Biomedical subjects

K Stone

Publications and source records attributed to K Stone.

At least 19 recordsLinked to original sources

PubMed1999

Elevated serum estradiol and testosterone concentrations are associated with a high risk for breast cancer. Study of Osteoporotic Fractures Research Group.

BACKGROUND: The relation between endogenous steroid hormones and risk for breast cancer is uncertain. Measurement of sex hormone levels may identify women at high risk for breast cancer who should consider preventive therapies. OBJECTIVE: To test the hypothesis that serum concentrations of estradiol and testosterone predict risk for breast cancer. DESIGN: Prospective case-cohort study. SETTING: Four clinical centers in the United States. PARTICIPANTS: 97 women with confirmed incident breast cancer and 244 randomly selected controls; all women were white, 65 years of age or older, and were not receiving estrogen. MEASUREMENTS: Sex-steroid hormone concentrations were assayed by using serum that was collected at baseline and stored at -190 degrees C. Risk factors for breast cancer were ascertained by questionnaire. Incident cases of breast cancer were confirmed by review of medical records during an average period of 3.2 years. RESULTS: The relative risk for breast cancer in women with the highest concentration of bioavailable estradiol (> or = 6.83 pmol/L or 1.9 pg/mL) was 3.6 (95% CI, 1.3 to 10.0) compared with women with the lowest concentration. The risk for breast cancer in women with the highest concentration of free testosterone compared with those with the lowest concentration was 3.3 (CI, 1.1 to 10.3). The estimated incidence of breast cancer per 1000 person-years was 0.4 (CI, 0.0 to 1.3) in women with the lowest levels of bioavailable estradiol and free testosterone compared with 6.5 (CI, 2.7 to 10.3) in women with the highest concentrations of these hormones. Traditional risk factors for breast cancer were similar in case-patients and controls. Adjustments for these risk factors had little effect on the results. CONCLUSIONS: Estradiol and testosterone levels may play important roles in the development of breast cancer in older women. A single measurement of bioavailable estradiol and free testosterone may be used to estimate a woman's risk for breast cancer. Women identified as being at high risk for breast cancer as determined by these hormone levels may benefit from antiestrogen treatment for primary prevention.

Aged↗

PubMed1998

Endogenous hormones and the risk of hip and vertebral fractures among older women. Study of Osteoporotic Fractures Research Group.

BACKGROUND AND METHODS: In postmenopausal women, the serum concentrations of endogenous sex hormones and vitamin D might influence the risk of hip and vertebral fractures. In a study of a cohort of women 65 years of age or older, we compared the serum hormone concentrations at base line in 133 women who subsequently had hip fractures and 138 women who subsequently had vertebral fractures with those in randomly selected control women from the same cohort. Women who were taking estrogen were excluded. The results were adjusted for age and weight. RESULTS: The women with undetectable serum estradiol concentrations (<5 pg per milliliter [18 pmol per liter]) had a relative risk of 2.5 for subsequent hip fracture (95 percent confidence interval, 1.4 to 4.6) and subsequent vertebral fracture (95 percent confidence interval, 1.4 to 4.2), as compared with the women with detectable serum estradiol concentrations. Serum concentrations of sex hormone-binding globulin that were 1.0 microg per deciliter (34.7 nmol per liter) or higher were associated with a relative risk of 2.0 for hip fracture (95 percent confidence interval, 1.1 to 3.9) and 2.3 for vertebral fracture (95 percent confidence interval, 1.2 to 4.4). Women with both undetectable serum estradiol concentrations and serum sex hormone-binding globulin concentrations of 1 microg per deciliter or more had a relative risk of 6.9 for hip fracture (95 percent confidence interval, 1.5 to 32.0) and 7.9 for vertebral fracture (95 percent confidence interval, 2.2 to 28.0). For those with low serum 1,25-dihydroxyvitamin D concentrations (< or =23 pg per milliliter [55 pmol per liter]), the risk of hip fracture increased by a factor of 2.1 (95 percent confidence interval, 1.2 to 3.5). CONCLUSIONS: Postmenopausal women with undetectable serum estradiol concentrations and high serum concentrations of sex hormone-binding globulin have an increased risk of hip and vertebral fracture.

