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S A Steel

Publications and source records attributed to S A Steel.

At least 19 recordsLinked to original sources
PubMed2006

The DXL Calscan heel densitometer: evaluation and diagnostic thresholds.

The DXL Calscan (Demetech AB) is a new dual energy X-ray absorptiometry device for determining heel bone mineral density (BMD). The system is based on the standard technique of dual energy X-ray absorptiometry (DXA), using a fan beam configuration, but introduces an additional laser measurement of heel thickness intended to improve accuracy. We have examined the utility, in vitro and in vivo performance of the DXL Calscan and established triage thresholds based on the UK's National Osteoporosis Society guidelines on peripheral densitometry. The Calscan proved convenient, easy to use and was stable over time and within a range of operating temperatures. Short-term in vitro precision as %CV, with phantom repositioning, was 0.75% and long term precision 0.73%. Precision in vivo, determined from duplicate right heel scans of 67 subjects, was 1.19%. Effective radiation dose to the patient was <0.1 microSv per scan. 140 white females (70 osteoporotic and 70 non-osteoporotic), aged 55-70 years underwent scans of both heels. Subjects were defined as osteoporotic or non-osteoporotic on the basis of axial DXA (spine L2-L4 and total hip). Triage thresholds for reassurance-referral or referral-treatment were 0.391 g cm(-2) and 0.306 g cm(-2) for non-dominant and 0.395 g cm(-2), 0.294 g cm(-2) for dominant heel, respectively. The non-dominant heel proved slightly superior to the dominant for triage purposes. Of the seven non-osteoporotic subjects misclassified as osteoporotic by Calscan of either heel, six had severe axial osteopenia. If operated by trained personnel and used in appropriate populations exhibiting risk factors, the Calscan is well suited for use in the management of post-menopausal osteoporosis.

Absorptiometry, Photon↗
PubMed2005

A list of device-specific thresholds for the clinical interpretation of peripheral x-ray absorptiometry examinations.

The UK National Osteoporosis Society (NOS) has recently issued new guidelines on the use of peripheral x-ray absorptiometry (pDXA) devices in managing osteoporosis. The NOS guidelines recommend a triage approach in which patients' bone mineral density (BMD) measurements are interpreted using upper and lower thresholds specific to each type of pDXA device. The thresholds are defined so that patients with osteoporosis at the hip or spine are identified with 90% sensitivity and 90% specificity. Patients with a pDXA result below the lower threshold are likely to have osteoporosis at the hip or spine, patients with a result above the upper threshold are unlikely to have osteoporosis, while those between the two thresholds require a hip and spine BMD examination for a definitive diagnosis. This report presents data from a multicenter study to establish the triage thresholds for a range of pDXA devices in use in the UK. The subjects were white female patients aged 55-70 years who met the normal referral criteria for a BMD examination. For each device, at least 70 women with osteoporosis at the hip or spine and 70 women without osteoporosis were enrolled. All women had hip and spine BMD measurements using axial DXA systems that were interpreted using the National Health and Nutrition Examination Survey (NHANES) reference range for the hip and the manufacturers' reference ranges for the spine. Data are presented for five different devices: the Osteometer DTX-200 (forearm BMD), the Schick AccuDEXA (hand BMD), the GE Lunar PIXI (heel BMD), the Alara MetriScan (hand BMD), and the Demetech Calscan (heel BMD). The clinical measurements were supplemented by theoretical modeling to estimate the age dependence of the triage thresholds and the effect of the correlation coefficient between pDXA and axial BMD on the percentage of women referred for an axial BMD examination. In summary, this study provides thresholds for implementing the new NOS guidelines for managing osteoporosis using pDXA devices. The figures reported apply to postmenopausal white women aged 55-70 years who meet the conventional criteria for a BMD examination. The results confirm that the thresholds are specific to each type of pDXA device and that the NOS triage algorithm requires 40% of women to have an axial DXA examination.

Absorptiometry, Photon↗
PubMed2005

Effect of intermittent compression therapy on bone mineral density in women with low bone mass.

