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Biomedical subjects

R Eastell

Publications and source records attributed to R Eastell.

At least 55 records · Page 3Linked to original sources
PubMed2001

Risk factors for ankle fracture.

Ankle fractures are frequently observed in postmenopausal women although the pattern of incidence and risk factor profile suggest that ankle fracture may not be a typical osteoporotic fracture. The aims of this study were to determine the prevalence of osteopenia and vertebral fracture and to evaluate the diagnostic accuracy of dual-energy X-ray absorptiometry (DXA), anthropometry, lifestyle and reproductive factors in women who have sustained an ankle fracture. We studied 103 women aged 50-80 years (mean 63.2, 7.9 SD) with ankle fracture. These were compared with 375 women aged 50-86 years (mean 64.5, 9.1 SD) from a population-based cohort. Bone mineral density (BMD) at the lumbar spine (LS) and contralateral proximal femur (including femoral neck (FN), Ward's triangle (WT) and trochanteric region (TR)) was measured by DXA. Quantitative ultrasound (QUS) of the calcaneus and proximal digits was measured using three different devices. Radiographs of the thoracolumbar spine were taken (anteroposterior and lateral views). There were no significant differences in the prevalence of osteoporosis (T<-2.5 level) at the LS, FN and WT sites. The population-based cohort had lower TR BMD than the ankle fracture cohort. Age-and weight-adjusted Z-scores of FN BMD were significantly lower in the ankle fracture group. Age- and weight-adjusted Z-scores of QUS gave contradictory results. There were no differences in the receiver operating characteristics of DXA compared with QUS. Twenty-seven women (7%) of the population-based cohort and 10 women (10%) of the ankle fracture cohort were found to have prevalent vertebral fractures; these were not significantly different.

Absorptiometry, Photon↗
PubMed2001

A single nucleotide polymorphism (SNP) in the leptin receptor is associated with BMI, fat mass and leptin levels in postmenopausal Caucasian women.

The human leptin (obese) receptor gene contains a number of single nucleotide polymorphisms, including GLN223ARG, which changes an amino acid on the extracellular region common to all isoforms of the receptor. Here, we demonstrate that, in postmenopausal Caucasian women, genotypes at that locus are associated with differences in body mass index (BMI), fat mass and serum leptin levels. Measurement of serum leptin-binding activity indicates that this may reflect changed receptor function associated with genotype. These observations indicate that functional variations in the leptin receptor gene are important factors in the regulation of adiposity and BMI.

Adipose Tissue↗
PubMed2001

Effect of high doses of oral risedronate (20 mg/day) on serum parathyroid hormone levels and urinary collagen cross-link excretion in postmenopausal women with spinal osteoporosis.

The present study describes the biological effects of risedronate, a pyridinyl bisphosphonate, on bone and assesses the safety and tolerability of risedronate when given at high doses, with or without calcium, to postmenopausal women with spinal osteoporosis. This single-center descriptive, double-blind, placebo-controlled, randomized, parallel group study included 32 postmenopausal white women with at least one radiographically confirmed vertebral compression fracture. Patients were randomized to one of four different dose regimen groups: (i) R-P, risedronate 20 mg/day for 14 days, followed by placebo for 42 days; (ii) R-CP-P, risedronate 20 mg/day for 14 days, followed by elemental calcium 1000 mg/day and placebo for 14 days, then by placebo for 28 days; (iii) R-CP-R-CP, risedronate 20 mg/day for 7 days, followed by elemental calcium 1000 mg/day and placebo for 21 days, then risedronate 20 mg/day for 7 days, and finally elemental calcium 1000 mg/day and placebo for 21 days; and (iv) P, placebo for 56 days. The biological response was investigated by measuring serum calcium, parathyroid hormone (PTH), and 2 h urinary pyridinoline/creatinine (Pyr/Cr) and deoxypyridinoline/creatinine (DPyr/Cr) ratios at baseline and at days 3, 7, 14, 21, 28, 35, 42, 49, 56, and 84. Overall, there were no consistent trends observed between the active group and placebo for serum calcium. In groups R-P, R-CP-P, and R-CP-R-CP, mean serum PTH levels were elevated above baseline values for the entire 56 day treatment period and remained elevated, although to a lesser extent, at the day 84 follow-up visit. The effect of calcium supplementation on PTH was variable. Urinary Pyr/Cr and DPyr/Cr ratios were decreased from baseline over the entire study period in all groups receiving risedronate. The maximum observed percent decreases from baseline for Pyr/Cr and DPyr/Cr were -46.9% and -58.8%, respectively, at day 49 in the R-CP-R-CP group. In conclusion, risedronate given orally at a dose of 20 mg/day, continuously for 7 or 14 days, resulted in the expected biological response in osteoporotic women. The time course of changes in PTH levels following cessation of dosing was unaffected by calcium supplementation. There was no evidence of a PTH-mediated rebound in bone resorption following cessation of therapy. Furthermore, based on collagen cross-link data, patients did not show an excessive reduction in bone turnover.

