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PubMedDate not supplied

Comparison of bone remodeling indicators in climacteric women.

OBJECTIVE: The objective was to study the polymorphism of collagen type 1 alpha 1 (COL1 A1) gene as a genetic marker, the biochemical markers of formation (osteocalcin) and bone reabsorption (cross-links of pyridinoline-CTx), bone mineral density and bone ultrasonometry compared to bone densitometry (DEXA). METHOD: The study included 82 women ranging in age from 45 to 60 years, menopausal from 1 to 10 years. Polymorphism of COL1 A1 was assessed by PCR (polymerase chain reaction), by the specific allele technique. Bone formation markers were studied using an ELISA (Novocalcin and Active Crosslaps). A Hologic 4500 A QDR (DEXA) densitometer and DBM Sonic 1200 IGEA ultrasonograph were employed. RESULTS: The bone reabsorption marker (cross-links of pyridinoline-CTx) demonstrated statistically significant negative correlation with bone mineral density (lumbar and femoral neck), while the bone formation marker (osteocalcin) did not display a correlation with bone mineral density. Bone ultrasonometry yielded a statistically significant positive correlation with bone densitometry. Collagen type 1 alpha 1 polymorphism was not identified by the technique employed. CONCLUSION: The bone reabsorption marker (cross-links of pyridinoline) and bone ultrasonometry and densitometry are measurements enabling evaluation of bone remodeling.

Amino Acids↗
PubMed2002

Validity of deuterium oxide dilution for the measurement of body fat among Singaporeans.

Body fat percent (BF%) was measured in 108 adult Chinese, 76 Malays, and 107 Indians in Singapore by densitometry, deuterium oxide dilution (hydrometry), dual energy x-ray absorptiometry (DXA) and a chemical four-compartment model (BF%4c). The hydration of the fat-free mass (FFM) was calculated. Subjects ranged in age from 18 to 69 years and their body mass index ranged from 16 to 40 kg/m2. BF%4c for the various subgroups were: Chinese females (33.5 +/- 7.5%), Chinese males (24.4 +/- 6.1%), Malay females (37.8 +/- 6.3%), Malay males (26.0 +/- 7.6%), Indian females (38.2 +/- 7.0%) and Indian males (28.1 +/- 5.5%). Biases were found between BF%4c and BF% measured by 2-compartment models (hydrometry, densitometry, DXA), with systematic underestimation by DXA and densitometry. On a group level hydrometry had the lowest bias while DXA gave the highest bias. When validated against BF%4c, 2-compartment models were found to be unsuitable for accurate measures of body fat due to high biases at the individual level and the violation of assumptions of constant hydration of FFM and density FFM among the ethnic groups. On a group level the best 2-compartment model for measuring body fat was found to be hydrometry.

Absorptiometry, Photon↗
PubMed2003

[Intravenous contrast imaging in diagnosis of acute renal allograft rejection: a comparative study with color flow Doppler imaging].

OBJECTIVE: To assess the value of intermittent contrast second harmonic imaging (SHI) incorporating acoustic densitometry in the diagnosis of acute renal allograft rejection in comparison with color Doppler flow imaging (CDFI) for determining the resistance index (RI). METHODS: Eight canine models of acute renal allograft rejection were established, subjected subsequently to examinations with SHI and acoustic densitometry to determine the acoustic density. Color flow Doppler was also performed to determine RI, and serum creatinine (Cr) levels were measured. RESULTS: The time-intensity curve (TIC) showed that the area under the curve, the peak intensity (PI) and RI all had linear correlation with serum Cr levels, with the correlation coefficient gamma of 0.978, 0.972 and 0.708 respectively (by SPSS10.0). CONCLUSION: Intermittent contrast SHI is effective to evaluate the perfusion of renal allograft, and when combined with acoustic densitometry, the resultant TIC parameters are in closer correlation with acute renal allograft rejection than RI.

Acute Disease↗
PubMed2005

[Alterations of bone metabolism in patients with chronic C virus hepatitis].