Intermittent pneumatic compression has been shown to increase blood flow in the leg which, in turn, may improve BMD. We performed a pilot study to assess whether intermittent compression of the leg could improve BMD at the femoral neck. 37 postmenopausal women with low bone density T score < -1 at either hip or spine were recruited into the study of whom 24 completed. Women applied intermittent compression for 2 h a day for 6 months to each leg in turn. The study lasted 1 year. Women were also given daily 1 g of Calcium and 800 IU of vitamin D (Calcichew D 3 forte Shire, UK). Lumbar spine BMD decreased by 0.5% at 12 months compared with baseline (mean difference 0.005 g/cm(2), 95% C.I -0.2287 to 0.03459, P = 0.28). At 12 months the right femoral neck BMD increased by 3% compared with baseline (mean 0.811 +/- 0.08, P = 0.22), while the left increased 2% (0.783 +/- 0.06, P = 0.16). There was no change in BMD at the distal tibia or heels and no site effect of the compression. The fat mass decreased by 4.6% in the right leg and 5% in the left leg (P = 0.005 and 0.003, respectively). Tissue thickness did not change. The analysis of the interaction between the degree of exercise and change in BMD showed a statistically significant increase in right femoral neck BMD following 6 months of right leg intermittent compression, but only in women whose exercise was minimal (P = 0.029). This effect was not seen in the left femur possibly due to the reduced number of patients who completed the study in this group. These preliminary results indicate that intermittent pneumatic leg compression may have a role in osteoporosis prevention. It may provide a mean of inhibiting decline in femoral neck BMD, particularly in sedentary women.

Aged↗
PubMed2005

Effect of pure genistein on bone markers and hot flushes.

OBJECTIVE: To evaluate the effect of 90 mg of daily genistein on markers of bone turnover and menopausal symptoms. DESIGN: This was a cross-over, placebo-controlled study involving 100 postmenopausal women. Subjects were randomly assigned to daily genistein or placebo for 6 weeks and crossed over to the alternative preparation for the following 6 weeks. Pure genistein was processed and encapsulated in accordance with British Pharmacopoeia standards. Each capsule contained 90 mg of pure genistein while the placebo contained just the recipients. RESULTS: In women with significant hot flushes (score (intensity x number) > or = 9), genistein reduced symptoms by 30% compared to baseline and the difference compared to placebo was statistically significant. No effect was observed on biochemical markers of bone turnover, possibly due to the short duration of each arm of the study. Genistein reduced osteocalcin, a marker of bone formation, by 3.6% compared to baseline and 0.31% compared to placebo (p = 0.81 and 0.40, respectively). Genistein increased cross-link telopeptide, a marker of bone resorption, by 1.8% compared to baseline and 0.29% compared to placebo; both differences were not statistically significant (p = 0.078 and 0.88, respectively). CONCLUSION: Pure genistein at a dose of 90 mg per day appears to reduce the number of hot flushes in postmenopausal women but the effect is mild.

Biomarkers↗
PubMed2004

Comparison of the effects of two different types of calcium supplementation on markers of bone metabolism in a postmenopausal osteopenic population with low calcium intake: a double-blind placebo-controlled trial.

OBJECTIVE: To investigate calcium supplements in postmenopausal women. Calcium supplements in postmenopausal women with a low calcium intake have been shown to prevent osteoporotic vertebral fracture, but calcium is variably absorbed and often poorly tolerated, which may limit effectiveness. METHODS: The study compared the efficacy and tolerability of 500 mg/day of calcium in the form of ossein-hydroxyapatite (OHC) versus 500 mg/day of tricalcium phosphate (TCP) and placebo in the prevention of postmenopausal bone loss. This was a prospective randomized study enrolling 153 postmenopausal osteopenic women. Serum and urine markers of bone turnover were collected at 3 and 6 months. Bone density measurement was performed at baseline and 6 months in all participants, and at 12 months in women taking OHC. RESULTS: At 3 and 6 months, both TCP and OHC decreased serum markers of bone formation significantly, compared with placebo. At 6 months, TCP and OHC decreased osteocalcin by 9.9% and 12.3%, respectively; the aminoterminal propeptide of type I procollagen (PINP) was decreased by 5.3% and 6.3%, respectively; bone-specific alkaline phosphatase was decreased by 4.3% and 6.7%, respectively, compared with baseline. The effects on bone resorption markers or on bone mineral density did not reach statistical significance, although OHC increased bone density by 0.8% at the spine at 12 months. Both forms of calcium were well tolerated and did not differ from placebo in terms of side-effects. CONCLUSIONS: While both OHC and TCP were well tolerated and significantly reduced bone turnover markers, the effect of ossein-hydroxyapatite seems slightly superior to that of tricalcium phosphate.

