Dispersion and monochromatization of x-rays using a beryllium prism.

We demonstrate experimentally and numerically that an x-ray prism made of beryllium can be used to disperse and monochromatize x-rays. A polished beryllium cuboid was employed as refractive and dispersive optics. The results of a proof-of-principle experiment and methods of performance optimization are presented. The spatial separation of undulator harmonics and their subsequent selection using a slit are described. A numerical study, assuming realistic beam and beamline parameters, suggests that undulator harmonics can be spatially separated in the range from 3 keV to beyond 20 keV, while maintaining throughput above 50%. Refractive optics is particularly suitable for low-repetition-rate sources such as free-electron lasers and other LINAC-based short-pulse sources.

Perceptions of participating in high-intensity functional exercise among older people dependent in activities of daily living (ADL).

The purpose of the study was to evaluate how older people, dependent in ADL perceive their participation in a high-intensity, functional exercise program compared to the perceptions of those participating in a control activity. Forty-eight older people living in residential care facilities answered a questionnaire about their perceptions of participating in an activity for three months. They were aged 65-98, had a mean score of 24 on Mini Mental State Examination (MMSE) and 14 on Barthel ADL Index. The participants had been randomized to exercise (n=20) or control activity (n=28). Differences in responses between exercise and control activity were evaluated using logistic and ordinal regression analyses. The results show that a majority of the exercise group perceived positive changes in lower limb strength, balance, and in the ability to move more safely and securely compared to a minority of the control group (p<0.001). Significantly more respondents in the exercise activity answered that they felt less tired due to the activity (p=0.027) and that they prioritized this activity above other activities (p=0.010). More exercise participants reported that meeting for three months was too short, and fewer that it was too long compared to the control group (p=0.038). This study shows that older people living in residential care facilities, dependent in ADL, and with mild or no cognitive impairment had positive perceptions about participating in high-intensity functional exercise. The findings support the use of a high-intensity exercise program in this population of older people.

Osteopontin functionalization of hydroxyapatite nanoparticles in a PDLLA matrix promotes bone formation.

We studied the osteoconductive tissue response of hydroxyapatite (HA) nanoparticles functionalized with osteopontin (OPN) in a matrix of poly-D,L-lactic-acid (PDLLA). In a canine endosseus 0.75-mm gap implant model, we tested the osteointegrative impact of the OPN functionalized composite as an implant coating, and a non-functionalized composite was used as reference control. During the four weeks of observation, the OPN functionalized composite coating significantly increased the formation of new bone in the porosities of the implant, but no differences were observed in the gap. The study provides evidence of its potential use either alone or in combination with other osteoconductive compounds.

Can sites prone to flow induced vascular complications in a-v fistulas be assessed using computational fluid dynamics?

Arterio-venous fistulas (shunts between arteries and veins) are the preferred vascular access for hemodialysis. Despite their superior patency, compared with synthetic tubes and grafts, functional problems and inadequate flow rates are the common complications. Local flow conditions, in particular low and oscillating wall shear stresses (WSS), are central to vascular problems and a robust framework for analyzing flow conditions in vascular structures could provide an understanding of the mechanisms leading to vascular complications, such as stenoses, aneurisms, and thromboses. We hypothesize that a validated computational fluid dynamics (CFD) framework can be used to identify critical fistula configurations with elevated risk of complications. Therefore, the aim of the present study was to develop a CFD framework for analyzing fluid flow in complex vascular structures, such as arterio-venous fistulas validated by comparisons of in vitro volume flows with CFD results and flow fields from ultrasound scans with CFD simulations. Volume flows measured in vitro and CFD data differed quantitatively. However, good relative correlations exist between the data using logarithmic scales. Qualitatively, visual comparisons between ultrasound and CFD images showed good agreement between the two methods. In addition, WSS levels and the oscillatory shear index (OSI) were calculated and visualized on the model surface. The method was successfully validated and the method is deemed suitable for more thorough investigations into the field of vascular complications in a-v fistulas.

Investigation of particle-functionalized tissue engineering scaffolds using X-ray tomographic microscopy.

