Bone Alkaline Phosphatase in Paget's Disease
Summary The measurement of bone proteins and peptides and their derived products has been very useful in the diagnosis and management of patients with skeletal disease. This group of assays includes alkaline phosphatase (AP) and bone Gla protein (BGP). We here describe the comparison of a new immunoassay that is specific for bone alkaline phosphatase (BAP) to measurements of total alkaline phosphatase (TAP) and BGP in Paget's disease. In our studies, we demonstrated that BAP was increased in the serum of patients with Paget's disease. Comparisons with the other measurements revealed that BAP correlated better with total AP (r = 0.92) than with BGP (r = 0.51); the lowest correlation occurred between BGP and total AP (r = 0.26). In patients with liver disease, the BAP was indistinguishable from normal whereas the TAP was elevated. These studies indicate that BAP assesses different aspects of bone cell function than BGP in Paget's disease. This discordancy also exists between BGP and total serum AP activity. BAP measurements by immunoassay offer a novel method of assessing skeletal status. Thus, the information that measurement of different bone-specific proteins provides should be separately useful in assessing the skeleton for a variety of metabolic bone diseases. Key words Paget's Disease — Metabolic Bone Diseases — Alkaline Phosphatase — Osteocalcin — Bone Gla Protein
Introduction Many new procedures have been developed to assess the human skeleton (Epstein 1989). Computer-enhanced densitometric procedures now provide more sensitive and specific information about skeletal status than X-rays. Improved histomorphometric procedures provide better quantification of bone metabolism and newer isotopes provide a better evaluation of the entire skeleton (Deftos and Glowacki 1984; Melton, Eddy and Johnston 1990). Substantial progress has also been made in the development of assay procedures for the measurement of bone-derived proteins and peptides in serum and other biological fluids (Price, Parthemore and Def-
Horm.metab.Res. 23(1991)559-561 © Georg Thieme Verlag Stuttgart • New York
tos 1980; Crofton 1982; Deftos, Parthemore and Price 1982). Assays for alkaline and acid phosphatase, procollagen and hydroxyproline, and bone Gla protein (BGP, osteocalcin), have yielded useful information when applied to clinical studies (Deftos, Parthemore and Price 1982; Duda, O'brien, Katzmann, Peterson, Mann and Riggs 1988; Simon, Krane, Wortman, Krane and Kovitz 1984). But each of these methodologies has significant clinical limitations (Cheung, Manolagas, Catherwood, Mosely, Mitas, Blantz and Deftos 1983). The most commonly used serum biochemical marker for bone diseases is alkaline phosphatase (AP) activity measurement (Crofton 1982). Although this procedure is valuable in many circumstances, it suffers from lack of specificity, because the alkaline phosphatase activity in blood is also contributed to by the liver, the gastrointestinal tract, the placenta, certain tumors, and perhaps other sources (Crofton 1982; Deftos and Glowacki 1984). Many procedures have been developed in an attempt to improve the specificity of the assay procedures for the AP that come from bone (Crofton 1982; Duda et al. 1988). With the exceptions discussed subsequently, these modifications have, in general, not been entirely successful and remain technically difficult. Accordingly, we undertook a comparison of classical osteoblast markers to bone-specific alkaline phosphatase (BAP) with a newly-developed procedure that is specific for BAP (Hill and Wolfert 1989). Materials and Methods We here describe preliminary clinical studies of a new serum marker for skeletal disease, BAP, and two established bone markers for skeletal disease, BGP and total alkaline phosphatase activity (TAP). Fasting blood samples were collected from normal adults, patients with alcoholic cirrhosis, and in 23 patients with Paget's disease of bone being followed as outpatients. The diagnosis of Paget's disease was established in all of them by clinical, biochemical, and radiologic criteria. Each sample was assayed for TAP with p-nitrophenylphosphate as substrate, for BGP with a previously described radioimmunoassay, and for BAP with a newly-developed two-site immunoradiometric assay (Weisman, Orth, Catherwood, Manolagas and Deftos 1986; Crofton 1982; Deftos, Parthemore and Price 1982; Hill and Wolfert 1989). The details of this assay have been recently described and will only be summarized here (Hill and Wolfert 1989). The assay uses two antibodies, designated 419 and 017, that have specificity for BAP over LAP (Hill and Wolfert 1989). It is likely that this specificity is conferred by a post-translational modification of BAP, since its isoenzymes are products of the same gene (Weiss, Henthorn, Lafferty, Slaughter, Raducha and Harris 1986). For the two-site format, the capture antibody is bound to a polystyrene bead and the second antibody is radioiodinated. The bead is incubated with the serum sample
Received: 16 Nov. 1990
Accepted: 28 March 1991
Downloaded by: National University of Singapore. Copyrighted material.
