Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Children with acute lymphoblastic leukaemia (ALL) have reduced bone turnover caused by the disease itself and early intensive chemotherapy, but the effects of later chemotherapy using different drug combinations are uncertain. We report here a longitudinal study on 9 children with ALL randomised to receive an additional third intensification block of chemotherapy, compared with 9 children receiving continuing chemotherapy over the same period. During third intensification, bone alkaline phosphatase, procollagen type I C-terminal propeptide, the carboxyterminal propeptide of type I collagen, procollagen type III N-terminal propeptide and lower leg length all decreased in response to dexamethasone, then returned to (but not beyond) baseline levels after dexamethasone was stopped and other drugs started. These changes were unrelated to circulating insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 or IGFBP-2. In all children, bone alkaline phosphatase remained below the population mean throughout. We conclude that dexamethasone decreased bone and soft tissue turnover, probably through direct effects on target tissues. The postdexamethasone phase of third intensification and continuing chemotherapy had no major deleterious effect on collagen turnover, but there was evidence of continuing suboptimal bone mineralisation.
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PMID:Effects of a third intensification block of chemotherapy on bone and collagen turnover, insulin-like growth factor I, its binding proteins and short-term growth in children with acute lymphoblastic leukaemia. 1053 79

Ipriflavone (IP), a synthetic isoflavone has been reported to prevent bone loss in both postmenopausal women and ovariectomized (ovx) rats. The purpose of this study was to compare and contrast some of the bone protective mechanisms of IP to those of 17beta-estradiol (E(2)) in ovarian hormone deficiency. Forty-eight 95-day-old Sprague-Dawley rats were assigned to four groups: sham, ovx, ovx+IP, and ovx+E(2). The doses of IP and E(2) were 100 mg and 10 microg/kg body weight per day, respectively. Rats were fed a diet that contained 0.4% calcium, 0.3% phosphorus, and 0.195 nmol vitamin D(3)/g diet. After sacrifice, left femoral bone densities were measured and bone histomorphometry was performed on the proximal tibial metaphysis. Ipriflavone as well as E(2) treatment completely prevented the ovx-induced femoral bone density loss. However, in contrast to E(2), IP did not lower the ovx-induced rise in serum alkaline phosphatase (ALP) activity or insulin-like growth factor (IGF)-I and IGF binding protein (IGFBP)-3 concentrations. On histomorphometry analysis, the ovariectomy-induced increase (P < 0. 09) in bone formation rate (BFR) was significantly (P < 0.05) suppressed by E(2) treatment, whereas this higher BFR was maintained in IP-treated animals. These findings indicate that IP is effective in preventing the ovx-associated bone loss. The bone protective mechanisms of IP in ovarian hormone deficiency may be different from those of E(2) and may involve increased rates of bone formation.
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PMID:The synthetic phytoestrogen, ipriflavone, and estrogen prevent bone loss by different mechanisms. 1060 47

Both a decrease in bone formation and an increase in bone resorption have been implicated in the pathogenesis of age-related (type II) femoral neck osteoporosis. While the increase in the bone resorption rate has been shown to be partially related to secondary hyperparathyroidism, the mechanisms underlying the decline in bone formation have not yet been identified. The aim of the present study was to test the hypothesis that the bone formation deficit associated with type II osteoporosis might be due to secondary hyperparathyroidism and/or to a deficiency of the insulin-like growth factor (IGF) system. Circulating concentrations of IGF-I, IGF-II, IGF binding protein (IGFBP)-3, IGFBP-4, IGFBP-5, 25-hydroxycholecalciferol (25(OH)D3), and intact parathyroid hormone (PTH) were measured in 50 elderly women after sustaining a hip fracture and in 50 healthy age-matched controls. In addition, serum levels of osteocalcin (OC), skeletal alkaline phosphatase, and N-terminal procollagen peptide and urinary pyridinium cross-links were determined as markers of bone remodeling, and bone mineral density (BMD) was assessed at the proximal femur. In the patient group, serum was drawn within 18 h of the fracture and prior to surgery. Circulating protein concentrations did not change over this time frame. No difference was found between mean IGFBP-4 serum levels in the two groups studied, while mean levels of IGF-I, IGF-II, IGFBP-3, IGFBP-5, 25(OH)D3, and markers of bone formation were significantly lower (p < 0.006) in patients as compared with healthy subjects. Serum PTH and urinary pyridinium cross-links, however, were markedly increased (p < 0.001) in the osteoporotic group. In pooled data from the normal and osteoporotic populations, age-adjusted multiple regression models based on IGF-I, IGF-II, IGFBP-3, and IGFBP-5 were found to be highly predictive of serum OC (R2 = 19%, p < 0.001) and BMD of femoral neck (R2 = 49%, p < 0.0001), consistent with an effect of the anabolic IGF components on overall bone formation rate. Similar models based on 25(OH)D3 and PTH, however, were statistically unrelated to OC. To address further the potential impact of trauma on circulating IGF system components, we measured IGF system component levels in 10 male patients within 18 h following tibial fracture and in 10 age-matched normal male subjects. There was no significant difference in serum level of any of the IGF system components between the two groups. Although limited by its cross-sectional design, the present study suggests that, in addition to bone resorption resulting from secondary hyperparathyroidism, impaired bone formation associated with deficiency of the IGF system might predispose elderly women to fragility fracture of the proximal femur.
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PMID:Down-regulation of the serum stimulatory components of the insulin-like growth factor (IGF) system (IGF-I, IGF-II, IGF binding protein [BP]-3, and IGFBP-5) in age-related (type II) femoral neck osteoporosis. 1062 75

