ucOC Levels Research Articles

Effect of GGCX gene polymorphism on the responses of serum undercarboxylated osteocalcin and bone turnover markers after treatment with vitamin K2 (menatetrenone) among postmenopausal Thai women

The purpose of this study was to evaluate the influence of gamma-glutamyl transferase (GGCX) gene polymorphisms on the response of serum undercarboxylated osteocalcin (ucOC) and bone turnover markers 3 months after treatment with menatetrenone. One hundred and forty postmenopausal Thai women were enrolled and assigned to receive 45 mg/day treatment of menatetrenone (MK-4) concurrently with calcium 1.2 g and vitamin D 400 IU for 3 months. Demographic characteristics, GGCX genotyping, serum bone turnover markers and ucOC levels were obtained from all participants at baseline. We evaluated the reduction of ucOC at 3 months and the reduction of beta-CTx and P1NP at 1 and 3 months. The responses were compared between the different genotypes of GG and GA + AA groups. There was a significant reduction of serum ucOC, beta-CTx and P1NP from the baseline at 3 months (p < 0.001) though there was no significant difference between genotypes (GG vs. GA + AA; p > 0.05). Nonetheless, a subgroup analysis of postmenopausal women who 65 years of age or over (N = 37) revealed a significant difference between the two groups in the reduction of ucOC. Menatetrenone significantly reduced serum ucOC as well as beta-CTX and P1NP from the baseline. GGCX polymorphism appeared to have an influence over the reduction of ucOC especially in older women (age ≥65). Furthermore, the groups which have "A" allele trend to being more efficient in reducing the serum ucOC level than the group which does not have it.

Relationships between undercarboxylated osteocalcin and vitamin K intakes, bone turnover, and bone mineral density in healthy women

Low vitamin K intakes and high levels of undercarboxylated osteocalcin (ucOC) are risk factors for hip fractures. However, the relationship between ucOC and vitamin K intakes, bone mineral density (BMD) and bone biochemical markers is not clarified. We enrolled 221 healthy women, and examined BMD, urinary type-I collagen cross-linked-N-telopeptide (uNTX), and nutrient intakes. BMD was measured at the lumbar spine and femoral neck. Vitamin K intakes were significantly and negatively correlated with ucOC after adjustment for age, height, and body weight (r=-0.305, p<0.0001). ucOC was negatively associated with lumbar BMD (r=-0.147, p<0.05), but not femoral neck BMD (r=-0.099, p=0.095) after adjustment for age, height, and body weight. In multiple regression analysis, even after adjustment for age, height, body weight, and vitamin K intake, a significant and positive correlation remained between ucOC and urinary NTX (r=0.493, p<0.0001). Moreover, in postmenopausal women, ucOC levels were positively correlated with urinary NTX, but not BMD. Dietary vitamin K intakes influence serum levels of ucOC in healthy women. Furthermore, ucOC may be linked to bone biochemical markers.

High level of serum undercarboxylated osteocalcin in patients with incident fractures during bisphosphonate treatment

To evaluate the possible interaction of metabolic effects in the mevalonate pathway between amino-bisphosphonates (amino-BP) and vitamin K, the serum level of undercarboxylated osteocalcin (ucOC) was measured in amino-BP users in relationship to incident fracture occurrence. Osteoporotic patients (mean age, 70.7 +/- 9.1 years; n = 231) treated with alendronate or risedronate were followed for 3.4 +/- 2.1 years, and observations regarding the presence or absence of incident fractures in their vertebrae were made based on vertebral X-ray films every year. During the observation period, new fractures were found in a total of 71 patients (incident vertebral fracture, n = 61; the remaining 10 patients had long bone fractures). The baseline data of the patients with incident fractures indicated that incident fractures are more likely to occur in older patients who have a higher number of prevalent vertebral fractures and lower baseline lumbar bone mineral density (LBMD) as compared to patients without incident fractures. There was no significant difference in the changes of LBMD and urinary excretion of NTX after treatment. On the other hand, the serum level of ucOC in patients with incident fractures and with amino-BP treatment was significantly higher (2.75 +/- 0.19 ng/ml) than that in patients without incident fractures and with amino-BP treatment (2.28 +/- 0.13 ng/ml) (P = 0.038). These results indicate that older age, a greater number of prevalent fractures and higher ucOC levels, and lower LBMD are risks for incident fractures despite use of amino-BP. The time-dependent incident fracture rate was higher in accordance with an increase in the number of risk items (P < 0.001 in log-rank and Wilcoxon tests). In conclusion, measurement of undercarboxylated osteocalcin may be useful for assessing fracture risk in patients receiving amino-BP treatment.

