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PubMed2005

Comparison of 18F-FDG and 68Ga PET imaging in the assessment of experimental osteomyelitis due to Staphylococcus aureus.

PURPOSE: Although positron emission tomography (PET) using 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) is a promising imaging modality for bone infections, the technique may still give false-positive results due to unspecific uptake in healing bone. This experimental study compared 18F-FDG and 68Ga in PET imaging of osteomyelitis and normal bone healing. METHODS: A diffuse osteomyelitis model of the tibia was applied in the rat (n=50). Two weeks after operation, PET imaging with 18F-FDG and 68Ga was performed, followed by peripheral quantitative computed tomography (pQCT) and radiography. Osteomyelitis was verified by quantitative bacteriology. In addition to in vivo imaging, ex vivo measurements of tissue radioactivity were performed to verify uptake of the tracers. RESULTS: Compared with controls with normal bone healing, the osteomyelitic tibias showed increased SUV ratios (i.e. radioactivity ratios between the operated and non-operated sides) for both 18F-FDG (1.74+/-0.37) and 68Ga (1.62+/-0.28) (P<0.001). Ex vivo measurements also showed increased tracer accumulation in the infected bone (P=0.003 for 18F-FDG and P<0.001 for 68Ga). The intensity of 68Ga uptake reflected pathological changes of osteomyelitic bones measured by pQCT. The uptake of 18F-FDG, however, did not show as close a correlation with the anatomical changes. The healing bones without infection exhibited slightly elevated uptake of 18F-FDG (SUV ratio 1.16+/-0.06), but 68Ga did not accumulate in the healing bone, as judged on the basis of both in vivo imaging (SUV ratio 1.02+/-0.05) and ex vivo measurements (SUV 0.92+/-0.21) (P=0.003 and P=0.022 compared with 18F-FDG uptake, respectively). CONCLUSION: This study suggests the feasibility of 68Ga PET imaging of bone infections. However, further studies are needed to clarify the value of 68Ga PET for clinical purposes.

Animals↗
PubMed2006

Effect of a V-ATPase inhibitor, FR202126, in syngeneic mouse model of experimental bone metastasis.

PURPOSE: It has been demonstrated that vacuolar ATPase (V-ATPase) is involved in various aspects of bone metastasis. The aim of this study is to investigate the effect of the anti-bone resorptive activity of the V-ATPase inhibitor FR202126 on bone metastases in mice with metastatic breast cancer. METHOD: As a spontaneous model of breast cancer metastasis to bone, mouse breast cancer cells, 4T1, were injected into the mammary fat pad in immunocompetent syngeneic mice. The mice were orally treated with FR202126 for 29 days. Tumor volume was measured once a week. Thirty days after the injection of the cells, the bone mineral density (BMD) of the proximal tibia was measured using peripheral quantitative computed tomography. Histomorphometric analysis of the distal femurs and the proximal tibiae was performed. To elucidate the mechanism behind the anti-osteolytic effect of FR202126, 4T1 cells were treated directly in vitro with FR202126. Cell viability was measured, and cell invasion was assessed using matrigel. RESULTS: Oral administration of FR202126 significantly increased BMD by reducing the eroded bone surface ratio. While FR202126 is known to potently inhibit osteoclast mediated bone resorption, it did not prevent invasion by cancer cells or their proliferation. CONCLUSION: The V-ATPase inhibitor FR202126 was found to be effective at ameliorating osteolysis induced by metastatic breast cancer, even when the cancer cells themselves are not significantly affected by it. These results suggest that the anti-bone resorptive effect of the V-ATPase inhibitor might be useful for treating bone metastases associated with breast cancer.

Aminoquinolines↗
PubMed2000

Age-related changes assessed by peripheral QCT in healthy Italian women.

