Aggregation‐induced changes in the chemical exchange saturation transfer (CEST) signals of proteins

Chemical exchange saturation transfer (CEST) is an MRI technique that allows mapping of biomolecules (small metabolites, proteins) with nearly the sensitivity of conventional water proton MRI. In living organisms, several tissue‐specific CEST effects have been observed and successfully applied to diagnostic imaging. In these studies, particularly the signals of proteins showed a distinct correlation with pathological changes. However, as CEST effects depend on various properties that determine and affect the chemical exchange processes, the origins of the observed signal changes remain to be understood. In this study, protein aggregation was identified as an additional process that is encoded in the CEST signals of proteins. Investigation of distinct proteins that are involved in pathological disorders, namely amyloid beta and huntingtin, revealed a significant decrease of all protein CEST signals upon controlled aggregation. This finding is of particular interest with regard to diagnostic imaging of patients with neurodegenerative diseases that involve amyloidogenesis, such as Alzheimer's or Huntington's disease. To investigate whether the observed CEST signal decrease also occurs in heterogeneous mixtures of aggregated cellular proteins, and thus prospectively in tissue, heat‐shocked yeast cell lysates were employed. Additionally, investigation of different cell compartments verified the assignment of the protein CEST signals to the soluble part of the proteome. The results of in vitro experiments demonstrate that aggregation affects the CEST signals of proteins. This observation can enable hypotheses for CEST imaging as a non‐invasive diagnostic tool for monitoring pathological alterations of the proteome in vivo.     

How the human brain exchanges information across sensory modalities to recognize other people

Recognizing the identity of other individuals across different sensory modalities is critical for successful social interaction. In the human brain, face‐ and voice‐sensitive areas are separate, but structurally connected. What kind of information is exchanged between these specialized areas during cross‐modal recognition of other individuals is currently unclear. For faces, specific areas are sensitive to identity and to physical properties. It is an open question whether voices activate representations of face identity or physical facial properties in these areas. To address this question, we used functional magnetic resonance imaging in humans and a voice‐face priming design. In this design, familiar voices were followed by morphed faces that matched or mismatched with respect to identity or physical properties. The results showed that responses in face‐sensitive regions were modulated when face identity or physical properties did not match to the preceding voice. The strength of this mismatch signal depended on the level of certainty the participant had about the voice identity. This suggests that both identity and physical property information was provided by the voice to face areas. The activity and connectivity profiles differed between face‐sensitive areas: (i) the occipital face area seemed to receive information about both physical properties and identity, (ii) the fusiform face area seemed to receive identity, and (iii) the anterior temporal lobe seemed to receive predominantly identity information from the voice. We interpret these results within a prediction coding scheme in which both identity and physical property information is used across sensory modalities to recognize individuals. Hum Brain Mapp, 36:324–339, 2015. © 2014 Wiley Periodicals, Inc .     

Impingement-Chirurgie als Prävention der Koxarthrose?

Premature bone to bone contact of the hip during joint motion is known as femoroacetabular impingement (FAI). The differentiation of the reason for this premature contact can be found in the zone between the femoral head and neck and is called Cam FAI. Acetabular irregularities can lead to a phenomenon known as Pincer impingement. Overlapping of these morphologies is frequent. The presence of FAI can lead to progressive damage to the acetabular labrum and adjacent hyaline cartilage and is discussed as a risk factor for early osteoarthritis of the hips. Various conservative and operative treatment procedures are discussed in the current literature. Surgical treatment includes the correction of the impingement cause as well as addressing concomitant pathologies. Whether impingement surgery can be considered for prevention of the emergence of osteoarthritis is discussed in this article with reference to the relevant literature. Recently published clinical studies indicate that surgery might be used as a preventive measure for osteoarthritis but the final evidence does not currently exist.