Undercarboxylated Osteocalcin Is a Biomarker of Carotid Calcification in Patients with Essential Hypertension

The development of vascular calcification is an active, highly regulated process with similarities to bone formation. Osteocalcin (OC), a vitamin K-dependent protein expressed by osteoblasts, contains 3 γ-carboxyglutamic acid residues derived from the vitamin K-dependent posttranslational modification of glutamic acid residues. Circulating undercarboxylated OC (ucOC) is increased in vitamin K deficiency and serum ucOC is reported to be a clinical marker of vitamin K status. Vitamin K deficiency is associated with vascular calcification as well as osteoporosis. We evaluated the relationship between ucOC and carotid artery calcification in 92 patients with essential hypertension. Ultrasound of the common carotid artery was performed to identify vascular calcification and subjects were divided into 2 groups: a calcification (+) group and a calcification (–) group. Serum creatinine and ucOC levels were higher in the calcification (+) group than in the calcification (–) group and serum ucOC correlated with serum creatinine. To identify the independent determinant factor for carotid artery calcification, we applied both ucOC and estimated glomerular filtration rate as independent factors in logistic regression analysis. Serum ucOC was an independent determinant of carotid calcification, suggesting that circulating ucOC may be an important biomarker of carotid artery calcification.

Response of Serum Carboxylated and Undercarboxylated Osteocalcin to Risedronate Monotherapy and Combined Therapy with Vitamin K2 in Corticosteroid-Treated Patients: A Pilot Study

The aim of this study was to investigate the responses of serum osteocalcin (OC), undercarboxylated osteocalcin (ucOC) and N-terminal telopeptide of type I collagen (NTx) to corticosteroids, and to examine the effects of risedronate therapy with or without vitamin K(2) supplementation on bone metabolic markers in corticosteroid-treated patients. Sixteen patients on corticosteroid therapy for neuromuscular disorders were assigned randomly to 2 groups (A: risedronate monotherapy, n=8; B: combined risedronate and vitamin K(2) therapy, n=8) and treated for 1 year. Another 6 patients who received intravenous steroid pulse therapy were assigned to group C for investigation of the effects of corticosteroids on OC and ucOC 1 month after pulse therapy. Serial measurements revealed that significant decreases of OC, ucOC and NTx persisted with a similar time course profile during 1 year of treatment in groups A and B, and between-group analysis failed to demonstrate any additional effects of vitamin K(2) on risedronate therapy. Intravenous steroid pulse therapy induced a transient depression of OC and ucOC within 1 week in group C. These results indicate that serum concentrations of OC and ucOC become consistently low during corticosteroid administration despite risedronate therapy with or without vitamin K(2) supplementation, and the serum ucOC level may not be a reliable indicator of vitamin K status under corticosteroid administration.

Vitamin K2 supplementation does not influence bone loss in early menopausal women: a randomised double-blind placebo-controlled trial