Aged↗
PubMed2003

Factors affecting long-term adherence to hormone replacement therapy after screening for osteoporosis.

OBJECTIVE: To investigate factors likely to influence adherence to hormone replacement therapy (HRT) in women known to have low bone mass. STUDY DESIGN: This was a prospective study of bone mineral density screening in 6282 women aged 50-54 years. RESULTS: Low bone mass at either the hip or spine was found in 1462 women. The principal route of HRT delivery, transdermal or oral, as well as the presence of climacteric symptoms before starting treatment, did not influence adherence. However, adherence to HRT type was significantly superior in hysterectomized women taking unopposed estradiol (median 32 months) compared with those on sequential HRT (median 28 months; p = 0.011). Overall, a 5-year adherence to HRT of 61% was achieved. CONCLUSION: Approximately 34% of women starting HRT are likely to stop in the first 2 years of use. Following this, the discontinuation rate is low. The combination of knowledge of risk for osteoporosis and regular follow-up positively influences long-term adherence to HRT.

Absorptiometry, Photon↗
PubMed2002

Attitudes towards and use of dietary supplementation in a sample of postmenopausal women.

OBJECTIVES: To assess the reason why people take food supplements in addition to or in place of medication, as well as the perceived efficacy and risk of these supplements. METHODS: A 20-item, computer-assisted telephone questionnaire was administered to 442 women over 60 years of age in Hull, to assess the prevalence of use and perception of efficacy and safety of food supplements. RESULTS: Data were available for 411 women, of whom 269 (65.4%) were currently taking food supplements, 76 (18.5%) were previous users and 66 (16%) were never-users. There was no difference in terms of age, smoking, consumption of fruit and vegetables, life-style and attitude towards conventional medicine between current or past users of supplements and never-users. The majority of users (n = 229, 66%) thought that food supplements help maintain good health (p < 0.001). Overall long-term (5 years) adherence was achieved in 244 cases of supplement uses (36%). Among users, 150 (43%) thought that supplements were very effective, and 171 (49.5%) women had noticed an improvement of various symptoms. Although the majority of users (n = 176, 51%) believed that supplements might have adverse effects, over 66% would not associate side-effects with the food supplement. Information regarding supplements was obtained primarily from the media, particularly magazine and newspaper articles (27%), with health professionals rarely being consulted (16%). CONCLUSIONS: Users believed supplements to be effective, although possibly with associated side-effects. However, they would not attribute adverse effects experienced to this form of treatment. Medical practitioners and health professionals are rarely informed or consulted, leaving potentially dangerous side-effects of food supplements to go unreported.

Aged↗
PubMed1999

Development and evaluation of a phantom for morphometric X-ray absorptiometry.

Morphometric X-ray absorptiometry (MXA) provides the potential to assess vertebral deformity using a technique with much lower radiation dose to the patient than standard radiographic procedures. MXA overcomes many other limitations such as cone beam distortion observed in conventional plane radiographs. A phantom has been designed to assess the accuracy of the MXA technique, to monitor long-term precision and to assess inter- and intra-operator variability. The phantom consists of two columns of 12 cylinders representing the vertebral bodies, one of regular components and one representing vertebral deformities. Each column may be inserted, as required, into a Perspex torso-mimicking block. Initial assessment on the Lunar Expert-XL demonstrates that the phantom provides image parameters reflecting those found clinically. Measurement of vertebral height was found to be consistently underestimated by 4.9%. Operator precision ranged from 0.6% for posterior height measurement to 1.0% for middle height measurement of the regular component column. The corresponding precision range for the column representing vertebral deformation was 0.6% (posterior) and 1.1% (middle). Analysis of 10 scans of each column by two independent operators demonstrated a few significant differences in height assessment confined to the 'thoracic' region of the regular column. However, inter-operator variability was found to increase with increasing complexity of vertebral shape producing several differences, particularly in posterior height assessment of the deformed column.

Absorptiometry, Photon↗
PubMed1999

Image resolution of the Lunar Expert-XL.

