Dual Energy X-ray Absorptometry Research Articles

Potential of electrical impedance spectroscopy to differentiate between healthy and osteopenic bone

Osteoporosis involves loss of structural stability of bone due to an increase in bone porosity. Dual energy X-ray absorptometry is used to evaluate bone in terms of quantity. However, it does not give an evaluation of the patient's bone quality. For this, present study has been carried out to assess the structural deterioration of bone using electrical impedance spectroscopy. MethodsElectrical Impedance Spectroscopy has been applied to evaluate the structural and compositional changes of cortical bone in the frequency range of 50 Hz to 5 MHz for the ovariectomized rat model. Initially, bone resorption in the ovariectomized group has been confirmed by estimating tartaric resistant acid phosphatase levels; morphometric parameters; bone matrix components, hydroxyapatite crystallite size and bone micro architecture. The mid diaphyseal regions from the femora and tibiae of sixty days post ovariectomy and control rats were used for the measurement of dielectric parameters. A dispersion model based analysis has been developed by a complex least square fitting of the dielectric data. FindingsIncreased tartaric resistant acid phosphatase levels, altered bone matrix components, hydroxyapatite crystallite size and disturbed microarchitecture in the ovariectomized group give us the confirmation of increased bone resorption following estrogen deficiency. These changes were shown to be reflected by single dispersion model based fitted parameters which shows the considerable change in all the parameters of ovariectomized group compared to the control. InterpretationIt has been demonstrated that the parameters of the dispersion model can reflect the bone structural and compositional changes.

Pioglitazone improves fat distribution, the adipokine profile and hepatic insulin sensitivity in non-diabetic end-stage renal disease subjects on maintenance dialysis: a randomized cross-over pilot study.

BackgroundFat redistribution, increased inflammation and insulin resistance are prevalent in non-diabetic subjects treated with maintenance dialysis. The aim of this study was to test whether pioglitazone, a powerful insulin sensitizer, alters body fat distribution and adipokine secretion in these subjects and whether it is associated with improved insulin sensitivity.Trial DesignThis was a double blind cross-over study with 16 weeks of pioglitazone 45 mg vs placebo involving 12 subjects.MethodsAt the end of each phase, body composition (anthropometric measurements, dual energy X-ray absorptometry (DEXA), abdominal CT), hepatic and muscle insulin sensitivity (2-step hyperinsulinemic euglycemic clamp with 2H2-glucose) were measured and fasting blood adipokines and cardiometabolic risk markers were monitored.ResultsFour months treatment with pioglitazone had no effect on total body weight or total fat but decreased the visceral/sub-cutaneous adipose tissue ratio by 16% and decreased the leptin/adiponectin (L/A) ratio from 3.63×10−3 to 0.76×10−3. This was associated with a 20% increase in hepatic insulin sensitivity without changes in muscle insulin sensitivity, a 12% increase in HDL cholesterol and a 50% decrease in CRP.Conclusions/LimitationsPioglitazone significantly changes the visceral-subcutaneous fat distribution and plasma L/A ratio in non diabetic subjects on maintenance dialysis. This was associated with improved hepatic insulin sensitivity and a reduction of cardio-metabolic risk markers. Whether these effects may improve the outcome of non diabetic end-stage renal disease subjects on maintenance dialysis still needs further evaluation.Trial RegistrationClinicalTrial.gov NCT01253928

Rapid determination of vertebral fat fraction over a large range of vertebral bodies

Vertebral body fat fraction (FF) has been found to vary between lumbar vertebrae using magnetic resonance spectroscopy (MRS). We aim to more quickly assess a larger number of adjacent vertebrae using a single T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) sequence. Five men had dual-energy X-ray absorptometry (DEXA) and 1.5-T MR scans performed. MRS was performed at L3, and a sagittal IDEAL sequence was also performed, resulting in separate fat-only and water-only readings from T10 to S2. For the IDEAL measurements, two independent observers followed a set reading protocol, with five observations each per vertebra. Intra- and interobserver variability were assessed as deviations from the mean within and between observers, respectively. For FF measurements there was limited intra-observer variation, with observers being on average within 3.4% of the pooled mean value. Similarly, there was good interobserver agreement, with an average variation of 2.1%. All men showed a reduction in FF of 1.6-7% between L5 and S1. Otherwise, there was a trend of increasing FF moving inferiorly from T10 to S2. This averaged 2.7% per vertebra (range 1.1-3.8%) and may not have been dependent on MRS-measured FF at the L3 level. There was poor correlation between MRS-measured FF at L2-4 and bone mineral density measured using DEXA (R(2) = 0.06). IDEAL measurements are generally reproducible between observers following a set protocol. There appears to be a gradient in FF moving from T10 to S2, with S1 showing a consistent decrease. This variation may better describe overall marrow function than a single-vertebra reading.