L. J. Deftos, R. L. Wolfert and C. S. Hill Department of Medicine, University of California, San Diego, and the San Diego VA Medical Center and Hybritech, Incorporated, San Diego, California, U. S. A.
Horm. metab. Res. 23 (1991)
Fig. 1 Comparison of serum total alkaline phosphatase activity (TAP) to immunoassay measurements of bone Gla protein (BGP) and bone-specific alkaline phosphatase (BAP) in Paget's disease. TAP was measured using p-nitrophosphate in the clinical laboratory assay with an upper limit of normal of 100 U/L. BGP was measured by a radioimmunoassay with a normal limit of 5 pmol/ml (Deftos, Parthemore and Price 1982). BAP was measured by a two-site immunoradiometric assay with a normal limit of 50 U/L. The correlation between BAP (Hill and Wolfert 1989) and TAP was 0.92, p < .001; between BGP and TAP, 0.26, p < .10; and between BGP and BAP, 0.34, p < .05).
and the labelled antibody for 2 hours at room temperature, washed, and counted in a gamma counter. BAP levels in the unknown sample are determined from a standard curve of BAP extracted from human osteoblast cells (Hill and Wolfert 1989). The procedure can readily accomodate 500 samples. Results and Discussion Figure 1 demonstrates the correlations among BAP, TAP and BGP in 23 patients with Paget's disease. All three measurements were elevated in these patients. By contrast, patients with liver disease had elevated TAP levels and BAP and BGP levels that were statistically indistinguishable from normal; the mean TAP in nine such patients was 331 U/L, the mean BAP was 90 U/L, the mean BGP was 5.5 pmol/ml, and there was no correlation among them. Therefore, the two-site assay that we have applied to these clinical studies is specific for BAP and does not appreciably crossreact with liver alkaline phosphatase (LAP). Thus, it is different from the method recently reported by Duda et al. (1988), where two antibodies, one equally reactive to BAP and LAP and the other with a 5-fold greater affinity for BAP, were used separately in immunoassays and the BAP was calculated from the two different measurements. In our assay, we use two antibodies that have been previously shown to have less than 15 % cross-reactivity with LAP for direct measurement of BAP (Hill and Wolfert 1989). In addition to this specificity, this two-site assay is rapid and convenient when compared to standard radioimmunoassay formats (Deftos, Parthemore and Price 1982). The direct measurement of BAP offers many obvious advantages over the measurement of TAP. In fact, the disadvantages of TAP measurement, especially its non-specificity, have caused it to become increasingly supplanted by BGP measurements in clinical studies of skeletal disease (Duda et al. 1988; Orwoll, Oviatt, McClung, Deftos and Sexton
L. J. Deftos, R. L. Wolfert and C. S. Hill 1990). However, it has become obvious that BGP does not measure the same components of osteoblast function that are reflected by TAP measurements or by calculated BAP measurements (Deftos, Parthemore and Price 1982; Delmas, Price and Mann 1990; Duda et al. 1988; Orwoll et al. 1990). Early studies identified discordancy among these measurements and they continue to appear (Deftos, Parthemore and Price 1982; Duda et al. 1988). The discordancy is best appreciated for Paget's disease where BGP measurements are distinguishable from other parameters of disease activity (Duda et al. 1988; Weiss et al. 1986). This may not be surprising when one considers that, although BGP and BAP are both osteoblast products, BGP is also incorporated into bone matrix (Deftos and Glowacki 1984; Price, Parthemore and Deftos 1980). Thus, there may be a moiety of BGP that is released upon resorption of bone matrix (Grundberg and Weinstein 1986; Simon et al. 1984). Because of these differences, it is very likely that BGP and BAP will not be redundant