Biomedical subjects

Klaus Engelke

Publications and source records attributed to Klaus Engelke.

9 recordsLinked to original sources

PubMed2004

Benefits of 2 years of intense exercise on bone density, physical fitness, and blood lipids in early postmenopausal osteopenic women: results of the Erlangen Fitness Osteoporosis Prevention Study (EFOPS).

BACKGROUND: Growing evidence indicates that physical exercise can prevent at least some of the negative effects on health associated with early menopause. Here we determine the effects of intense exercise on physical fitness, bone mineral density (BMD), back pain, and blood lipids in early postmenopausal women. METHODS: The study population comprised 50 fully compliant women, with no medication or illness affecting bone metabolism, who exercised over 26 months (exercise group [EG]), and 33 women who served as a nontraining control group (CG). Two group training sessions per week and 2 home training sessions per week were performed in the EG. Both groups were individually supplemented with calcium and cholecalciferol. Physical fitness was determined by maximum strength and cardiovascular performance. Bone mineral density was measured at the lumbar spine (dual-energy x-ray absorptiometry [DXA] and quantitative computed tomography [QCT]), the proximal femur (DXA), and the forearm (DXA). In serum samples taken from a subset of the study participants, we determined bone formation (serum osteocalcin) and resorption (serum cross-links) markers as well as blood lipid levels. Vasomotor symptoms related to menopause and pain were also assessed. RESULTS: After 26 months, significant exercise effects determined as percentage changes compared with baseline were observed for physical fitness (isometric strength: trunk extensors [EG +36.5% vs CG +1.7%], trunk flexors [EG +39.3% vs CG -0.4%], and maximum oxygen consumption [EG +12.4% vs CG -2.3%]); BMD (lumbar spine [DXA L1-L4, EG +0.7% vs CG -2.3%], QCT L1-L3 trabecular region of interest [EG +0.4% vs CG -6.6%], QCT L1-L3 cortical region of interest [EG +3.1% vs CG -1.7%], and total hip [DXA, EG -0.3% vs CG -1.7%]); serum levels (total cholesterol [EG -5.0% vs CG +4.1%] and triglycerides [EG -14.2% vs CG +23.2%]); and pain indexes at the spine. CONCLUSION: General purpose exercise programs with special emphasis on bone density can significantly improve strength and endurance and reduce bone loss, back pain, and lipid levels in osteopenic women in their critical early postmenopausal years.

Absorptiometry, Photon↗

PubMed2004

Interactive 3D editing tools for image segmentation.

Segmentation is an important part of image processing, which often has a large impact on quantitative image analysis results. Fully automated operator independent segmentation procedures that successfully work in a population with a larger biological variation are extremely difficult to design and usually some kind of operator intervention is required, at least in pathological cases. We developed a variety of 3D editing tools that can be used to correct or improve results of initial automatic segmentation procedures. Specifically we will discuss and show examples for three types of editing tools that we termed: hole-filling (tool 1), point-bridging (tool 2), and surface-dragging (tool 3). Each tool comes in a number of flavors, all of which are implemented in a truly 3D manner. We describe the principles, evaluate efficiency and flexibility, and discuss advantages and disadvantages of each tool. We further demonstrate the superiority of the 3D approach over the time-consuming slice-by-slice editing of 3D datasets, which is still widely used in medical image processing today. We conclude that performance criteria for automatic segmentation algorithms may be eased significantly by including 3D editing tools early in the design process.

Algorithms↗

PubMed2004

Hypertension, sodium retention, calcium excretion and osteopenia in Dahl rats.

BACKGROUND: Salt-sensitive hypertension in the Dahl rat is associated with abnormalities in both calcium (Ca2+) and sodium (Na) homeostasis. OBJECTIVE: To test the hypothesis that salt-induced abnormal Ca(2+) handling in Dahl salt-sensitive (DSS) rats is associated with negative Ca(2+) balance and bone disease. METHODS: Ca(2+) excretion in acute and chronic Na(+) loading and electrolyte and water balance were determined by balance studies in Dahl salt-resistant (DSR) and salt-sensitive (DSS) rats fed 8 or 0.1% NaCl for 4 weeks. A dry ashing procedure was used to determine Na(+), Ca(2+), and water content and their association with blood pressure in the rats. RESULTS: When fed 8% NaCl, DSS rats initially maintained a positive Ca(2+) balance and showed decreased natriuresis compared with DSR rats. During the course of Na(+) loading, DSS rats increased natriuresis and calciuresis. After 4 weeks of salt loading, cumulative Na balance was greater and cumulative Ca(2+) balance was less in DSS than in DSR rats. In addition, DSS rats developed osteopenia. Bone mineral content correlated inversely with blood pressure in DSS rats. Acute saline volume expansion in DSS rats demonstrated their ability to excrete the Na load fully, but led to an exaggerated renal loss of Ca(2+) compared with DSR rats. CONCLUSION: DSS, but not DSR, develop Ca(2+) loss and ostopenia during chronic Na(+) loading. We speculate that Na retention in DSS rats fed a high Na diet may be in part a compensatory mechanism to maintain Ca(2+) balance.