Vitamin K2 may preserve bone strength and reduce fracture risk. In this randomised double-blind placebo-controlled trial among healthy postmenopausal Norwegian women, 1 year supplementation of vitamin K2 in the form of Natto capsules had no effect on bone loss rates. Japanese studies indicate that vitamin K2 (menaquinone-7 (MK-7)) intake may preserve bone strength, but this has not been documented in Europeans. The aim of this study was to assess the effect of MK-7 on bone mineral density (BMD) changes in postmenopausal Norwegian women. Three hundred thirty-four healthy women between 50 and 60 years, 1-5 years after menopause, were recruited to a randomised double-blind placebo-controlled trial. The participants were randomly assigned into two groups, one receiving 360 microg MK-7 in the form of Natto capsules and the other the same amount of identical-looking placebo capsules containing olive oil. BMD was measured at total hip, femoral neck, lumbar spine and total body at baseline and 12 months together with serum levels of bone-specific alkaline phosphatase, Crosslaps, total osteocalcin (N-mid OC), carboxylated (cOC) and under-carboxylated osteocalcin (ucOC). After 12 months, there were no statistical differences in bone loss rates between the groups at the total hip or any other measurement site. Serum levels of cOC increased and ucOC decreased in the treatment versus the placebo group (p < 0.001). MK-7 taken as Natto over 1 year reduced serum levels of ucOC but did not influence bone loss rates in early menopausal women.

骨粗鬆症治療薬(BP, SERM)がucOC値に与える影響, および骨折既往歴とucOCの関係

骨粗鬆症治療薬(BP, SERM)がucOC値に与える影響, および骨折既往歴とucOCの関係

The effect of menaquinone-7 (vitamin K2) supplementation on osteocalcin carboxylation in healthy prepubertal children

Vitamin K contributes to bone health, probably through its role as cofactor in the carboxylation of osteocalcin. Intervention studies in adults have demonstrated that markedly higher osteocalcin carboxylation is obtained by intakes of vitamin K well above the current recommended dietary intake. However, the relationship between increased vitamin K2 intake and enhanced osteocalcin carboxylation has never been shown in healthy children. The objective was to study the effect of 45 microg menaquinone-7 (MK-7; one of the vitamin K2 species) on the circulating levels of undercarboxylated osteocalcin (ucOC) and carboxylated osteocalcin (cOC) in healthy prepubertal children. We hypothesised that MK-7 supplementation will reduce the ucOC:cOC ratio (UCR), indicating an improved vitamin K status. The present study is a double-blind randomised placebo-controlled trial examining the effect of 8 weeks MK-7 supplementation on the carboxylation of osteocalcin in healthy children (n 55). Serum levels of ucOC, cOC and MK-7 were measured at baseline and after 8 weeks, together with bone markers and coagulation parameters. The UCR was used as an indicator of vitamin K status. In the MK-7-supplemented group (n 28), the circulating concentration of inactive ucOC reduced and the UCR improved whereas the concentration of MK-7 increased. Within the placebo group, ucOC, cOC, UCR and MK-7 did not significantly change over time. In both groups, bone markers and coagulation parameters remained constant over time. These findings demonstrate that in healthy, prepubertal children, modest supplementation with MK-7 increases circulating concentrations of MK-7 and increases osteocalcin carboxylation.

Low Serum Levels of Undercarboxylated Osteocalcin in Postmenopausal Osteoporotic Women Receiving an Inhibitor of Bone Resorption

Osteocalcin, a bone-specific protein synthesized by osteoblasts, undergoes vitamin K-dependent gamma-carboxylation. Undercarboxylated osteocalcin (ucOC) represents inadequately carboxylated osteocalcin, and this fraction increases with vitamin K insufficiency. Alendronate is a bisphosphonate that inhibits bone resorption, thereby increasing bone mineral density (BMD), while also reducing bone formation closely coupled with bone resorption. The aim of this cross-sectional study was to evaluate the influence of alendronate on serum levels of ucOC, cross-linked N-telopeptide of type 1 collagen (NTx), a marker of bone resorption, and bone alkaline phosphatase (BAP), a marker of bone formation. Forty-six postmenopausal osteoporotic women were divided into three groups: patients receiving alendronate (5 mg/day or 35 mg/week) for >or= 6 months (n = 29) or < 6 months (n = 7), and patients receiving no medication related to bone metabolism (n = 10). Serum ucOC levels were significantly lower in patients with long-term treatment (p < 0.0001) or short-term treatment (p = 0.0223) than in untreated patients. Serum ucOC levels correlated positively with both BAP (r = 0.695, p < 0.0001) and NTx (r = 0.494, p = 0.0004) in all participants. Since low serum levels of BAP and NTx are associated with decreased levels of bone formation and bone resorption, respectively, these findings suggest that low serum ucOC levels may reflect the suppression of bone turnover. In conclusion, low serum ucOC levels reflect suppressed bone turnover and/or adequate levels of vitamin K in patients receiving an inhibitor of bone resorption.

