Microscopy and Mass Spectrometry Imaging Reveals the Distributions of Curcumin Species in Dried Turmeric Root

Plants contain many secondary metabolites, which are sometimes used as spices and herbal medicines. However, the three-dimensional distribution of metabolites is usually unknown. In this study, the spatial distribution of curcumin, one of the main components of dried turmeric root, was examined. Because dried turmeric samples are extremely hard and impossible to section with existing cryomicrotomes, we introduced a new sectioning method and analyzed the two-dimensional distribution of curcumin in turmeric sections cut in different directions. The geometrical analysis of the imaging results suggested that curcumin forms tubular components inside turmeric. The wide-target analysis showed that the spatial distribution of curcumin analogues was similar to that of curcumin. Thus, mass spectrometry imaging was successfully implemented for clarifying the distribution of secondary metabolites in dry plant samples. Understanding the distribution of metabolites inside the plant body might contribute to improving their production processes, including the methods for extraction of active ingredients.

How bold is blood oxygenation level-dependent (BOLD) magnetic resonance imaging of the kidney? Opportunities, challenges and future directions

Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. Yet, in vivo assessment of renal haemodynamics and tissue oxygenation remains a challenge. Many of the established approaches are invasive, hence not applicable in humans. Blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) offers an alternative. BOLD-MRI is non-invasive and indicative of renal tissue oxygenation. Nonetheless, recent (pre-) clinical studies revived the question as to how bold renal BOLD-MRI really is. This review aimed to deliver some answers. It is designed to inspire the renal physiology, nephrology and imaging communities to foster explorations into the assessment of renal oxygenation and haemodynamics by exploiting the powers of MRI. For this purpose, the specifics of renal oxygenation and perfusion are outlined. The fundamentals of BOLD-MRI are summarized. The link between tissue oxygenation and the oxygenation-sensitive MR biomarker T2∗ is outlined. The merits and limitations of renal BOLD-MRI in animal and human studies are surveyed together with their clinical implications. Explorations into detailing the relation between renal T2∗ and renal tissue partial pressure of oxygen (pO2 ) are discussed with a focus on factors confounding the T2∗ vs. tissue pO2 relation. Multi-modality in vivo approaches suitable for detailing the role of the confounding factors that govern T2∗ are considered. A schematic approach describing the link between renal perfusion, oxygenation, tissue compartments and renal T2∗ is proposed. Future directions of MRI assessment of renal oxygenation and perfusion are explored.