measurements but rather complementary assays for evaluating skeletal disease. Our studies demonstrate that in Paget's disease there is a high correlation between BAP and TAP, higher than that between BGP and TAP (Figure 1). Since the elevated TAP in Paget's disease comes primarily from bone, our measurement of BAP correlates more closely with this classical index of osteoblast activity that does BGP (Crofton 1982; Wilkinson, Wagstaffe, Delbridge, Wiseman and Posen 1986). Thus, BAP may be superior to BGP in this respect and reflect disease activity more accurately (Duda et al. 1988; Wilkinson etal. 1986). Furthermore, BAP may be less influenced by renal failure than BGP (Cheung et al. 1983). However, prospective clinical studies will be needed to evaluate these possibilities. Less speculatively, our studies also demonstrate another advantage of BAP over TAP measurement, the lack of substantial reactivity in the assay of LAP (Hill and Wolfert 1989). When coupled with the technical ease of the two-site BAP assay, this feature should make BAP measurement a most valuable tool for assessing skeletal function. Since the BAP assay measures immunological activity and the TAP measures enzymatic activity, the two measurements do not coincide in absolute units. Although only subtle differences of alkaline phosphatase have been reported in osteoporosis, the specificity and sensitivity of the BAP two-site assay may increase the clinically utility of this measurement in this frustrating disease also (Epstein 1989; Ismail, Epstein, Pacifici, Droke, Thomas and Avioli 1986). However, extensive clinical trials are necessary to test this hypothesis (Wilkinson et al. 1986). Abbreviations BGP - bone GlaProtein AP — Alkaline Phosphatase TAP — total serum alkaline phosphatase activity BAP — bone alkaline phosphatase LAP — liver alkaline phosphatase Acknowledgements This work was supported by the Department of Veterans Affairs, Rehabilitation R & D , and the National Institutes of Health. The authors were assisted by Kathy Smith, Cheryl Chalberg and Debbie Hussong.
Downloaded by: National University of Singapore. Copyrighted material.
560
Bone Alkaline Phosphatase
Horm. metab. Res. 23 (1991)
561
metabolism in postmenopausal osteoporosis. Calcified Tissue International 39:230-233 (1986) L. J., D. M. Eddy, C. C. Johnston: Screening for osteoporosis. Cheung, A. K., S. C. Manolagas, B. D. Catherwood, C. A. Mosely Jr., Melton, J. Annals of Internal Medicine 112:516-528(1990) A. Mitas II, R. C. Blantz, L. J. Deftos: Determinants of serum Orwoll, E. S., S. K. Oviatt, M. R. McClung, L. J. Deftos, G. Sexton: The 1,25(OH)2D levels in renal disease. Kidney International 24:104— rate of bone mineral loss in normal men and the effects of calcium 109(1983) and cholecalciferol supplementation. Annals of Internal MediCrofton, P. M.: Biochemistry of alkaline phosphatase isoenzymes. cine 112: 29-34 (1990) CRC critical reviews of clinical laboratory science 16: 161 — 194 Price, P. A., J. G. Parthemore, L. J. Deftos: A new biochemical marker (1982) for bone metabolism. Journal of Clinical Investigation 66: 878— Deftos, L. J„ J. Glowacki: Mechanisms of bone metabolism. In: 883(1980) "Pathophysiology", third edition, Kem, D. C. and E. Frohlick Simon, L. S., S. M. Krone, P. D. Wortman, I. M. Krane, K. L. Kovitz: (eds.), J. B. Lippincott, Co., Philadelphia (1984), pp. 445-468 Serum levels of type I and III procollagen fragments in Paget's disDeftos, L. J., J. G. Parthemore, P. A. Price: Changes in plasma bone ease of the bone. Journal of Clinical Endocrinology and Gla protein during treatment of bone disease. Calcified Tissue InMetbolism 58: 110-120 (1984) ternational 34: 121-124 (1982) Delmas, P.D..P.A. Price, K. G. Mann: Validation of the bone Gla pro- Weisman, M. H., R. W. Orth, B. D. Catherwood, S. C. Manolagas, L. J. Deftos: Measures