The purpose of this study was to describe the normal cross-sectional pattern of radial bone loss associated with aging in healthy women and to generate a normative database using peripheral quantitative computed tomography (pQCT). Subjects with suspected conditions affecting bone metabolism or receiving any drugs affecting bone mineralization were excluded. The trabecular bone mineral density (BMD) and the total bone density of the ultradistal radius at the nondominant forearm was measured using the Norland-Stratec XCT-960 pQCT scanner in 386 healthy pre-, peri-, and postmenopausal females aged 15-81 years. The long-term in vivo precision error was 1.6 % CV (coefficient of variation) for trabecular and 0.8% CV for total BMD measurements. The highest value of trabecular and total BMD measured was observed at the age group 15-39 years. Beyond these ages both trabecular and total BMD showed a linear decline with aging, decreasing by an overall slope of -1.28 and -0.55 mg/cm3 per year for total and trabecular BMD measurements, respectively. The test of parallelism between the regression slopes of the peri- and postmenopausal women showed a statistically significant difference for total BMD measurement (p = 0.003). Measurement of total and trabecular BMD was not influenced by weight, height or body mass index, but it was correlated with natural logarithm of years since menopause. We conclude that pQCT of the ultradistal radius is a precise method for measuring the true volumetric BMD and for detecting age-related bone loss in the trabecular and total bone of female subjects encompassing the adult age range and menopausal status.

Adolescent↗
PubMed2006

New ENU-induced semidominant mutation, Ali18, causes inflammatory arthritis, dermatitis, and osteoporosis in the mouse.

Inflammation is a complex cellular and humoral response against trauma and infection, and its presence leads to destruction of tissue in humans. The mechanisms that initiate inflammatory diseases remain largely unknown because of complex interactions between multiple genetic and environmental factors during pathogenesis. Animal models for human diseases offer dissection of complex pathogenesis by inbred genetic backgrounds and controlled circumstances. In this article we report a chemically induced new mutation, Ali18 (Abnormal limb), as a mouse model for inflammatory arthritis and dermatitis. Ali18/+ mice exhibit rubor and swelling of footpads in hindlimbs in adults. In Ali18/Ali18 mice, the digits in forelimbs and hindlimbs and tails were necrotic and/or deformed by severe swelling. Histologic analysis revealed infiltration of mixed populations of inflammatory cells into bone marrow, peripheral joints, and skin in the affected areas of Ali18/Ali18 mice. In addition, generalized osteoporosis-like phenotypes were confirmed by dual energy X-ray absorptiometry (DXA), microcomputed tomography (muCT), and peripheral quantitative computed tomography (pQCT) in homozygous animals. Whereas the Ali18 mutation was mapped to a single locus, the phenotype presentation was altered by complex modifier effects from other inbred genetic backgrounds. Detailed analysis of the Ali18 phenotype and identification of the mutation and its modifier genes may provide molecular insights into the complex nature of inflammatory diseases and the relationship between inflammation and bone metabolism.

Absorptiometry, Photon↗
PubMed1999

Quantitative trait loci for bone density in C57BL/6J and CAST/EiJ inbred mice.

Genetic analyses for loci regulating bone mineral density have been conducted in a cohort of F(2) mice derived from intercross matings of (C57BL/6J x CAST/EiJ)F(1) parents. Femurs were isolated from 714 4-month-old females when peak adult bone density had been achieved. Bone mineral density (BMD) data were obtained by peripheral quantitative computed tomography (pQCT), and genotype data were obtained by Polymerase Chain Reaction (PCR) assays for polymorphic markers carried in genomic DNA of each mouse. Genome-wide scans for co-segregation of genetic marker data with high or low BMD revealed loci on eight different chromosomes, four of which (Chrs 1, 5, 13, and 15) achieved conservative statistical criteria for suggestive, significant, or highly significant linkage with BMD. These four quantitative trait loci (QTLs) were confirmed by a linear regression model developed to describe the main effects; none of the loci exhibited significant interaction effects by ANOVA. The four QTLs have been named Bmd1 (Chr 1), Bmd2 (Chr 5), Bmd3 (Chr 13), and Bmd4 (Chr 15). Additive effects were observed for Bmd1, recessive for Bmd3, and dominant effects for Bmd2 and Bmd4. The current large size of the QTL regions (6-->31 cM) renders premature any discussion of candidate genes at this time. Fine mapping of these QTLs is in progress to refine their genetic positions and to evaluate human homologies.

Age Factors↗
PubMed2004

[Clinical trial for differentiation between corticoid-induced osteoporosis and periarticular demineralization via digital radiogrammetry in patients suffering from rheumatoid arthritis].