Anthropometric Variables Accurately Predict Dual Energy X-Ray Absorptiometric-Derived Body Composition and Can Be Used to Screen for Diabetes

The current world-wide epidemic of obesity has stimulated interest in developing simple screening methods to identify individuals with undiagnosed diabetes mellitus type 2 (DM2) or metabolic syndrome (MS). Prior work utilizing body composition obtained by sophisticated technology has shown that the ratio of abdominal fat to total fat is a good predictor for DM2 or MS. The goals of this study were to determine how well simple anthropometric variables predict the fat mass distribution as determined by dual energy x-ray absorptometry (DXA), and whether these are useful to screen for DM2 or MS within a population. To accomplish this, the body composition of 341 females spanning a wide range of body mass indices and with a 23% prevalence of DM2 and MS was determined using DXA. Stepwise linear regression models incorporating age, weight, height, waistline, and hipline predicted DXA body composition (i.e., fat mass, trunk fat, fat free mass, and total mass) with good accuracy. Using body composition as independent variables, nominal logistic regression was then performed to estimate the probability of DM2. The results show good discrimination with the receiver operating characteristic (ROC) having an area under the curve (AUC) of 0.78. The anthropometrically-derived body composition equations derived from the full DXA study group were then applied to a group of 1153 female patients selected from a general endocrinology practice. Similar to the smaller study group, the ROC from logistical regression using body composition had an AUC of 0.81 for the detection of DM2. These results are superior to screening based on questionnaires and compare favorably with published data derived from invasive testing, e.g., hemoglobin A1c. This anthropometric approach offers promise for the development of simple, inexpensive, non-invasive screening to identify individuals with metabolic dysfunction within large populations.

Potential role of FRAX analysis in postmenopausal women with osteopenia

AbstractEarly diagnosis of osteoporosis and estimation of subjects that are at high risk for fracture, is neccesary for osteoporosis treatment. Dual-energy X-ray absorptometry (DXA) is a modern method for bone mineral density (BMD) evaluation. However, along BMD, clinical risk factors may significantly influence fracture development. Therefore, FRAX algorithm was designed for the assessment of a ten-year risk for serious osteoporotic fractures (SOF), as well as hip fractures. In the current study, we tried to evaluate the possible lumbal spine and hip BMD influence on ten year risk for SOF and hip fractures and potential role of FRAX in predicting the therapy in postmenopausal women with osteopenia. We performed the study on 385 postmenopausal women. According to the DXA measurements, at the lumbal (L) spine (L1–L4) and hip (femor neck), patients were then classified as normal, osteopenic, or osteoporotic. BMD evaluation included the L spine and the hip (subgroup 1), and only on the L spine (subgroup 2). By filling up the FRAX questionnaire, a ten-year risk for SOF fracture and hip fracture was calculated. BMD evaluation, in complete patient’s group and in subgroup 1, resulted in the highest number of osteoporosis (61.04%, 48.08%, retrospectively), while ospeopenia was a main finding in subgroup 2. In the subgroup 1, a high risk for SOF and hip fracture was detected in 16.45% and with high risk for hip fracture in 11.38% subjects. In subgroup 2, only high risk for hip fracture was observed in 3.16% subjects, indicating the active medicament treatment. Simultaneously, correlation of BMD results with FRAX values for SOF and hip fracture, showed significant negative correlation (p<0.001). Obtained results showed significant role of femur neck BMD evaluation in predicting the future factors, which may, together with FRAX analysis, improve the therapy approach in postmenopausal women with ospeopenia.