Aged↗

PubMed1998

The association of radiographically detected vertebral fractures with back pain and function: a prospective study.

BACKGROUND: Vertebral fractures are a hallmark of postmenopausal osteoporosis and an important end point in trials of osteoporosis treatment, but the clinical significance of these fractures remains uncertain. OBJECTIVE: To determine the association of new vertebral fractures with back pain and back-related functional limitation in older women. DESIGN: Prospective observational study. SETTING: Multicenter Study of Osteoporotic Fractures. PARTICIPANTS: 7223 white women aged 65 years and older. MEASUREMENTS: Lateral spine radiographs were obtained at baseline and at a follow-up examination an average of 3.7 years later. Prevalent and incident radiographic vertebral fractures were assessed by quantitative morphometry. Frequency and severity of back pain, disability in doing six activities involving the back, and days of bed rest and days of limited activity due to back pain were assessed annually by questionnaire during follow-up. RESULTS: Among women without a vertebral fracture at baseline, those with at least one incident vertebral fracture were more likely to have increased back pain (odds ratio [OR], 2.4 [95% CI, 1.7 to 3.3]) and back disability (OR, 2.6 [CI, 1.9 to 3.7]) and at least 1 day of bed rest due to back pain (OR, 6.7 [CI, 4.4 to 10.2]) and 7 days of limited activity due to back pain per year (OR, 3.8 [CI, 2.7 to 5.0]). Among women with a fracture at baseline, those with an incident vertebral fracture also had a greater risk for increased back pain (OR, 2.0 [CI, 1.4 to 2.8]) and back disability (OR, 2.2 [CI, 1.5 to 3.1]) and at least 1 day of bed rest (OR, 7.9 [CI, 4.9 to 12.9]) and 7 days of limited activity per year (OR, 3.5 [CI, 2.4 to 5.0]). Women with incident fracture had about 10 additional limited-activity days and 1 to 2 days of bed rest per year. New vertebral fractures that did not come to medical attention were associated with increased back pain and functional limitation. CONCLUSION: New vertebral fractures, even those not recognized clinically, are associated with substantial increases in back pain and functional limitation due to back pain in older white women. Prevention of new vertebral fractures should reduce the burden of back pain and functional limitation in women with vertebral osteoporosis.

Activities of Daily Living↗

PubMed1998

Serum fructosamine level and the risk of hip fracture in elderly women: a case-cohort study within the study of osteoporotic fractures.

PURPOSE: While a high serum fructosamine level may be an indicator of undiagnosed diabetes, a low level may be indicative of poor nutrition or frailty. As malnutrition is a risk factor for osteoporosis, low serum fructosamine levels may be associated with an increased risk of osteoporotic fracture. We examined the association between serum fructosamine levels and the risk of subsequent hip and vertebral fracture. SUBJECTS AND METHODS: We performed a case-cohort study within the Study of Osteoporotic Fractures. Subjects were elderly, ambulatory, community-dwelling, Caucasian, women. Fructosamine levels were measured in baseline serum. Incident vertebral fractures were identified by comparing baseline spinal radiographs to those obtained an average of 3.5 years later. Hip fractures were confirmed by radiograph. We randomly selected 101 women who suffered a hip fracture, 100 women who developed a vertebral fracture, and 276 controls. We compared fructosamine levels in women with subsequent osteoporotic fractures to controls. All analyses were adjusted for age, weight, and use of estrogens. RESULTS: Women with fructosamine levels in the lowest decile (< or = 223 micromol/L) had a three-fold increase in the risk of hip fracture (95% confidence interval 1.4-6.4), compared with all other women. Adjustment for markers of frailty, including smoking, functional status, and serum albumin levels, reduced the strength of this association. No clear association was observed between serum fructosamine level and the risk of vertebral fracture. CONCLUSION: Low serum fructosamine levels, which likely reflect frailty or malnutrition, may be a useful clinical tool to identify women at risk for hip fracture.