of bone loss in rheumatoid arthritis. Archives of tein (osteocalcin) assay. Journal of Bone and Mineral Research 5: Internal Medicine 146: 701-704 (1986) 3-4(1990) Duda, J. R., J. F. O'brien, J. A. Katzmann, J. M. Peterson, K. G. Mann,Weiss, M. H., P. S. Henthorn, M. A. Lafferty, C. Slaughter, M. Raducha, H. Harris: Isolation and characterization of a cDNA encodB. L. Riggs: Concurrent assays of circulating bone Gla-protein and ing a human liver/bone/kidney-type alkaline phosphatase. Probone alkaline phosphatase: Effects of sex, age and metabolic bone ceedings of the National Academy of Science of the USA 83: disease. Journal of Clinical Endocrinology and Metabolism 66:1 — 7182-7194(1986) 7(1988) Epstein, S.: Bone-derived proteins. Trends in Endocrinology and Me- Wilkinson, M. R., C. Wagstaffe, L. Delbridge, J. Wiseman, S. Posen: Serum osteocalcin concentrations in Paget's disease of bone. Artabolism 1: 9-14 (1989) chives of Internal Medicine 46:268-271(1986) Grundberg, C. M., R. S. Weinstein: Multiple immunoreactive forms of osteocalcin in uremic serum: Journal of Clinical Investigation 77: 1762-1767(1986) Hill, C. S., R. L. Wolfert: The preparation of monoclonal antibodies Requests for reprints should be addressed to: which react preferentially with human bone alkaline phosphatase and not liver alkaline phosphatase. Clinica Chimica Acta 186: Leonard J. Deftos, M. D. 315-320(1989) 3350 La Jolla Village Drive Ismail, F., S. Epstein, R. Pacifici, D. Droke, S. B. Thomas, V. Avioli:Mail Code V-l 11C Serum bone Gla protein (BGP) and other markers of bone mineral San Diego, CA 92161 (U. S. A.)
Downloaded by: National University of Singapore. Copyrighted material.
References
Summary The measurement of bone proteins and peptides and their derived products has been very useful in the diagnosis and management of patients with skeletal disease. This group of assays includes alkaline phosphatase (AP) and bone Gla protein (BGP). We here describe the comparison of a new immunoassay that is specific for bone alkaline phosphatase (BAP) to measurements of total alkaline phosphatase (TAP) and BGP in Paget's disease. In our studies, we demonstrated that BAP was increased in the serum of patients with Paget's disease. Comparisons with the other measurements revealed that BAP correlated better with total AP (r = 0.92) than with BGP (r = 0.51); the lowest correlation occurred between BGP and total AP (r = 0.26). In patients with liver disease, the BAP was indistinguishable from normal whereas the TAP was elevated. These studies indicate that BAP assesses different aspects of bone cell function than BGP in Paget's disease. This discordancy also exists between BGP and total serum AP activity. BAP measurements by immunoassay offer a novel method of assessing skeletal status. Thus, the information that measurement of different bone-specific proteins provides should be separately useful in assessing the skeleton for a variety of metabolic bone diseases. Key words Paget's Disease — Metabolic Bone Diseases — Alkaline Phosphatase — Osteocalcin — Bone Gla Protein
Introduction Many new procedures have been developed to assess the human skeleton (Epstein 1989). Computer-enhanced densitometric procedures now provide more sensitive and specific information about skeletal status than X-rays. Improved histomorphometric procedures provide better quantification of bone metabolism and newer isotopes provide a better evaluation of the entire skeleton (Deftos and Glowacki 1984; Melton, Eddy and Johnston 1990). Substantial progress has also been made in the development of assay procedures for the measurement of bone-derived proteins and peptides in serum and other biological fluids (Price, Parthemore and Def-
Horm.metab.Res. 23(1991)559-561 © Georg Thieme Verlag Stuttgart • New York