Patients affected with chronic hepatitis are prone to alterations in bone metabolism, osteoporosis and osteopoenia being the most common manifestations. Bone mineral densitometry is the method of choice for assessing bone mass; nevertheless, this is a static parameter whereas biochemical markers of bone remodelling reveal the dynamics of bone resorption and formation. With this study we used bone mineral densitometry and biochemical markers to evaluate bone metabolism in a group of male patients with chronic C virus hepatitis and in a group of healthy males. In the hepatitis group 56% of the patients proved osteopoenic or osteoporotic and bone depletion increased as the histological score of the disease increased. Crosslaps are a parameter of osteoclastic activity: their measurement showed alterations in all the age groups of the hepatitis patients studied, which goes to show that there is intense bone remodelling in these individuals due mainly to osteoclastic resorption. Hepatitis C is a risk factor for bone depletion: we believe that when this type of hepatitis is diagnosed it is useful to assess bone metabolism with bone mineral densitometry and with the crosslaps assay.

Adult↗
PubMed1989

Anomaly in western blot band intensities perceived by visual inspection.

Quantitation of Western blots from polyacrylamide gels is commonly accomplished by either visual inspection or densitometry. However, due to absorption of protein and staining reagents by the blotting membrane it is possible that visual inspection and reflectance densitometry will given anomalous results. In this paper we show such an example, and discuss how transmission densitometry can provide more accurate results.

Blotting, Western↗
PubMed1995

Body composition measurement in elite heavyweight oarswomen: a comparison of five methods.

The study was designed to evaluate the range of body composition in elite heavyweight oarswomen as well as the level of agreement between various methods used to measure this variable. Percent body fat was determined at the start of the competitive season by densitometry, taken to represent the reference standard, and measurement of total body potassium, skinfold thicknesses, bioelectrical impedance analysis and body mass index. The athletes were studied within a two week period with all measurements in any individual taken during one morning. We demonstrated a surprisingly large range of percent fat between these oarswomen, 13.6 to 29.3% by densitometry, which was a feature common to all methods. Percent body fat by total body potassium was lower (p < 0.05) while from body mass index higher (p < 0.01) than the reference value from densitometry. Similar methodologies generated significantly different estimates of % fat (SFT1 versus SFT2, p < 0.01 and BIAv versus BIAB, p < 0.01) highlighting the potential problems that may arise with the use of different regression equations to convert primary measurements into % fat. The limits of agreement between various methods were wide and reflect the large variability about the estimated mean bias. Practically this negates the correction of "non reference" values by adding or subtracting the mean difference or bias between the techniques in individuals. These methodological problems need to be considered when setting specific body composition targets for an athlete.

Adipose Tissue↗
PubMed1994

[Bone involvement in endocrinopathies].

Progress in bone densitometry, particularly biphotonic absoptiometry, has made it possible to better identify the effects of endocrinopathies on bone. Both cortical and trabecular bone structures can be evaluated quantitatively and topographically revealing important information on the pathophysiology of bone loss. Sex hormones play a major role in the regulation of bone mineralization and hypogonadism, whatever the origin, can lead to deleterious effects. Bone loss is known to be significative in high performance female athletes with amenorrhoea; long-term consequences are not yet determined, but stress fractures have been reported in up to 50%. Other hypogonadisms leading to bone demineralization include anorexia nervosa, chronic intake of gonadotrophin releasing hormone analogues and anti-oestrogens, and hyperprolactinism. Hyperthyroidism leads to a negative calcium balance and demineralization with remodelling, predominantly in cortical bone. In hypothyroid states a 10% bone loss is observed in vertebrae. In both cases, bone densitometry should be performed in order to evaluate the effect of treatment. The deleterious effect of spontaneous or iatrogenic hypercortisism is well known, leading to spontaneous wedge fractures of the vertebrae due to predominating trabecular bone loss. The mechanism of action of corticosteroids on bone metabolism is complex, but the major effect is an inhibition of osteoblast maturation. Recovery may be possible, but no large long-term series have yet been reported. Hyperparathyroidism and acromegaly also affect bone mineralization. The information provided by bone densitometry is essential to properly manage patients with endocrinopathies affecting bone mineralization.

Acromegaly↗
PubMed1994

A justification for high resolution hematocrit measurement.