The current studies were intended to determine whether the anabolic effects of calcitonin (CT) on human osteoblast-line cells were (1) unique to osteosarcoma cells or also evident in osteoblast-line cells derived from normal human bone; and/or (2) associated with effects on several insulin-like growth factor (IGF) system components. Preliminary studies identified several osteoblastic cell lines, derived from normal human bone, which showed calcitonindependent increases in cell proliferation, alkaline phosphatase activity, and/or (45)Ca uptake (P < 0.05-P < 0.001). Two of these cell lines-(human vertebrae) HBV-155 and HBV-163-were included with the human osteosarcoma cell line, SaOS-2, in most of our subsequent studies of calcitonin effects on selected IGF system components: IGF-II, IGF-I, and IGF binding proteins -3, -4, and -5. The results of those studies revealed that a 48 hour exposure to salmon CT caused a dose-dependent (0.03-3 mU/ml) increase in the net extracellular level of IGF-II (r = 0.96, P < 0.01) in serum-free cultures of SaOS-2 cells, with a maximal 60% increase at the highest tested dose (P < 0.02). Similar effects were seen with HBV-163 cells (r = 0.90, P < 0.01) and HBV-155 cells (r = 0.55, P < 0.02). The effect of calcitonin on the extracellular level of IGF-II was biphasic with respect to time: it decreased at 6 hours (P < 0.005 and P < 0.001, for SaOS-2 cells and HBV-163 cells, respectively) and increased at 24 hours (P < 0.02 and P < 0.05). These calcitonin-dependent increases in the extracellular level of IGF-II were associated with parallel increases in IGF-I (P < 0.005 for SaOS-2 cells and P < 0.03 for HBV-163 cells), but calcitonin did not affect the extracellular level of transforming growth factor (TGF)-beta. The calcitonin-dependent changes in IGF-II were not associated with changes in the extracellular levels of IGF binding proteins -3, -4, or -5. Finally, our studies showed that two other members of the CT superfamily-CT gene-related peptide and amylin-did not mimic the effect of CT to increase the extracellular level of IGF-II. Together, these data demonstrate that human osteoblast-line cells derived from normal human bone can respond to CT, and that those responses can include CT dose- and time-dependent increases in the extracellular levels of IGF-I and IGF-II.</hea
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PMID:Calcitonin increases the concentration of insulin-like growth factors in serum-free cultures of human osteoblast-line cells. 1095 80

Soy isoflavones are hypothesized to exert hormonal effects in women and thus may play a role in bone metabolism throughout life. In 2 randomized, cross-over studies, 14 pre- and 17 postmenopausal women were given 3 soy protein isolates containing different amounts of isoflavones [control, 0.13; low isoflavone (low-iso), 1.00; and high-iso, 2.01 mg/kg body wt/day, averaging 8, 65, and 130 mg/day, respectively], for over 3 months each. Food records, blood samples, and 24-h urine collections were obtained throughout the studies. The endpoints evaluated included plasma or serum concentrations of bone-specific alkaline phosphatase, osteocalcin, insulin-like growth factor-I (IGFI), IGF binding protein-3 (IGFBP3), and urine concentrations of deoxypyridinoline cross-links and carboxy-terminal telopeptide of type I collagen. In premenopausal women, IGFI and IGFBP3 concentrations were increased by the low-iso diet, and deoxypyridinoline cross-links was increased by both the low- and high-iso diets during certain phases of the menstrual cycle. In postmenopausal women, bone-specific alkaline phosphatase was decreased by both the low- and high-iso diets, and there were trends toward decreased osteocalcin, IGFI, and IGFBP3 concentrations with increasing isoflavone consumption. Although soy isoflavones do affect markers of bone turnover, the changes observed were of small magnitude and not likely to be clinically relevant. These data do not support the hypothesis that dietary isoflavones per se exert beneficial effects on bone turnover in women.
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PMID:Effects of soy isoflavones on markers of bone turnover in premenopausal and postmenopausal women. 1099 83