Bone marrow stromal cell therapy improves femoral bone mineral density and mechanical strength in ovariectomized rats

This study aimed to determine the influence of bone marrow stromal cells (BMSC) on the degree and sustainability of ovariectomy-induced bone loss. Allogenic BMSC were injected into either the left or right femur of 15 ovariectomized rats (OVX). Saline was injected into the contralateral femur as a vehicle control. Five rats were killed at 8 weeks and 5 rats at 24 weeks. The other five OVX rats received serial injections 4 weeks after the first injection and were killed 24 weeks after the first injection. To confirm osteoporotic model, five rats received sham operation. Bone mineral density (BMD) was measured using dual-energy X-ray absorptometry. Mechanical properties were evaluated by three-point bending. The OVX rats showed significantly lower BMD compared with that of the sham operated rats. BMD at the femoral mid-shaft was significantly greater in the BMSC-injected bones compared with the control bones. At week 8, ultimate load and stiffness were also improved in the BMSC-injected bones compared with controls. At 24 weeks, the stiffness of control and BMSC-injected bones was statistically indistinguishable. The additional injection aided preservation of both BMD and mechanical properties. The present study suggests that bone strength may be improved by direct BMSC injection.

Prevention of Early Loss of Bone Mineral Density After Liver Transplantation by Prostaglandin E1

Introduction As a result of preexisting chronic liver disease and immunosuppression, the majority of liver transplant patients develop bone mineral density (BMD) loss in the first 3 to 6 months posttransplantation, leading to an increased fracture risk. Using basic prophylaxis and treatment by administration of vitamin D, calcium, and bisphosphonates, BMD loss may be controlled in the long term. In contrast, there is no established medical concept for prevention of early posttransplant BMD loss. Material and Methods The aim of this trial was to evaluate the effect of prostaglandin E1 on BMD after liver transplantation. Between 1998 and 2004, 29 patients were enrolled in this study. BMD measurement was performed at lumbar spine and femoral neck using dual energy x-ray absorptometry pretransplant, and 3, 6, 12, and 24 months posttransplant. All patients received calcium and vitamin D as basic prophylaxis. In 13 patients, prostaglandin E1 (PGE) was additionally administered for 12 days posttransplant. Results BMD loss was significantly lower at 3 and 6 months posttransplant in the PGE group (lumbar spine, P < .03; femoral neck, P < .009). Development of BMD loss was comparable between both groups during further follow-up. In the PGE group there was a significantly lower fracture rate compared with the controls ( P < .02). Conclusion The application of PGE 1 proved to be beneficial in compensating the early posttransplant BMD loss and in subsequently reducing fracture rate. These positive effects of PGE 1 could be demonstrated in both the femoral neck and lumbar spine.

Sex differences in the association between leptin and CRP: Results from the Dallas Heart Study

Objective Higher C-reactive protein (CRP) levels in women compared with men may reflect sex differences in the relationship between obesity and inflammation. We evaluated how the adipokine leptin influenced these relationships. Methods and results Dual energy X-ray absorptometry measurements of fat mass and plasma levels of leptin and CRP were measured in 1188 women and 1102 men from the Dallas Heart Study. Analyses were stratified by sex and a leptin/percent fat index was created to evaluate the association between leptin and CRP independent of fat mass. Women had higher body mass index, percent fat mass, and plasma levels of CRP and leptin. CRP levels correlated with leptin levels in both women (Spearman ρ = 0.48, p < 0.0001) and in men ( ρ = 0.27, p < 0.0001). In multivariable models adjusting for confounders including total fat mass, leptin/percent fat index remained significantly associated with log CRP in women ( p = 0.005), but not in men ( p = 0.95). A significant interaction was observed between sex and leptin levels on CRP ( p interaction = 0.03). Conclusion Leptin was associated with CRP independent of other measures of obesity in women, but not in men. These findings suggest that sex differences in CRP may reflect sex-related differences in the inflammatory responses to obesity, and may in part, be mediated by leptin.