Aged↗

PubMed1998

Fractionation of aqueous cigarette tar extracts: fractions that contain the tar radical cause DNA damage.

Previously, we have shown that aqueous cigarette tar (ACT) extracts contain a long-lived tar radical that associates with DNA in isolated rat alveolar macrophages and causes DNA damage in isolated rat thymocytes. These ACT solutions reduce oxygen to produce superoxide and, ultimately, hydrogen peroxide. In this study, we report the fractionation of ACT solutions prepared from the tar from five cigarettes using Sephadex columns. The fractions were analyzed by UV and electron paramagnetic resonance (EPR) spectroscopy and gas chromatography/mass spectrometry (GC/MS). The fractions containing polyphenolic species (principally catechol and hydroquinone, as determined by MS) caused most of the observed DNA damage in rat thymocytes. These DNA-damaging fractions produced superoxide, H2O2, and hydroxyl radicals. Stable free radicals were identified as o- and p-benzosemiquinone radicals by EPR spectroscopy. Hydroxyl radicals were detected by EPR spin-trapping with 5, 5-dimethyl-1-pyrroline N-oxide (DMPO). Catalase inhibited the EPR signal of the DMPO-OH adduct, indicating that H2O2 is the precursor of the hydroxyl radical spin adduct. The Sephadex separation resulted in a 90-fold concentration of the hydrogen peroxide-generating capacity of the fractions that contained polyphenols, relative to the unfractionated ACT solution. Another fraction, which contained nicotine, caused some DNA damage, but this damage was 28-fold less than the damage caused by the most damaging phenolic fraction. These results support our hypothesis that the tar radical system is an equilibrium mixture of semiquinones, hydroquinones, and quinones. The tar radical associates with DNA, causes DNA damage, and very likely is involved in the toxicity associated with cigarette smoking.

Animals↗

PubMed1998

Hormonal predictors of bone loss in elderly women: a prospective study. The Study of Osteoporotic Fractures Research Group.

To test the hypotheses that baseline concentrations of sex steroids, sex hormone binding globulin (SHBG), and calciotropic hormones predict rates of bone loss in elderly women, sera were stored at -190 degrees, and calcaneal bone mineral density (BMD) was measured in 9704 community-dwelling white women aged 65 and over (1986-1988). Hip BMD was measured 2 years later (1900). Repeat measurements of a calcaneal and hip BMD were obtained in 1993-1994, after 5.7 and 3.5 years of follow-up, respectively. In 1994, sera were assayed for circulating hormone levels in random subcohorts of 231 and 218 women who did not report current use of hormone replacement therapy at baseline. Lower levels of endogenous estrogens and higher SHBG concentrations were associated with more rapid subsequent bone loss from both the calcaneus and hip. After adjusting for age and weight, women with high SHBG levels (highest quartile < or = 2.3 micrograms/dI) experienced an average of 2.2% (95% confidence interval = 1.6%, 2.9%) calcaneal bone loss per year compared with 1.2% (0.7%, 1.2%) among women with low SHBG concentrations (lowest quartile < 1.1 micrograms/dI; p < 0.01). This association was independent of concentrations of other sex hormones. Women with estradiol levels > or = 10 pg/ml averaged only 0.1% (-0.7%, 0.5%) annual hip bone loss while women with levels below 5 pg/ml averaged 0.8% (0.3, 1.2) hip bone loss per year. Lower 25-hydroxyvitamin D levels were associated with increased hip but not calcaneal bone loss. Levels of parathyroid hormone, 1,25-dihydroxyvitamin D, and Calcium were not significantly associated with bone loss from the calcaneus or hip.

Absorptiometry, Photon↗

PubMed1998

Effect of neuromuscular blockers and opiates on the cerebrovascular response to endotracheal suctioning in adults with severe head injuries.