PURPOSE: To investigate a new bone densitometric technology based on digital radiogrammetry (DXR) with respect to its ability to measure severity-dependent variations of bone mineral density (BMD) in patients with rheumatoid arthritis and to differentiate between corticoid-induced and periarticular bone mineral density loss. PATIENTS AND METHODS: A total of 153 randomly selected patients suffering from verified rheumatoid arthritis underwent digitally performed plain radiographs of the non-dominant hand and also measurements of dual-energy X-ray absorptiometry (DXA) regarding total femur and lumbar spine in 102 patients and peripheral quantitative computed tomography (pQCT) regarding the distal radius in 51 patients. Using DXR the radiographs of the non-dominant hand were analyzed for cortical bone mineral density calculation. The severity was classified in the DXA group using the Ratingen score. Furthermore, both study populations were divided into patients with and without corticoid therapy. RESULTS: Correlations between BMD determined by DXR and by DXA (R=0.44 for lumbar spine and R=0.61 for total femur) versus pQCT (0.46<R<0.59) were all significant. An appropriate association was confirmed between pQCT and DXA (R=0.61 for total femur and 0.73 for LWS). In the subgroup of patients with corticoid therapy (mean dose: 5 mg/d for a period of more than 6 month), our data showed-similar to the collective of all patients-significant correlations (0.34<R<0.59) between DXR and the other methods. In contrast to pQCT (0.37<R<0.59) the study revealed a poor association between DXR- and DXA-parameters in the subgroup of patients without corticoid therapy; only the correlation between DXA-BMD of total femur and DXR-BMD achieved a significant level (R=0.38, p<0.05). The mean value of BMD measured by DXR decreased severity dependently from 0.59 g/cm(2) (Stage 1) to 0.46 g/cm(2) (Stage 5). Similar results were verified for the metacarpal index (DXR). The relative decrease of BMD between the highest and lowest score was 21% (p<0.05). Otherwise the reduction of bone mineral density using DXA revealed no significant results. CONCLUSION: The DXR-based BMD calculation can distinguish severity and progress of disease-related periarticular demineralization in contrast to those of DXA. In this context, DXA primarily measures the systemic (corticoid-induced) osteoporosis and pQCT partially estimates disease-related bone mineral density loss, whereas DXR can predominantly analyze and quantify the periarticular demineralization, which often shows a manifestation at an early stage of rheumatoid arthritis. Therefore DXR seems to be a diagnostic tool in the course of rheumatoid arthritis.

Absorptiometry, Photon↗
PubMed2003

Muscle activity during computer-based office work in relation to self-reported job demands and gender.

The aim was to investigate whether quantitative job demands influence muscle activity among women, and whether there are gender differences in duration of computer, mouse, and keyboard use and muscle activity of shoulder and forearm muscles during work. The study was carried out in an occupational setting, and 24 women and 11 men from a municipal administration participated. The duration of computer, mouse, and keyboard use was measured by a commercial software package. Quantitative job demands were registered by questionnaire. Electromyography (EMG) was measured bilaterally from the upper trapezius and the extensor digitorum communis muscles. No association was found between self-reported quantitative job demands and muscle activity among the women ( n=24). The women used the keyboard more frequently ( p=0.020) and tended to perform fewer mouse clicks compared to men ( p=0.057), but no difference was seen in EMG activity between men ( n=11) and women ( n=11) from the same department. However, office assistants (six women) showed significantly higher static EMG activity levels ( p=0.042) and almost significantly shorter EMG gap times ( p=0.060) than the rest of the subjects (5 women and 11 men). This indicated that shorter muscular resting periods among female office assistants as compared to the other subjects were due to differences in job content rather than gender differences.

Activities of Daily Living↗
PubMed2005

Effects of time pressure and precision demands during computer mouse work on muscle oxygenation and position sense.

The present study investigated the effects of time pressure and precision demands during computer mouse work on muscle oxygenation and position sense in the upper extremity. Twenty-four healthy subjects (12 males and 12 females) performed a 45-min standardized mouse-operated computer task on two occasions. The task consisted of painting rectangles that were presented on the screen. On one occasion, time pressure and precision demands were imposed (more demanding task, MDT), whereas, on the other occasion, no such restraints were added (less demanding task, LDT). The order of the two task versions was randomized. Tissue oxygen saturation in the trapezius and extensor carpi radialis muscles was recorded throughout, and the position-matching ability of the wrist was measured before and after the tasks. In addition, measurements of autonomic nervous system reactivity and subjective ratings of tenseness and physical fatigue were obtained. Performance was measured in terms of the number of rectangles that were painted during the task. During MDT, oxygen saturation in extensor carpi radialis decreased (P < 0.05) compared to LDT. These data were paralleled by increased electrodermal activity (P < 0.05), skin blood flow (P < 0.05), ratings of tenseness and fatigue (P < 0.01), and increased performance (P < 0.01) during MDT. Females exhibited lower oxygen saturation than males, during rest as well as during the computer tasks (P < 0.01). Wrist repositioning error increased following LDT as compared to MDT (P < 0.05). In conclusion, computer mouse work under time pressure and precision demands caused a decrease in forearm muscle oxygenation, but did not affect wrist position sense accuracy. We attribute our changes in oxygenation more to increased oxygen consumption as a result of enhanced performance, than to vasoconstriction.

