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Biomedical subjects

Michael Kleerekoper

Publications and source records attributed to Michael Kleerekoper.

At least 19 recordsLinked to original sources
PubMed2005

Usefulness of bone mineral density to predict significant coronary artery disease.

Low bone mineral density (BMD) and coronary artery disease (CAD) share common risk factors. To investigate whether low BMD (osteoporosis and/or osteopenia) independently predicts CAD compared with traditional cardiovascular risk factors, a retrospective analysis was performed in consecutive ambulatory patients (n = 209, 89% women) who underwent dual-energy x-ray absorptiometry and coronary angiography within the same 12-month period. Angiograms were classified as showing significant CAD if > or =50% luminal narrowing in a major coronary artery was noted. Clinical variables associated with CAD (age, hypertension, diabetes, high fasting glucose level, smoking, family history of CAD, and dyslipidemia) were examined. Dual-energy x-ray absorptiometric scans were classified based on World Health Organization criteria: normal (T score >-1.0 SD), osteopenia (T score -1.0 to -2.5 SD), and osteoporosis (T score <-2.5 SD). Univariate and multivariate analyses were employed to determine whether low BMD independently predicts CAD. Univariate predictors of CAD were hypertension, smoking, diabetes, high fasting glucose level, dyslipidemia, family history of CAD, and low BMD. Multivariate predictors were hypertension, family history of CAD, fasting glucose level, and osteoporosis. Odds ratio for the prediction of angiographically documented CAD was highest for osteoporosis (odds ratio 5.6, 95% confidence interval 2.6 to 12.0, p <0.0001). In conclusion, low BMD appears to independently predict significant CAD in women, with a higher odds ratio than traditional risk factors. Our study is the first to report osteoporosis as a predictor of angiographically proved CAD in a population predominantly of women.

Absorptiometry, Photon↗
PubMed2005

Bone response to treatment with lower doses of conjugated estrogens with and without medroxyprogesterone acetate in early postmenopausal women.

Lower doses of conjugated estrogens (CE) alone or combined with lower doses of medroxyprogesterone acetate (MPA) increase mean bone mineral density (BMD) from baseline at the spine and hip in early postmenopausal women. However, not all women on therapy gain BMD. The incidence of continued bone loss (defined as a loss of BMD of > 2% from baseline) among women using lower doses of CE and CE/MPA is unknown. This randomized, double-blind, placebo-controlled, multicenter substudy of the Women's Health, Osteoporosis, Progestin, Estrogen (Women's HOPE) trial investigated the incidence of continued bone loss with lower-dose CE and CE/MPA. Eight hundred twenty-two healthy postmenopausal women with intact uteri received CE 0.625, CE 0.625/MPA 2.5, CE 0.45, CE 0.45/MPA 2.5, CE 0.45/MPA 1.5, CE 0.3, CE 0.3/MPA 1.5 (all doses in mg/day), or placebo for 2 years along with 600 mg/day of calcium. Changes from baseline in spine and total hip BMD were compared among treatment groups in an intent-to-treat analysis. At 12 months, < 10% of women on active treatment lost > 2% of spinal BMD (except CE 0.3/MPA 1.5 [15.6%]), compared with 41.2% of women on placebo. At 24 months, the percentages of women on active treatment who lost > 2% of spine BMD ranged from 4.5% with CE 0.45/MPA 1.5-15.6% with CE 0.3/MPA 1.5, compared with 55.2% of women taking placebo. More than 85% of women on active treatment did not experience continued BMD loss at the hip at 12 months and 24 months, in contrast to 30.6% of women on placebo at 12 months and 36.5% at 24 months. Women receiving active treatment who lost > 2% of spine or hip BMD also had a lesser reduction in biochemical markers of bone turnover. In summary, continued bone loss among early postmenopausal women treated with lower doses of CE or CE/MPA is uncommon.

Adult↗
PubMed2005

Prevention of postmenopausal bone loss and treatment of osteoporosis.

Osteoporosis is now recognized as an increasingly prevalent disorder throughout the world. Fragility fractures and their subsequent short- and long-term complications are the adverse outcomes of this disease that is essentially silent until fractures occur. Given that the presence of one fragility fracture is an important predictor of the risk of subsequent fractures, prevention of the first fracture is critical whenever possible. Two key elements in fracture prevention that are discussed in this article are the attainment of optimal peak bone mass and the prevention of bone loss at menopause, with the major focus on the prevention of postmenopausal bone loss.