Utility of screening tools for the prediction of low bone mass in African American men

Osteoporosis remains under-diagnosed, particularly in African American men, despite the availability of reliable diagnostic tests. In women, several screening tools, including heel ultrasound and clinical assessment tools, reliably predict low bone mass, however the usefulness of these screening tools in African American men is unknown. The aim of this study was to determine the utility of screening tools, namely heel ultrasound, the osteoporosis self-assessment tool (OST), weight-based criterion (WBC) and body mass index (BMI), in screening for low bone mass in African American men. African American men 35 years of age and older were invited to participate. The OST risk index is a score based on age and weight [(weight in kilograms--age in years)x0.2]. Bone mineral density (BMD) of the heel was measured by heel ultrasound, and BMD of both the lumbar spine and hip were determined by dual energy X-ray absorptometry (DXA). One hundred and twenty-eight men fulfilled the inclusion criteria for our study. The population prevalence of osteopenia and osteoporosis were 39% and 7%, respectively. Using a heel ultrasound T-score cut-off value of -1 or less, we predicted low bone mass (T-score of -2 or less at the hip) with a sensitivity of 83%, a specificity of 71% and an area under the curve (AUC) of 0.80. Using an OST cut-off value of 4, we predicted low bone mass with a sensitivity of 83%, a specificity of 57% and an AUC of 0.83. The OST risk index ranged from 18.1 to -6.1, based on which we categorized risk as: low, 5 or greater; moderate, 0-4; high, -1 or less. Of the men with a high-risk OST score, 87% had either osteopenia or osteoporosis based on World Health Organization (WHO) criteria. Using the WBC alone with a cut-off value of 85 kg, we predicted low bone mass with a sensitivity of 74%, a specificity of 50% and an AUC of 0.70. A BMI cut-off value of 30 or greater yielded a sensitivity of 83%, a specificity of 43% and an AUC of 0.70 for the diagnosis of low bone mass. The prevalence of osteopenia and osteoporosis were unexpectedly high in outpatient African American male veterans, who are considered to be at low risk for low bone mass. Heel ultrasound was able to predict low bone mass with sufficiently high sensitivity and specificity for use as a screening tool. Surprisingly, WBC and BMI proved ineffective in predicting low bone mass with adequate sensitivity and specificity. The OST, a clinical formula based on weight and age, appeared to be an easy and reliable screening tool for identifying men at high risk for low bone mass.

Ten-year prediction of osteoporosis from baseline bone mineral density: development of prognostic thresholds in healthy postmenopausal women. The Danish Osteoporosis Prevention Study

Osteopenia is common in healthy women examined in the first year or two following menopause. Short-term fracture risk is low, but we lack algorithms to assess long-term risk of osteoporosis. Because bone loss proceeds at only a few percent per year, we speculated that baseline bone mineral density (BMD) would predict a large proportion of 10-year BMD and be useful for deriving predictive thresholds. We aimed to identify prognostic thresholds associated with less than 10% risk of osteoporosis by 10 years in the individual participant, in order to allow rational osteodensitometry and intervention. We analyzed dual energy X-ray absorptometry (DXA) of the lumbar spine (LS) and femoral neck (FN) from 872 women, who participated in the non-HRT arms of the Danish Osteoporosis Prevention Study and had remained on no HRT, bisphosphonates or raloxifene since inclusion 10 years ago. We defined development of a T -score below -2.5 at the LS and/or FN or incident fracture as end-point, and we derived prognostic thresholds for baseline BMD, defining 90% NPV (negative predictive value) and 90% sensitivity, respectively. Seventy-six percent of the variation in BMD of the LS at 10 years was predicted by baseline BMD. In an individual participant, a baseline BMD T -score above -1.4 (FN or LS, whichever was lower) was associated with a 10-year risk of less than 10% of developing osteoporotic BMD or fracture. This covered 69% of the population. By contrast, participants with T -scores below -1.4 had a 56% risk of fracture or low BMD within 10 years. At the population level, baseline T -score cutoffs below 0 at the LS (68% of the population), 0 at the FN (72%) or -0.6 (62%) at the lower of the two sites capture 90% of the population that developed osteoporosis during the following 10 years. A BMD measurement, performed in the first two years following menopause, is a strong long-term predictor of BMD in healthy women. The association is strong enough to provide robust prognostic thresholds, which can be used to divide the population into two prognostic classes at menopause.