The Lunar Expert-XL is an example of the latest generation of fan beam densitometers, with the X-ray source and detector array mounted on a C-arm to enable supine lateral imaging. Image resolution for anteroposterior (AP) spine, femur, hand, forearm and lateral morphometry on the Expert-XL were assessed in vitro with the 07-541 Nuclear Associates line pair test pattern. Each scan type was investigated at all available tube currents and scan speeds, and at the maximum, minimum and default bed heights. The effect of soft tissue thickness on resolution was investigated by using varying amounts of Perspex attenuator. The in vitro median lateral (x-axis) resolutions at the default bed height for the default scan types were 0.9 line pairs (lps)/mm for the 5 mA fast AP spine and femur scans, and l.0 lps/mm for 1 mA fast hand, forearm and 5 mA fast morphometry scans. This equates to a resolution of about 1 mm. The best resolution achieved was 1.2 lps/mm (0.83 mm), obtainable on all scan modes with the bed at maximum elevation, but only consistently with the forearm mode. Lower tube current did not affect resolution but did change the range of soft tissue thickness over which an image could be resolved. Turbo scan modes greatly reduced longitudinal (y-axis) resolution but had little effect on lateral resolution. This study demonstrates the importance of including an assessment of resolution when validating new equipment, especially if morphometric investigations are to be conducted.

Absorptiometry, Photon↗
PubMed1999

Premature greying of the hair is not associated with low bone mineral density.

In two recent case-control studies premature greying of the hair was associated with a lowering of bone mineral density (BMD) and osteopenia, suggesting that this might be a clinically useful risk marker for osteoporosis. We report a further re-examination of this proposal in 52 prematurely grey-haired women from East Yorkshire who responded to an advertisement inviting them for bone densitometry. Thirty-five had no clinical or drug history that could influence bone density. All were Caucasian with a mean age of 52.8 years. In the group as a whole the mean BMD values at the lumbar spine and femoral neck were no different from those of a young adult, but there was a trend toward a greater than average BMD than that of the local age-matched population (p = 0.097 and 0.218, respectively). Twenty women were premenopausal, with an average age of 45.3 years. Mean BMD values at the lumbar spine and femoral neck in this group were no different from those of young adults. There was, however, a trend toward a BMD greater than that of the local age-matched population at the femoral neck (p = 0.117). Fifteen women were postmenopausal with an average age of 62.9 years and an average age at menopause of 51.1 years. Mean BMD values at both the lumbar spine and femoral neck in this group were lower than those of young adults, but no different from those of the local age-matched population. In conclusion, our group of prematurely grey-haired women had average BMD for their age, and we are therefore unable to support the proposed clinical usefulness of premature greying as a risk marker for osteoporosis.

Absorptiometry, Photon↗
PubMed1998

Prevalence of osteoporosis and related risk factors in UK women in the seventh decade: osteoporosis case finding by clinical referral criteria or predictive model?

The objectives of the study were: to determine the prevalence of osteoporosis in women in their seventh decade; to determine the number of women who conformed to at least one of the current East Yorkshire Clinical Referral Criteria for Osteoporosis; and to determine the sensitivity and specificity of these referral criteria in the diagnosis of osteoporosis and to compare this with the receiver operating characteristic (ROC) curve of a logistic regression model incorporating variables that were significantly associated with the risk of osteoporosis. An observational study was carried out at the Centre for Metabolic Bone Disease, Hull Royal Infirmary, on women in their seventh decade from three general practices. Densitometric assessment of lumbar spine and femoral neck was carried out using dual-energy X-ray absorptiometry (DXA) and a detailed medical history taken. The main outcome measures were prevalence of osteoporosis in women in their seventh decade and efficacy of agreed clinical referral criteria at osteoporosis case finding. Of 823 Caucasian women who underwent DXA, 24% proved to have osteoporosis at hip, spine or both according to WHO criteria. A further 49% had osteopenia detected at hip, spine or both. At least one of the referral criteria was present in 47% of the women assessed. The sensitivity of the clinical referral criteria for detection of osteoporosis was 58% with a corresponding specificity of 60%. This point lies below the ROC curve (area under fitted curve, Az = 0.73) of a logistic regression model incorporating weight, age at menopause and current use of hormone replacement therapy. In conclusion, osteoporosis according to WHO criteria was found in almost 25% of women in their seventh decade. A simple logistic regression model provided a more sensitive method of osteoporosis case finding than the selective screening component of the clinical referral criteria employed in our practice.