Aged↗
PubMed2005

Activity of estradiol and selective estrogen receptor modulators in the mouse N20.1 oligodendrocyte/astrocytes cell line.

OBJECTIVE: The mechanism through which estrogen exerts its neuroprotective and anti-neurodegenerative effects in the central nervous system is poorly understood. Human glial cells are implicated in the pathogenesis of Alzheimer's disease and have both alpha and beta estrogen receptors (ER). We developed a glial cell model for ER function using the N20.1 mouse oligodendroglial cell line to evaluate the response of ERalpha and ERbeta to estradiol (E2), a raloxifene analog LY117018 (LY) and 4-hydroxytamoxifen (4OHT). DESIGN: We tested the ability of exogenous ER to activate transcription in response to ligands (100 nM) using the glial cell line N20.1 in a transient cotransfection assay with an ERalpha or ERbeta expression vector, an ERE-driven reporter and a Renilla luciferase transfection control. RESULTS: Endogenous ER was not detected in the N20.1 cells by Western immunoblotting. E2 stimulated both ERalpha and ERbeta on both ERE- and AP-1 driven promoters. The transcription stimulation by E2 in the ERalpha and ERbeta through the AP-1driven promoter, though significant, was not of the same magnitude as the stimulation of the ERalpha through the ERE-driven promoter. 4OHT and LY did not show significant transcriptional activation of either the ERalpha or ERbeta, through either the ERE or AP-1 driven promoters. LY, at a 10-fold higher concentration than E2, showed a difference in its antagonist activity on the ERbeta through the AP-1 pathway when compared with the ERE- driven promoter, demonstrating not only promoter specificity, but also receptor specificity. CONCLUSIONS: This is the first description of the activity of 4OHT and LY on estrogen receptors in glia.

Animals↗
PubMed2004

Body composition profiles derived from dual-energy X-ray absorptiometry, total body scan, and mortality.

Little has been reported on the association of derived body composition data and cardiovascular mortality. The authors defined body composition profiles based on one- and two-variable measures from dual-energy x-ray absorptiometry (DXA) total body scans. Scan results are labeled "apple" if Z score for percent of total fat in trunk is >0 and "pear" if Z score for height-corrected limb fat is > or = 0. The fat measures were combined to define four body composition profiles: "pickle," "avocado," "mango," and "barrel." A third axis, the Z score of height-corrected limb lean tissue, is an index of skeletal muscle mass and was used to label subjects as "hard" or "soft." Subjects (n=324) who were in good health from Malmö, Sweden, underwent body composition analysis using DXA and were followed for 10 years. The distribution of body composition profiles was similar for both genders and across age groups. Among subjects aged 50-74 years at baseline (n=116), there were 21 deaths. Barrel had the highest mortality rate: 13/39 (33.3%) mortality for barrels, compared with 8/77 (10.4%) mortality for non-barrels; mortality odds ratio, 3.2; 95% confidence interval, 1.45-7.08. The increased mortality was principally attributable to cardiovascular cause-related deaths. Soft (sarcopenia) was also associated with increased mortality (25.9%; p=0.05), but not cardiovascular cause-related deaths, whereas the total mortality among apples was not significantly increased but cardiovascular cause-related deaths were predominant (75%; p=0.02). The authors propose that DXA-body composition profiles can identify increased mortality risk of magnitude similar to major cardiovascular risk factors and may prove useful in health assessment.

Absorptiometry, Photon↗
PubMed2003

Prevention and treatment of postmenopausal osteoporosis.

Osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration of the skeleton leading to enhanced bone fragility and an increased risk of fracture. Prior to fracture, diagnosis is established by documenting low bone mass. In the first section of this article we review the clinical use of bone mass measurements and biochemical markers of bone remodeling in selecting patients most in need of preventive therapy at menopause. Women with high bone turnover lose bone at menopause more rapidly than those with normal bone turnover and are more likely to derive benefit from the several preventive therapies available. The second section addresses the available technologies used to diagnose osteoporosis and/or establish fragility fracture risk using noninvasive bone mass measurement and biochemical markers of bone remodeling separately or in combination. In the third section we review the several treatment options available for patients with osteoporosis, including alendronate (alendronic acid), risendronate (risedronic acid), calcitonin, teriparatide, and raloxifene, and the approaches to monitoring the therapeutic response. The final section deals with fall protection--an often forgotten aspect of management of the patient at risk for sustaining and osteoporotic fragility fracture.