Adult↗
PubMed2005

A comparison of muscular activity during single and double mouse clicks.

Work-related musculoskeletal disorders (WMSDs) in the neck/shoulder region and the upper extremities are a common problem among computer workers. Occurrences of motor unit (MU) double discharges with very short inter-firing intervals (doublets) have been hypothesised as a potential additional risk for overuse of already exhausted fibres during long-term stereotyped activity. Doublets are reported to be present during double-click mouse work tasks. A few comparative studies have been carried out on overall muscle activities for short-term tasks with single types of actions, but none on occurrences of doublets during double versus single clicks. The main purpose of this study was to compare muscle activity levels of single and double mouse clicks during a long-term combined mouse/keyboard work task. Four muscles were studied: left and right upper trapezius, right extensor digitorum communis (EDC) and right flexor carpi ulnaris. Additionally, MU activity was analysed through intramuscular electromyography in the EDC muscle for a selection of subjects. The results indicate that double clicking produces neither higher median or 90th percentile levels in the trapezius and EDC muscles, nor a higher disposition for MU doublets, than does single clicking. Especially for the 90th percentile levels, the indications are rather the opposite (in the EDC significantly higher during single clicks in 8 of 11 subjects, P < 0.05). Although it cannot be concluded from the present study that double clicks are harmless, there were no signs that double clicks during computer work generally constitute a larger risk factor for WMSDs than do single clicks.

Action Potentials↗
PubMed2006

Oxygenation, EMG and position sense during computer mouse work. Impact of active versus passive pauses.

We investigated the effects of active versus passive pauses implemented during computer mouse work on muscle oxygenation and EMG of the forearm extensor carpi radialis muscle, and on wrist position sense. Fifteen healthy female subjects (age: 19-24 years) performed a 60-min mouse-operated computer task, divided into three 20 min periods, on two occasions separated by 3-6 days. On one occasion a passive pause (subjects resting) was implemented at the end of each 20-min period, and on another occasion an active pause (subjects performed a number of high intensity extensions of the forearm) was implemented. Also at the end of each 20-min period, test contractions were conducted and subjective ratings of fatigue and stress were obtained. Another parameter of interest was total haemoglobin calculated as the summation of oxy-and deoxy-haemoglobin, since it reflects blood volume changes. The most interesting findings were an overall increasing trend in total haemoglobin throughout the mouse work (P<0.001), and that this trend was greater for the active pause as compared to the passive pause (P<0.01). These data were accompanied by an overall increase in oxygen saturation (P<0.001), with a tendency, albeit not significant, toward a higher increase for the active pause (P=0.13). EMG amplitude and median frequency tended to decrease (P=0.08 and 0.05, respectively) during the mouse work but was not different between pause types. Borg ratings of forearm fatigue showed an overall increase during the activity (P<0.001), but the perceptions of stress did not change. Position sense did not change due to the mouse work for either pause type. While increasing trends were found for both pause types, the present study lends support to the hypothesis of an enhancement in oxygenation and blood volume for computer mouse work implemented with active pauses. However, a presumption of an association between this enhancement and attenuated fatigue during the mouse work was not supported.

Adult↗
PubMed2000

Experimental muscle pain modulates muscle activity and work performance differently during high and low precision use of a computer mouse.

