.
Publications
- Kim, W. K., Ford, B. C., Mitchell, A. D., Elkin, R. G. and Leach, R. M. 2004. Comparative assessment of bone among wild-type, restricted ovulator and out-of-production hens. Br. Poultry Sci. 45:463-470.
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Progress 01/01/03 to 12/31/03
Outputs
Components of bone matrix that appear in the blood are commonly used as biomarkers of bone metabolism. These biomarkers can represent synthetic gene products that "escape" into blood or degradation products derived from bone resorption. In the laying hen, medullary bone differs from cortical bone by virtue of a high content of the glycosaminoglycan (GAG) keratan sulfate. We have demonstrated that KS is present in laying hen plasma under various physiological situations. Restricted ovulator (RO) hens were studied in order to determine if plasma KS represents synthesis or degradation. Both total GAG and KS levels in the plasma of RO hens were markedly higher than wild-type (WT) hens. Since these hens do not have cyclic medullary bone metabolism associated with egg formation, the results suggest that plasma KS activity reflects intensive medullary bone formation in response to increased plasma estrogen observed by others in RO hens. This conclusion is further supported
by the extremely low osteoclastic activity observed in the femurs of RO hens, which makes it unlikely that plasma KS is derived from bone degradation.
Impacts
Diseases related to skeletal metabolism represent a serious economic loss to the poultry industry. Eggshell breakage and bone fragility are two examples of skeletal related problems. Medullary bone is an important source of calcium, the major component of eggshell. Cortical bone fractures occur during the handling and processing of carcasses and render the meat unsuitable for human consumption. At the present time there is no non-invasive techniques available for monitoring bone metabolism in the laying hen. The results of this research indicate that plasma keratan sulfate is a useful biomarker for avian medullary bone metabolism.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
Medullary bone is found in abundance in the marrow cavity of the long bones of laying birds. In the domestic hen, this bone supplies 30-40 percent of the calcium of each eggshell and thus cycles in synchrony with the egg laying cycle. Medullary bone may also play a role in the development of osteoporosis since it is formed at the expense of cortical (structural) bone. Thus, we are interested in developing non-invasive markers for evaluating bone metabolism in the laying hen. This is based on the common practice of measuring osteoblast specific gene products that "escape" into blood as markers of bone metabolism. We have found that cortical bone, medullary bone and blood contain the same osteoblast specific gene products: osteocalcin, dentin matrix protein-1 and bone sialoprotein. However, medullary bone does differ from cortical bone by virtue of a high content of the glycosaminoglycan keratan sulfate (KS). We have found medullary bone KS to be attached to a specific
isoform of bone sialoprotein that is not present in cortical bone. Using a biochemical method we have demonstrated the presence of KS in laying hen plasma under various physiological situations. However, the procedure is tedious, expensive and subject to experimental error. Since medullary bone KS does not cross-react with monoclonal antibodies (MAbs) to corneal and cartilage KS, we are in the process of developing a MAb specific for medullary bone KS. This will be used to quantitate and identify forms of KS in the blood of laying hens under physiological conditions that influence bone metabolism.
Impacts
Diseases related to skeletal metabolism represent a serious economic loss to the poultry industry. Eggshell breakage and bone fragility are two examples of skeletal related problems. Bone is an important source of calcium, the major component of eggshell. Fragile bones result in fractures during the handling and processing of carcasses that renders the meat unsuitable for human consumption. At the present time there are no non-invasive techniques available for monitoring bone metabolism in the laying hen. This research will lead to the development of tests that can be utilized for this purpose.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Medullary bone is found in abundance in the marrow cavity of the long bones of laying birds. In the domestic laying hen, medullary bone supplies 30-40 percent of the calcium of each eggshell. Thus, metabolic activity of this bone is in synchrony with the egg laying cycle. It would be valuable to have the ability to monitor medullary bone metabolism by measuring a marker present in blood. Medullary bone differs from cortical bone in the amount and type of proteoglycan. Keratan sulfate proteoglycans (KSPG) are unique to medullary bone and thus have the potential as serving as markers for medullary bone metabolism. Research has focused on the identification of the core protein of the KSPG present in medullary bone. Since the KSPG was present in the EDTA extracts of medullary bone, the core protein was isolated and purified after treatment of the extracts with keratanase. Sequencing of this protein revealed its identity to be bone sialoprotein (BSP), a non-collagenous
protein common to bone tissue. Further examination of medullary bone extracts showed that osteopontin and osteonectin were also glycosylated with keratan sulfate (KS). Since these proteins were not glycosylated with KS in cortical bone, post-transitional modification of proteins with this glycosaminoglycan is specific for medullary bone. However, Western blotting of serum with an antibody to BSP did not reveal an isoform specific to the laying hen. These results shift the focus to the examination of serum for metabolites of keratan sulfate as markers of medullary bone metabolism. These experiments are in progress.
Impacts
Diseases related to skeletal metabolism represent a serious economic loss to the poultry industry. Eggshell breakage and bone fragility are two examples of skeletal related problems. Bone is an important source of calcium, the major component of eggshell. Fragile bones result in fractures during the handling and processing of carcasses that renders the meat unsuitable for human consumption. At the present time there are no non-invasive techniques available for monitoring bone metabolism in the laying hen. This research will lead to the development of tests that can be utilized for this purpose.
Publications
- No publications reported this period
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