The purpose of this study was to determine the feasibility of using a 6" digital caliper and a 20x viewing microscope to measure hematocrit (HCT) from microhematocrit tubes. The reliability and validity of the digital caliper technique (DC) was simultaneously compared with that of the conventional "turntable" style microhematocrit method (MC) and the Coulter Counter hematocrit (CC) for a comprehensive comparison of the three methods. The reliability of the three methods was assessed by computing the standard error of the measurement (SEm) on triplicate readings of human blood samples. The SEm for MC, CC, and DC methods were 0.3555, 0.3004, and 0.1491, respectively. Validity was assessed by comparing the average of the triplicate HCT readings for each method with HCT determined by densitometry. Average HCT values (+/- SE) for the MC, CC, DC, and densitometry methods were 42.3 +/- 3.2, 42.4 +/- 3.4, 43.1 +/- 3.4, 43.7 +/- 3.3, respectively. Only the DC HCT values were not different from the densitometry HCT (P > 0.05). The MC and CC values were significantly lower (P < 0.01). It is concluded that accurate, highly precise measurements of HCT are obtainable using the digital caliper. The significance for this is the increased ability to perform extremely accurate measurement of changes in plasma volume. With this information, research labs can reliably measure smaller changes in plasma than was previously possible with commercial procedures.

Adolescent↗
PubMed1994

Measurement of height: practical considerations for the study of osteoporosis.

Osteoporotic vertebral fractures result in loss of height and so regular measurement of stature may be a useful method for detecting the onset of the disease and monitoring its progress. The aim of this study was to evaluate the reliability of height measurement in a clinical setting by estimating its precision and the effects of diurnal variation and supine bone densitometry. Duplicate measurements of standing height were made in 50 normal volunteers (25 female) in the morning and 7h later; similar measurements were made in 25 female patients before and after densitometry (spine, one hip and whole body). Portable Harpenden stadiometers were used. The pooled standard deviation (coefficient of variation) ranged from 0.9 mm (0.05%) to 1.7 mm (0.11%). Significant height decrease (> 6 mm) occurred in volunteers during the course of a day while patients showed a significant increase (> 5 mm) after lying supine for an average period of 49 min. Height can be estimated precisely if measurements are made consistently, i.e. using the same equipment and technique, at the same time of day and before bone densitometry. The provision of stadiometers in primary care surgeries and hospital clinics would provide a simple, inexpensive and non-invasive method of assessing the progress of spinal osteoporosis.

Absorptiometry, Photon↗
PubMed1991

Bone density measurements.

Early diagnosis of osteoporosis is difficult. Bone density measurements, however, are helpful in screening patients at risk. Technology now provides means of measuring densities of both peripheral and central bones. The most practical method is dual X-ray densitometry, which is of good sensitivity and accuracy. Single photon absorptiometry on peripheral bones can be used to screen populations at risk. Computed tomography is also useful but the radiation dose is relatively high. In dual X-ray densitometry, calibration methods and comparisons with reference values are fairly reliable. The best sites for measurements are the lumbar spine and proximal femur, in which osteoporotic fractures are common. In general, however, one measurement is not enough. Biological variation is great. Repeated measurements will allow estimation of the rate of bone loss. Precise location of a previous site is sometimes difficult on reexamination and extraskeletal calcifications can be sources of error. Bone densitometry in connection with the prevention and treatment of osteoporosis is fairly easily performed with a single patient. Knowledge about the correlation between bone density and fracture risk is not yet adequate. The results of measurement of bone mineral density relate only to mineral content, not bone quality, i.e., differential diagnosis of osteoporosis and osteomalacia is not possible.

Absorptiometry, Photon↗
PubMed2003

Identification of risk factors for future fracture in patients following distal forearm fracture.