BACKGROUND: Intracranial hypertension occurs in response to routine procedures such as endotracheal suctioning in patients with severe head injuries. In some patients, the intracranial pressure does not immediately return to baseline levels. OBJECTIVES: To examine the effect of drug administration on cerebrovascular response to endotracheal suctioning in adults with severe head injuries. METHODS: Seventy-one subjects were divided into 3 groups: those who received no drugs, those treated with opiates only (morphine sulfate and fentanyl citrate), and those treated with a neuromuscular blocking agent (vecuronium bromide) plus opiates. A controlled protocol involving 2 sequences of endotracheal suctioning that included hyperoxygenation, hyperinflation, and suctioning was used for all subjects. Two-way repeated-measures analyses of variance were done with type of drug as the between-subject factor and phase of suctioning as the within-subject factor. Survival analysis was used to compare the return of intracranial pressure to baseline levels among the 3 groups. RESULTS: Changes in intracranial pressure were significantly smaller in subjects who received a neuromuscular blocking agent plus opiates than in subjects who did not receive any drugs or received opiates only. The greatest increase in intracranial pressure from baseline was in the first and second phases of suctioning. The 3 groups showed no significant difference in the return of intracranial pressure to baseline level. CONCLUSIONS: Neuromuscular blockers attenuate the increases in intracranial pressure that occur with endotracheal suctioning. It is not known whether control of procedurally induced elevations in intracranial pressure affects long-term outcomes in adults with severe head injuries.

APACHE↗

PubMed1997

Outcome of anxiety and depressive disorders in primary care.

BACKGROUND: Factors related to the outcome of depression and anxiety in primary care are not fully understood. METHOD: Adult patients in general practice with depressive, anxiety or panic disorder (n = 148; DSM-III-R criteria) were studied prospectively for six months to determine the factors most closely associated with outcome. The Psychiatric Assessment Schedule, Hamilton Depression Rating Scale, Clinical Anxiety Scale and Life Events and Difficulties Schedule interviews were performed at index consultations and repeated six months later. Variables associated with outcome were assessed by multiple regression analysis. RESULTS: Good outcome was predicted by mild depression at initial assessment, high educational level, and being in employment. At follow-up the most important predictor of improvement was reduction in marked difficulties over the six months. Recognition and management by the GP was most frequent in patients with severe disorder; such patients were least likely to improve because of the severity of their depression and marked social difficulties. CONCLUSIONS: This naturalistic study helps to provide a framework for further studies with more precisely defined groups of people with depression. An effective treatment strategy for people with marked depression and ongoing social difficulties is especially needed.

Adolescent↗

PubMed1997

Low thyrotropin levels are not associated with bone loss in older women: a prospective study.

The relationship between excess thyroid hormone and bone loss is controversial. To determine whether low TSH levels, indicating excessive thyroid hormone, are associated with low bone mass or accelerated bone loss in older women, we performed a prospective cohort study of 458 women over age 65 yr participating in the multicenter Study of Osteoporotic Fractures. Three hundred and twenty-three women were randomly selected from the entire cohort of 9704; an additional 135 randomly selected thyroid hormone users were studied. Medical history, medication use, and calcaneal bone mineral density (BMD) were assessed at the baseline visit. Serum was collected and stored at -190 C. Hip and spine BMD were measured approximately 2 yr later, and follow-up calcaneal and hip BMD measurements were obtained after mean follow-up periods of 5.7 and 3.5 yr, respectively. TSH levels were determined in baseline serum samples using a third generation chemiluminescent assay. After adjustment for age, weight, previous hyperthyroidism, and use of estrogen, bone loss over 4-6 yr was similar in women with low, normal, or high TSH. For example, femoral neck bone loss was -0.3%/yr (95% confidence interval, -0.8%, 0.3%) among women with low TSH (< or = 0.1 mU/L) and -0.5%/yr (95% confidence interval, -0.7%, -0.3%) in those with normal TSH (0.1-5.5 mU/L). There were no statistically significant differences in baseline bone mass of the calcaneus, spine, or femoral neck or trochanteric hip subregions. Baseline total hip BMD was 6% lower (P = 0.01) in women with low TSH. Similar results were obtained in analyses confined to women not taking estrogens. We found no consistent evidence that low TSH, a sensitive biochemical marker of excess thyroid hormone, was associated with low BMD or accelerated bone loss in older ambulatory women.