Aged↗
PubMed2001

The effect of 17beta-estradiol on production of cytokines in cultures of peripheral blood.

Estrogen's action on bone may be mediated by cytokines produced by monocytes. We have reported a decreased ratio of interleukin-1beta (IL-1beta) to interleukin-1 receptor antagonist (IL-1ra) produced by whole blood cultures in vivo in women taking hormone replacement therapy (HRT). Also, one study has shown an effect of estradiol on tumor necrosis factor-alpha (TNF-alpha) secretion by separated monocytes in vitro. The aim of this study was to evaluate the effect of estrogen in vitro on the secretion of cytokines using whole blood cultures. Subjects consisted of 12 healthy postmenopausal women, ages 57-69 years, 4-20 years since menopause. Cytokines IL-1beta, interleukin-1alpha (IL-1alpha), IL-1ra, interleukin-6 (IL-6), TNF-alpha, and granulocyte macrophage-colony stimulating factor (GM-CSF) were measured in unstimulated and in stimulated (500 ng/mL lipopolysaccharide [LPS]) whole blood cultures treated with 17beta-estradiol (E(2)) at concentrations of 10(-12)--10(-6) mol/L. We found significant decreases in the spontaneous secretion of IL-6, TNF-alpha, IL-1ra, IL-1beta, and ratio of IL-1beta/IL-1ra compared with control, at physiological concentrations of E(2). The action of E(2) was blocked by the use of the antiestrogen ICI 182780 in coculture. A decrease in cytokine secretion was not observed when the inactive form of estrogen, 17alpha-estradiol, was used in place of 17beta-estradiol. GM-CSF and IL-1alpha were not detectable in unstimulated cultures. Cytokine levels measured in stimulated cultures were not attenuated by treatment with E(2). We conclude that E(2) inhibits the spontaneous secretion of cytokines measured in whole blood cultures at physiological concentrations, and that the powerful stimulatory effect of LPS prevents any significant inhibition by E(2) in stimulated cultures.

Aged↗
PubMed2001

Biochemical markers of bone metabolism in growing thoroughbreds: a longitudinal study.

