Fat and bone: the multiperspective analysis of a close relationship

The study of bone has for many years been focused on the study of its mineralized component, and one of the main objects of study as radiology developed as a medical specialty. The assessment has until recently been almost limited to its role as principal component of the scaffolding of the human body. Bone is a very active tissue, in continuous cross-talk with other organs and systems, with functions that are endocrine and paracrine and that have an important involvement in metabolism, ageing and health in general. Bone is also the continent for the bone marrow, in the form of "yellow marrow" (mainly adipocytes) or "red marrow" (hematopoietic cells and adipocytes). Recently, numerous studies have focused on these adipocytes contained in the bone marrow, often referred to as marrow adipose tissue (MAT). Bone marrow adipocytes do not only work as storage tissue, but are also endocrine and paracrine cells, with the potential to contribute to local bone homeostasis and systemic metabolism. Many metabolic disorders (osteoporosis, obesity, diabetes) have a complex and still not well-established relationship with MAT. The development of imaging methods, in particular the development of cross-sectional imaging has helped us to understand how much more laid beyond our classical way to look at bone. The impact on the mineralized component of bone in some cases (e.g., osteoporosis) is well-established, and has been extensively analyzed and quantified through different radiological methods. The application of advanced magnetic resonance techniques has unlocked the possibility to access the detailed study, characterization and quantification of the bone marrow components in a non-invasive way. In this review, we will address what is the evidence on the physiological role of MAT in normal skeletal health (interaction with the other bone components), during the process of normal aging and in the context of some metabolic disorders, highlighting the role that imaging methods play in helping with quantification and diagnosis.

Nystatin antifungal micellar systems on endotracheal tubes: development, characterization and in vitro evaluation

Decontamination of patients' clinical devices in intensive care units is generally performed with an antifungal suspension. Nystatin is a widely-used high spectrum antifungal due to its low systemic absorption. However, nystatin has high hydrophobicity which hinders the contact with the internal lumen of the devices. In this work, hydrophilic micellar systems of nystatin were developed with sodium deoxycholate on silicone endotracheal tubes. The physical characteristics of the micellar system at different nystatin:deoxycholate ratios were studied using scanning electron microscopy, X-ray powder diffraction and differential scanning calorimetry. The electron microscopy results reveal that the deoxycholate micellar system altered the surface morphology, and the size of the aggregates was observed to be smaller. The hydrophilic structures of deoxycholate produce systems with a high surface area containing nystatin molecules on their interior. The X-ray and differential scanning calorimetry assays revealed a typical change in the crystallinity of micellar systems when the deoxycholate proportion increases. The endothermic peak of nystatin was not observed in the micellar systems as a consequence of the reduced crystallinity. Nystatin was homogenously dispersed in the surfactant matrix. Micellar systems with 1:0.8 nystatin:deoxycholate ratio (MS-N:DC [1:0.8]) showed increased antifungal activity compared to nystatin raw material. Micellar systems also achieved an over 40% inhibition of Candida albicans biofilm formation. The results obtained in this study conclude that the higher hydrophilic characteristic of the surfactant deoxycholate enhances nystatin penetration into the surface of the endotracheal tubes.

Imaging of Bone Marrow: From Science to Practice

The study of the bone marrow may pose important challenges, due to its changing features over the life span, metabolic stress, and in cases of disease or treatment. Bone marrow adipocytes serve as storage tissue, but they also have endocrine and paracrine functions, contributing to local and systemic metabolism.Among different techniques, magnetic resonance (MR) has the benefit of imaging bone marrow directly. The use of advanced MR techniques for bone marrow study has rapidly found clinical applications. Beyond the clinical uses, it has opened up pathways to assess and quantify bone marrow components, establishing the groundwork for further study of its implications in physiologic and pathologic conditions.We summarize the features of the bone marrow as an organ, address the different modalities available for its study, with a special focus on MR advanced techniques and their addition to analysis in recent years, and review some of the challenges in interpreting the appearance of bone marrow.