The challenge for healthcare systems around the world is delivering timely preventative strategies to subjects most likely to develop fragility fractures. The success or failure of national campaigns will be determined at local level, and many studies to date have found under-utilization of osteoporosis treatment strategies due to reduced public and healthcare professional awareness. An important link between the at-risk patients and their appropriate therapy is their identification and assessment. In the context of a medium sized secondary care provider, this study examined the efficiency of a nurse-led service for assessing women following distal forearm fracture, looking for additional risk factors for future fracture and also looking at uptake of the assessment programme among the target population. Two hundred and two women, median (range) age 69 (50-91) years presented with distal forearm fracture over a 9-month period. Fifty-four subjects did not participate in the study: they were significantly older than those who did ( P<0.002). One hundred and forty-eight subjects underwent assessment of falls risk, future hip fracture risk and calcaneal ultrasound attenuation measurement: 107 attended for assessment at the hospital and 41 required a health professional to visit at their place of residence-the latter group were significantly older ( P<0.0002). Of 148 subjects assessed, 76 (51%) had one or more risk factors for a fall: these subjects were significantly older ( P<0.0002) and more likely to have required a home visit ( P<0.002). Twenty-seven (18%) were considered at risk of a future hip fracture: again they were older and more likely to have required a home visit ( P<0.0005). Ninety-one subjects (61%) had a calcaneal ultrasound attenuation T-score below -2.0, and were referred for bone densitometry: again, they were older ( P<0.0002) and more likely to have required a home visit ( P<0.05). Bone densitometry demonstrated osteoporosis in 47 (52%) of those with low attenuation, osteopenia in 31 and normal bone density in 13. Of 76 subjects deemed to be at risk of falls, 31 (41%) had osteoporosis demonstrated on bone densitometry and of those at risk of future hip fracture, 12 (44%) had osteoporosis. Only nine (22%) subjects who received home visits had no risk factors for falls or hip fracture and normal bone density, compared to 45 (42%) of those who attended hospital. This study has demonstrated that the efficiency of a program to assess additional risk of future fracture in a population who have already fractured may be influenced by where the assessment is delivered: it may be that the patients at greatest risk did not avail of the service.

Accidental Falls↗
PubMed2002

Mandibular radiomorphometric indices in the diagnosis of reduced skeletal bone mineral density.

Diagnosis of osteoporosis allows the delivery of preventive and therapeutic intervention and is usually achieved using bone densitometric techniques. One referral criterion for densitometry is osteopenia on radiographs. The aim of this study was to measure the validity of mandibular cortical indices measured on panoramic radiographs in the diagnosis of reduced skeletal bone density. Seventy-four women underwent bone densitometry of the femoral neck, lumbar spine and the forearm. Fifty-five patients (74%) were classified as having a reduced bone density (T-score < or = -1). Twenty-seven patients had a T-score of < -2.5 observed at one or more of the three measurement sites. A panoramic radiograph was taken of each patient and two observers made measurements of cortical thickness at the mental foramen (mental index, MI), antegonion (antegonial index, AI) and gonion (gonial index, GI) regions. Logistic regression and receiver operating characteristic (ROC) curve analyses were used to measure the validity of cortical indices in the diagnosis of reduced bone mineral density. Only MI contributed significantly to a diagnosis of low skeletal bone mineral density (T-score < or = -1). The 95% limits of agreement between observers in measurement of MI were 1.32 to +1.32 mm. When data for both observers were combined, the area under the ROC curve was 0.733 (SE = 0.072; 95% confidence interval = 0.618 to 0.83), indicating moderate accuracy. A diagnostic threshold for MI of 3 mm (or less) is suggested as the most appropriate threshold for referral for bone densitometry. However, the study provided only limited support for the use of panoramic radiomorphometric indices in diagnosing low skeletal bone mineral density. They might, questionably, be used as part of a method of osteoporosis risk assessment.

Absorptiometry, Photon↗
PubMed2001

Response of cortical bone to antiresorptive treatment.

