Improved Performance of Hip DXA Using a Novel Region of Interest in the Upper Part of the Femoral Neck: In Vitro Study Using Bone Strength as a Standard of Reference

We tested the hypothesis that bone mineral density (BMD) and bone mineral content (BMC) in proximal human femur specimens in the upper neck region of interest (ROI) and femoral neck axis length (FNAL) provide a significantly better prediction of femoral bone strength than standard ROIs in vitro. BMD and BMC were measured in 110 proximal femur specimens using a standard dual-energy X-ray absorptiometry (DXA) scanner. The analysis included a new ROI in the upper neck as well as the standard ROIs. FNAL was obtained from the scan images. The specimens' failure-load was measured in a mechanical loading device, simulating a fall on the greater trochanter. For the standard ROIs, correlations between failure-load and BMD ranged from R2 = 0.64 (shaft ROI) to R2 = 0.70, p < 0.001 (femoral neck). Prediction of strength by BMD did not significantly differ from those of BMC (R2 ranging from 0.65 to 0.75, p < 0.001). In the upper neck ROI, for both BMD and BMC correlations with failure-load were higher (R2 = 0.76 and 0.81, respectively; p < 0.001). A lower, yet still significant, correlation was found between FNAL and bone strength (R2 = 0.23, p < 0.001). Normalization of failure-load with respect to FNAL did not significantly increase the correlations with densitometric measures. This study provides in vitro evidence indicating that among the ROIs of the proximal femur the newly defined upper neck ROI provides the best prediction of bone strength. Only a weak association was observed between failure load and FNAL.     

Sex differences of human trabecular bone microstructure in aging are site-dependent.

In this study, we characterize bone microstructure, specifically sex differences, at multiple skeletal sites in 165 subjects >52 yr of age, using microCT technology in vitro. Significant sex differences are observed at the distal radius, femoral neck, and femoral trochanter, but not at the iliac crest, calcaneus, and lumbar vertebral body. Correlations in BV/TV between sites ranged from r = 0.13 to 0.56. INTRODUCTION: The goals of this study were (1) to assess potential sex differences of bone microstructure and their difference between skeletal sites and (2) to explore the relationship of trabecular microstructural properties between relevant skeletal sites. MATERIALS AND METHODS: Trabecular bone microstructural properties were measured in vitro in 165 subjects 52-99 yr of age using microCT. Defined volumes of interest (cylinders with 6 mm diameter and 6 mm length) were scanned at a resolution of 26 microm (isotropic) in six different anatomical sites: distal radius, femoral neck and trochanter, iliac crest, calcaneus, and second lumbar vertebral body. RESULTS: At the radius and femoral neck, trabecular bone displayed a more plate-like structure, thicker trabeculae, smaller separation/higher trabecular number, higher connectivity, and a higher degree of anisotropy in men than in women (p < 0.05). At the trochanter, men displayed more plate-like structure and thicker trabeculae (p < 0.05), but no differences in trabecular separation or other parameters compared with the women. At the calcaneus, iliac crest, and second lumbar vertebra none of the bone parameters displayed significant differences between sexes. The BV/TV at one site explained a range of only 2-32% of the variability at other sites. CONCLUSIONS: These results suggest that trabecular bone microstructural properties are remarkably heterogeneous throughout the skeleton. Significant differences between men and women are observed at some, but not at all, sites. The magnitude of sex differences in trabecular microstructure coincides with that of fracture incidence observed for some of the sites in epidemiological studies.     

MRI gadolinium enhancement of bone marrow: age-related changes in normals and in diffuse neoplastic infiltration

 Objective: To quantify gadolinium-related enhancement in the bone marrow of the spine in normals and in patients with homogeneous diffuse malignant bone marrow infiltration. Design and patients: The patients consisted of two groups: group 1 comprised 94 healthy adults (18–86 years) without bone marrow disease and group 2 comprised 30 patients with homogeneous diffuse malignant bone marrow infiltration due to myeloma (n=20) or breast carcinoma (n=10). All patients received intravenous gadopentetate dimeglumine (Gd-DTPA), 0.1 mmol/kg body weight. Pre- and postcontrast signal intensity (SI) on T1-weighted spin-echo (SE) images (TR/TE: 572 ms/15 ms) was measured over a region of interest (ROI) and the percentage SI increase was calculated. The results were confirmed by bone marrow biopsy (n=20) and clinical parameters (n=10). Dynamic contrast-enhanced studies using a spoiled gradient-recalled-echo (GRE) sequence (TR/TE/α: 68 ms/6 ms 75°) were performed in 10 controls with normal bone marrow. Results and conclusion: Contrast material enhancement in healthy persons can vary greatly (range 3–59%, mean 21%, SD 11%). With increasing age there is a significant decrease in contrast enhancement (Pearson’s correlation, P<0.01). The percentage SI increase in patients with intermediate-grade (biopsy 20–50 vol%) and high-grade (biopsy >50 vol%) diffuse malignant bone marrow infiltration was significantly higher than in normals (mean 67%, SD 34%, P<0.001). Low-grade (biopsy <20 vol%) diffuse malignant bone marrow infiltration can not be assessed by non-enhanced T1-weighted SE images or Gd-DTPA application. In conclusion, contrast material enhancement in healthy persons can vary greatly and is dependent on age, while intermediate-grade and high-grade diffuse malignant bone marrow infiltration can be objectively assessed with SI measurements.     