Aged↗

PubMed1997

Consequences of foot binding among older women in Beijing, China.

OBJECTIVES: This study examined the prevalence and consequences of foot binding in older Chinese women. METHODS: Women older than 70 years in Beijing, China, were assessed for bound feet, falls, functional status, and bone density. RESULTS: Thirty-eight percent of women aged 80 years and older and 18% of women aged 70 through 79 years had bound-foot deformities. Women with bound feet were more likely to fall, less able to squat, and less able to stand up from a chair without assistance than women with normal feet. They also had 14.3% less functional reach (a test of balance) and 5.1% lower hip bone density. CONCLUSIONS: Foot binding has caused substantial disability that is still evident in many elderly Chinese women.

Accidental Falls↗

PubMed1996

Aspirin and NSAID use in older women: effect on bone mineral density and fracture risk. Study of Osteoporotic Fractures Research Group.

Prostaglandin inhibition by aspirin or nonsteroidal anti-inflammatory drug (NSAIDs) may inhibit bone loss and preserve bone mineral density (BMD) in vitro and in animal models. The effect of these agents on BMD and fracture risk in postmenopausal women in unknown. We assessed the risk factors for osteoporosis and the use of aspirin and NSAIDs in 7786 white women over age 65. Axial BMD was measured at the same time, and fractures were prospectively documented over the subsequent 4 years of follow-up. In age-adjusted analyses, daily use of aspirin or NSAIDs was associated with a 2.3-5.8% increase in BMD of the hip and spine. The relationship persisted even after adjustment for weight, a variety of medications, self-reported arthritis, and for radiographic findings of osteoarthritis, but the multiply adjusted increase in BMD was only 1.0-3.1%. Fracture risk was similar among daily users of aspirin and NSAIDs and nonusers. After adjustment for potential confounders, among daily aspirin users the relative risk of hip fracture was 1.1 (95% confidence interval [CI]: 0.7, 1.6), and among daily NSAID users the risk was 0.9 (CI: 0.6, 1.4). Considering all nonspine fractures together, the risk among aspirin users was 1.0 (CI: 0.8. 1.2), and among NSAID users the risk was also 1.0 (CI; 0.8, 1.2). Regular use of aspirin or NSAIDs may have a modest beneficial effect on BMD in postmenopausal women. This effect persists after adjustment for obesity and the presence of osteoarthritis. However, among women who take aspirin or NSAIDs regularly, there is no clinically significant protective effect on the subsequent risk of fractures.

Aged↗

PubMed1996

Measurement of pulmonary artery diastolic pressure from a right ventricular pressure transducer in patients with heart failure.

Recent studies have demonstrated that pulmonary artery diastolic (PAD) pressure can be measured from a transducer positioned in the right ventricle (RV) based on the finding that PAD and RV pressures are equal at the time of pulmonary valve opening, which is associated with the time of maximum positive rate of pressure development (dP/dtmax) in the ventricle. The objective of this study was to assess the correlation between estimated PAD (ePAD) pressure, obtained through a RV transducer, and actual PAD (aPAD) pressure in patients with heart failure who have abnormal hemodynamics, reduced systolic function, and variable degrees of mitral regurgitation (MR) and tricuspid regurgitation (TR). Simultaneous measurements of pulmonary artery and RV pressures were obtained with a high-fidelity Millar catheter (Millar Instruments, Houston, TX) in 10 patients with New York Heart Association class III-IV heart failure who were being evaluated for cardiac transplantation. The overall correlation between ePAD and aPAD pressures was .92 (R2 = .878). This was not significantly different during the Valsalva maneuver (r = .96, R2 = .943), submaximal bicycle exercise (r = .87, R2 = .756), or infusions of dobutamine and nitroglycerin (r = .82, R2 = .730). The overall average difference between the average ePAD (24.6 +/- 7.0 mmHg) and aPAD (23.6 +/- 7.0 mmHg) pressures was 1.0 +/- 3.4 mmHg. The average difference between the two pressures in patients with mild to severe MR or TR was not different compared to those patients with no or trace MR or TR. The estimation of PAD pressure from an RV transducer is valid in patients with heart failure who have abnormal hemodynamics, reduced systolic function, and variable degrees of MR and TR. This correlation was observed at rest and during several provocative maneuvers. These data will be important for the development of a chronic, implantable hemodynamic monitor for patients with heart failure.