This study describes longitudinal changes in serum levels of biochemical markers of bone cell activity in a group of 24 thoroughbred foals from birth to 18 months of age. The markers of bone formation included the type I collagen carboxy-terminal propeptide (PICP), the bone-specific isoenzyme of alkaline phosphatase (BAP), and osteocalcin (OC). Levels of the cross-linked telopeptide of type I collagen (ICTP), a marker of bone resorption, and the N-terminal propeptide of type III collagen (PNIIIP), a marker of soft tissue turnover, were also measured. Levels of all markers fell significantly between birth and 18 months of age (70-80 per cent); this decrease being most marked between 0 and 6 months. However, a transient increase in levels of the markers then occurred between 6 and 14 months of age. The timing of this increase was specific for each parameter. ICTP and OC concentrations increased between October and December. PICP concentrations increased between December and April whereas the increase in PIIINP was coincident with the peak in weight gain between April and June. Changes in BAP concentration were less distinct at this time. Season was shown to have significant effects on the biochemical markers independent from the effect of age. Concentrations of all markers decreased with increasing body weight and at any given age heavier horses had lower marker levels. These results show that biochemical markers of bone cell activity and soft tissue turnover follow characteristic patterns of change in growing thoroughbreds influenced by age, season and bodyweight. The demonstration that the reference ranges for the biochemical markers change from month to month means that single samples from individuals are of little value for monitoring bone cell activity in growing thoroughbreds.

Alkaline Phosphatase↗
PubMed2001

Long-term retention of injected barium-133 in man.

Data are presented on the whole-body retention of 133Ba (half-life 10.74 y), over periods of up to 13 y after injection into six healthy male volunteers aged 25-81, and on their levels of biochemical markers for bone turnover. The results are relevant to propositions underlying the ICRP's current (Publication 67) and former (Publication 20) models of alkaline earth metabolism. The tracer was predominantly skeletal within weeks of the injection, as predicted in the current model. The mean retention accorded satisfactorily throughout with predictions based on the current model, but this accord does not necessarily validate the model, for two reasons. First, parameter values attributed to barium were influenced by data emerging during the early years of this study. Second, bone resorption rates in these subjects, as indicated by urinary markers, appear insufficient to explain the long-term reductions in skeletal retention which, in the present model, arise exclusively through this mechanism.

Adult↗
PubMed2001

Secondary prevention of osteoporosis: when should a non-vertebral fracture be a trigger for action?

The burden of non-vertebral fractures is enormous. Hip fractures account for nearly 10% of all fractures (and a much greater proportion in the elderly), while wrist fractures may account for up to 23% of all limb fractures. The best available predictors of non-vertebral fracture risk are low BMD and a tendency to fall. Hip, forearm, proximal humerus and rib fractures have all been associated with low BMD, though ankle fracture is not strongly related to osteoporosis. Although clinical risk factors identify only about one-third of postmenopausal women at increased risk of osteoporotic fracture, the occurrence of one fracture commonly predicts a second fracture. Guidelines are presented for identifying and treating patients at risk of non-vertebral osteoporotic fractures, especially those with a previous fracture, based on the algorithm recently published by the Royal College of Physicians and the Bone and Tooth Society. Prevention of falls and use of external hip protectors may reduce the occurrence of hip fracture. Treatment options for patients presenting with hip fracture include HRT, bisphosphonates, and calcium plus vitamin D, and for Colles' fracture include general measures, HRT, bisphosphonates, or calcitonin plus calcium.

Accidental Falls↗
PubMed2001

Glucocorticoid-induced osteoporosis.

Glucocorticoids remain a key component in the management of many inflammatory disorders but the adverse consequences, especially on bone, can be devastating. The incidence of glucocorticoid-induced osteoporosis (GIO) may be as high as 50% after 6 months' treatment with steroids. This manifests itself as a 30 to 400% increase in the incidence of low trauma fractures. The incidence rates can be even greater in specific clinical settings such as following organ transplantation. The pathogenesis of glucocorticoid-induced osteoporosis remains complex and perplexing.The concomitant prescription of bone-active drugs for the prevention and treatment of GIO in the United Kingdom population remains low, despite the availability of effective therapies. In addition, there remain many unanswered questions about the pathogenesis of GIO and clinical management. These include identification of the optimum bone mineral density threshold at which to intervene with bone-active drugs, the dose or duration of exposure to steroid therapy that warrants intervention, and the demonstration of the efficacy of fracture prevention for different bone-active drugs or for a combination of these drugs.

Glucocorticoids↗
PubMed2001

Intrauterine programming of adult body composition.