Strength Increases Do Not Correlate To Delta Changes In Lean Soft Tissue

Strength training results in increased lean soft tissue and maximal strength. However, the relationship between lean soft tissue (LST) and pre- and post-training maximal strength, and Delta changes in LST and Delta changes in strength due to resistance training are less clear. PURPOSE To determine the correlations between total and regional LST and maximal strength both pre- and post-training, and Delta changes in total body and regional LST and maximal strength caused by resistance training in women. METHODS Twelve experienced women resistance trainers (41.9 ± 1.6 yrs) performed a total body resistance training program using adjustable variable cam resistance training machines 3 days per week for 12 weeks. Each training session included 3 sets of 10 repetitions of each of 11 exercises and 20 minutes of aerobic training at a minimal of 60% of each subject's age predicted maximal heart rate. One repetition maximal weights (1 RM) and total body and regional LST were determined using dual-energy X-ray absorptometry pre- and post-training. Dependant-t tests were used to determine pre- to post-training differences in variables. Pearson product moment correlations were calculated between absolute 1 RM and absolute LST measures pre- and post-training and between Delta changes in these same variables. RESULTS 1 RM significantly increased (25–30%) in all exercises (bench press, leg press, lat pull-down, overhead press) tested. Total body, arm, trunk and total upper body (arm + trunk) LST also significantly increased (2.2 – 4.5%). While leg LST showed a small, but not significant change. Generally pre and post of training significant correlations were demonstrated between total body and regional LST and the 1 RM of all exercises tested (r = 0.58–0.90) except for the leg press. While generally non significant correlations were shown between Delta changes in 1 RM and Delta changes in total and regional LST except for the bench press (r = 0.64–0.76). CONCLUSIONS The lack of significant correlations between Delta changes in LST and Delta changes in maximal strength indicate factors other than LST changes in part account for maximal strength changes caused by resistance training. Supported by Strive Fitness Inc.

Strength Increases Do Not Correlate To Delta Changes In Lean Soft Tissue

Strength training results in increased lean soft tissue and maximal strength. However, the relationship between lean soft tissue (LST) and pre- and post-training maximal strength, and Delta changes in LST and Delta changes in strength due to resistance training are less clear. PURPOSE To determine the correlations between total and regional LST and maximal strength both pre- and post-training, and Delta changes in total body and regional LST and maximal strength caused by resistance training in women. METHODS Twelve experienced women resistance trainers (41.9 ± 1.6 yrs) performed a total body resistance training program using adjustable variable cam resistance training machines 3 days per week for 12 weeks. Each training session included 3 sets of 10 repetitions of each of 11 exercises and 20 minutes of aerobic training at a minimal of 60% of each subject's age predicted maximal heart rate. One repetition maximal weights (1 RM) and total body and regional LST were determined using dual-energy X-ray absorptometry pre- and post-training. Dependant-t tests were used to determine pre- to post-training differences in variables. Pearson product moment correlations were calculated between absolute 1 RM and absolute LST measures pre- and post-training and between Delta changes in these same variables. RESULTS 1 RM significantly increased (25–30%) in all exercises (bench press, leg press, lat pull-down, overhead press) tested. Total body, arm, trunk and total upper body (arm + trunk) LST also significantly increased (2.2 – 4.5%). While leg LST showed a small, but not significant change. Generally pre and post of training significant correlations were demonstrated between total body and regional LST and the 1 RM of all exercises tested (r = 0.58–0.90) except for the leg press. While generally non significant correlations were shown between Delta changes in 1 RM and Delta changes in total and regional LST except for the bench press (r = 0.64–0.76). CONCLUSIONS The lack of significant correlations between Delta changes in LST and Delta changes in maximal strength indicate factors other than LST changes in part account for maximal strength changes caused by resistance training. Supported by Strive Fitness Inc.

