Wireless magnetothermal deep brain stimulation Chen, Ritchie; Romero, Gabriela; Christiansen, Michael G. ...
Science (American Association for the Advancement of Science),
03/2015, Volume:
347, Issue:
6229
Journal Article
Peer reviewed
Open access
Wireless deep brain stimulation of well-defined neuronal populations could facilitate the study of intact brain circuits and the treatment of neurological disorders. Here, we demonstrate minimally ...invasive and remote neural excitation through the activation of the heat-sensitive capsaicin receptor TRPV1 by magnetic nanoparticles. When exposed to alternating magnetic fields, the nanoparticles dissipate heat generated by hysteresis, triggering widespread and reversible firing of TRPV1+ neurons. Wireless magnetothermal stimulation in the ventral tegmental area of mice evoked excitation in subpopulations of neurons in the targeted brain region and in structures receiving excitatory projections. The nanoparticles persisted in the brain for over a month, allowing for chronic stimulation without the need for implants and connectors.
Inverted teaching, not to be confused with hybrid learning, is a relatively new pedagogy in which lecture is shifted outside of class and traditional homework is done in class. Though some inverted ...teaching (IT) designs have been published in different fields, peer-reviewed reports in university chemistry remain quite rare. To that end, herein is disclosed a sophomore organic chemistry course design in which two groups of students were each taught by one of two methods: Group 1 through traditional lecture (TL) and Group 2 through IT. Design rationale and objectives are discussed. Academic performances are compared, along with anonymous student feedback contrasting the two techniques (TL vs IT). Student attendance and viewership, instructor prep time, and total lecture time are also presented for both styles.
This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe2O4 (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using ...magnetic and structural nanoparticle characterization, we identify key synthetic parameters in the thermal decomposition of organometallic precursors that yield optimized magnetic nanoparticles over a wide range of sizes and compositions. The developed synthetic procedures allow for gram-scale production of magnetic nanoparticles stable in physiological buffer for several months. Our magnetic nanoparticles display some of the highest heat dissipation rates, which are in qualitative agreement with the trends predicted by a dynamic hysteresis model of coherent magnetization reversal in single domain magnetic particles. By combining physical simulations with robust scalable synthesis and materials characterization techniques, this work provides a pathway to a model-driven design of magnetic nanoparticles tailored to a variety of biomedical applications ranging from cancer hyperthermia to remote control of gene expression.
Magnetic actuation offers a means to wirelessly control flow in ferrofluids for applications including microfluidic pumping and targeted drug delivery. Despite the promise of these concepts, ...practical use of synthetic ferrofluids as actuators of flow frequently requires high concentrations and is hindered by low ferrohydrodynamic coupling efficiency and inhomogeneous flow fields. Inspired by the magnetic properties and hydrodynamic forms displayed by magnetotactic bacteria (MTB), this work studies the use of these microbes as a living, self‐replicating ferrofluid for improved fluidic transport via magnetically coerced rotation. Using multicore iron oxide nanoparticles as a performance benchmark, MTB under rotating magnetic fields are shown to produce more homogeneous and efficient flow. Coupling is enhanced whether the comparison is made in terms of volume of magnetic material or total volume fraction. To clarify the mechanistic role of interactions with boundaries in transport, a computational model is developed and validated experimentally. Applying this model, two distinct and feasible magnetic control strategies are predicted: a rotating gradient field that generates directional flow despite boundaries that promote flow in opposing directions and a magnetostatic gating field that enables spatially selective actuation. The advantageous properties identified for MTB open a design space for these strategies to be realized.
This work elucidates the potential of magnetotactic bacteria as flow mediators in fluidic transport applications. By measuring flow homogeneity and coupling efficiency, this living ferrofluid is shown to outperform a synthetic counterpart. Considering the unique magnetic and hydrodynamic properties of magnetotactic bacteria, two control strategies using this living flow mediator are proposed for microfluidic pumping and selective drug delivery applications.
Fruit flies injected with magnetic nanoparticles and genetically modified to sensitize neural circuits to the rate of change in temperature have enabled subsecond behavioural responses to magnetic ...stimuli and multi-channel magnetic control.
