Biomedical subjects

Thomas F Lang

Publications and source records attributed to Thomas F Lang.

4 recordsLinked to original sources

PubMed2003

The effects of parathyroid hormone and alendronate alone or in combination in postmenopausal osteoporosis.

BACKGROUND: Parathyroid hormone increases bone strength primarily by stimulating bone formation, whereas antiresorptive drugs reduce bone resorption. We conducted a randomized, double-blind clinical study of parathyroid hormone and alendronate to test the hypothesis that the concurrent administration of the two agents would increase bone density more than the use of either one alone. METHODS: A total of 238 postmenopausal women (who were not using bisphosphonates) with low bone mineral density at the hip or spine (a T score of less than -2.5, or a T score of less than -2.0 with an additional risk factor for osteoporosis) were randomly assigned to daily treatment with parathyroid hormone (1-84) (100 microg; 119 women), alendronate (10 mg; 60 women), or both (59 women) and were followed for 12 months. Bone mineral density at the spine and hip was assessed by dual-energy x-ray absorptiometry and quantitative computed tomography. Markers of bone turnover were measured in fasting blood samples. RESULTS: The bone mineral density at the spine increased in all the treatment groups, and there was no significant difference in the increase between the parathyroid hormone group and the combination-therapy group. The volumetric density of the trabecular bone at the spine increased substantially in all groups, but the increase in the parathyroid hormone group was about twice that found in either of the other groups. Bone formation increased markedly in the parathyroid hormone group but not in the combination-therapy group. Bone resorption decreased in the combination-therapy group and the alendronate group. CONCLUSIONS: There was no evidence of synergy between parathyroid hormone and alendronate. Changes in the volumetric density of trabecular bone, the cortical volume at the hip, and levels of markers of bone turnover suggest that the concurrent use of alendronate may reduce the anabolic effects of parathyroid hormone. Longer-term studies of fractures are needed to determine whether and how antiresorptive drugs can be optimally used in conjunction with parathyroid hormone therapy.

Absorptiometry, Photon↗

PubMed2003

Poor correlation of mid-femoral measurements by CT and hip measurements by DXA in the elderly.

BACKGROUND AND AIMS: Hip fracture is a devastating event in terms of outcome in the elderly, and the best predictor of hip fracture risk is hip bone density, usually measured by dual X-ray absorptiometry (DXA). However, bone density can also be ascertained from computerized tomography (CT) scans, and mid-thigh scans are frequently employed to assess the muscle and fat composition of the lower limb. Therefore, we examined if it was possible to predict hip bone density using mid-femoral bone density. METHODS: Subjects were 803 ambulatory white and black women and men, aged 70-79 years, participating in the Health, Aging and Body Composition (Health ABC) Study. Bone mineral content (BMC, g) and volumetric bone mineral density (vBMD, mg/cm3) of the mid-femur were obtained by CT, whereas BMC and areal bone mineral density (aBMD, g/cm2) of the hip (femoral neck and trochanter) were derived from DXA. RESULTS: In regression analyses stratified by race and sex, the coefficient of determination was low with mid-femoral BMC, explaining 6-27% of the variance in hip BMC, with a standard error of estimate (SEE) ranging from 16 to 22% of the mean. For mid-femur vBMD, the variance explained in hip aBMD was 2-17% with a SEE ranging from 15 to 18%. Adjusting aBMD to approximate volumetric density did not improve the relationships. In addition, the utility of fracture prediction was examined. Forty-eight subjects had one or more fractures (various sites) during a mean follow-up of 4.07 years. In logistic regression analysis, there was no association between mid-femoral vBMD and fracture (all fractures), whereas a 1 SD increase in hip BMD was associated with reduced odds for fracture of approximately approximately 60%. CONCLUSIONS: These results do not support the use of CT-derived mid-femoral vBMD or BMC to predict DXA-measured hip bone mineral status, irrespective of race or sex in older adults. Further, in contrast to femoral neck and trochanter BMD, mid-femur vBMD was not able to predict fracture (all fractures).

Absorptiometry, Photon↗

PubMed2003

Association between bone mineral density and the use of nonsteroidal anti-inflammatory drugs and aspirin: impact of cyclooxygenase selectivity.

UNLABELLED: BMD was examined in users of NSAIDs (by COX selectivity) and aspirin in the Health ABC cohort (n = 2853). Significantly higher BMD was found in users of relative COX-2 selective NSAIDs with aspirin (COX-2/ASA) compared with nonusers. This suggests a role for COX-2/ASA in osteoporosis. INTRODUCTION: The purpose of this study was to determine the relationship of nonsteroidal anti-inflammatory drug (NSAID) use, by cyclo-oxygenase selectivity (COX), and aspirin use on bone mineral density (BMD) in participants from the Health, Aging, and Body Composition (Health ABC) population-based cohort. It is known that NSAIDs inhibit the COX enzyme and decrease production of prostaglandins, which are involved in regulation of bone turnover. COX has two isoforms, COX-1 and COX-2. Production of prostaglandins associated with bone loss is primarily mediated through the COX-2 pathway. In addition, aspirin may have effects on bone independent of the prostaglandin pathway. MATERIALS AND METHODS: NSAID (by COX selectivity) and aspirin use and BMD were assessed in 2853 adults (49.5% women, 50.5% men: 43.1% black, 56.9% white; mean age: 73.6 years) from the Health ABC cohort. For the purposes of this analysis, relative COX-1 selective NSAIDs were defined as having a ratio of COX-1 IC50 to COX-2 IC50 of > 1 in whole blood, and relative COX-2 selective NSAIDs were defined as having a ratio of COX-1 IC50 to COX-2 IC50 of < 1 in whole blood. Analysis of covariance was used to compare BMD across each NSAID use and aspirin use category adjusting for age, race, gender, weight, height, study site, calcium and vitamin D supplementation, Womac score, history of rheumatoid arthritis, history of arthritis other than rheumatoid, and smoking status. RESULTS: After adjustment for possible confounders, current use of relative COX-2 selective NSAIDs with aspirin was associated with higher BMD at the whole body (4.2%, 1.2-7.3 CI) and total hip (4.6%, 0.5-8.8 CI) by DXA and at both trabecular (34.1%, 15.4-52.7 CI) and cortical spine (12.8%, 2.3-23.3 CI) by quantitative computed tomography. CONCLUSIONS: Our data suggest that the combination of relative COX-2 selective NSAIDs and aspirin is associated with higher BMD at multiple skeletal sites in men and women.

Aged↗

PubMed2002

Quantitative computed tomography.

Quantitative computed tomography (QCT) is an established technique for measuring bone mineral density (BMD) in the axial spine and peripheral skeleton (forearm, tibia). QCT can determine in three dimensions the true volumetric density (mg/cm 3) of trabecular or cortical bone at any skeletal site. However, because of the high responsiveness of spinal trabecular bone and its importance for vertebral strength, QCT has been principally employed to determine trabecular BMD in the vertebral body. QCT has been used for assessment of vertebral fracture risk, measurement of age-related bone loss, and follow-up of osteoporosis and other metabolic bone diseases. This article reviews the current capabilities of QCT at different skeletal sites and the recent technical developments, including volumetric acquisition.

Hip↗