Diet and exercise during growth have site-specific skeletal effects: a co-twin control study

Exercise and improved nutrition offer safe, low-cost and widely applicable approaches to potentially reduce the burden of fractures. We conducted a cross-sectional study of 30 monozygotic and 26 dizygotic male twin pairs, aged 7-20 years to test the following hypotheses: (1) Associations between bone mass and dimensions and exercise are greater than between bone mass and dimensions and protein or calcium intakes; (2) exercise or nutrient intake are associated with appendicular bone mass before puberty and axial bone mass during and after puberty. Total body and posteroanterior (PA) lumbar spine bone mineral content (BMC) and mid-femoral shaft dimensions were measured using dual energy X-ray absorptometry (DEXA). Relationships between within-pair differences in nutrient intake (determined by weighed-food diaries) or exercise duration (determined by questionnaire) and within-pair differences in BMC and bone dimensions were tested using linear regression analysis. In multivariate analyses, within-pair differences in exercise duration were associated with within-pair differences in total body, leg and spine BMC, and cortical thickness. Every-hour-per-week difference in exercise was associated with a 31-g (1.2%) difference in total body BMC, a 10-g (1.4%) difference in leg BMC, a 0.5-g difference in spine BMC and a 0.1-mm difference in cortical thickness ( p <0.01- p <0.1). A 1-g difference in protein intake was associated with a 0.8-g (0.4%) difference in arm BMC ( p <0.05). These relationships were present in peri-pubertal and post-pubertal pairs but not in pre-pubertal pairs. Exercise during growth appears to have greater skeletal benefits than variations in protein or calcium intakes, with the site-specific effects evident in more mature twins.

Abnormal bone collagen morphology and decreased bone strength in growth hormone-deficient rats

Patients with growth hormone deficiency (GHD) have an increased risk of bone fractures. In these patients, the well-described decrease in bone mineral density (BMD) and content (BMC) may, however, not alone explain the increase in fracture rate. Accordingly, the aim of this study was to evaluate collagen morphology and bone mineralisation in cortical bone as well as bone strength in GHD rats to try to clarify the explanation for the increased fracture rate. The Dw-4 rat was used as a model for GHD. This strain of rats has an autosomal recessive disorder, reducing GH synthesis to approximately 10% and growth rate to approximately 40–50% when compared to normal control rats. Five male Dw-4 rats were examined at age 12 weeks and five healthy Lewis rats served as age-matched controls. The animals were examined for (1) bone mineral status by dual energy X-ray absorptometry (DXA) and ash weight/bone volume, (2) biomechanical properties, (3) serum insulin-like growth factor I (IGF-I) and IGF binding protein 3 (IGFBP-3), and (4) collagen morphology of cortical bone from the right femurs was examined by scanning and transmission electron microscopy. A significant decrease was found in serum IGF-I, IGFBP-3 and biomechanical properties in GHD rats compared to controls ( P < 0.009). While DXA-derived BMD was decreased, no significant difference was found in ash weight/bone volume. Electron microscopy showed a significant decrease in the number and a significant increase in the diameter of collagen microfibrils in GHD rats as compared to their controls ( P < 0.009). In conclusion, we report for the first time that collagen morphology in bone is markedly altered in rats with isolated GHD. Whether similar conditions are present in GHD patients need further investigations. The changes described, however, may provide a co-explanation for the increased fracture rate in GHD.

Gelatin sheet incorporating basic fibroblast growth factor enhances sternal healing after harvesting bilateral internal thoracic arteries

Objective We previously reported that a gelatin sheet incorporating basic fibroblast growth factor accelerated sternal healing after bilateral internal thoracic artery removal in normal and diabetic rats. The aim of this study was to evaluate the effects of this therapeutic modality on sternal healing in a large-animal model before performing a clinical trial. Methods After median sternotomy and bilateral internal thoracic artery removal in a pedicled fashion, 14 beagle dogs received either a gelatin sheet incorporating basic fibroblast growth factor (100 μg per sheet) on the posterior table of the sternum (FGF group, n = 7) or did not receive a gelatin sheet (control, n = 7). We compared sternal healing 4 weeks after surgical intervention between the groups. Results Scintigraphic images obtained by using technetium 99 methylene diphosphonate bone scanning were assessed visually, and the impulse rate was quantified 30 and 60 minutes after injection of technetium 99 methylene diphosphonate to evaluate the sternal perfusion. Sternal uptake was significantly increased in the FGF group (30 minutes: 221% ± 30% vs 180% ± 36%; 60 minutes: 267% ± 26% vs 197% ± 42%; P < .01). Apparent sternal dehiscence, as assessed radiographically, was observed only in the control animals. Histologically, complete healing of the sternum with marked angiogenesis was observed in the FGF group, whereas poor healing with limited angiogenesis was seen in the control animals. Both bone mineral content (134 ± 49 vs 52 ± 32 mg, P < .01) and bone mineral density (133 ± 53 vs 66 ± 32 mg/mm 2, P < .05) along the incision line of the sternum, as assessed by means of dual-energy x-ray absorptometry, were higher in the FGF group. Conclusions A gelatin sheet incorporating basic fibroblast growth factor enhances sternal perfusion and accelerates sternal bone healing in large animals. 23