Epidemiological studies suggest an association between weight in infancy and the risk of osteoporosis in later life. The extent to which this reflects environmental influences on skeletal growth and metabolism before birth or during the first year of postnatal life remains uncertain. We therefore examined the association between birth weight and adult body composition (bone, lean, and fat mass) in a cohort of 143 men and women, aged 70-75 yr, who were born in Sheffield, UK, and still lived there. The subjects underwent assessment of body composition by dual energy x-ray absorptiometry. Neonatal anthropometric information included birth weight, birth length, head size, and abdominal circumference. There were significant (P < 0.01) positive associations between birth weight and adult, whole body, bone, and lean mass among men and women. These were mirrored in significant (P < 0.03) associations between birth weight and bone mineral content at the lumbar spine and femoral neck. Associations between birth weight and whole body fat were weaker and not statistically significant. The associations of birth weight with whole body bone mineral and lean mass remained statistically significant after adjustment for age, sex, and adult height. They also remained significant after adjustment for cigarette smoking, alcohol consumption, dietary calcium intake, and physical inactivity. These data are in accord with previous observations that anthropometric measures in infancy are associated with skeletal size in adulthood. The presence of these relationships at birth adds to the evidence that bone and muscle growth may be programmed by genetic and/or environmental influences during intrauterine life.

Absorptiometry, Photon↗
PubMed2001

Measuring bone mineral density of the pelvis and proximal femur after total hip arthroplasty.

We aimed to evaluate the precision and longitudinal sensitivity of measurement of bone mineral density (BMD) in the pelvis and to determine the effect of bone cement on the measurement of BMD in femoral regions of interest (ROI) after total hip arthroplasty (THA). A series of 29 patients had duplicate dual-energy x-ray absorptiometry (DXA) scans of the hip within 13 months of THA. Pelvic analyses using 3- and 4-ROI models gave a coefficient of variation (CV) of 2.5% to 3.6% and of 2.5% to 4.8%, respectively. Repeat scans in 17 subjects one year later showed a significant change in BMD in three regions using the 4-ROI model, compared with change in only one region with the 3-ROI model (p < 0.05). Manual exclusion of cement from femoral ROIs increased the net CV from 1.6% to 3.6% (p = 0.001), and decreased the measured BMD by 20% (t = 12.1, p < 0.001). Studies of two cement phantoms in vitro showed a small downward drift in bone cement BMD giving a measurement error of less than 0.03 g/cm2/year associated with inclusion of cement in femoral ROIs. Changes in pelvic periprosthetic BMD are best detected using a 4-ROI model. Analysis of femoral ROI is more precise without exclusion of cement although an awareness of its effect on the measurement of the BMD is needed.

Adult↗
PubMed2001

Effect of pamidronate in preventing local bone loss after total hip arthroplasty: a randomized, double-blind, controlled trial.

Acute periprosthetic bone loss occurs after total hip arthroplasty. Bone loss undermines the support of the implant and may contribute to prosthetic failure. At present, there is no established prophylaxis for this process. We studied the effect of a single-dose infusion of 90 mg of pamidronate on early periprosthetic bone mineral density (BMD), biochemical markers of bone turnover, radiological, and clinical outcome in a 26-week, prospective, randomized, double-blinded study of 47 men and women undergoing total hip arthroplasty. Pamidronate therapy led to a significant reduction in bone loss compared with placebo for both the proximal femur and the pelvis (repeated measures analysis of variance [ANOVA]); p = 0.001 and p = 0.01, respectively). Pamidronate therapy was associated with suppression of all biochemical markers of bone turnover compared with placebo (repeated measures ANOVA; p < 0.05 for all comparisons), with the exception of urinary free deoxypyridinoline. Pamidronate did not interfere with the clinical improvement in symptoms after total hip arthroplasty, or radiological outcome, and was not associated with an increase in adverse events. This study provides clinical data on the efficacy and safety of bisphosphonates for the prevention of bone loss after total hip arthroplasty and supports the establishment of larger-scale clinical trials to determine the long-term clinical efficacy of this intervention using implant failure as the primary endpoint.