Limb lengthening in the left tibia of 30 mature female Yucatan micropigs was performed using distraction osteogenesis. A treatment group of 15 animals received recombinant porcine growth hormone (r-pGH) (100 microg/kg/day) while the others served as controls. Serial serum measurements of total insulin-like growth factor I (IGF-I), free IGF-I, IGF binding proteins -1, -2, -3 and -4 (IGFBP-1 to -4) were performed. Bone-specific alkaline phosphatase (bone-ALP) and the serum carboxyl-terminal telopeptide of type I collagen (ICTP) were measured as bone turnover markers. The GH-treated animals showed a significant increase in total IGF-I, free IGF-I and IGFBP-3 after surgery (P<0.001). Similarly, the treated animals showed a significantly higher level of bone-ALP (P<0.001) throughout the experiment compared to the controls. There was a significant correlation between bone-ALP and total IGF-I (r=0.76) in the GH-treated group and an even higher correlation for free IGF-I (r=0.90). There was no difference in the ICTP serum levels between the two groups. These data indicate that the application of species-specific growth hormone results in a stimulation of bone formation in distraction osteogenesis which may be mediated by IGF-I. The stronger correlation between free IGF-I and bone-ALP indicates that the anabolic effect of IGF-I may be regulated through the IGFBPs by binding and inactivating IGF-I.
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PMID:The effect of growth hormone on insulin-like growth factor I and bone metabolism in distraction osteogenesis. 1173 50

Most women with Turner syndrome (TS) have no gonadal activity and thus lack estrogen. Bone mineral density (BMD) is often reduced, leading to an increased risk of osteoporosis and fractures. However, growth retardation with reduced final height and other endocrine disturbances may compromise interpretation of skeletal measurements. The aim of the present study was to explore skeletal findings, bone metabolism, and calcium homeostasis in TS. Sixty women with TS (age, 37 +/- 9 yr) and 181 normal age-matched female controls were studied. Bone area (A; square centimeters), bone mineral content (BMC; grams), area-adjusted BMD (aBMD; grams/square centimeter), and volumetric BMD (vBMD; grams/cubic centimeter) were measured at lumbar spine, femoral neck, and forearm using dual energy x-ray absorptiometry. Twenty-eight percent had osteopenia, and 23% had osteoporosis, according to World Health Organization criteria. At the lumbar spine, A, BMC, aBMD, and vBMD were reduced by 18, 27, 11, and 6%, respectively; at the femoral neck, A, BMC, and aBMD were reduced by 2, 10, and 8%, respectively, whereas the 9% reduction in vBMD was insignificant (P = 0.07); and in the forearm, A, BMC, and aBMD were reduced by 53, 55, and 9%, respectively. Bone markers indicated an enhanced bone resorption (21 and 23% increase in C-terminal and N-terminal cross-linking telopeptides of type I collagen/creatinine, respectively) with unchanged (osteocalcin, procollagen I N-terminal propeptide) or reduced (54% reduction in bone alkaline phosphatase) bone formation. Plasma levels of calcium and 25-hydroxyvitamin D (26%) were reduced, and PTH levels increased (74%) in TS. IGF-I (30%), IGF binding protein 3 (18%), testosterone (50%), and SHBG (40%) were reduced in TS. In summary, A, BMC, and aBMD were found to be universally reduced in TS, whereas vBMD was slightly reduced in the spine. Increased resorption of bone was present, with normal or blunted bone formation, suggesting uncoupling or imbalance in bone remodeling. Skeletal changes may be induced by chromosome abnormalities or by secondary endocrine or metabolic changes related to a relative estrogen deficiency, testosterone deficiency, reduced IGF-I, low vitamin D status, and secondary hyperparathyroidism.
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PMID:Marked disproportionality in bone size and mineral, and distinct abnormalities in bone markers and calcitropic hormones in adult turner syndrome: a cross-sectional study. 1205 Feb 53