Gelatin Sheet Incorporating Basic Fibroblast Growth Factor Enhances Healing of Devascularized Sternum in Diabetic Rats

Background Poor healing of the sternum often limits the use of bilateral internal thoracic arteries (BITAs) after coronary bypass surgery in diabetic patients. We have reported that a gelatin sheet that incorporates basic fibroblast growth factor (bFGF) accelerates sternal healing after BITA removal in normal rats. This study evaluated the effects of the above method for sternal healing in diabetic animals. Methods and Results Diabetic Wistar rats with blood glucose levels &gt;400 mg/dL and body-weight loss &gt;20 g were established by a single intravenous injection of streptozotocin (55 mg/kg). After median sternotomy and BITA removal, 16 diabetic rats received either a gelatin sheet that incorporated bFGF (100 μg/sheet) on the posterior table of the sternum (FGF group, n=9) or no gelatin sheet (control, n=7). Peristernal blood flow, as measured by a noncontact laser Doppler 4 weeks after surgery in the FGF group, recovered to the preoperative level (106±10% versus 82±9%, P &lt;0.01), and marked angiogenesis was also observed around the sternum in the FGF group (30.5±3.2 versus 15.8±2.7 vessels/unit area, P &lt;0.01). Deep sternal wound complications developed in 5 control rats but only in 1 rat in the FGF group ( P &lt;0.05). In the FGF group, histological examination showed improved sternal healing (excellent in 6 rats and slow/poor healing in 3). Bone mineral content as assessed by dual-energy x-ray absorptometry was greater in the FGF group (75.9±18.1 versus 48.9±10.7 mg, P &lt;0.05). Bone mineral density of the sternum was similar between the 2 groups. Conclusions A gelatin sheet that incorporates bFGF may offset sternal ischemia and accelerate sternal bone regeneration and healing, even in diabetic patients.

The Long-term Effects of Unilateral Lower Limb Musculoskeletal Injury on Bone Mineral Density and Isometric Quadriceps Strength

Summary Musculoskeletal injuries of the lower limb are commonplace and can lead to long-standing deficits in bone mineral density (BMD) and muscle strength. This may predispose subjects to re-injury and lower their threshold for functional ability. This study aims to investigate the relationship between BMD and peak isometric quadriceps strength and considers whether subsequent strength training is of benefit. Ten subjects (two female) with previous lower limb musculoskeletal injuries were assessed. The BMD in the knee region was measured bilaterally using dual energy X-ray absorptometry (DEXA, model DPX-L). The peak isometric quadriceps strength was assessed using the KinCom 500H isokinetic dynamometer. The injured limb was compared to the uninjured limb (I/UI%). Significant differences were seen between the injured and uninjured limb for BMD in the femur (p = 0.039), tibia (p = 0.014) and in the combined site (p = 0.017); and peak isometric quadriceps strength (p > 0.001). No relationship was found between the decrements in muscle strength and BMD. A further pilot study (n = 6) was conducted to assess the impact of a 12-week home exercise training programme on the BMD and isometric quadriceps strength deficits. These results were encouraging with increases in the quadriceps strength and/or BMD and a statistically significant increase in the load lifted in training.

Recent development of radiation measurement instrument for industrial and medical applications

Recently, computer imaging technology has developed very high-quality image and fast processing time. X-rays have been used for many purposes such as medical diagnosis and analyzing the structure of industrial materials. However, as X-rays are hazardous to the human body, it is desirable to reduce its exposed dose to a minimum. For this purpose, it is necessary to use a semiconductor radiation detector with a high efficiency for X-rays. We have developed photon-counting CdTe array detector system for medical and industrial use. The bone densitometer for Dual Energy X-ray Absorptometry (DEXA) has been developed to make diagnosis of osteoporosis, and it is developed to analyze a material element for industrial use. Recently, we have developed a monochromatic X-ray CT using a 256 ch CdTe array detector. We found that the array detector systems are very useful for medical and industrial applications.