Aged↗
PubMed2000

Randomized trial of the effects of risedronate on vertebral fractures in women with established postmenopausal osteoporosis. Vertebral Efficacy with Risedronate Therapy (VERT) Study Group.

The purpose of this randomized, double-masked, placebo-controlled study was to determine the efficacy and safety of risedronate in the prevention of vertebral fractures in postmenopausal women with established osteoporosis. The study was conducted at 80 study centers in Europe and Australia. Postmenopausal women (n = 1226) with two or more prevalent vertebral fractures received risedronate 2.5 or 5 mg/day or placebo; all subjects also received elemental calcium 1000 mg/day, and up to 500 IU/day vitamin D if baseline levels were low. The study duration was 3 years; however, the 2.5 mg group was discontinued by protocol amendment after 2 years. Lateral spinal radiographs were taken annually for assessment of vertebral fractures, and bone mineral density was measured by dual-energy X-ray absorptiometry at 6-month intervals. Risedronate 5 mg reduced the risk of new vertebral fractures by 49% over 3 years compared with control (p<0.001). A significant reduction of 61% was seen within the first year (p = 0.001). The fracture reduction with risedronate 2.5 mg was similar to that in the 5 mg group over 2 years. The risk of nonvertebral fractures was reduced by 33% compared with control over 3 years (p = 0.06). Risedronate significantly increased bone mineral density at the spine and hip within 6 months. The adverse-event profile of risedronate, including gastrointestinal adverse events, was similar to that of control. Risedronate 5 mg provides effective and well-tolerated therapy for severe postmenopausal osteoporosis, reducing the incidence of vertebral fractures and improving bone density in women with established disease.

Absorptiometry, Photon↗
PubMed2000

Ethnic and gender differences in bone mineral density and bone turnover in young adults: effect of bone size.

Generally, the incidence of osteoporotic fracture is lower in black populations and in men. These effects of ethnicity and gender may result from differences in peak bone mineral density (PBMD) and bone turnover (BT), which in turn are affected by bone size. Therefore, the aims of this study were to examine the effects of ethnicity and gender on bone mineral density (BMD) and BT in young African-Caribbean and Caucasian adults, and to adjust for the effect of bone size on BMD and BT. BMD was measured at the lumbar spine, L2-L4 (LS), total body (TB) and femoral neck (FN) by dual-energy X-ray absorptiometry in 44 blacks (16 men, 28 women) and 59 whites (28 men, 31 women) ages 20-37 years. We measured serum bone-specific alkaline phosphatase (BAP) and serum osteocalcin (OC) as markers of bone formation and urinary immunoreactive free deoxypyridinoline (ifDpd) and crosslinked N-telopeptide of type I collagen (NTx) as markers of bone resorption. To adjust the data for any differences in bone size, we calculated: (a) bone mineral apparent density (BMAD), an estimated volumetric bone density which attempts to normalize BMD measurements for bone size; and (b) bone resorption markers as a ratio to total body bone mineral content (TB BMC). Two-way analysis of variance was used to compare the effects of race and gender, and to test for any interaction between these two factors. Blacks had higher BMD compared with whites at the TB (p<0.001), LS (p = 0.0001) and FN (p = 0.0005). This increase remained significant at the LS only after calculating BMAD. Men had higher BMD at all sites (except at the LS). This increase was no longer significant at the FN after calculating BMAD, and LS BMAD was actually greater in women (p<0.0001). Blacks and whites had similar concentrations of turnover markers, but men had higher bone turnover markers than women (BAP, p<0.0001; OC, p = 0.002; ifDpd, p = 0.03; NTx, p < 0.0001). This increase in bone resorption markers was no longer significant after adjusting for TB BMC (except for NTx in whites). We conclude that the skeletal advantage in blacks during young adulthood is not explained by bone size. However, it seems probable that bone size effects partially explain gender differences in BMD and bone turnover.