Natürliche Familienplanung

The symptothermal method (STM) is the most effective method of natural family planning, if two parameters to determine the beginning as well as the end of the fertile phase are used (double-check). The main parameters observed by women are BBT and cervical mucus changes. The method-effectiveness is 0.3–0.5 pregnancies per 100 women years, if there is no unprotected intercourse in the self-detected fertile phase. The use-effectiveness is about 2 in Germany. These results are derived from large European databases. In developed countries, the STM replaces the old calendar and temperature methods and the Billings method.     

Analysis of three-dimensional sinter shrinkage of copings made from alumina in an innovative direct shaping process.

The three-dimensional (3D) evaluation and comparison of free-form-surfaces is a complex problem [Dent. Mater. 8 (1992) 49; J. Dent. Res. 76 (1997) 1799; Dent. Mater. 16 (2000) 145; J. Prosthet. Dent. 70 (1993) 457; Dent. Mater. 19 (2003) 19]. However, it is essential in order to analyze the sinter shrinkage of dental ceramic-restorations where isotropic and linear shrinkage is desired for accurate fit on the prepared teeth. In this article, we examine the 3D sinter shrinkage in general and for nine copings from alumina in particular. Using various scaled CAD-models in an iteration scheme, each model was compared to the filtered point cloud of the coping, determining the surface-cloud difference. The magnitude of deviations from linear sinter shrinkage was investigated. Furthermore, a new fabrication process for ceramic-restorations is introduced.     

Zur Eliminationskinetik des Digoxin vor und während Spironolactonbehandlung

Zusammenfassung Im Tierversuch konnte unter hohen Spironolactondosen eine Beschleunigung der Digoxinelimination nachgewiesen werden, die auf eine vermehrte Metabolisierung des Digoxins nach Induktion mikrosomaler Leberenzyme zurückgeführt wurde. Deshalb wurde bei 8 Patienten die Eliminationskinetik des Digoxins vor Spironolactonbehandlung untersucht, wobei morgens nüchtern 0,1 mg³H-Digoxin intravenös als einmalige Dosis verabreicht wurde. Zur Messung der Digoxinkonzentration wurden venöse Blutproben zu bestimmten Zitpunkten bis zu 120 h entnommen, der Urin fraktioniert 5 Tage lang gesammelt. Zusätzlich wurde während der gesamten Versuchsperiode die im Stuhl ausgeschiedene Digoxinmenge bestimmt. Während der Messung der Digoxinelimination wurden gleichzeitig nicht-invasive Parameter des mikrosomalen Leberenzymsystems wie Antipyrinhalbwertszeit, Antipyrinclearance, Gamma-Glutamyl-transpeptidase im Blut und d-Glucarsäureausscheidung im 24 h-Urin gemessen. Danach wurde jedem Patienten 15 Tage lang eine therapeutische Erhaltungsdosis von 150 mg Spironolacton täglich verabreicht. 10 Tage nach Beginn der Spironolactonbehandlung wurde die oben beschriebene Untersuchung der Digoxinelimination zusammen mit den Parametern des mikrosomalen Leberenzymsystems wiederholt.Aufgrund der errechneten pharmakokinetischen Parameter ließen sich unter Spironolactonbehandlung keine Änderungen der globalen Eliminationskonstante respektive der Halbwertszeit des Digoxins nachweisen. Ebenso blieb das Verteilungsvolumen, die renale und metabolische Clearance unbeeinflußt, die Digoxinausscheidung im Faeces war während beiden Versuchsperioden nicht signifikant verschieden und betrug für die gemessene Zeitperiode etwa 15% der verabreichten Dosis. Außerdem zeigten die Parameter des mikrosomalen Enzymsystems der Leber keinerlei Änderungen vor und unter Spironolactonbehandlung. Aufgrund dieser Ergebnisse konnte unter den klinisch üblichen Spironolactondosen keine Veränderung der Digoxinelimination nachgewiesen und eine Enzyminduktion sicher ausgeschlossen werden. Deshalb sind die in der Literatur berichteten Änderungen der Digoxinausscheidung auf eine zu hohe Dosierung im Tierversuch zurückzuführen und haben für den Menschen keine therapeutische Bedeutung.Herrn Prof. Dr. E. Bauereisen zum 65. Geburtstag in Dankbarkeit gewidmet     

Mitochondrial DNA sequences reveal close relationships between social parasitic ants and their host species

In the tribe Leptothoracini, the phylogenetic relationship of socially parasitic ants (Doronomyrmex kutteri, D. goesswaldi and Harpagoxenus sublaevis) and their host species Leptothorax acervorum has been controversial. Even more controversial is the relationship between the socially parasitic ant Chalepoxenus muellerianus and its host species Leptothorax unifasciatus, L. nigriceps, L. interruptus and L. recedens. On the basis of morphological, ecological and ethological criteria it has been argued that socially parasitic ants and their respective hosts always evolved from common ancestors, and hence it has been postulated that these species should be included in common taxonomical groups. This would require the division of the tribe Leptothoracini into two subgroups, one comprising the subgenus Leptothorax (s. str.) and the other the subgenus Myrafant, together with their respective parasitic genera. We have used the polymerase chain reaction (PCR) to compare a 360-bp sequence of the mitochondrial cytochrome b gene of 14 species belonging to the tribe Leptothoracini and an outgroup species Tetranorium impurum (Tetramoriini). The results generally agree with the morphological studies which suggest that a common ancestral species differentiated into host and parasite species. This relationship is very obvious within the Leptothorax (s. str.) group but less pronounced in the species belonging to the Myrafant group. Leptothorax (Temnothorax) recedens shows a greater sequence divergence than the outgroup species T. impurum.