Adult↗

PubMed1996

Osteoporosis: association of recent fractures with quantitative US findings.

PURPOSE: To study the association of quantitative ultrasound (US) parameters and bone mineral density (BMD) in patients with and patients without recent fractures. MATERIALS AND METHODS: The authors studied 4,698 women (69 years or older) who had sustained 1,363 new fractures, including 106 hip fractures, during the 7 years prior to the study. Broadband ultrasound attenuation (BUA) and other velocity parameters were measured by means of quantitative US of the calcaneus. BMD was measured at the spine, hip, and calcaneus. RESULTS: The standardized age-adjusted odds ratio for all fractures was 1.5 (95% confidence interval [CI] = 1.4, 1.7) for BUA and up to 1.6 (95% CI = 1.5, 1.7) for BMD. For hip fractures, the odds ratio was 1.9 (95% CI = 1.5, 2.4) for BUA and up to 2.6 (95% CI = 2.0,3.4) for BMD. Sensitivity and specificity with BUA, velocity parameters, and BMD were comparable. Results of multivariate analysis showed that both BUA and BMD were independently associated with fractures and that combined measurements improved sensitivity and specificity. CONCLUSION: Quantitative US parameters are strongly associated with risk of fracture and partly independent of BMD. This simple, low-cost, portable, and radiation-free approach may complement bone densitometry in assessing risk of osteoporotic fracture.

Aged↗

PubMed1995

Peroxynitrite causes DNA nicks in plasmid pBR322.

Peroxynitrite causes single-strand breaks in pBR322 supercoiled DNA as evidenced by agarose gel electrophoresis analysis. The effect of three free radical scavengers, namely mannitol, benzoate and dimethylsulfoxide, were studied. Mannitol failed to protect DNA from damage by peroxynitrite while benzoate and dimethylsulfoxide amplified the damage. These results suggest the damage caused by peroxynitrite alone is not mediated by free radicals since typical free radical scavengers fail to prevent the damage.

Benzoates↗

PubMed1995

The ESR properties, DNA nicking, and DNA association of aged solutions of catechol versus aqueous extracts of tar from cigarette smoke.

Previous studies in our laboratories have shown that extracts from mainstream or sidestream tobacco smoke nick DNA. These solutions contain the tar semiquinone free radical, and the tar radical becomes associated with cellular DNA. Aged solutions of catechol contain a semiquinone species that has ESR properties similar to those of the radical in cigarette tar extracts, and we have used these catechol solutions as a model for the tar radical. Both the radical in aged catechol solutions and the cigarette tar radical become associated with the DNA in mammalian cells and also nick DNA. The nicking of DNA caused by both tar and aged catechol solutions follows saturation kinetics. Aged catechol solutions thus allow the study of a model for the radical present in cigarette tar, without interference from the other toxic constituents in tar extracts.

Animals↗

PubMed1995

Risk factors for hip fracture in white women. Study of Osteoporotic Fractures Research Group.