The aim was to investigate the influence of experimental muscle pain on performance and upper extremity muscle activity during occupational work requiring different levels of precision. Experimental muscle pain was induced by infusing hypertonic saline (0.3 ml, 5% NaCl) into the extensor carpi ulnaris (ECU) muscle. The same amount of isotonic saline was infused on a separate day to act as a control. Tasks requiring use of a computer mouse with high and low levels of precision were performed during the two sessions. Electromyographic (EMG) activity was measured from the ECU, the flexor carpi radialis (FCR) and the trapezius muscles. A group of 13 men participated in the study. Performance measured as work cycle time, cursor movements on the screen, and velocity of cursor movement were unaffected by muscle pain. The ECU muscle pain did not modulate EMG profiles of either the trapezius or FCR muscles either during high or during low precision work. During the low precision work the painful ECU muscle showed lower EMG activity in specific phases of the work cycle (highest activity phases) compared to the control session (P<0.05), whereas during the high precision work, experimental pain had no effect on the activity of the ECU muscle. In conclusion experimental muscle pain seems to modulate motor control differently depending on the precision level of the task. This may be of importance for our understanding of why some tasks lead to chronic musculoskeletal disorders.

Adult↗
PubMed2002

Insulin-like growth factor-binding protein-2 (IGFBP-2) overexpression negatively regulates bone size and mass, but not density, in the absence and presence of growth hormone/IGF-I excess in transgenic mice.

Insulin-like growth factor-binding protein-2 (IGFBP-2) has been suggested to be a negative regulator of bone growth and maintenance. The objective of this study was to characterize the effect of elevated IGFBP-2 on the skeletal phenotype of adult transgenic mice, in the absence and presence of growth hormone (GH) excess. 43 male mice were examined at an age of 4 months (7 IGFBP-2 transgenic mice, 12 GH transgenic mice, 10 mice carrying both transgenes, and 14 controls). The bone mineral content of the total skeleton and of isolated bones was quantified by dual energy X-ray absorptiometry (DXA), after validation versus ash analysis. Cortical and trabecular bone was quantified by peripheral quantitative computed tomography (pQCT), after validation versus microCT. A strong linear relationship was found between DXA and ash weight, and between pQCT and micro CT ( r>0.95). Bone size and bone mineral content were significantly reduced in IGFBP-2 transgenic mice, the magnitude of the effect varying between skeletal sites and between bone compartments. Elevated IGFBP-2 negatively modulated the GH-stimulated increase in bone size and mineral content, and completely blocked GH-effects at cortical sites. Notably, bone density was not decreased in IGFBP-2 transgenic animals compared with controls. In conclusion, IGFBP-2 is identified as a potent negative regulator of normal and GH-stimulated bone growth in vivo. Interestingly, elevated IGFBP-2 levels did not lead to a decrease in bone density, suggesting that IGFBP-2 negatively affects bone size and mineral content, but not bone maintenance in adult mice.

Absorptiometry, Photon↗
PubMed2003

Bone density measurements in pediatric patients with renal osteodystrophy.

Peripheral quantitative computed tomography (pQCT) can selectively measure the densities of cortical and trabecular bone, but there is limited information about its use in patients with renal osteodystrophy. Thus pQCT (Norland XCT-2000, Stratec, Pforzheim, Germany) was performed at the ultradistal radius in 21 patients aged 16+/-3.6 (SD) years on continuous cycling peritoneal dialysis. Trabecular bone density (TBD) was higher in patients, 206+/-16 mg/cm(3), than in controls, 182.7+/-24.8 mg/cm(3) ( P<0.0001), whereas cortical bone density (CBD) was lower in patients, 946.5+/-147.5 mg/cm(3), than in controls, 1,153+/-25.4 mg/cm(3) ( P<0.001). TBD was inversely correlated with age ( r=-0.59, P=0.05), height ( r=-0.59, P<0.01), and weight ( r=-0.51, P<0.05). In contrast, CBD was positively correlated with age ( r=0.53, P<0.05), height ( r=0.56, P<0.05), and weight ( r=0.53, P<0.05). CBD was inversely related to serum alkaline phosphatase ( r=-0.71, P<0.001) and parathyroid hormone levels ( r=-0.50, P<0.05). In patients with adynamic bone, TBD was less, 192+/-9 mg/cm(3), than in those with high-turnover lesions, 215+/-13 mg/cm(3), P<0.001. CBD, however, was lower in patients with high-turnover lesions, 900+/-151 mg/cm(3), than in those with low turnover, 1,022+/-111 mg/cm(3), P<0.05. Compared with controls, in patients with high-turnover lesions, CBD was lower ( P<0.0001) and TBD higher ( P<0.0001). These findings suggest that pQCT may be an additional tool in the assessment of renal osteodystrophy.

Adolescent↗
PubMed2003

pQCT bone strength index may serve as a better predictor than bone mineral density for long bone breaking strength.