Accidental Falls↗
PubMed2002

Assessment and recommendations on factors contributing to preanalytical variability of urinary pyridinoline and deoxypyridinoline.

BACKGROUND: Pyridinoline (PYD) and deoxypyridinoline (DPD) are two of the most extensively characterized biochemical bone markers, but the interpretation of results is hampered by biologic and other preanalytical variability. We reviewed factors contributing to preanalytical variation of pyridinium cross-links in urine. METHODS: We searched four databases for English-language reports on PYD and/or DPD in urine. Searches were restricted to humans, except for studies of stability, when the search was expanded to other species. The 599 identified articles were supplemented with references from those articles and with articles known to the authors. RESULTS: The mean reported within-day variability was 71% for PYD (range, 57-78%) and 67% for DPD (range, 53-75%). The mean interday variability was 16% for both DPD and PYD (range for PYD, 12-21%; range for DPD, 5-24%). The mean intersubject variabilities across studies were 26% for PYD (range, 12-63%) and 34% for DPD (range, 8-98%) for healthy premenopausal women and 36% (range, 22-61%) and 40%, (range, 27-54%) for postmenopausal women, respectively. Specimen instability and errors in creatinine measurements were additional sources of variability. CONCLUSIONS: Intra- and intersubject variability can be reduced by collecting specimens at a specific time of the day and by maintaining similar patient status at each specimen collection regarding factors such as medications and dietary supplements.

Amino Acids↗
PubMedDate not supplied

Effect of lower doses of conjugated equine estrogens with and without medroxyprogesterone acetate on bone in early postmenopausal women.

CONTEXT: Lower-than-commonly-prescribed doses of conjugated equine estrogens (CEEs) with medroxyprogesterone acetate (MPA) improve vasomotor symptoms and vaginal atrophy, provide acceptable bleeding and lipid profiles, and afford endometrial protection. This lower-dose therapy's protection against loss of bone mineral density (BMD) associated with menopause has not been thoroughly investigated. OBJECTIVE: To determine the effects of lower doses of CEEs only or CEEs-MPA on spine and hip BMD, total body bone mineral content (BMC), and biochemical markers of bone turnover in postmenopausal women. DESIGN AND SETTING: Two-year randomized, double-blind, placebo-controlled substudy of the Women's Health, Osteoporosis, Progestin, Estrogen trial, conducted at 19 US centers between August 1995 and October 2000. PARTICIPANTS: Eight hundred twenty-two healthy postmenopausal women aged 40 to 65 years who were within 4 years of their last menstrual period. INTERVENTIONS: Patients were randomly assigned to receive CEEs, 0.625; CEEs, 0.625 and MPA, 2.5; CEEs, 0.45; CEEs, 0.45 and MPA, 2.5; CEEs, 0.45 and MPA, 1.5; CEEs, 0.3; CEEs 0.3 and MPA, 1.5 (all doses in mg/d); or placebo for 2 years. All participants also received elemental calcium at 600 mg/d. MAIN OUTCOME MEASURES: Changes from baseline in spine and total hip BMD, total body BMC, and biochemical markers of bone turnover (serum osteocalcin and urinary cross-linked N-telopeptides of type I collagen), assessed at 6-month intervals and compared among treatment groups with a modified intention-to-treat approach. RESULTS: At 24 months, women assigned to all of the active treatment groups had significant gains from baseline (P<.001) in spine and hip BMD and total body BMC (except total body BMC in the group receiving CEEs, 0.3 mg/d). These changes were significantly different from those in the placebo group, in which losses of bone mass in spine and total body were evident over the course of the study (P<.001). The loss in hip BMD from baseline in the placebo group was significant at 18 (P =.02) but not at 24 months (P =.06). Osteocalcin and N-telopeptides of type I collagen were significantly reduced from baseline (P<.001) for all active treatment groups at all time points; no changes were found for the placebo group. For women treated with CEEs alone, the gains in spine BMD for the group taking CEEs, 0.625 mg/d, were significantly higher than those of the group taking CEEs, 0.3 mg/d (P =.02), but not the group treated with CEEs, 0.45 mg/d (P =.48). CONCLUSIONS: Doses of CEEs or CEEs-MPA lower than 0.625 mg/d effectively increase BMD and BMC in early postmenopausal women.

Adult↗