BACKGROUND: Many risk factors for hip fractures have been suggested but have not been evaluated in a comprehensive prospective study. METHODS: We assessed potential risk factors, including bone mass, in 9516 white women 65 years of age or older who had had no previous hip fracture. We then followed these women at 4-month intervals for an average of 4.1 years to determine the frequency of hip fracture. All reports of hip fractures were validated by review of x-ray films. RESULTS: During the follow-up period, 192 women had first hip fractures not due to motor vehicle accidents. In multivariable age-adjusted analyses, a maternal history of hip fracture doubled the risk of hip fracture (relative risk, 2.0; 95 percent confidence interval, 1.4 to 2.9), and the increase in risk remained significant after adjustment for bone density. Women who had gained weight since the age of 25 had a lower risk. The risk was higher among women who had previous fractures of any type after the age of 50, were tall at the age of 25, rated their own health as fair or poor, had previous hyperthyroidism, had been treated with long-acting benzodiazepines or anticonvulsant drugs, ingested greater amounts of caffeine, or spent four hours a day or less on their feet. Examination findings associated with an increased risk included the inability to rise from a chair without using one's arms, poor depth perception, poor contrast sensitivity, and tachycardia at rest. Low calcaneal bone density was also an independent risk factor. The incidence of hip fracture ranged from 1.1 (95 percent confidence interval, 0.5 to 1.6) per 1,000 woman-years among women with no more than two risk factors and normal calcaneal bone density for their age to 27 (95 percent confidence interval, 20 to 34) per 1,000 woman-years among those with five or more risk factors and bone density in the lowest third for their age. CONCLUSIONS: Women with multiple risk factors and low bone density have an especially high risk of hip fracture. Maintaining body weight, walking for exercise, avoiding long-acting benzodiazepines, minimizing caffeine intake, and treating impaired visual function are among the steps that may decrease the risk.

Aged↗

PubMed1995

Quantitative ultrasound and vertebral fracture in postmenopausal women. Fracture Intervention Trial Research Group.

Quantitative ultrasound is a promising technique to evaluate fracture risk. To test the hypothesis that reduction of one ultrasound measurement, broadband ultrasound attenuation (BUA), is associated with an increased risk of vertebral fracture in postmenopausal women, we performed a cross-sectional analysis of 442 women aged 55-80 years enrolling in a clinical trial of alendronate. Prior to randomization, we obtained bone mineral density (BMD) measurements of the hip, spine, and whole body, radiographs of lateral lumbar and thoracic spine, and duplicate measurements of calcaneal BUA with a Walker Sonix UBA575. Vertebral fractures were defined by morphometry and semiquantitative reading by a radiologist. After adjustment for potential confounders, the relative risk of vertebral fracture was 1.8 (95% CI 1.4-2.3) for each standard deviation reduction in BUA; for each standard deviation reduction in BMD, the relative risk was 1.7 (95% CI 1.3-2.1) at the femoral neck, and 2.2 (95% CI 1.7-2.9) at the spine. Adjustment for hip, spine, or whole body BMD did not significantly alter the relation between BUA and vertebral fracture. For example, after adjusting for spine BMD, the relative risk of vertebral fracture was 1.5 (95% CI 1.1-2.0) for each standard deviation reduction in BUA. We conclude that low BUA is associated with the presence of vertebral fractures in postmenopausal women. The relation between BUA and vertebral fracture is similar to that observed for BMD and vertebral fractures. Furthermore, the relation between BUA and vertebral fracture persists after adjustment for BMD.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

Detection of free radicals in aqueous extracts of cigarette tar by electron spin resonance.

Aqueous extracts of cigarette tar (ACT) autooxidize to produce semiquinone, hydroxyl, and superoxide radicals in air-saturated buffered aqueous solutions. The semiquinone species were detected by direct electron spin resonance (ESR) measurements and identified as o- and p-benzosemiquinone radicals by comparison with the ESR signals of catechol and hydroquinone radicals under similar conditions. The rate of formation of these radicals was dependent on pH. Hydroxyl and superoxide radicals were detected as 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin adducts by ESR spin trapping. Superoxide dismutase (SOD) (20 units/ml) inhibited the formation of the superoxide spin adduct of DMPO completely. Addition of Fe2+ to this system increased the ESR signal intensity of hydroxyl radical spin adduct of DMPO three to five times. These results indicate that superoxide and hydroxyl radicals are produced during the autooxidation of hydroquinone- and catechol-related species in ACT.

Cyclic N-Oxides↗