Bone mineral density (BMD) is commonly used to predict osteoporotic fracture risk without considering the geometry of the bone. However, geometric parameters are also important in determination of bone strength. An index including both material and geometric properties may be therefore more relevant in prediction of fracture risk. We studied the correlation between parameters measured by noninvasive peripheral quantitative computed tomography (pQCT) and bone bending strength of the diaphysis of 45 fresh goat humeri and 27 femora. Multislice pQCT was used for measuring volumetric diaphyseal cortical BMD, total BMD, diaphyseal and cortical cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI) and their derived bone strength indices (BSIs), including BSI(CSMI) (cortical BMD x CSMI) and BSI(CSA) (cortical BMD x cortical CSA). Conventional dual-energy absorptiometry (DXA) was also conducted to measure areal BMD of diaphysis for comparison. Ultimate fracture load was obtained via three-point bending test. Results showed that for femora, fracture load was correlated better with BSI(CSA) ( r = 0.697, P < 0.001) than cortical BMD ( r = 0.304, P > 0.05) and total BMD ( r = 0.387, P > 0.05) measured using pQCT and areal BMD ( r = 0.612, P < 0.001) measured using DXA. For humeri, fracture load was also correlated with BSI(CSA) ( r = 0.579, P < 0.001) but not with other pQCT parameters including cortical BMD and total BMD ( r = 0.282 and 0.305, respectively; P > 0.05, both). The best correlation was found with areal BMD measured by DXA ( r = 0.760, P < 0.001). In conclusion, pQCT noninvasive BSI(CSA) derived from cortical BMD (material) and its cortical CSA (bone geometry or distribution) may serve as an important noninvasive index for predicting long bone bending strength. The bending strength was also predicted by bone mass (areal BMD) measured by DXA, an integration of bone mineral and geometry. Further clinical studies are needed to validate the predictive value of BSI in long bone osteoporotic fracture.

Animals↗
PubMed2003

Effects of an isopropanolic extract of Cimicifuga racemosa on urinary crosslinks and other parameters of bone quality in an ovariectomized rat model of osteoporosis.

A potential bone-sparing effect of Rhizoma actaeae (= cimicifugae) racemosae (black cohosh) was evaluated in ovariectomized Sprague-Dawley rats. The rats were ovariectomized at 12 weeks of age (body weight, 219-226 g) and placed on a soy-free diet 6 days after surgery. Animals were randomly assigned the following groups: control (n = 10), soy-free diet only; RAL (n = 10), soy-free diet plus raloxifene 3 mg/kg intragastrically; and REM (n = 10), soy-free diet supplemented with an isopropanolic black cohosh extract (Remifemin) with a daily intake of 4500 micro g triterpeneglycosides. Urinary levels of pyridinoline (PYR) and deoxypyridinoline (DPY), specific markers for bone loss, were measured at baseline and at weekly intervals. At the end of the study, the animals were killed and bone loss was determined by volumetric bone mineral density (BMD) measurements and peripheral quantitative computed tomography (pQCT). Mechanical resistance to fracture was also determined. Results demonstrated that an isopropanolic extract of black cohosh significantly diminished the urinary content of PYR and DPY and the morphometric correlates of bone loss associated with ovariectomy in rats. Reversal of the effects of ovariectomy on bone loss began 2-5 weeks after the start of treatment and continued through at least 7 weeks. Results similar in quality and magnitude were obtained in the group treated with raloxifene, a known selective estrogen receptor modulator (SERM). Because extracts of black cohosh are already recognized as safe and effective in the treatment of certain gynecological disorders, a longer-term clinical trial of this herbal remedy for the treatment of osteoporosis is warranted.

2-Propanol↗
PubMed2003

Mandible bone loss in osteoporosis rats.