A total of 113 postmenopausal women (69 controls, 33 using hormone replacement therapy (HRT), and 11 using bisphosphonate) were evaluated twice over 2 years with a new noninvasive, radiogrammetry-based technique called digital X-ray radiogrammetry (DXR) and conventional bone densitometry of the spine, hip, and forearm. Longitudinal changes in bone densitometry were compared with changes captured by DXR: BMD evaluated by DXR (BMDDXR), cortical thickness of the second metacarpal (CTMC2), and porosity of cortical bone. The expected annual postmenopausal reduction in BMD in the control group was detected by BMDspine (-0.8%, P < 0.01), BMDhip (-1.6%, P < 0.001), BMDforearm (-1.5%, P < 0.001), DXR-BMD (-0.8%, P < 0.001), and CTMC2 (-1.1%, P < 0.001). In the HRT group, smaller reductions were seen in BMDDXA, but only significant at the hip (-1.0%, P < 0.01) and distal forearm (-1.0%, P < 0.02). In the bisphosphonate group, cortical porosity was significantly reduced (P < 0.025). Comparing longitudinal changes in age-matched subsamples of controls and bisphosphonate treated, BMDDXR, CTMC2, and porosity of cortical bone all differed significantly (P < 0.01, P < 0.05, P < 0.05, respectively), whereas the BMDDXA measurements did not. In conclusion, DXR provides a densitometry equivalent measurement of the distal forearm and hand and seems to offer new information on the porosity of cortical bone. This may prove useful in the evaluation of bone loss and offer new insight into the effects of different antiresorptive treatment regimens used in the prevention of osteoporosis.

Absorptiometry, Photon↗
PubMed2004

Development and validation of the osteoporosis prescreening risk assessment (OPERA) tool to facilitate identification of women likely to have low bone density.

Osteoporosis and its consequent increase in fracture risk is a major health concern for postmenopausal women and older men and has the potential to reach epidemic proportions. The "gold standard" for osteoporosis diagnosis is bone densitometry. However, economic issues or availability of the technology may prevent the possibility of mass screening. The goal of this study was to develop and validate a clinical scoring index designed as a prescreening tool to help clinicians identify which women are at increased risk of osteoporosis [bone mineral density (BMD) T-score -2.5 or less] and should therefore undergo further testing with bone densitometry. Records were analyzed for 1522 postmenopausal females over 50 years of age who had undergone testing with dual-energy X-ray absorptiometry (DXA). Osteoporosis risk index scores were compared to bone density T-scores. Hologic QDR 4500 technology was used to measure BMD at the femoral neck and lumbar spine (L1-L4). Participants who had a previous diagnosis of osteoporosis or were taking bone-active medication were excluded. Receiver-operating characteristic (ROC) analysis was used to identify the specific cutpoint value that would identify women at increased risk of low BMD. A simple algorithm based on age, weight, history of previous low impact fracture, early menopause, and corticosteroid therapy was developed. Validation of this five-item osteoporosis prescreening risk assessment (OPERA) index showed that the tool, at the recommended threshold (or cutoff value) of two, had a sensitivity that ranged from 88.1 [95% confidence interval (CI) for the mean: 86.2-91.9%] at the femoral neck to 90% (95% CI for the mean: 86.1-93.1%) at the lumbar spine area. Corresponding specificity values were 60.6 (95% CI for the mean: 57.9-63.3%) and 64.2% (95% CI for the mean: 61.4-66.9%), respectively. The positive predictive value (PPV) ranged from 29 at the femoral neck to 39.2% at the lumbar spine, while the corresponding negative predictive values (NPVs) reached 96.5 and 96.2%, respectively. Based on this cutoff value, the area under the ROC curve was 0.866 (95% CI for the mean: 0.847-0.882) for the lumbar spine and 0.814 (95% CI for the mean: 0.793-0.833) for the femoral neck. We conclude that the OPERA is a free and effective method for identifying Italian postmenopausal women at increased risk of osteoporosis. Its use could facilitate the appropriate and more cost-effective use of bone densitometry in developing countries.

Absorptiometry, Photon↗
PubMed1989

Monitoring skeletal response to estrogen.

Estrogen replacement therapy at accepted doses is not fully effective in preventing bone loss and fractures in postmenopausal women. Bone densitometry is useful for monitoring estrogen replacement therapy to assess dose, foster compliance, and check for secondary bone loss. The most appropriate site for bone loss monitoring is probably the spine because it shows larger decreases at the menopause than appendicular sites, it shows larger increases with therapy, and it has clinical import in terms of fracture. Both dual-photon absorptiometry (or dual-energy x-ray absorptiometry) and computed tomography are the preferred monitoring methods. The precision of these densitometry methods is generally adequate to permit interim decisions with regard to continuing therapy, as well as conclusive decisions on therapeutic efficacy after 1 to 2 years of monitoring. Judicious use of densitometry in combination with biochemical determinations can enhance therapeutic control and provide both patient and physician confidence in long-term estrogen replacement therapy.

