Comparison of [18F] NaF PET/CT dynamic analysis methods and a static analysis method including derivation of a semi-population input function for site-specific measurements of bone formation in a population with chronic kidney disease-mineral and bone disorder

Purpose The purpose of this study is to compare dynamic and static whole-body (WB) [18F]NaF PET/CT scan methods used for analysis of bone plasma clearance in patients with chronic kidney disease-mineral and bone disorder (CKD-MBD). Methods Seventeen patients with CKD-MBD underwent a 60-min dynamic scan followed by a 30-min static WB scan. Tracer kinetics in four thoracic vertebrae were analysed using nonlinear regression and Patlak analysis using image-derived arterial input functions. The static WB scan was analysed using a simplified Patlak method requiring only a single data point in combination with a fixed y-intercept value (V0), both obtained using a semi-population function. The semi-population function was constructed by combining a previously derived population input function in combination with data from venous blood samples. Static WB scan analysis data, obtained from the semi-population input functions, was compared with paired data obtained using dynamic input functions. Results Bone plasma clearance (Ki) from Patlak analyses correlated well with nonlinear regression analysis, but Ki results using Patlak analysis were lower than Ki results using nonlinear regression analysis. However, no significant difference was found between Ki obtained by static WB scans and Ki obtained by dynamic scans using nonlinear regression analysis (p = 0.29). Conclusion Bone plasma clearance measured from static WB scans correlates with clearance data measured by dynamic analysis. Static [18F]NaF PET/CT scans can be applied in future studies to measure Ki in patients with CKD-MBD, but the results should not be compared uncritically with results obtained by dynamic scan analysis.

Dissecting the NK Cell Population in Hematological Cancers Confirms the Presence of Tumor Cells and their Impact on NK Population Function

Natural killer (NK) cells are part of the innate immune system, protects against pathogens and tumor cells and are the main cell effectors of monoclonal antibodies (mAbs) generating antibody-dependent cell cytotoxicity (ADCC). Hence it is relevant to understand NK physiology and status to investigate the biological effect of mAbs in the clinic. The presence of viral-sculpted NK cell populations has already been described, but the presence of cancer-sculpted NK remains unknown. Cancer induces a broad NK cell dysfunction. We investigated the NK cell population by Uniform Manifold Approximation and Projection (UMAP) embed maps in Hodgkin lymphoma (HL) and acute myeloid leukemia (AML) patients at diagnosis and at least 30 days after treatment, which correlates with tumor cell clearance. The NK lineage largely responded to the tumor by generating antitumor NK cells and renewing the population with a subset of immature NK cells. However, we failed to identify specific “memory-like” subsets. Moreover, in patients in relapse we found essentially the same NK populations that at diagnostic, suggesting that NK cells equally respond to the first or second tumor rise. Finally, previous CMV infection largely affects tumor-associated changes in NK population, but the CMV-associated CD57+NKG2C+ NKs do not appear to play any role in tumor immunity.

Heterogeneity and ‘memory’ in stem cell populations

ABSTRACTModern single cell experiments have revealed unexpected heterogeneity in apparently functionally ‘pure’ cell populations. However, we are still lacking a conceptual framework to understand this heterogeneity. Here, we propose that cellular memories – the ability of individual cells to record their developmental past and adapt their response to their environment accordingly – are an essential ingredient in any such theory. We illustrate this idea by considering a simple age-structured model of stem cell proliferation. Using this model we argue that heterogeneity is central to stem cell population function, and memories naturally explain why stem cell numbers increase through life, yet regenerative potency simultaneously declines.

ESTROGENS AND BRAIN

Recent data upon molecular mechanisms of pleiotropic action of estrogens in human brain is presented in the article. Given detailed descriptions of properties of classical and membrane bound estradiol receptors, that maintain gene expression regulation, modulation of neurotransmittent systems and signal cascade activation in neuronal cells. Data upon regional distribution of estradiol receptor subtypes in the brain, their participation in main cell population function control (including progenitor cells) is given. Special attention is paid to estrogen participation in neurogenesis, inflammation and apoptosis regulation in central nervous system; in the control of formation and functioning of cerebral vessels.