Change in the mandible during the development of osteoporosis has not been studied extensively. Thus, the present study was undertaken to clarify the target loci in the mandible during the development of experimental osteoporosis in aged female rats. Experimental osteoporosis was studied in 76 Wistar strain female rats, 35 weeks old, by means of ovariectomy and dietary calcium deficiency. The rats were divided into the following three groups: (1) group 1, unoperated basal control (Basal), maintained on a diet containing 1.0% calcium; (2) group 2, sham-operated (Sham), maintained on a diet containing 0.01% calcium; and (3) group 3, ovariecomized (OVX), maintained on a diet containing 0.01% calcium. Fifteen rats of each group, except the basal rats (10 and 6 rats), were killed at 3 and 6 months following ovariectomy, respectively. The mandible was extracted, cleaned, and then subjected to bone mineral content (BMC) and bone mineral density (BMD) analyses using a peripheral quantitative computed tomography (pQCT) bone scanner. Each mandible was scanned from the mesial margin of the first molar to distal margin of the second molar. The results showed that dietary calcium deficiency and ovariectomy caused significant decreases of trabecular and cortical BMCs and BMDs in Sham and OVX rats compared with Basal rats. Decreases due to dietary calcium deficiency were greater than those caused by ovariectomy. However, significant age-related changes were not observed in BMC and BMD in Sham and OVX rats for 3-6 months. In addition, the cortical and trabecular BMCs and BMDs obtained were found to relate to location in the mandible for each group.

Animals↗
PubMed2004

Bone densitometry: which skeletal sites are best predicted by bone mass determinants?

Evaluation of bone mineral content/bone mass density (BMC/BMD) is important to determine bone mass development among adolescents in health and disease. It is uncertain at which skeletal site BMC/BMD is best predicted by bone mass determinants. On the other hand, intrapersonal BMC/BMD data can be clustered into a composite index score to facilitate correlation and outcome prediction analysis. This study aimed to identify the skeletal site that was best predicted by bone mass determinants and to develop a composite index score based on multisite BMC/BMD values in healthy adolescent girls. Eleven BMD/BMC variables per subject were evaluated by using dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) in 236 healthy girls aged 12-15 years. Bone mass determinants, namely, weight, height, puberty, dietary calcium, physical activity, and bone turnover markers, were determined. Factor analysis was used to develop composite index scores that summarized characteristics of multisite BMC/BMD. Results showed that lumbar spinal BMD and BMC (by DXA) and tibial integral BMD (by pQCT) were the BMC/BMD sites better predicted by bone mass determinants (R2, 0.57-0.77) in multiple regression analysis. On the other hand, three composite index scores representing areal BMD, areal BMC, and vBMD were derived to summarize the original BMC/BMD values. The composite index scores had similar predicting power (R2, 0.419-0.749) compared to those of original BMC/BMD, indicating that the composite index scores were representative of the original variables. To conclude, lumbar spinal BMD and BMC and tibial integral BMD were the three BMC/BMD variables better predicted by bone mass determinants. This evaluation would help select appropriate skeletal sites as outcome measures for bone mass evaluation in future studies. Also, the development of composite index scores could help reduce the number of variables for correlation and outcome prediction analyses.

Absorptiometry, Photon↗
PubMed2004

Correlations of calcaneal QUS with pQCT measurements at distal tibia and non-weight-bearing distal radius.

Quantitative ultrasound (QUS) is used for prediction for risks of osteoporotic fractures at various skeletal sites, irrespective of weight-bearing or non-weight-bearing skeletons. In the current study, we investigated the correlation between calcaneal QUS measurements (BUA, VOS, and Soundness) and volumetric trabecular, cortical, and its integral bone mineral density (tBMD, cBMD, and iBMD) using peripheral quantitative computed tomography (pQCT) of the weight-bearing distal tibia and non-weight-bearing distal radius in 198 healthy Chinese women between 40 and 62 years of age. Results showed that BUA, VOS, and Soundness measured by calcaneal QUS were significantly correlated with tBMD, cBMD, and iBMD of both distal tibia and distal radius (r = 0.210-0.447; all P < 0.01). The correlation coefficients of all the individual parameters between calcaneus and distal tibia were correspondingly higher (r = 0.214-0.447; all P < 0.01) than that of distal radius (r = 0.210-0.368; all P < 0.01). QUS Soundness showed the highest correlation (r = 0.447; P < 0.01) with tBMD of distal tibia when comparing with all other parameters between these two measurement devices. Stronger "within-device" correlations (r = 0.640-0.764; all P < 0.01) were found in pQCT measurements between distal tibia and radius. In addition, the largest and significant age-related decline was found in tBMD of the distal radius measured by pQCT and Soundness of the QUS measurement in the postmenopausal group. In conclusion, heel QUS measurement demonstrated slightly better correlation with trabecular bone of the weight-bearing skeleton than that of the non-weight-bearing skeleton measured by pQCT.

Adult↗