Animals↗

PubMed2004

High-resolution imaging of osteoarthritis using microcomputed tomography.

Three-dimensional imaging of osteoarthritis is so far limited to late stages of the disease. In this chapter we introduce microcomputed tomography (microCT) as a new imaging tool that offers exciting features for diagnosis of earlier disease stages and for disease monitoring. microCT provides spatial resolution better than 100 microm, but the size of the objects that can be scanned is restricted to several centimeters. The strength of X-ray-based techniques like micro CT is the excellent visualization of bone. Therefore, the main application of microCT in osteoarthritis (OA) will be the analysis of bone in small-animal models or of human bone biopsies. As an example, we will exemplarily describe the application of microCT for the examination of knee joints of male STR1N mice. This inbred strain spontaneously develops OA that carries many characteristics of the human disease. With microCT it is possible to monitor the prominent bony alterations such as osteophyte formation, trabecular remodeling, subchondral bone plate thickening, and subchondral sclerosis. We discuss sample preparation, scanning procedures, data processing, and analysis as well as implications and restrictions for in vivo and in vitro applications.

Animals↗

PubMed2003

The Erlangen Fitness Osteoporosis Prevention Study: a controlled exercise trial in early postmenopausal women with low bone density-first-year results.

OBJECTIVE: To investigate the effect of a 2-year vigorous, combined high-impact, strength, and endurance training program on bone mineral density (BMD) determined by dual-energy x-ray absorptiometry (DXA), quantitative computed tomography (QCT), and ultrasound in early postmenopausal women with osteopenia. DESIGN: Nonrandomized controlled trial, reporting 1-year data. SETTING: Community. PARTICIPANTS: Early postmenopausal (1-8y postmenopausal) osteopenic women (DXA T score at lumbar spine or total hip between -1 and -2.5 standard deviations). The exercise group (n=59; mean age, 55.1+/-3.4y) and control group (n=41; mean age, 55.9+/-3.1y) were recruited from community registers. INTERVENTION: Fourteen months of exercise training, with 2 joint sessions and 2 additional home training sessions. Exercise and control groups were supplemented individually with calcium and cholecalciferol up to 1500mg of calcium and 500IU of vitamin D per day. MAIN OUTCOMES MEASURES: BMD at the lumbar spine and total hip measured by DXA, isometric maximum strength, and maximal oxygen consumption (VO2max) during a stepwise running test to exhaustion. RESULTS: Bone density increased significantly at the lumbar spine for the exercise group (1.3%, P<.001) and decreased in the control group (-1.2%, P<.01). Differences at the total hip (-0.3%, not significant vs -0.8%, P<.05) and the femoral neck (-0.8%, P<.05 vs -1.8%, P<.001) were nonsignificant. Changes in isometric maximum strength were significant for each region (grip strength, trunk flexors and extensors, hip flexors, leg adductors and abductors, arm flexors and extensors) in the exercise group (11%-39%) compared with nonrelevant changes (-1.1% to 3.9%) in the control group. Between-group differences were significant (P<.01-.001) for all strength parameters. VO2max increased significantly by 11% (P<.001) in the exercise group but decreased in the control group by 4% (P<.05) while showing significant between-group differences. CONCLUSION: High-intensity exercise training can have a positive influence on bone density in early postmenopausal osteopenic women.

Absorptiometry, Photon↗

PubMed2003

Implant stability and histomorphometry: a correlation study in human cadavers using stepped cylinder implants.

The aim of the present study was to determine the correlation between the primary stability of dental implants placed in edentulous maxillae and mandibles, the bone mineral density and different histomorphometric parameters. After assessing the bone mineral density of the implant sites by computed tomography, 48 stepped cylinder screw implants were installed in four unfixed human maxillae and mandibles of recently deceased people who had bequeathed their bodies to the Anatomic Institute I of the University of Erlangen-Nuremberg for medical-scientific research. Peak insertion torque, Periotest values and resonance frequency analysis were assessed. Subsequently, histologic specimens were prepared, and bone-to-implant contact, the trabecular bone pattern factor (TBPf), the density of trabecular bone (BV/TV) and the height of the cortical passage of the implants were determined. The correlation between the different parameters was calculated statistically. The mean resonance frequency analysis values (maxilla 6130.4+/-363.2 Hz, mandible 6424.5+/-236.2 Hz) did not correlate with the Periotest measurements (maxilla 13.1+/-7.2, mandible -7.9+/-2.1) and peak insertion torque values (maxilla 23.8+/-2.2 N cm, mandible 45.0+/-7.9 N cm) (P=0.280 and 0.193, respectively). Again, no correlations could be found between the resonance frequency analysis, the bone mineral density (maxilla 259.2+/-124.8 mg/cm(3), mandible 349.8+/-113.3 mg/cm3), BV/TV (maxilla 19.7+/-8.8%, mandible 34.3+/-6.0%) and the TBPf (maxilla 2.39+/-1.46 mm-1, mandible -0.84+/-3.27 mm-1) (P=0.140 and 0.602, respectively). However, the resonance frequency analysis values did correlate with bone-to-implant contact of the oral aspect of the specimens (maxilla 12.6+/-6.0%, mandible 35.1+/-5.1%) and with the height of the crestal cortical bone penetrated by the implants in the oral aspect of the implant sites (maxilla 2.1+/-0.7 mm, mandible 5.1+/-3.7 mm) (P=0.024 and 0.002, respectively). The Periotest values showed a correlation with the height of the crestal cortical bone penetrated by the implants in the buccal aspect of the implant sites (maxilla 2.5+/-1.2 mm, mandible 5.4+/-1.2 mm) (P=0.015). The resonance frequency analysis revealed more correlations to the histomorphometric parameters than the Periotest measurements. However, it seems that the noninvasive determination of implant stability has to be improved in order to give a more comprehensive prediction of the bone characteristics of the implant site.