Effect of supplementation with fortified olive oil on biochemical markers of bone turnover in healthy women

Osteocalcin (OC) is a bone Gla protein synthesized by osteoblasts which have a high affinity for calcium. To adequately carboxylate OC to form carboxylated OC (cOC), the osteoblasts require sufficient vitamin K. If vitamin K is deficient, under-carboxylated OC (ucOC) is produced. The ratio between ucOC and cOC (UCR) as well as the levels of circulating ucOC are used as indicators of the vitamin K status of bone. The aim of the present study was to compare the vitamin K status of bone by measuring the plasma levels of ucOC and UCR in healthy adult women before and after 3 weeks of oral supplementation with 20 ml/day Petrini Plus extra virgin olive oil. Petrini Plus is an organic olive oil enriched with vitamins D3, K1 and B6. Enrolled in the study were 15 healthy female volunteers (aged 25–40 years). Plasma levels of ucOC and cOC were measured by ELISA. ucOC was found to be reduced and UCR was reduced by 44% after Petrini Plus olive oil supplementation. Petrini Plus extra virgin olive oil might therefore be useful for bone protection as it was able to counteract bone loss in healthy volunteers.

High prevalence of vitamin K and D deficiency and decreased BMD in inflammatory bowel disease

Vitamin K and D deficiency and decreased bone mineral density (BMD) were highly prevalent in patients with inflammatory bowel disease (IBD), especially Crohn's disease (CD). Dietary intakes of these vitamins, however, were above the Japanese adequate intakes in IBD patients, suggesting that malabsorption is the basis for hypovitaminosis K and D and decreased BMD. We have studied the possible involvement of vitamin K and D deficiency in the pathogenesis of decreased BMD in IBD. Seventy patients with IBD were evaluated for their BMD; plasma levels of vitamin K; phylloquinone (PK), menaquinone-7 (MK-7), and 25OH-D; serum PTH, protein induced by vitamin K absence (PIVKA-II), and undercarboxylated osteocalcin (ucOC) levels; and their food intake. Compared with ulcerative colitis (UC) patients, CD patients had significantly lower plasma vitamin K and 25OH-D concentrations; significantly higher serum levels of PTH, PIVKA-II, and ucOC; and significantly lower BMD scores at almost all measurement sites. More IBD patients were vitamin K deficient in bone than in liver. Multiple regression analyses revealed that low plasma concentrations of vitamin K and 25OH-D were independent risk factors for low BMD and that they were associated with the patients' fat intake, but not with their intake of these vitamins. IBD patients have high prevalence of decreased BMD and vitamin K and D deficiency probably caused by malabsorption of these vitamins.

Measurement of serum undercarboxylated osteocalcin by ECLIA with the "Picolumi ucOC" kit

We evaluated the effectiveness of the "Picolumi ucOC" kit for measuring the serum level of ucOC. When used with an autoanalyzer, the kit achieved highly sensitive and rapid measurement over a range of 0.39 to 50 ng/mL. Assessment of reproducibility testing showed good results, since the coefficient of variation was <or= 10%, the recovery rate for spiked samples was 93 - 106%, and there was no influence of interfering substances at normal levels. Among healthy individuals, serum ucOC levels were shown to be high in teenagers, who have very active bone metabolism, and in women aged 45 years or older, whose bone metabolism is influenced by menopause.