In recent decades, dysregulation of proteases and atypical proteolysis have become increasingly recognized as important hallmarks of cancer, driving community-wide efforts to explore the proteolytic ...landscape of oncologic disease. With more than 100 proteases currently associated with different aspects of cancer development and progression, there is a clear impetus to harness their potential in the context of oncology. Advances in the protease field have yielded technologies enabling sensitive protease detection in various settings, paving the way towards diagnostic profiling of disease-related protease activity patterns. Methods including activity-based probes and substrates, antibodies, and various nanosystems that generate reporter signals, i.e., for PET or MRI, after interaction with the target protease have shown potential for clinical translation. Nevertheless, these technologies are costly, not easily multiplexed, and require advanced imaging technologies. While the current clinical applications of protease-responsive technologies in oncologic settings are still limited, emerging technologies and protease sensors are poised to enable comprehensive exploration of the tumor proteolytic landscape as a diagnostic and therapeutic frontier. This review aims to give an overview of the most relevant classes of proteases as indicators for tumor diagnosis, current approaches to detect and monitor their activity in vivo, and associated therapeutic applications.
Magnetic Strategies for Nervous System Control Christiansen, Michael G; Senko, Alexander W; Anikeeva, Polina
Annual review of neuroscience,
07/2019, Volume:
42, Issue:
1
Journal Article
Peer reviewed
Open access
Magnetic fields pass through tissue undiminished and without producing harmful effects, motivating their use as a wireless, minimally invasive means to control neural activity. Here, we review ...mechanisms and techniques coupling magnetic fields to changes in electrochemical potentials across neuronal membranes. Biological magnetoreception, although incompletely understood, is discussed as a potential source of inspiration. The emergence of magnetic properties in materials is reviewed to clarify the distinction between biomolecules containing transition metals and ferrite nanoparticles that exhibit significant net moments. We describe recent developments in the use of magnetic nanomaterials as transducers converting magnetic stimuli to forms readily perceived by neurons and discuss opportunities for multiplexed and bidirectional control as well as the challenges posed by delivery to the brain. The variety of magnetic field conditions and mechanisms by which they can be coupled to neuronal signaling cascades highlights the desirability of continued interchange between magnetism physics and neurobiology.
Rotating magnetic fields enable biomedical microrobots to overcome physiological barriers and promote extravasation and accumulation in tumors. Nevertheless, targeting deeply situated tumors requires ...suppression of off-target actuation in healthy tissue. Here, we investigate a control strategy for applying spatially selective torque density to microrobots by combining rotating fields with magnetostatic selection fields. Taking magnetotactic bacteria as diffuse torque-based actuators, we numerically model off-target torque suppression, indicating the feasibility of centimeter to millimeter resolution for human applications. We study focal torque application in vitro, observing off-target suppression of actuation-dependent effects such as colonization of bacteria in tumor spheroids. We then design and construct a mouse-scale torque-focusing apparatus capable of maneuvering the focal point. Applying this system to a mouse tumor model increased accumulation of intravenously injected bacteria within tumors receiving focused actuation compared to non-actuated or globally actuated groups. This control scheme combines the advantages of torque-based actuation with spatial targeting.
Danish premature birth rates during the COVID-19 lockdown Hedermann, Gitte; Hedley, Paula Louise; Bækvad-Hansen, Marie ...
Archives of disease in childhood. Fetal and neonatal edition,
01/2021, Volume:
106, Issue:
1
Journal Article
Peer reviewed
Open access
To explore the impact of COVID-19 lockdown on premature birth rates in Denmark, a nationwide register-based prevalence proportion study was conducted on all 31 180 live singleton infants born in ...Denmark between 12 March and 14 April during 2015-2020.The distribution of gestational ages (GAs) was significantly different (p=0.004) during the lockdown period compared with the previous 5 years and was driven by a significantly lower rate of extremely premature children during the lockdown compared with the corresponding mean rate for the same dates in the previous years (OR 0.09, 95% CI 0.01 to 0.40, p<0.001). No significant difference between the lockdown and previous years was found for other GA categories.The reasons for this decrease are unclear. However, the lockdown has provided a unique opportunity to examine possible factors related to prematurity. Identification of possible causal mechanisms might stimulate changes in clinical practice.
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