Aged↗

PubMed2003

A new accurate and precise 3-D segmentation method for skeletal structures in volumetric CT data.

We developed a highly automated three-dimensionally based method for the segmentation of bone in volumetric computed tomography (CT) datasets. The multistep approach starts with three-dimensional (3-D) region-growing using local adaptive thresholds followed by procedures to correct for remaining boundary discontinuities and a subsequent anatomically oriented boundary adjustment using local values of cortical bone density. We describe the details of our approach and show applications in the proximal femur, the knee, and the skull. The accuracy of the determination of geometrical parameters was analyzed using CT scans of the semi-anthropomorphic European spine phantom. Depending on the settings of the segmentation parameters cortical thickness could be determined with an accuracy corresponding to the side length of 1 to 2.5 voxels. The impact of noise on the segmentation was investigated by artificially adding noise to the CT data. An increase in noise by factors of two and five changed cortical thickness corresponding to the side length of one voxel. Intraoperator and interoperator precision was analyzed by repeated analysis of nine pelvic CT scans. Precision errors were smaller than 1% for trabecular and total volumes and smaller than 2% for cortical thickness. Intraoperator and interoperator precision errors were not significantly different. Our segmentation approach shows: 1) high accuracy and precision and is 2) robust to noise, 3) insensitive to user-defined thresholds, 4) highly automated and fast, and 5) easy to initialize.

Algorithms↗

PubMed2002

Exercise effects on fitness and bone mineral density in early postmenopausal women: 1-year EFOPS results.

PURPOSE: To determine the effect of an intense exercise training on physical fitness, coronary heart disease (CHD), bone mineral density (BMD), and parameters related to quality of life in early postmenopausal women with osteopenia. METHODS: Fifty-nine fully compliant women (55.1 +/- 3.4 yr) without any medication or illness affecting bone metabolism took part in intensive exercise training (>2 sessions per week); 41 women served as nontraining control. Both groups received calcium and vitamin D (cholecalciferol) up to a maximum of 1500 mg x d(-1) calcium and 500 IU x d(-1) vitamin D. Bone density of the lumbar spine and hip (DXA Hologic QDR 4500), maximum isometric and dynamic strength (Schnell M3, Schnell-Trainer), VO2max (ZAN 600), and quality of life parameters including vasomotor symptoms related to menopause were measured at baseline and after 14 months. RESULTS: After 14 months, there were significant differences between exercise and control groups concerning changes of bone density (LS exercise: +1.3%, P < 0.001 vs control: -1.2%, P < 0.001), maximum isometric strength (exercise: +11 to +32% (P < 0.001) vs control: -1.1 to +3.9%), VO2max (exercise: +11% (P < 0.001) vs control: -4% (P < 0.05)), and quality of life parameters (e.g., lower back pain). Dynamic strength (1RM tests) at four exercises, which was assessed in the exercise group only, increased significantly by 15-43% (all P < 0.001). CONCLUSION: The intense exercise training program presented here was effective in improving strength, endurance, quality of life parameters, and even BMD in women in their critical early postmenopausal years.

Bone Density↗

PubMed2002

Universal standardization of forearm bone densitometry.

As part of an effort to quantify device-dependent differences in forearm bone density, 101 women, aged 20-80 years (approximately 16 women in each age decade), were scanned on six forearm bone densitometers: the Aloka DCS-600EX, the Hologic QDR-4500A, the Lunar PIXI, the Norland pDEXA, the Osteometer DTX-200, and the Pronosco X-posure System. Regression statistics are reported for all similar regions of interest (ROIs). However, comparisons were confounded because of large differences in the ROI size and placement. The number of ROIs reported for a single scan by each device varied from 1 to 12. The correlation coefficients ranged from 0.7 < r < 0.97, with the highest correlation coefficients and lowest SEs for comparisons between the most similar ROIs. Standardized units of bone mineral density are derived for distal (sdBMD), mid-(smBMD), and proximal (spBMD) ROTs that allow for comparable mean bone densities to be derived for patient populations. Five phantoms were scanned and characterized on five of the devices and the precision and mean values were reported. These phantom values will aid in the in vitro cross-calibration between manufacturers to recreate the presented in vivo relationships. Care should be exercised when using these equations for cross-calibrating patient databases or pooling clinical data from different devices because the least significant differences detectable from measurements taken on two different machines can be increased substantially.

Absorptiometry, Photon↗