tos 1980; Crofton 1982; Deftos, Parthemore and Price 1982). Assays for alkaline and acid phosphatase, procollagen and hydroxyproline, and bone Gla protein (BGP, osteocalcin), have yielded useful information when applied to clinical studies (Deftos, Parthemore and Price 1982; Duda, O'brien, Katzmann, Peterson, Mann and Riggs 1988; Simon, Krane, Wortman, Krane and Kovitz 1984). But each of these methodologies has significant clinical limitations (Cheung, Manolagas, Catherwood, Mosely, Mitas, Blantz and Deftos 1983). The most commonly used serum biochemical marker for bone diseases is alkaline phosphatase (AP) activity measurement (Crofton 1982). Although this procedure is valuable in many circumstances, it suffers from lack of specificity, because the alkaline phosphatase activity in blood is also contributed to by the liver, the gastrointestinal tract, the placenta, certain tumors, and perhaps other sources (Crofton 1982; Deftos and Glowacki 1984). Many procedures have been developed in an attempt to improve the specificity of the assay procedures for the AP that come from bone (Crofton 1982; Duda et al. 1988). With the exceptions discussed subsequently, these modifications have, in general, not been entirely successful and remain technically difficult. Accordingly, we undertook a comparison of classical osteoblast markers to bone-specific alkaline phosphatase (BAP) with a newly-developed procedure that is specific for BAP (Hill and Wolfert 1989). Materials and Methods We here describe preliminary clinical studies of a new serum marker for skeletal disease, BAP, and two established bone markers for skeletal disease, BGP and total alkaline phosphatase activity (TAP). Fasting blood samples were collected from normal adults, patients with alcoholic cirrhosis, and in 23 patients with Paget's disease of bone being followed as outpatients. The diagnosis of Paget's disease was established in all of them by clinical, biochemical, and radiologic criteria. Each sample was assayed for TAP with p-nitrophenylphosphate as substrate, for BGP with a previously described radioimmunoassay, and for BAP with a newly-developed two-site immunoradiometric assay (Weisman, Orth, Catherwood, Manolagas and Deftos 1986; Crofton 1982; Deftos, Parthemore and Price 1982; Hill and Wolfert 1989). The details of this assay have been recently described and will only be summarized here (Hill and Wolfert 1989). The assay uses two antibodies, designated 419 and 017, that have specificity for BAP over LAP (Hill and Wolfert 1989). It is likely that this specificity is conferred by a post-translational modification of BAP, since its isoenzymes are products of the same gene (Weiss, Henthorn, Lafferty, Slaughter, Raducha and Harris 1986). For the two-site format, the capture antibody is bound to a polystyrene bead and the second antibody is radioiodinated. The bead is incubated with the serum sample
Received: 16 Nov. 1990
Accepted: 28 March 1991
Downloaded by: National University of Singapore. Copyrighted material.
L. J. Deftos, R. L. Wolfert and C. S. Hill Department of Medicine, University of California, San Diego, and the San Diego VA Medical Center and Hybritech, Incorporated, San Diego, California, U. S. A.
Horm. metab. Res. 23 (1991)
Fig. 1 Comparison of serum total alkaline phosphatase activity (TAP) to immunoassay measurements of bone Gla protein (BGP) and bone-specific alkaline phosphatase (BAP) in Paget's disease. TAP was measured using p-nitrophosphate in the clinical laboratory assay with an upper limit of normal of 100 U/L. BGP was measured by a radioimmunoassay with a normal limit of 5 pmol/ml (Deftos, Parthemore and Price 1982). BAP was measured by a two-site immunoradiometric assay with a normal limit of 50 U/L. The correlation between BAP (Hill and Wolfert 1989) and TAP was 0.92, p < .001; between BGP and TAP, 0.26, p < .10; and between BGP and BAP, 0.34, p < .05).