Absorptiometry, Photon↗
PubMed1998

An assessment of the radiation dose to patients and staff from a Lunar Expert-XL fan beam densitometer.

Dual-energy x-ray absorptiometry (DXA) is a widely used technique for measuring bone mineral density for the identification and management of osteoporotic subjects. The original DXA pencil beam systems expose patients to an effective dose of ionizing radiation of around 2 muSv and require no additional protective shielding for staff. The new fan beam densitometers incorporate solid state detectors and have a higher photon flux, enabling faster acquisition times and giving improved resolution. However, this may be at the expense of higher radiation dose. This study was conducted to assess the radiation dose to patients and staff from the standard scan modes using a Lunar Expert-XL fan beam densitometer. This is, we believe, the first dose assessment of the Expert-XL. The results indicate that the scatter dose at 1 m from the scan table, assuming four AP spine and femoral neck examinations per hour, is about 4 muSv h-1. This is well below the limit of 7.5 muSv h-1 set by the UK's Ionising Radiation Regulations for defining a Controlled Area but above the lesser limit of 2.5 muSv h-1 for a Supervised Area. Typical effective doses to patients are 59 muSv for an AP lumbar spine scan, up to 56 muSv for AP femoral neck, 71 muSv for lateral spine morphometry and 75 muSv for whole body. Although exceeding those of pencil beam DXA machines, these doses are less than for standard radiographic procedures, particularly of the lumbar spine. Where reduced scan time, improved image resolution or morphometric analysis of the spine are required, the patient doses from the Lunar Expert-XL are not prohibitive.

Absorptiometry, Photon↗
PubMed1998

A phantom based study on the effect of subject positioning on morphometric X-ray absorptiometry using the Lunar Expert-XL.

Morphometric X-ray absorptiometry (MXA) relies on accurate measurement of vertical dimensions of vertebrae from a lateral perspective. Deviations resulting from scoliotic curvature or poor patient positioning produce distortions of visible vertebral dimensions and may lead to analysis error. This study utilized a phantom developed at this centre to assess the effect of vertebral malalignment on the accuracy of the MXA technique on the Lunar Expert-XL. Measured vertebral heights were found to be consistently underestimated by an average of 3.7%. Precision ranged from 0.79% for anterior height measurement to 1.03% for middle height measurement. Vertebral malalignment was investigated as the effect of rotation around the anteroposterior, lateral and superoinferior axes. Rotation around the lateral axis produced little discernible effect. However, superoinferior axial rotation showed a change of more than two standard deviations in the mid/posterior ratios of biconcave vertebrae at comparatively small angles of rotation. Anteroposterior axial rotation produced an increase in observed height at small angles of rotation, and a rapid decrease in vertebral height as rotation increased. The results suggest that whilst kyphosis or lordosis of up to at least 5.8 degrees has a minimal effect on MXA, scoliosis of 4.6 degrees or above produces a distinctive effect on the defining crush height ratios.

Absorptiometry, Photon↗
PubMed1998

The effectiveness of several current soft contact lens care systems against Aspergillus.

PURPOSE: Fungal contamination of contact lenses is a common occurrence. In this study, we tested the effectiveness of currently used soft contact lens care systems against Aspergillus fumigatus. METHODS: We prepared and added 100 microL inoculums of 1 x 10(6) colony forming units/mL to each test solution. We exposed fungi to disinfectant for 4, 6, and 8 hours or to cleaning solution for 1 minute. We then diluted and plated the samples. After 48 hours, we counted the number of colony forming units. RESULTS: We represented the cleaning agent results as a percentage of the number of colony forming units found in the control at the same exposure period: Quick CARE Starting Solution--0%, MiraFlow--12%, Opti-Free Daily Cleaner--41%, and PureEyes Cleaner/Rinse--82%. We calculated the percent control for 4, 6 and 8 hour exposures for each disinfecting solution: Opti-One--197%, 163%, and 109%; Quick-CARE Finishing Solution--84.6%, 55%, and 31%; ReNu--97.4%, 17%, and 4%; Complete--10%, 1%, and 0.4%; PureEyes Disinfectant/Soaking Solution--0%, 0%, and 0%; and Hydrocare--0%, 0%, and 0%. CONCLUSION: This study of contact lens care systems provides a direct comparison of their effectiveness against the same strain of Aspergillus. The results allow practitioners to select the appropriate care system for each patient.

