Radiolabeling and initial biological evaluation of [18F]KBM-1 for imaging RAR-α receptors in neuroblastoma

Retinoic acid receptor alpha (RAR-α) plays a significant role in a number of diseases, including neuroblastoma. Children diagnosed with high-risk neuroblastoma are treated 13-cis-retinoic acid, which reduces risk of cancer recurrence. Neuroblastoma cell death is mediated via RAR-α, and expression of RAR-α is upregulated after treatment. A molecular imaging probe that binds RAR-α will help clinicians to diagnose and stratify risk for patients with neuroblastoma, who could benefit from retinoid-based therapy. In this study, we report the radiolabeling, and initial in vivo evaluation of [¹⁸F]KBM-1, a novel RAR-α agonist. The radiochemical synthesis of [¹⁸F]KBM-1 was carried out through KHF₂ assisted substitution of [¹⁸F]^? from aryl-substituted pinacolatoesters-based retinoid precursor. In vitro cell uptake assay in human neuroblastoma cell line showed that the uptake of [¹⁸F]KBM-1 was significantly inhibited by all three blocking agents (KBM-1, ATRA, BD4) at all the selected incubation times. Standard biodistribution in mice bearing neuroblastoma tumors demonstrated increased tumor uptake from 5 min to 60 min post radiotracer injection and the uptake ratios for target to non-target (tumor: muscle) increased 2.2-fold to 3.7-fold from 30 min to 60 min post injection. Tumor uptake in subset of 30 min blocking group was 1.7-fold lower than unblocked. These results demonstrate the potential utility of [¹⁸F]KBM-1 as a RAR-α imaging agent.     

Biocatalyzed esterification of oleic acid using cell suspension and dried biomass of Aspergillus sp. RBD01

Esterification is an industrially important reaction in the field of food and fuel industries. In biofuel and allied industries, long-chain alkyl esters are generally produced from different fat rich feedstocks including non-edible oils, acid oils, and tallow, using a variety of catalysts. Amongst these, whole cell systems have prominently been explored in recent past. The present study focused on the use of Aspergillus sp. RBD01 as a whole cell catalyst, in dry and whole cell suspension, to esterify oleic acid with different alcohols as acyl acceptors. Esterification with dried biomass resulted in better conversion of oleic acid to its respective ester as compared to cell suspension. Further, increase in chain length of alcohol resulted in decrease in the yield from ethyl oleate (98% EO) to decyl oleate (77% DO) with alcohols having an even number of carbon atoms giving better yield of esters over alcohols with odd numbers.     

Application of antimicrobial polypeptide host defenses to aquaculture: Exploitation of downregulation and upregulation responses

Antimicrobial polypeptides (AMPPs), consisting of peptides and small proteins with antimicrobial activity, are an integral component of innate immunity. Their often potent properties and widespread prevalence in fish suggests that designing means of manipulating their levels has considerable potential for maintaining or improving fish health. There is evidence that a number of chronic stresses lead to significant downregulation of AMPPs and thus their monitoring could be a highly sensitive measure of health status and risk of an infectious disease outbreak. Conversely, upregulation of AMPP expression could be used to enhance disease resistance in stressful environments, as well as improve the efficacy of traditional antimicrobial drugs. However, further work is required in linking levels of a number of AMPPs to physiological function since, while a number of studies have documented the down- or upregulation of AMPPs via gene expression, relatively few studies have quantitatively examined changes in protein expression. In addition, not all AMPPs appear to be expressed at microbicidal levels in vivo, suggesting that at least some may have functions other than being directly protective. Nonetheless, in fish, there is evidence that some constitutively expressed AMPPs, such as piscidins and histone-like proteins, are expressed at microbicidal levels and that they decline with stress. Furthermore, certain AMPPs derived from hemoglobin-β are upregulated to microbicidal levels after experimental challenge. The likely widespread distribution of these three AMPP groups in fish provides the opportunity to design strategies to greatly improve the health of cultured fish populations.     

Moving Cell Boundaries Drive Nuclear Shaping during Cell Spreading

The nucleus has a smooth, regular appearance in normal cells, and its shape is greatly altered in human pathologies. Yet, how the cell establishes nuclear shape is not well understood. We imaged the dynamics of nuclear shaping in NIH3T3 fibroblasts. Nuclei translated toward the substratum and began flattening during the early stages of cell spreading. Initially, nuclear height and width correlated with the degree of cell spreading, but over time, reached steady-state values even as the cell continued to spread. Actomyosin activity, actomyosin bundles, microtubules, and intermediate filaments, as well as the LINC complex, were all dispensable for nuclear flattening as long as the cell could spread. Inhibition of actin polymerization as well as myosin light chain kinase with the drug ML7 limited both the initial spreading of cells and flattening of nuclei, and for well-spread cells, inhibition of myosin-II ATPase with the drug blebbistatin decreased cell spreading with associated nuclear rounding. Together, these results show that cell spreading is necessary and sufficient to drive nuclear flattening under a wide range of conditions, including in the presence or absence of myosin activity. To explain this observation, we propose a computational model for nuclear and cell mechanics that shows how frictional transmission of stress from the moving cell boundaries to the nuclear surface shapes the nucleus during early cell spreading. Our results point to a surprisingly simple mechanical system in cells for establishing nuclear shapes.