A low-density, porous chitosan/poly-(dl-lactide-co-glycolide) (PLGA) microparticle composite scaffold was produced by thermally induced phase separation followed by lyophilization, to provide a bicontinuous microstructure potentially suitable for tissue engineering and locally controlled drug release. PLGA particles were mixed into the chitosan solution and subsequent phase separation during chitosan solidification forced PLGA particles into chitosan phase (Plateau borders). The distributions of volume, surface area, and elongation of 15,422 inclusions of agglomerated PLGA particles were calculated and approximated with log-normal distribution functions from nanotomography reconstructions. Cluster analysis revealed a homogenous inclusion distribution throughout the scaffold. The spatial location and orientation of individual inclusions within the Plateau borders of the scaffold were determined and from these the nearest-neighbor inter-inclusion distance distribution calculated, showing a mean of 2.5 microm. The depth of the inclusions in Plateau borders peaks at 700 or 125 nm, respectively, indicating a step-wise drug release from inclusions successively exposed during scaffold decomposition. Particle diameter ranged from 400 nm to 3 microm and inclusion Feret lengths ranged from 800 nm to 12 microm. These findings on composite morphology and distribution of inclusions are fundamental for predicting scaffold deterioration and particle-mediated drug release during ex vivo and in vivo cell cultivation.

Batch accuracy of on-line fat determination.

A new method for determination of the fat content of large meat batches without sampling is presented. It is based on dual-energy X-ray (DXR) scanning of meat trimmings prior to mixing, in order to determine the exact fat content of the resulting meat batch. Twenty-seven samples of three types of pork trimmings with a fat content ranging from 24 to 63% were collected and combined into batch sizes of 27-241 kg. At small batch sizes (27 kg) the nature of the measurement error is mainly random, resulting in a prediction error (root mean square error of prediction) of 0.57% against the reference method. At a batch size of 241 kg the error was reduced to 0.34%. The DXR method determines the fat content of all meat in a batch without any sampling required, thus reducing the sampling error to a minimum. This is essential, as the results show that the sampling error is large: when 27-kg samples were homogenized and measured by the reference method, the standard deviation of high-fat samples was 4.7%.

Inhibition of human cytomegalovirus UL80 protease by specific intramolecular disulfide bond formation.

A symmetrically substituted disulfide compound, CL13933, was identified as a potent inhibitor of human cytomegalovirus UL80 protease. Two types of inhibited protease were observed, depending on inhibitor concentration. At high concentrations, CL13933 formed a covalent adduct with the protease on Cys residues. At lower concentrations, this compound induced specific intramolecular disulfide formation between Cys84 and Cys87, and between Cys138 and Cys161. In contrast, Cys202 did not form disulfide bonds. Inhibition was reversed upon reduction of the protease. Each of the five cysteines of the UL80 protease was individually mutated to Ala. Each of the mutant proteases retained enzymatic activity, but mutants C138A and C161A were resistant to inhibition by CL13933, suggesting that disulfide bond formation between Cys138 and Cys161 is responsible for inhibition. This disulfide is apparently not induced by air oxidation. Examination of the CL13933 loading patterns of wild type and the five mutant proteases by mass spectrometry revealed that residues Cys87, Cys138, and Cys161 react with CL13933, and that the disulfide pair partner of each (Cys84, Cys161, and Cys138, respectively) is able to displace the compound via thiol-disulfide exchange. The possible significance of these reactive thiols in the protease is discussed.

Anorexia nervosa. Treatment and triggering factors.

In the period from 1976 to 1983, 84 anorexia nervosa (AN) patients were treated in the Medical and Child Psychiatry Units of the University Hospital of Bergen. Five were men, 79 women. The criteria used for diagnosis are DSM-III (1) A,B,D and E, but not C. All the patients in this study were treated according to the methods of Bassøe & Eskeland (2) and Bassøe (3) in order to give the patients the necessary insight into the pathophysiology of hunger and to inform them about the symptoms. Those of the patients with personal problems connected with their family or social milieu were given help through therapeutic discussions. However, we stressed that very sick patients should not be put under any pressure to undergo this treatment. I will describe the treatment we employed and the results obtained. It was found to be of great importance that the patients received treatment in the early stages of the condition. Also that the patient, as a part of the prophylaxis of the condition, was informed about the dangers of slimming. A short survey of other methods of treatment found in the literature is given. My conclusion is that AN is triggered by a combination of genetic disposition plus some kind of stress followed by a primary weightloss.