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1.  Dietary Restriction of Caenorhabditis elegans by Axenic Culture Reflects Nutritional Requirement for Constituents Provided by Metabolically Active Microbes 
In Caenorhabditis elegans, several manipulations that affect nutrition slow development, reduce fecundity, and increase life span. These are viewed as dietary restriction (DR) and include culture in semidefined, nutrient-rich liquid medium that is axenic (i.e., there is no microbial food source). Here we describe convenient ways to exert DR by culture on agar plates containing axenic medium. We used these to explore whether effects of axenic culture really reflect DR. Our results imply that major nutrient components of axenic medium, and overall caloric content, are not limiting for life span. However, adding growth-arrested Escherichia coli as an additional food source rescued the effects of axenic culture. We then sought to identify the component of E. coli that is critical for normal C. elegans nutrition using add-back experiments. Our results suggest that C. elegans has a nutritional requirement for live, metabolically active microbes or, possibly, an unidentified, heat-labile, nonsoluble component present in live microbes.
PMCID: PMC4333221  PMID: 18375873
Dietary restriction; C. elegans; E. coli; Aging; Axenic culture
2.  High spectral and spatial resolution X-ray transmission radiography and tomography using a Color X-ray Camera 
High resolution X-ray radiography and computed tomography are excellent techniques for non-destructive characterization of an object under investigation at a spatial resolution in the micrometer range. However, as the image contrast depends on both chemical composition and material density, no chemical information is obtained from this data. Furthermore, lab-based measurements are affected by the polychromatic X-ray beam, which results in beam hardening effects. New types of X-ray detectors which provide spectral information on the measured X-ray beam can help to overcome these limitations. In this paper, an energy dispersive CCD detector with high spectral resolution is characterized for use in high resolution radiography and tomography, where a focus is put on the experimental conditions and requirements of both measurement techniques.
PMCID: PMC3864699  PMID: 24357889
Computed tomography; Color X-ray Camera; pnCCD; Spectral X-ray imaging
3.  Extracorporeally irradiated autografts for the treatment of bone tumours: tips and tricks 
International Orthopaedics  2010;35(6):889-895.
We retrospectively reviewed 107 patients with 108 malignant or locally aggressive bone tumours treated between 1978 and 2009 by extracorporeal irradiation with 300 Gy to eradicate the tumour, and reimplantation of the bone as an orthotopic autograft. Patient subgroups were defined according to resection type. We describe the local recurrence rate, the graft infection rate and the factors affecting graft healing and graft survival. No local recurrences were detected in the irradiated grafts. At five-year follow-up, graft healing had occurred in 64% of patients, providing a stable and lasting reconstruction. For various reasons, 11% of grafts were removed, although no single factor was predictive of failure. All patient subgroups had comparable results. Early infection predicted the development of pseudarthrosis. Pelvic reconstructions had a worse graft survival. Rigid fixation and bridging of the graft appeared to be important technical points.
PMCID: PMC3103959  PMID: 20652247
4.  High-resolution proxies for wood density variations in Terminalia superba 
Annals of Botany  2010;107(2):293-302.
Background and Aims
Density is a crucial variable in forest and wood science and is evaluated by a multitude of methods. Direct gravimetric methods are mostly destructive and time-consuming. Therefore, faster and semi- to non-destructive indirect methods have been developed.
Profiles of wood density variations with a resolution of approx. 50 µm were derived from one-dimensional resistance drillings, two-dimensional neutron scans, and three-dimensional neutron and X-ray scans. All methods were applied on Terminalia superba Engl. & Diels, an African pioneer species which sometimes exhibits a brown heart (limba noir).
Key Results
The use of X-ray tomography combined with a reference material permitted direct estimates of wood density. These X-ray-derived densities overestimated gravimetrically determined densities non-significantly and showed high correlation (linear regression, R2 = 0·995). When comparing X-ray densities with the attenuation coefficients of neutron scans and the amplitude of drilling resistance, a significant linear relation was found with the neutron attenuation coefficient (R2 = 0·986) yet a weak relation with drilling resistance (R2 = 0·243). When density patterns are compared, all three methods are capable of revealing the same trends. Differences are mainly due to the orientation of tree rings and the different characteristics of the indirect methods.
High-resolution X-ray computed tomography is a promising technique for research on wood cores and will be explored further on other temperate and tropical species. Further study on limba noir is necessary to reveal the causes of density variations and to determine how resistance drillings can be further refined.
PMCID: PMC3025726  PMID: 21131386
High-resolution X-ray tomography; neutron imaging; drilling resistance; Terminalia superba; wood density

Results 1-4 (4)