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Background and purpose: At high altitude the brain is exposed to hypoxic stress, which may result in neurological conditions, with acute mountain sickness (AMS) being the most common. We aimed to test the hypothesis that rapid ascent to high altitude alters neuro‐axonal integrity, which can be detected by increased concentration of serum neurofilament light (sNfL) in the blood and may even be exaggerated in people with AMS. Methods: Serum neurofilament light was measured using a single‐molecule array (Simoa, Quanterix, Lexington, MA, USA) assay at low altitude (423 m) in 47 healthy study participants and 44 h after rapid and active ascent to high altitude (4559 m). Peripheral oxygen saturation (SpO2) and partial pressures of oxygen (pO2) were obtained at low and high altitude. The Acute Mountain Sickness‐Cerebral (AMS‐C) scoring system was used to assess AMS incidence and AMS severity. Results: There was an increase in sNfL from its baseline value compared with its value at high altitude (6.34 ± 1.96 vs. 7.19 ± 3.14 pg/ml; p = 0.014), but sNfL level did not correlate with SpO2 (r = −0.19; p = 0.066) or pO2 (r = −0.19; p = 0.068). The incidence of AMS at high altitude was 62%. Neither at low altitude (p = 0.706) nor at high altitude (p = 0.985) was there a difference in sNfL between participants with and without AMS as measured 3 days after rapid ascent and 44 h of high‐altitude exposure. Altitude sNfL did not correlate with AMS‐C, either overall or with single‐item scores such as headache severity. Conclusions: Rapid ascent of healthy people to high altitude provokes an increase in sNfL 44 h after arrival at 4559 m, which is not related to the magnitude of hypoxemia or AMS incidence and severity, suggesting that neuro‐axonal injury does not directly contribute to AMS. [ABSTRACT FROM AUTHOR]

Abstract: Nanoparticles, especially from carbon, have great potential in biomedicine. However, prior to clinical use, biocompatibility and biodistribution of these nanoobjects have to be assessed. Currently, particle detection is mostly based on surface‐bound labels, inevitably altering materials' properties by surface modification. Further obstacles include bleaching, dissociation of labels from the surface, weak emission of fluorophores due to insufficient tissue opacity or hampered light penetration or the need for specific excitation wavelengths. These characteristics greatly constrain employment of such nanoparticles to address complex analytical questions. To overcome these drawbacks, the use of intrinsic structural features of nanoobjects is highly desirable: the particle surface remains unchanged and the nanoobject exhibits its innate behavior. Thus, for sensitive detection and quantification, labels should be incorporated in the nanoparticle core, thereby avoiding cleavage and warranting unchanged surface characteristics. The incorporation of clinically approved radionuclide 32P into the lattice of nanodiamond particles using highly defined ion implantation is described here. The properties, uptake, and biodistribution are studied in vivo, in the developing hen's egg model (hen's egg test on chorioallantoic membrane assay). It is found that 32P labeling of diamond nanoparticles allows their reliable localization and sensitive quantification in a cost efficient, highly reliable, and safe way using available autoradiographic devices and analytical methods. [ABSTRACT FROM AUTHOR]

Irradiation impacts on the viability and differentiation capacity of tissue-borne mesenchymal stem cells (MSC), which play a pivotal role in bone regeneration. As a consequence of radiotherapy, bones may develop osteoradionecrosis. When irradiating human bone-derived MSC in vitro with increasing doses, the cells' self-renewal capabilities were greatly reduced. Mitotically stalled cells were still capable of differentiating into osteoblasts and pre-adipocytes. As a large animal model comparable to the clinical situation, pig mandibles were subjected to fractionized radiation of 2 χ 9 Gy within 1 week. This treatment mimics that of a standardized clinical treatment regimen of head and neck cancer patients irradiated 30 χ 2 Gy. In the pig model, fractures which had been irradiated, showed delayed osseous healing. When isolating MSC at different time points post-irradiation, no significant changes regarding proliferation capacity and osteogenic differentiation potential became apparent. Therefore, pig mandibles were irradiated with a single dose of either 9 or 18 Gy in vivo, and MSC were isolated immediately afterwards. No significant differences between the untreated and 9 Gy irradiated bone with respect to proliferation and osteogenic differentiation were unveiled. Yet, cells isolated from 18 Gy irradiated specimens exhibited a reduced osteogenic differentiation capacity, and during the first 2 weeks proliferation rates were greatly diminished. Thereafter, cells recovered and showed normal proliferation behaviour. These findings imply that MSC can effectively cope with irradiation up to high doses in vivo. This finding should thus be implemented in future therapeutic concepts to protect regenerating tissue from radiation consequences. [ABSTRACT FROM AUTHOR]