Absorptiometry, Photon↗
PubMed2000

Prevention of bone loss with risedronate in glucocorticoid-treated rheumatoid arthritis patients.

The aim of the study was to assess risedronate's effect on bone mineral density in postmenopausal women with rheumatoid arthritis receiving glucocorticoids. We carried out a two center, 2 year, double-masked, placebo-controlled trial with a third year of nontreatment follow-up. We studied 120 women requiring long-term glucocorticoid therapy at > 2.5 mg/day prednisolone randomized to treatment with daily placebo; daily 2.5 mg risedronate; or cyclical 15 mg risedronate (2 out of 12 weeks). At 97 weeks, bone mineral density was maintained at the lumbar spine (+1.4%) and trochanter (+0.4%) in the daily 2.5 mg risedronate group, while significant bone loss occurred in the placebo group (-1.6%, p = 0.03; and 4.0%, p < 0.005, respectively). At the femoral neck, there was a nonsignificant bone loss in the daily 2.5 mg risedronate group (-1.0%) while in the placebo group bone mass decreased significantly (-3.6%, p < 0.001). The difference between placebo and daily 2.5 mg risedronate groups was significant at the lumbar spine (p = 0.009) and trochanter (p = 0.02) but did not reach statistical significance at the femoral neck. Although not significantly different from placebo at the lumbar spine, the overall effect of the cyclical regimen was similar to that of the daily 2.5 mg risedronate regimen. Treatment withdrawal led to bone loss in the risedronate groups that was significant at the lumbar spine. A similar number of patients experienced adverse events (including upper gastrointestinal events) across treatment groups and risedronate was generally well tolerated. Thus risedronate preserves bone mass in postmenopausal women with rheumatoid arthritis receiving glucocorticoids while patients receiving a placebo have significant bone loss.

Administration, Oral↗
PubMed2000

The role of bone turnover markers and risk factors in the assessment of osteoporosis and fracture risk.

The clinical evaluation of osteoporosis in individual patients involves confirmation of the diagnosis, the investigation of secondary causes of osteoporosis and the evaluation of subsequent fracture risk. Optimum clinical assessment involves bone mineral densitometry with the treatment thresholds modified by clinical risk factors for individual patients. Bone turnover markers and clinical risk factors can be used to identify patients at risk of osteoporotic fracture and those who have secondary osteoporosis. Risk assessment should involve the evaluation of absolute rather than relative risk. Further work is required to improve the integration of clinical risk factors, bone turnover markers and bone densitometry into appropriate models to enable the assessment of the absolute risk of fracture for individual patients.

Biomarkers↗
PubMed2000

Relative contributions of testosterone and estrogen in regulating bone resorption and formation in normal elderly men.

Young adult males who cannot produce or respond to estrogen (E) are osteopenic, suggesting that E may regulate bone turnover in men, as well as in women. Both bioavailable E and testosterone (T) decrease substantially in aging men, but it is unclear which deficiency is the more important factor contributing to the increased bone resorption and impaired bone formation that leads to their bone loss. Thus, we addressed this issue directly by eliminating endogenous T and E production in 59 elderly men (mean age 68 years), studying them first under conditions of physiologic T and E replacement and then assessing the impact on bone turnover of withdrawing both T and E, withdrawing only T, or only E, or continuing both. Bone resorption markers increased significantly in the absence of both hormones and were unchanged in men receiving both hormones. By two-factor ANOVA, E played the major role in preventing the increase in the bone resorption markers, whereas T had no significant effect. By contrast, serum osteocalcin, a bone formation marker, decreased in the absence of both hormones, and both E and T maintained osteocalcin levels. We conclude that in aging men, E is the dominant sex steroid regulating bone resorption, whereas both E and T are important in maintaining bone formation.

Aged↗