and the labelled antibody for 2 hours at room temperature, washed, and counted in a gamma counter. BAP levels in the unknown sample are determined from a standard curve of BAP extracted from human osteoblast cells (Hill and Wolfert 1989). The procedure can readily accomodate 500 samples. Results and Discussion Figure 1 demonstrates the correlations among BAP, TAP and BGP in 23 patients with Paget's disease. All three measurements were elevated in these patients. By contrast, patients with liver disease had elevated TAP levels and BAP and BGP levels that were statistically indistinguishable from normal; the mean TAP in nine such patients was 331 U/L, the mean BAP was 90 U/L, the mean BGP was 5.5 pmol/ml, and there was no correlation among them. Therefore, the two-site assay that we have applied to these clinical studies is specific for BAP and does not appreciably crossreact with liver alkaline phosphatase (LAP). Thus, it is different from the method recently reported by Duda et al. (1988), where two antibodies, one equally reactive to BAP and LAP and the other with a 5-fold greater affinity for BAP, were used separately in immunoassays and the BAP was calculated from the two different measurements. In our assay, we use two antibodies that have been previously shown to have less than 15 % cross-reactivity with LAP for direct measurement of BAP (Hill and Wolfert 1989). In addition to this specificity, this two-site assay is rapid and convenient when compared to standard radioimmunoassay formats (Deftos, Parthemore and Price 1982). The direct measurement of BAP offers many obvious advantages over the measurement of TAP. In fact, the disadvantages of TAP measurement, especially its non-specificity, have caused it to become increasingly supplanted by BGP measurements in clinical studies of skeletal disease (Duda et al. 1988; Orwoll, Oviatt, McClung, Deftos and Sexton
L. J. Deftos, R. L. Wolfert and C. S. Hill 1990). However, it has become obvious that BGP does not measure the same components of osteoblast function that are reflected by TAP measurements or by calculated BAP measurements (Deftos, Parthemore and Price 1982; Delmas, Price and Mann 1990; Duda et al. 1988; Orwoll et al. 1990). Early studies identified discordancy among these measurements and they continue to appear (Deftos, Parthemore and Price 1982; Duda et al. 1988). The discordancy is best appreciated for Paget's disease where BGP measurements are distinguishable from other parameters of disease activity (Duda et al. 1988; Weiss et al. 1986). This may not be surprising when one considers that, although BGP and BAP are both osteoblast products, BGP is also incorporated into bone matrix (Deftos and Glowacki 1984; Price, Parthemore and Deftos 1980). Thus, there may be a moiety of BGP that is released upon resorption of bone matrix (Grundberg and Weinstein 1986; Simon et al. 1984). Because of these differences, it is very likely that BGP and BAP will not be redundant measurements but rather complementary assays for evaluating skeletal disease. Our studies demonstrate that in Paget's disease there is a high correlation between BAP and TAP, higher than that between BGP and TAP (Figure 1). Since the elevated TAP in Paget's disease comes primarily from bone, our measurement of BAP correlates more closely with this classical index of osteoblast activity that does BGP (Crofton 1982; Wilkinson, Wagstaffe, Delbridge, Wiseman and Posen 1986). Thus, BAP may be superior to BGP in this respect and reflect disease activity more accurately (Duda et al. 1988; Wilkinson etal. 1986). Furthermore, BAP may be less influenced by renal failure than BGP (Cheung et al. 1983). However, prospective clinical studies will be needed to evaluate these possibilities. Less speculatively, our studies also demonstrate another advantage of BAP over TAP measurement, the lack of substantial reactivity in the assay of LAP (Hill and Wolfert 1989). When coupled with the technical ease of the two-site BAP assay, this feature should make BAP measurement a most valuable tool for assessing skeletal function. Since the BAP assay measures immunological activity and the TAP measures enzymatic activity, the two measurements do not coincide in absolute units. Although only subtle differences of alkaline phosphatase have been reported in osteoporosis, the specificity and sensitivity of the BAP two-site assay may increase the clinically utility of this measurement in this frustrating disease also (Epstein 1989; Ismail, Epstein, Pacifici, Droke, Thomas and Avioli 1986). However, extensive clinical trials are necessary to test this hypothesis (Wilkinson et al. 1986). Abbreviations BGP - bone GlaProtein AP — Alkaline Phosphatase TAP — total serum alkaline phosphatase activity BAP — bone alkaline phosphatase LAP — liver alkaline phosphatase Acknowledgements This work was supported by the Department of Veterans Affairs, Rehabilitation R & D , and the National Institutes of Health. The authors were assisted by Kathy Smith, Cheryl Chalberg and Debbie Hussong.
Downloaded by: National University of Singapore. Copyrighted material.