Absorptiometry, Photon↗
PubMed1996

Characterization of idiopathic premature ovarian failure.

OBJECTIVE: To characterize women with idiopathic premature ovarian failure (POF) by their ovarian ultrasonographic appearances to establish the prevalence of follicular activity and relationship to autoimmunity, estrogen status, and historical background. DESIGN: Retrospective analysis of clinical, endocrine, autoimmune, ultrasonographic, and bone densitometry parameters. SETTING: Reproductive Endrocrinology Clinics of The Middlesex Hospital, London, United Kingdom. PATIENTS: Data from 135 women with idiopathic POF were analyzed. A reference group of 18 women with normal ovarian function, studied in their follicular phase, was used for comparison of endocrine and ultrasound data. A reference group of 57 women with normal ovarian function was used for comparison of bone densitometry measurements. MAIN OUTCOME MEASURES: Serum E2 concentrations, autoantibody screen, ultrasonographic measures of ovarian volume, uterine cross-sectional area and endometrial thickness and dual roentgenogram bone mineral densitometry of the lumbar spine. RESULTS: The detection of ovaries by ultrasound (in 76%) and follicular activity (in 60% of patients) was associated with higher bone mineral density compared with women in whom ovaries could not be identified. Of 13 patients presenting with primary amenorrhea, ultrasonography identified ovaries in 62% and follicles in 38% whereas 38% had positive autoimmunity. Evidence of autoimmunity was found in 31% of patients overall and these were indistinguishable from the nonautoimmune remainder in every respect. CONCLUSIONS: Ovarian follicular activity, previously considered to be rare, as in the "resistant ovary syndrome," is found in the majority of women with POF using pelvic ultrasonography. Patients presenting with primary amenorrhea have a similar degree of ovarian function, determined by ultrasound, and autoimmunity as those presenting with secondary amenorrhea. The role of autoimmunity in the pathogenesis of POF is not distinguished from nonautoimmune ovarian damage by the measurements made in this study.

Adolescent↗
PubMed2000

Changes in cytoskeletal proteins in childhood cataract lenses

Purpose: Approximately 50% of congenital and childhood cataracts seen in the clinic is of undetermined origin. Biochemical analysis of the cataracts is rare. This study analyzes lens proteins to determine the mechanism of congenital and childhood cataracts. Method: We analyzed the lens proteins from 10 young patients after cataract operations, using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), densitometry analysis, and Western immunoblotting.Results: Densitometry of separated proteins showed a decrease in the high molecular protein bands of posterior subcapsular cataract (PSC). Specifically, spectrin (235 kDa), filensin (100 kDa), and vimentin (57 kDa) were absent from the SDS-PAGE of PSC. Increases in filensin and vimentin were observed in a Christmas tree cataract and lamellar cataracts. Western immunoblots confirmed the densitometry of SDS-PAGE.Conclusion: These results suggest that changes in cytoskeletal proteins may contribute to congenital and childhood cataracts.

Journal Article↗
PubMed1994

European semi-anthropomorphic phantom for the cross-calibration of peripheral bone densitometers: assessment of precision accuracy and stability.

A semi-anthropomorphic 'distal radius like' phantom, developed by Kalender and Ruegsegger for use in peripheral bone densitometry using single photon (DPA) dual X-ray (DXA) and quantitative computed tomography (QCT) machines, has been studied with a view to cross-calibrating different types and brands of densitometers in current use. In the context of an EU 'Concerted Action' (second Framework Programme) the phantom was repeatedly measured on six SPA machines, three DXA machines and nine QCT machines (545 measurements). Linear regression equations were derived, individual to each machine, which allowed the derivation of 'standardized densities'. In this way we converted measurements made by machines of the same modality to a common scale of measurements. Two machines (one DXA, one SPA) showed statistically significant instability over time emphasising the need for rigorous quality control in the application of densitometry. In other respects these results provide an encouraging basis for the derivation of standardized normative ranges and the more effective use of peripheral densitometry in future clinical and epidemiological studies.

Absorptiometry, Photon↗