Guido Kühne

Identification of the End Stage of Scrapie Using Infected Neural Grafts

Although the formal pathogenesis of spongiform encephalopathies has been described in detail, it is not known whether the infectious agent targets primarily neurons, glial cells, or both. To address this question, we have transplanted transgenic embryonic neural tissue overexpressing PrPc into the forebrain of Prnp ‐knockout mice, and infected it with scrapie prions. After infection, grafts developed severe spongiform encephalopathy. As the infected hosts were not clinically affected, we were able to prolong the experiment and to assess changes in the graft over periods of time, which vastly exceeded the normal life span of scrapie‐infected mice. Sequential contrast‐enhanced magnetic resonance imaging (MRI) revealed progressive impairment of blood‐brain barrier properties in infected grafts. However, loss of astrocytes was not observed. Subtotal neuronal loss occurred during the progression of the disease in the grafts, reactive astrocytes persisted until the terminal stage of disease. We conclude that scrapie encephalopathy primarily leads to neuronal death, while degeneration of astrocytes does not occur. Functional impairment of the blood‐brain barrier suggests involvement of astrocytes and endothelial cells in the pathological process.

New features in cold neutron radiography and tomography Part I: thinner scintillators and a neutron velocity selector to improve the spatial resolution

Abstract The tomography setup developed at the PGA facility of the Swiss spallation source SINQ has provided encouraging results in the field of cold neutron imaging. Performances of the detection system based on a CCD camera and a converter screen have been recently improved using 6 LiF/ZnS:Ag scintillators with different thickness. Indeed, reducing the layer of the scintillator improved considerably the spatial resolution while keeping a reasonable efficiency. Furthermore, a neutron velocity selector was temporarily added to the setup to perform radiography and tomography experiments with monochromatic neutron beams. Basic properties of transmitted beams were studied to assess the applicability of this device in neutron imaging. Of interest was the enhancement of the L / D -ratio by selecting neutron beams of short wavelengths. Cold neutron tomography demonstrated to be a useful technique in various spheres of activity, such as aerospatial industry or radioactive waste storage. Various applications of the neutron velocity selector are described in the second part, namely, New features in cold neutron radiography and tomography—Part II: Applied energy-selective neutron radiography and tomography.

Resynthesis of muscle glycogen after soccer specific performance examined by 13C-magnetic resonance spectroscopy in elite players

Abstract. The purpose of this study was to examine using 13C-magnetic resonance spectroscopy whether muscle glycogen (Gly) utilized during a simulation of a fatiguing soccer match followed by repeated sprints would be resynthesized during the next 24xa0h while players consumed their habitual diet. A group of 12xa0elite young players [mean age 17.5xa0(SDxa00.8)xa0years, mean body mass 68.9xa0(SDxa06.6)xa0kg, mean height 177.0xa0(SDxa05.4)xa0cm] participated in the study. Average muscle Gly content before the simulation was 134xa0(SDxa016)xa0mmol·(kg wet mass)–1 and decreased during the test (P<0.001) to 80xa0(SDxa029)xa0mmol·(kg wet mass)–1. The value had increased (P<0.01) to 122xa0(SDxa033)xa0mmol·(kg wet mass)–1 24xa0h later but it was not significantly different from the value obtained before the soccer test. Dietary analysis of the food intake during the 24xa0h after the running test revealed that players consumed an average of 2,681xa0(SDxa0970)xa0kcal·day–1. Mean daily protein, fat, and carbohydrate (CHO) intakes were 85xa0(SDxa029), 99xa0(SDxa044), and 327xa0(SDxa0116)xa0g, respectively. The mean amounts of CHO intake normalised to body mass were 4.8xa0(SDxa01.8)xa0g·(kg body mass)–1. In conclusion, the results of this study showed that despite a CHO intake of less than 5xa0g·(kg body mass)–1 the habitual diet of soccer players might be sufficient to replenish in 24xa0h the muscle Gly utilized during soccer specific performance. However, cumulative deficits of about 10% in Gly replenishment as found in the present study might provoke decrements in performance. Thus, players should pay attention to their habitual diets and add more carbohydrates to replenish their daily deficits and perhaps increase their basal levels of intake.

Material inspections by different methods of neutron radiography-specific problem solutions

This paper gives an overview about the investigation of technical objects and processes by different neutron radiography methods in order to solve several tasks and problems nondestructively. It is important to mention that for each problem, the approach was tried which seemed to be best suited. This was possible due to the high flexibility in respect to variable beam conditions at the NEUTRA and the NCR stations at SINQ and the different detection methods available. In some cases, the limitations of neutron imaging were reached, caused by too low transmission through the objects or missing sensitivity to certain materials. The comparison and the complementaries to conventional X-ray techniques can complete the inspection of objects in some special cases by parallel application.

Creatine feeding does not enhance intramyocellular glycogen concentration during carbohydrate loading: an in vivo study by31P-and13C-MRS

The main aim of this study was to examine the hypothesis that creatine (Cr) feeding enhances myocellular glycogen storage in humans undergoing carbohydrate loading. Twenty trained male subjects were randomly assigned to have their diets supplemented daily with 252 g of glucose polymer (GP) and either 21 g of Cr (CRGP, n=10) or placebo (PL-GP, n=10) for 5 days. Changes in resting myocellular glycogen and phosphocreatine (PCr) were determined with Magnetic Resonance Spectroscopy (13C- and31P-MRS, respectively). After CR-GP, the levels of intramyocellular glycogen increased from 147±13 (standard error) mmol·(kg wet weight)−1) to 182±17 mmol·(kg wet weight)−1, while it increased from 134±17 mmol·(kg wet weight)− to 182±17 mmol·(kg wet weight)−1 after PL-GP; the increments in intramyocellular glycogen concentrations were not statistically different. The increment in the PCr/ATP ratio after CR-GP (+0.20±0.12) was significantly different compared to PL-GP (−0.34±0.16) (p<0.05). The present results do not support the hypothesis that Cr loading increases muscle glycogen storage.ResumenEl principal objetivo de este estudio fue examinar la hipótesis que la suplementación con creatina (Cr) aumenta la concentración de glucógeno intramiocelular en humanos durante un periodo de ingesta elevada de hídratos de carbono. Veinte hombres entrenados fueron asignados de manera randomizada a dietas suplementadas diariamente con 252 g de polímeros de glucosa (GP) y bien 21 g de Cr (CR-GP, n=10) o placebo (PL-GP, n=10) durante 5 días. Los cambios en los níveles de glucógeno intramiocelular, y fosfocreatina (PCr) y ATP fueron determinados en reposo con Espectroscopía de Resonancia Magnética (13C-and31PMRS, respectivamente). Despues de CR-GP, Los níveles de glucógeno incrementaron desde 147±13 (error standard) mmol·(kg peso húmedo−1) a 172±13 mmol·(kg peso húmedo1), mientras incrementó desde 134±17 mmol·(kg peso húmedo−1) a 182±17 mmol·(kg peso húmedo−1) despues de PL-GP; los incrementos en la concentración de glucógeno intramiocelular en CR-GP y PL-GP no fueron estadisticamente diferentes. El incremento en el cociente PCr/ATP después de CR-GP (+0.20±0.12) fue estadisticamente diferente comparado con el cambio después de PL-GP (−0.34±0.16) (p<0.05). Los resultados no apoyan la hipótesis de que la creatina incrementa la concentración de glucógeno intramiocelular.