A Preliminary Assessment of Vitamin K1 Intakes and Serum Undercarboxylated Osteocalcin Levels in 11–13 Year Old Irish Girls

Low vitamin K1 intakes have been associated with low bone mineral density in women and reduced bone turnover in girls. No European data exist on the relationship between vitamin K1 and serum undercarboxylated osteocalcin (ucOC), an indicator of K1 status in adolescents. The aim of the current study was to assess intakes of vitamin K1 in relation to serum ucOC status in Irish girls. A detailed dietary history method, which measured habitual intakes from a typical 14-day period, was used to estimate vitamin K1 intakes in 18 girls aged 11-13 years. Recently compiled and validated food composition data for vitamin K1 were used to determine vitamin K1 intakes. An enzyme immunoassay was used to measure ucOC in fasting serum samples. The mean (+/- SD) intake of vitamin K1 in the girls was 72.4 microg/day (SD 34.4). Vegetables (particularly broccoli, composite dishes, and lettuce) contributed 53% of total vitamin K1 intakes. Thirty-Seven percent of the girls failed to meet the current U.S. adequate intake for adolescents of 60 microg/day vitamin K1. Serum ucOC levels were inversely related to body weight-adjusted vitamin K1 intakes, controlling for energy intake (partial correlation r = -0.538; p = 0.026). The data indicate that large-scale studies to examine relationships between vitamin K1 (and green vegetable) intakes and bone growth and development in adolescents are warranted.

Phylloquinone (vitamin K1) intakes and serum undercarboxylated osteocalcin levels in Irish postmenopausal women

Low phylloquinone (vitamin K1) intakes have been associated with low bone mineral density in older adults. Phylloquinone intakes and serum undercarboxylated osteocalcin (ucOC) levels were assessed in ninety-seven apparently healthy, free-living Irish women aged 50-75 years. Phylloquinone intakes were estimated using a detailed dietary history, which measured habitual food intakes from a typical 14 d period, and recently published food composition data for phylloquinone. Fasting serum ucOC was measured using an enzyme immunoassay. The median daily intake of phylloquinone in the group from all sources was 108.8 microg and from food sources only was 106.6 microg, indicating that approximately 99 % of the phylloquinone came from food. Vegetables and vegetable dishes contributed 67 % of the total phylloquinone intake, but further analysis showed that broccoli, cabbage and lettuce were the primary sources, making a total contribution of 44 %. Twenty per cent of the women had a phylloquinone intake below the UK recommendation of 1 microg/kg body weight per day and 34 % failed to meet the US Adequate Intake value of 90 microg/day. Mean serum ucOC levels in the women were 6.2 (SD 1.7) ng/ml and were predicted by phylloquinone intake (beta -2.20, generated from log-transformed phylloquinone intake data; P=0.04). On the basis of comparisons with both UK recommendations and US Adequate Intakes for phylloquinone, the habitual intakes of phylloquinone in a high proportion of Irish postmenopausal women may not be adequate.

Associations between vitamin K biochemical measures and bone mineral density in men and women.

Few data exist on the association between vitamin K status and bone mineral density (BMD) in men and women of varying ages. We examined cross-sectional associations between biochemical measures of vitamin K status and BMD at the hip and spine in 741 men and 863 women (mean age, 59 yr; range, 32-86 yr) who participated in the Framingham Heart Study (1996-2000). Vitamin K status was assessed by plasma phylloquinone and percentage undercarboxylated osteocalcin (%ucOC). Among the men, low plasma phylloquinone concentrations adjusted for triglycerides and elevated serum %ucOC levels were associated with low BMD at the femoral neck (P = 0.03 and 0.009, respectively). Among postmenopausal women not using estrogen replacements, low plasma phylloquinone concentrations were associated with low spine BMD (P = 0.007), with a nonsignificant trend of an elevated serum %ucOC with low spine BMD (P = 0.08). In contrast, there were no significant associations between biochemical measures of vitamin K and BMD in either premenopausal women or postmenopausal women using estrogen replacements. Clinical trials are required to isolate any putative effects of vitamin K on rates of bone loss. The target population in these trials, particularly in regard to estrogen use, may be critical, as suggested by the findings of this study.

Undercarboxylated osteocalcin measured with a specific immunoassay predicts hip fracture in elderly women: the EPIDOS Study.