560
Bone Alkaline Phosphatase
Horm. metab. Res. 23 (1991)
561
metabolism in postmenopausal osteoporosis. Calcified Tissue International 39:230-233 (1986) L. J., D. M. Eddy, C. C. Johnston: Screening for osteoporosis. Cheung, A. K., S. C. Manolagas, B. D. Catherwood, C. A. Mosely Jr., Melton, J. Annals of Internal Medicine 112:516-528(1990) A. Mitas II, R. C. Blantz, L. J. Deftos: Determinants of serum Orwoll, E. S., S. K. Oviatt, M. R. McClung, L. J. Deftos, G. Sexton: The 1,25(OH)2D levels in renal disease. Kidney International 24:104— rate of bone mineral loss in normal men and the effects of calcium 109(1983) and cholecalciferol supplementation. Annals of Internal MediCrofton, P. M.: Biochemistry of alkaline phosphatase isoenzymes. cine 112: 29-34 (1990) CRC critical reviews of clinical laboratory science 16: 161 — 194 Price, P. A., J. G. Parthemore, L. J. Deftos: A new biochemical marker (1982) for bone metabolism. Journal of Clinical Investigation 66: 878— Deftos, L. J„ J. Glowacki: Mechanisms of bone metabolism. In: 883(1980) "Pathophysiology", third edition, Kem, D. C. and E. Frohlick Simon, L. S., S. M. Krone, P. D. Wortman, I. M. Krane, K. L. Kovitz: (eds.), J. B. Lippincott, Co., Philadelphia (1984), pp. 445-468 Serum levels of type I and III procollagen fragments in Paget's disDeftos, L. J., J. G. Parthemore, P. A. Price: Changes in plasma bone ease of the bone. Journal of Clinical Endocrinology and Gla protein during treatment of bone disease. Calcified Tissue InMetbolism 58: 110-120 (1984) ternational 34: 121-124 (1982) Delmas, P.D..P.A. Price, K. G. Mann: Validation of the bone Gla pro- Weisman, M. H., R. W. Orth, B. D. Catherwood, S. C. Manolagas, L. J. Deftos: Measures of bone loss in rheumatoid arthritis. Archives of tein (osteocalcin) assay. Journal of Bone and Mineral Research 5: Internal Medicine 146: 701-704 (1986) 3-4(1990) Duda, J. R., J. F. O'brien, J. A. Katzmann, J. M. Peterson, K. G. Mann,Weiss, M. H., P. S. Henthorn, M. A. Lafferty, C. Slaughter, M. Raducha, H. Harris: Isolation and characterization of a cDNA encodB. L. Riggs: Concurrent assays of circulating bone Gla-protein and ing a human liver/bone/kidney-type alkaline phosphatase. Probone alkaline phosphatase: Effects of sex, age and metabolic bone ceedings of the National Academy of Science of the USA 83: disease. Journal of Clinical Endocrinology and Metabolism 66:1 — 7182-7194(1986) 7(1988) Epstein, S.: Bone-derived proteins. Trends in Endocrinology and Me- Wilkinson, M. R., C. Wagstaffe, L. Delbridge, J. Wiseman, S. Posen: Serum osteocalcin concentrations in Paget's disease of bone. Artabolism 1: 9-14 (1989) chives of Internal Medicine 46:268-271(1986) Grundberg, C. M., R. S. Weinstein: Multiple immunoreactive forms of osteocalcin in uremic serum: Journal of Clinical Investigation 77: 1762-1767(1986) Hill, C. S., R. L. Wolfert: The preparation of monoclonal antibodies Requests for reprints should be addressed to: which react preferentially with human bone alkaline phosphatase and not liver alkaline phosphatase. Clinica Chimica Acta 186: Leonard J. Deftos, M. D. 315-320(1989) 3350 La Jolla Village Drive Ismail, F., S. Epstein, R. Pacifici, D. Droke, S. B. Thomas, V. Avioli:Mail Code V-l 11C Serum bone Gla protein (BGP) and other markers of bone mineral San Diego, CA 92161 (U. S. A.)
Downloaded by: National University of Singapore. Copyrighted material.
References