Pre- and postoperative bone metabolism of primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a well-known indicator of severe bone loss. However, the recovery process of bone mineral density after surgery in PHPT patients is not sufficiently clear. We examined postoperative bone metabolism in 24 PHPT patients. Subjects were 24 patients with PHPT upon whom we performed parathyroidectomy in the Department of Surgery II, Fukushima Medical University. Mean age was 54.2 years and the male-to-female ratio was 10:14; mean time of follow-up was 27.3 months. Patients were divided histopathologically into 16 adenomas and eight hyperplasias, and classified by heredity into seven familial (six, MEN 1; one, MEN 2) and 17 sporadic types. Bone mineral density was measured by dual energy X-ray absorptometry (DXA) and digital image processing (DIP). Age-matched values of these parameters were obtained. Serum bone metabolic parameters; ionized calcium (CaF), phosphorus, intact PTH (iPTH), c-PTH, ALP, osteocalcin (OC) and PTHrP were measured. PHPT patient preoperative bone mineral densities were significantly lower than those of healthy controls. Those by DIP method were lower than those by DXA. High CaF, iPTH, OC and ALP levels were indicated before surgery, but all parameters immediately became normal. Longitudinal bone mineral density changes of asymptomatic cases increased more than those of patients with renal stone and/or ostitis fibrosa. In adenoma cases, tumor weights were significantly inversely, which correlated with preoperative DIP bone density measurements. Preoperative PHPT patients showed decreased bone density; bone loss in symptomatic cases was especially prominent compared to asymptomatic cases. Most PHPT patients had not completed the BMD recovery after surgery, so even asymptomatic and mild PHPT patients should undergo parathyroidectomy to minimize irreversible bone loss.

Bone regeneration at rabbit skull defects treated with transforming growth factor-beta1 incorporated into hydrogels with different levels of biodegradability.

Skull bone regeneration induced by transforming growth factor-beta1 (TGFbeta1)-containing gelatin hydrogels (TGFbeta1-hydrogels) was investigated using a rabbit skull defect model. Different strengths of TGFbeta1 were examined and compared: different TGFbeta1 doses in gelatin hydrogels with a fixed water content, different water contents in gelatin hydrogels with a fixed TGFbeta1 dose, and TGFbeta1 in solution form. In addition, regenerated skull bone was observed over long time periods after treatment. Soft x-ray, dual energy x-ray absorptometry, and histological studies were performed to assess the time course of bone regeneration at a 6-mm-diameter skull defect in rabbits after treatment with TGFbeta1-hydrogels or other agents. The influence of TGFbeta1 dose and hydrogel water content on skull bone regeneration by TGFbeta1-hydrogels was evaluated. Gelatin hydrogels with a water content of 95 wt% that incorporated at least 0.1 microg of TGFbeta1 induced significant bone regeneration at the rabbit skull defect site 6 weeks after treatment, whereas TGFbeta1 in solution form was ineffective, regardless of dose. The in vivo degradability of the hydrogels, which varied according to water content, played an important role in skull bone regeneration induced by TGFbeta1 -hydrogels. In our hydrogel system, TGFbeta1 is released from hydrogels as a result of hydrogel degradation. When the hydrogel degrades too quickly, it does not retain TGFbeta1 or prevent ingrowth of soft tissues at the skull defect site and does not induce bone regeneration at the skull defect. It is likely that hydrogel that degrades too slowly physically impedes formation of new bone at the skull defect. Following treatment with 0.1-microg TGFbeta1-hydrogel (95 wt%), newly formed bone remained at the defect site without being resorbed 6 and 12 months later. The histological structure of the newly formed bone was similar to that of normal skull bone. Overgrowth of regenerated bone and tissue reaction were not observed after treatment with TGFbeta1 -hydrogels. A TGFbeta1-hydrogel with appropriate biodegradability will function not only as a release matrix for the TGFbeta1, but also as a space provider for bone regeneration. The TGFbeta1-hydrogel is a promising surgical tool for skull defect repair and skull base reconstruction.