Cancer nanotherapeutics are rapidly progressing and are being implemented to solve several limitations of conventional drug delivery systems such as nonspecific biodistribution and targeting, lack of water solubility, poor oral bioavailability, and low therapeutic indices. To improve the biodistribution of cancer drugs, nanoparticles have been designed for optimal size and surface characteristics to increase their circulation time in the bloodstream. They are also able to carry their loaded active drugs to cancer cells by selectively using the unique pathophysiology of tumors, such as their enhanced permeability and retention effect and the tumor microenvironment. In addition to this passive targeting mechanism, active targeting strategies using ligands or antibodies directed against selected tumor targets amplify the specificity of these therapeutic nanoparticles. Drug resistance, another obstacle that impedes the efficacy of both molecularly targeted and conventional chemotherapeutic agents, might also be overcome, or at least reduced, using nanoparticles. Nanoparticles have the ability to accumulate in cells without being recognized by P-glycoprotein, one of the main mediators of multidrug resistance, resulting in the increased intracellular concentration of drugs. Multifunctional and multiplex nanoparticles are now being actively investigated and are on the horizon as the next generation of nanoparticles, facilitating personalized and tailored cancer treatment.

https://clincancerres.aacrjournals.org/content/clincanres/14/5/1310.full.pdf

Therapeutic Nanoparticles for Drug Delivery in Cancer

Magnetic Nanoparticles in MR Imaging and Drug Delivery

This article reviews the requirements for successful compressed sensing (CS), describes their natural fit to MRI, and gives examples of four interesting applications of CS in MRI. The authors emphasize on an intuitive understanding of CS by describing the CS reconstruction as a process of interference cancellation. There is also an emphasis on the understanding of the driving factors in applications, including limitations imposed by MRI hardware, by the characteristics of different types of images, and by clinical concerns.

/pdf/compressed-sensing-mri-2wgw41cvre.pdf

Compressed Sensing MRI

Optogenetics in neural systems.

Repeated hippocampal seizures lead to brain-wide reorganization of circuits and seizure propagation pathways.

Imaging time using PILS is reduced by using multiple coils with localized sensitivities with each coil having a separate demodulation channel thereby permitting parallel signal processing and image reconstruction. Images from the multiple coils are then combined to form an image with a larger field of view (FOV).

Multi-coil reconstruction of MRI signals using linear phase multiplied data with separate demodulators for each coil

High-sensitivity detection of optogenetically-induced neural activity with functional ultrasound imaging.

Balanced-steady-state free precession (b-SSFP) functional magnetic resonance imaging (fMRI) encompasses several recently developed methods that utilize b-SSFP acquisition for fMRI. Short repetition time (TR) and readout durations of b-SSFP allow distortion-free acquisition, 3D imaging, and high-resolution isotropic voxel acquisition. b-SSFP fMRI can be categorized into two different classes depending on which contrast mechanism it exploits. Transition-band b-SSFP fMRI is a technique that utilizes the sharp transition of the b-SSFP profile relying on the fact that oxygenated and deoxegenated hemoglobin has different resonance frequencies. On the other hand, passband b-SSFP fMRI utilizes b-SSFP in the relatively large flat portion of the b-SSFP off-resonance spectrum where oxygenation contrast is expected to be generated from the rapid refocusing in the presence of off-resonance due to oxy- and deoxy-hemoglobin. While both methods share the advantage of b-SSFP acquisition such as distortion-free, 3D high-resolution functional imaging, the main distinction of the two methods come from the contrast mechanism and spatial coverage. In this article, the two classes of b-SSFP-based functional brain imaging methods' characteristics will be compared and discussed. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 23–30, 2010

Balanced steady state free precession fMRI

Understanding how stem cell-derived neurons functionally integrate into the brain upon transplantation has been a long sought-after goal of regenerative medicine. However, methodological limitations have stood as a barrier, preventing key insight into this fundamental problem. A recently developed technology, termed optogenetic functional magnetic resonance imaging (ofMRI), offers a possible solution. By combining targeted activation of transplanted neurons with large-scale, noninvasive measurements of brain activity, ofMRI can directly visualize the effect of engrafted neurons firing on downstream regions. Importantly, this tool can be used to identify not only whether transplanted neurons have functionally integrated into the brain, but also which regions they influence and how. Furthermore, the precise control afforded over activation enables the input-output properties of engrafted neurons to be systematically studied. This review summarizes the efforts in stem cell biology and neuroimaging that made this development possible and outlines its potential applications for improving and optimizing stem cell-based therapies in the future.

/pdf/probing-neural-transplant-networks-in-vivo-with-optogenetics-15ohvbq411.pdf

Jin Hyung Lee

Papers

Repeated hippocampal seizures lead to brain-wide reorganization of circuits and seizure propagation pathways.

Multi-coil reconstruction of MRI signals using linear phase multiplied data with separate demodulators for each coil

High-sensitivity detection of optogenetically-induced neural activity with functional ultrasound imaging.

Balanced steady state free precession fMRI

Probing Neural Transplant Networks In Vivo with Optogenetics and Optogenetic fMRI