Aspergillus fumigatus↗
PubMed1997

A phantom for evaluating bone mineral density of the hand by dual-energy x-ray absorptiometry.

Dual-energy x-ray absorptiometry (DXA) is a precise, widely used method for measuring bone mineral density (BMD), usually of the lumbar spine and femoral neck. Recent developments, such as a lower x-ray tube current and pixel by pixel analysis, enable smaller bones and thinner tissues volumes, as in the hand, to be measured. Measurements of hand bone mineral content (BMC) and BMD could be useful in assessing disease severity in early rheumatoid arthritis and in monitoring disease progression and response to therapeutic intervention. A phantom is required for evaluating the software, measuring long-term precision and comparing with other DXA methods. This note describes the design and evaluation of a hand phantom for use on a Lunar DPX-L dual-energy x-ray absorptiometer. The phantom consists of three sections representing the metacarpals, and proximal and distal phalanges, using aluminum and Perspex as the bone and lean tissue equivalents respectively. The BMD of the three sections is approximately 1.0, 0.6 and 0.3 g cm-2. The phantom demonstrates limitations in the potential accuracy of BMD determination at low densities using the Small Animal Software on the Lunar DPX-L. Improved recognition of low-density regions was obtained with the Lunar EXPERT with precision values of 0.9, 1.1 and 2.0% for the three sections of the phantom respectively.

Absorptiometry, Photon↗
PubMed1997

The effects of disposable daily wear contact lenses on goblet cell count.

PURPOSE: The number of goblet cells on the inferior bulbar conjunctiva increases in response to daily wear contact lens use. We conducted a study to examine whether daily wear soft contact lenses worn on a 2-week disposable schedule would also induce the same goblet cell response. METHODS: Twenty-eight subjects who had never worn contact lenses were fit with 38% water polymacon lenses. The lenses were worn on a daily wear basis and replaced every two weeks over a 6-month period. Goblet cell count was determined by impression cytology of the inferior bulbar conjunctiva. RESULTS: No significant increase in goblet cell count was observed in the subjects during the 6 months period; the 3.23% baseline goblet cell count was never exceeded. In our previous study, after 6 months of conventional daily wear lens use, the goblet cell count increased from a baseline of 4.19% to 8.0%. CONCLUSIONS: It appears that wearing daily wear soft contact lenses on a disposable basis may be less irritating to the ocular surface than wearing soft contact lenses on a conventional daily wear basis.

Adolescent↗
PubMed1995

Coeliac disease and bone mineral density in adult female patients.

A cross sectional study was undertaken to examine the relationship between coeliac disease and bone mineral density. The 135 female coeliac patients registered on the database of the Department of Gastroenterology at Hull Royal Infirmary were approached by letter, advising them of a potential risk of osteoporosis and inviting them to undergo bone densitometry. A total of 81 registered women (60%) attended the Osteoporosis Laboratory, Princess Royal Hospital and underwent dual energy x ray absorptiometry at the lumbar spine (L2-L4) and femoral neck. Historical data relating to the time of diagnosis and adherence to a gluten free diet were obtained. A control group was selected from the local normal population and was first matched for height, weight, and menopausal status. Postmenopausal patients were then further matched to controls of equivalent menopausal age. In coeliac patients, bone mineral density expressed in g/cm2 as mean (SD) was significantly lower at the lumbar spine (1.076 (0.186)) than in the control group (1.155 (0.143), p < 0.001). This was also the case at the femoral neck (0.887 (0.142) versus 0.965 (0.127), p < 0.001). When the coeliac patients were stratified by menopausal status, it was found that femoral neck bone mineral density was significantly below control values in both premenopausal and postmenopausal women. Spinal bone mineral density exhibited a significant decrement only in the postmenopausal group. The age at diagnosis of coeliac disease and adherence to a gluten free diet did not influence bone mineral density at either hip or spine. These results confirm coeliac patients' higher risk of osteopenia. Coeliac disease should be added to the list of medical conditions which constitute an indication for bone densitometry in order that the individual risk of osteoporosis related fracture may be determined.

Adult↗