Skeletal cells synthesize IGFs and their six IGF binding proteins (IGFBP). IGFBP-5 was reported to stimulate bone cell growth in vitro and selected parameters of osteoblastic function in vivo, but its actual effects on bone formation are not established. We investigated the direct effects of IGFBP-5 on bone remodeling in two lines of transgenic mice overexpressing IGFBP-5 under the control of the osteocalcin promoter. Static and dynamic histomorphometry revealed that IGFBP-5 transgenic mice had a transient decrease in trabecular bone volume secondary to reduced trabecular number and thickness and a transient decrease in bone mineral apposition rate. Osteoblast number was normal, indicating impaired osteoblastic function. Osteoclast number and bone resorption were normal. Total, vertebral, and femoral bone mineral densities were reduced in IGFBP-5 transgenics by 14-27% at 4 wk of age, but not in older animals. Stromal cells expressing the IGFBP-5 transgene displayed decreased expression of alkaline phosphatase, osteocalcin, core binding factor 1, and type I collagen transcripts when compared with cells from wild-type animals. In conclusion, transgenic mice overexpressing IGFBP-5 in the bone microenvironment have a transient decrease in trabecular bone volume, impaired osteoblastic function, and osteopenia.
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PMID:Transgenic mice overexpressing insulin-like growth factor binding protein-5 display transiently decreased osteoblastic function and osteopenia. 1223 7

BACKGROUND: Insulin-like growth factor (IGF) system components are important regulators of bone formation. Alterations of individual IGF system components have been described in osteoporosis (OP) patients; however, no study has addressed changes in free IGF-I and in all six IGF binding proteins (IGFBPs). METHODS: A cross-sectional study was performed in 45 OP patients and 100 healthy matched controls. Serum levels of free and total insulin-like growth factor I (IGF-I), IGFBP-1 through -6, intact parathyroid hormone (PTH), 25-OH-vitamin D(3) (25OHD(3)), 1,25-(OH)(2)-vitamin D(3) (1,25-(OH)(2)D(3)), osteocalcin (OSC), bone alkaline phosphatase (B-ALP), and carboxyterminal propeptide of type-I procollagen (PICP) were measured with specific assays. Bone mineral density (BMD) of the lumbar spine was determined by dual-energy X-ray absorptiometry (DEXA). RESULTS: Compared with age- and sex-matched control subjects, OP patients showed a 73% decrease in free IGF-I, a 29% decrease in total IGF-I, a 10% decrease in IGFBP-3, and a 52% decrease in IGFBP-5 levels; they had higher levels of IGFBP-1 (4.1-fold), IGFBP-2 (1.8-fold), IGFBP-4 (1.3-fold), and IGFBP-6 (2.1-fold). Alterations in IGF system components were most evident in 13 OP patients with vertebral fractures in the past 4 years compared to patients without fractures. In OP patients with fractures, the ratio between IGFBP-4 and IGFBP-5 was increased whereas levels of OSC were decreased. CONCLUSIONS: Our data provide strong indirect evidence for a functional connection between circulating IGF system components and bone metabolism and the susceptibility to fractures in OP patients.
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PMID:Serum levels of insulin-like growth factor (IGF)-I and IGF binding protein (IGFBP)-1 to -6 and their relationship to bone metabolism in osteoporosis patients. 1255 8

Postmenopausal hormone-sensitive breast cancer is currently treated with either antioestrogens or aromatase inhibitors (AIs), due to the clinical efficacy and safety of these drugs. Today's challenge is the sequential use of AIs with different structure and no cross-resistance to improve the therapeutic outcome. The present study describes the biological action of the steroidal structure (SS)-AI exemestane (EXE), in patients progressing on aminoglutethimide (AG) or other non-steroidal structure (NSS)-AIs (letrozole or anastrozole). Thirteen patients were evaluated for serum insulin-like growth factor (IGF) components [total IGF-1, IGF-2 and IGF binding protein (IGFBP)-3], interleukin (IL)-6 system [IL-6 and soluble IL-6 receptor (sIL-6-R)] and bone metabolism markers [bone gla protein/osteocalcin (BGP), bone-specific isoform of alkaline phosphatase (BAP) and carboxy-telopeptide of type I procollagen (ICTP)]. IGF system components show a trend to increase both in patients progressing on AG and in patients progressing on other NSS-AIs. Such an increase depends on the wash-out length from the previous treatment and is strictly linked to the circulating oestrogen levels. Serum IL-6 and sIL-6-R are mainly related to the patients' clinical outcome. Bone formation (BGP and BAP) and bone resorption (ICTP) markers seem to be at equilibrium with oestrogen levels when starting EXE and do not appear to be uncoupled over treatment. The observed variations seem to be mainly linked to the circulating oestrogen levels rather than directly to the way of action of the AI employed.
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PMID:Could exemestane affect insulin-like growth factors, interleukin 6 and bone metabolism in postmenopausal advanced breast cancer patients after failure on aminoglutethimide, anastrozole or letrozole? 1268 75


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