Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 4 de 4
Filter
2.
J Bone Miner Res ; 19(6): 875-81, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15125786

ABSTRACT

UNLABELLED: The phenotype of the vitamin D binding and macrophage activating protein, Gc, is a predictor of premenopausal bone fracture risk, possibly mediated through activation of osteoclasts. This was concluded from a study on 595 Danish perimenopausal women 45-58 years of age (30,040 person years). INTRODUCTION: The multifunctional plasma protein Gc, also known as group-specific component, Gc globulin, or vitamin D binding protein (DBP), has two functions with relation to bone tissue: it is the major carrier protein of vitamin D in the circulation, and deglycosylation converts it into a very potent macrophage- and osteoclast-activating factor (Gc-MAF). There are several phenotypes of Gc, and in this study, we examined the relation between Gc phenotype and bone fragility. MATERIALS AND METHODS: By isoelectric focusing we identified the Gc phenotype of 595 white recent postmenopausal women enrolled into the Danish Osteoporosis Prevention Study (DOPS) and identified three groups: Gc1-1 (n = 323), Gc1-2 (n = 230), and Gc2-2 (n = 42). Differences between the three groups were examined with respect to number of fractures before enrollment, BMC and BMD, and various biochemical and clinical parameters, including the concentration of Gc measured by immunonephelometry and the concentration of the macrophage marker soluble CD163 measured by ELISA. RESULTS AND CONCLUSIONS: The risk of having at least one premenopausal bone fracture (total number of women with fracture = 179) differed significantly (p = 0.017) in women with phenotype Gc1-1 (110/323 = 0.34), Gc1-2 (63/230 = 0.27), and Gc2-2 (6/42 = 0.14). The differences were even more striking (p = 0.005) for fractures caused by low-energy traumas. Using logistic regression, we found the relative risk of premenopausal fracture to be 0.32 (0.13-0.80) in Gc2-2 compared with Gc1-1. We propose that the Gc phenotypes cause differences in osteoclast activity, a theory supported by our finding of lower levels of Gc and of soluble CD163 in women with Gc2-2 compared with Gc1-1.


Subject(s)
Fractures, Bone/genetics , Premenopause , Vitamin D-Binding Protein/genetics , Antigens, CD/genetics , Antigens, Differentiation, Myelomonocytic/genetics , Bone Density , Denmark , Enzyme-Linked Immunosorbent Assay , Female , Humans , Middle Aged , Phenotype , Polymorphism, Genetic , Receptors, Cell Surface/genetics , Risk Factors
3.
Eur J Endocrinol ; 150(3): 355-62, 2004 Mar.
Article in English | MEDLINE | ID: mdl-15012622

ABSTRACT

OBJECTIVE: Studies in animals and humans indicate that growth hormone (GH) and insulin-like growth factor-I (IGF-I) modulate immune function. Recently, it was reported that GH therapy increased the level of mannan-binding lectin (MBL) in normal patients, and that treatment of acromegalics with pegvisomant decreased the levels of MBL. The effect on MBL was thought to be due to a specific action of GH, since IGF-I treatment did not affect MBL. Whether it is advantageous or not to have high or low levels of MBL is not known. Likewise, it is not clear how the modifications induced by GH affect immune function. In the present study we examined whether GH or hormone replacement therapy (HRT) in Turner syndrome (TS) influence the serum concentrations of MBL and two other proteins partaking in the innate immune defence, surfactant protein D (SP-D) and vitamin D binding protein (DBP). DESIGN: Study 1: a double-blind crossover study of 12 healthy TS adolescents examined during treatment with either placebo or GH for 2 months, and compared with a control group. Study 2: triple-blind crossover study of 9 healthy TS adolescents randomized to treatment with placebo, GH or GH+17beta-estradiol. Study 3: 60 adult TS patients (55 received HRT) compared with 59 age-matched controls. Study 4: 27 patients with TS were examined before and during sex hormone replacement with 17beta-estradiol and norethisterone and compared with age-matched controls (n=24). METHODS: Measurement of MBL, SP-D, DBP, and other inflammation markers. RESULTS: Study 1: the levels of MBL (P=0.002) and SP-D (P=0.012) increased during GH treatment, whereas no changes were observed in comparison with controls. DBP was unchanged by GH, but was significantly higher in TS compared with controls (P=0.017). Study 2: treatment with GH increased MBL (P=0.045) and SP-D (P=0.05) concentrations in TS, while treatment with GH+17beta-estradiol did not increase levels further. DBP was unchanged by treatment. Study 3: levels of MBL, SP-D, and DBP were similar in adult TS and control subjects. Study 4: DBP levels decreased in response to HRT, while MBL and SPD levels were unchanged. Levels of all three plasma proteins were similar to controls. CONCLUSION: We show that treatment with GH significantly increases MBL and SP-D concentrations in TS, while HRT marginally decreases DBP. Whether the present findings, suggesting a link between the endocrine and the immune system, have clinical consequences needs to be studied further.


Subject(s)
Estrogen Replacement Therapy , Human Growth Hormone/therapeutic use , Mannose-Binding Lectin/blood , Pulmonary Surfactant-Associated Protein D/blood , Turner Syndrome/blood , Turner Syndrome/drug therapy , Vitamin D-Binding Protein/blood , Adolescent , Adult , Aged , C-Reactive Protein/metabolism , Child , Cross-Over Studies , Double-Blind Method , Estradiol/therapeutic use , Female , Haptoglobins/metabolism , Humans , Middle Aged , Norethindrone/therapeutic use , Transferrin/metabolism
4.
J Clin Endocrinol Metab ; 87(6): 2798-808, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12050253

ABSTRACT

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.


Subject(s)
Bone Density , Bone and Bones/metabolism , Bone and Bones/pathology , Calcium/metabolism , Hormones/metabolism , Turner Syndrome/metabolism , Turner Syndrome/pathology , Adult , Aged , Biomarkers , Female , Gonadal Steroid Hormones/metabolism , Homeostasis , Humans , Karyotyping , Middle Aged , Multivariate Analysis , Organ Size , Somatomedins/metabolism , Turner Syndrome/genetics
SELECTION OF CITATIONS
SEARCH DETAIL
...