Increased levels of circulating undercarboxylated osteocalcin (ucOC), measured indirectly with the hydroxyapatite (HAP) binding assay, have been shown to predict hip fracture risk in a small group of elderly institutionalized women. The aim of this study was to confirm these findings in a prospective cohort study (EPIDOS prospective study) of 7598 healthy, independently living women over 75 yr of age. One hundred and four women who sustained a hip fracture during a 22-month follow-up period were age matched with 255 controls who did not fracture. Baseline samples were collected before hip fracture for measurement of total OC and ucOC, assessed either with the HAP binding assay or directly with a new enzyme-linked immunosorbent assay (ELISA). This direct ELISA uses human recombinant noncarboxylated OC as a standard and two monoclonal antibodies, one of which was raised against the 14-30 Glu synthetic peptide. We found that the intra- and interassay variations are less than 11%, and this assay exhibits a 5% cross-reactivity with purified human bone OC, used as a source of carboxylated OC. ucOC levels measured with this ELISA correlated well with the HAP binding assay in the population of 359 elderly women (r = 0.82; P < 0.0001). We estimated the risk of hip fracture for women with levels of ucOC in the highest quartile of values for the 255 controls. We found that increased levels of ucOC measured by ELISA were associated with increased hip fracture risk with an odds ratio (OR) of 1.9 (95% confidence interval, 1.2-3.0), and the ELISA had a greater sensitivity than the HAP assay. In contrast, total OC was not associated with hip fracture risk. After adjustment for femoral neck bone mineral density (BMD) and mobility status assessed by gait speed, ucOC still predicted hip fracture with an OR of 1.8 (1.0-3.0). Women with both femoral neck BMD in the lowest quartile and ucOC in the highest quartile were at higher risk of hip fracture, with an OR of 5.5 (2.7-11.2), than those with only low BMD or high ucOC levels. In conclusion, we have developed a new specific ELISA for serum ucOC, with low cross-reactivity with carboxylated OC and increased specificity and sensitivity over the HAP assay. Using this new ELISA, we found that ucOC, but not total OC, predicts hip fracture risk independently of femoral neck BMD in elderly women drawn from the general population. Thus, ucOC measurement could be combined with bone mass determination to improve the assessment of hip fracture risk in elderly women.

Influence of vitamin D and retinoids on the gammacarboxylation of osteocalcin in human osteosarcoma MG63 cells.

Osteocalcin (OC) is a bone matrix protein, synthesized by osteoblasts, which contains three residues of gammacarboxyglutamic acid (GLA). A fraction of circulating OC, which is not fully carboxylated and does not bind to hydroxyapatite, is called undercarboxylated OC (ucOC). In elderly institutionalized women, we have shown an increase of circulating ucOC level which may result not only from vitamin K deficiency but also from vitamin D deficiency (Szulc et al., J Clin Invest 91:1769; 1993). This intriguing finding prompted us to study the effect of vitamin D on the secretion of ucOC by osteoblastic cells in vitro in the presence of warfarin, an inhibitor of gammacarboxylation of GLA-containing proteins. The potential influence of retinoic acid (RA) was also studied, because its mechanism of action involves pathways that are similar to vitamin D. In the presence of warfarin (0.05 microg/mL), 1alpha,25(OH)2D (10(-8)-10(-6) mol/L) decreased dose dependently ucOC secretion by human osteosarcoma MG63 cells (from 3.87 +/- 0.96 to 2.12 +/- 0.13 ng/10(6) cells). When expressed as a fraction of total OC, secretion ucOC decreased from 47.4 +/- 1.4% to 24.8 +/- 3.2% in the MG63 cells. The secretion of total OC was stimulated by RA and by Ro 13-7410, which is a specific ligand of retinoic acid receptor (RAR), but not by 9-cis retinoic acid (9-cisRA), which is a physiologic ligand of retinoid X receptor (RXR). RA and Ro 13-7410 decreased ucOC secretion and ucOC% in warfarin-treated MG63 cells (RA: from 50.4 +/- 13.3% to 13.5 +/- 2.8%; Ro 13-7410: from 28.4 +/- 8.2% to 11.3 +/- 8.4%). 9-cisRA had no effect on OC gammacarboxylation. These results show that vitamin D, RA, and Ro 13-7410, but not 9-cisRA, may modify the gammacarboxylation of OC in human MG63 cells.