Electroceuticals

Solid state NMR is a powerful tool to probe membrane protein structure and motions in native lipid structures. Sample heating, caused by magic angle spinning and radio frequency irradiation in solid state NMR, produces uncertainties in sample temperature and thermal broadening caused by temperature distributions, which can also lead to sample deterioration. To measure the sample temperature in real time, and to quantify thermal gradients and their dependence on radio frequency irradiation or spinning frequency, we use the chemical shift thermometer TmDOTP, a lanthanide complex. Compared to other NMR thermometers (e.g., the proton NMR signal of water), the proton spectrum of TmDOTP exhibits higher thermal sensitivity and resolution. In addition, the H6 proton in TmDOTP has a large chemical shift (−175 ppm at 275 K) and is well resolved from the rest of the proton spectrum. We identified two populations of TmDOTP, with differing temperatures and dependency on the radio frequency irradiation power, within proteoliposome samples. We interpret these populations as arising from the supernatant and the pellet, which is sedimented from the sample spinning. Our results indicate that TmDOTP is an excellent internal standard for monitoring temperatures of biophysically relevant samples without distorting their properties.

Evaluation of SAR Using MR Thermometry with Thulium1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(Methylene Phosphonate) (TmDOTP5-) for RF Safety in MRI, LL-PHS-WE3B, 11002408, Shalmali Dharmadhikari,

This thesis presents sodium magnetic resonance as an in vivo means for non-invasively visualizing the changes in cell sodium ion homeostasis that occur in ischemic tissue during acute stroke. Single quantum sodium magnetic resonance imaging (MRI) was used to determine the time course of tissue sodium concentration (TSC) in a non-human primate model of reversible focal brain ischemia. In each animal, TSC increased slowly and linearly as a function of time after the onset of focal brain ischemia. Changes in the TSC accumulation were seen upon reperfusion. The results demonstrate that the increase in TSC in ischemic tissue is readily measurable using sodium MRI at clinical magnetic field strengths (3.0 T) in acceptable imaging times (5 minutes). The results also indicate that sodium MRI could predict the stroke onset time in patients that are unsure when their symptoms began, potentially extending the use of thrombolytic therapy to patients that would otherwise not receive treatment. Many studies have hypothesized that the best means for the in vivo study of the changes in cell sodium ion homeostasis that occur during brain ischemia is to use imaging schemes that isolate the sodium NMR signal from the intracellular compartment. This thesis investigates the contribution of the extracellular sodium pool to the brain's triple quantum (TQ) sodium MR signal in the rat using the thulium shift reagent, TmDOTP5-. Within the SNR of the experiment, there was no evidence of any contribution to the TQ sodium MR signal from the sodium in the extracellular brain, vascular, and muscle spaces in the head. Finally, TQ sodium MR images in the in vivo non-human primate are presented for the first time. Moreover, these images were obtained in clinically acceptable 18 minute data acquisition times. TQ sodium MRI during non-human primate focal brain ischemia identified large changes in the ischemic region as early as 34 minutes after the onset of ischemia. The increase in the TQ sodium MRI signal intensity observed in the ischemic hemisphere is hypothesized to be due to an increase in the intracellular sodium concentration as a result of impaired ion homeostasis during evolving brain ischemia.

Magnetic Resonance Imaging (MRI) is a popular imaging modality due to its ability to provide excellent soft tissue contrast without exposure to ionizing radiation. It can be used for temperature monitoring (thermometry) as well as for assessing the biochemistry in vivo (MRS). This dissertation focuses separately on the development, application and quantitation issues of these two aspects of MRI. Radiofrequency (RF)-induced tissue heating is a concern in MRI. The dosimetric quantity for monitoring RF heating is the Specific Absorption Rate (SAR) defined as the RF power absorbed per unit mass of tissue. A novel approach for imaging SAR from absolute temperature images obtained using a paramagnetic lanthanide complex-Thulium 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis (methylene phosphonate) (TmDOTP5-) was developed. The effects of a bare-ended, insulated conductor in a phantom were investigated by 3D SAR imaging. 3D SAR maps were also generated using a high SAR sequence while varying the pulse duration. The high spatial resolution SAR maps correctly identified the local SAR rise near the wire end and also revealed increasing SAR with increasing pulse duration in the high SAR sequence, as expected. These results demonstrate the potential of MR thermometry with paramagnetic lanthanide complexes for evaluating safety of implants, medical devices as well as different pulse sequences. The second part of the thesis is dedicated to the technique of measuring in vivo levels of the neurotransmitter γ-aminobutyric acid (GABA) using MRS. GABA is an inhibitory neurotransmitter in the brain which is involved in the control of fine movement and balance. GABA MRS with spectral editing was performed and GABA was quantified using custom fitting parameters in the tool LCModel to measure changes in movement disorders - particularly Parkinson's disease (PD) and sleep bruxism. Higher levels of thalamic GABA were detected in PD with correlation to disease severity indicating the possibility to use GABA MRS as a biomarker for PD progression. On the other hand, in the bruxers, lower levels of GABA correlating with higher levels of glutamate in the dorso-lateral prefrontal cortex were detected indicating disturbances in the GABAergic and glutamatergic pathways. Lastly, since GABA quantification is a much discussed topic in literature with no one, clear and best approach, an effort was made to compare some popular fitting approaches in LCModel. Semi-synthetic simulated GABA spectra were used to test the accuracy, sensitivity and specificity of methods, all of which handled the baseline and macromolecules in the GABA spectra differently. Overall, the approaches using

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Clusters of superparamagnetic (SP) magnetite crystals have recently been identified in free nerve endings in the upper-beak skin of homing pigeons and are interpreted as being part of a putative magnetoreceptor system. Motivated by these findings, we developed a physical model that accurately predicts the dynamics of interacting SP clusters in a magnetic field. The main predictions are: 1), under a magnetic field, a group of SP clusters self-assembles into a chain-like structure that behaves like a compass needle under slowly rotating fields; 2), in a frequently changing field as encountered by a moving bird, a stacked chain is a structurally more stable configuration than a single chain; 3), chain-like structures of SP clusters disrupt under strong fields applied at oblique angles; and 4), reassemble on a timescale of hours to days (assuming a viscosity of the cell plasma η∼1 P).

Since brain's microvasculature is compromised in gliomas, intravenous injection of tumor-targeting nanoparticles containing drugs (D-NPs) and superparamagnetic iron oxide (SPIO-NPs) can deliver high payloads of drugs while allowing MRI to track

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Use this page to view details for NCD - Electrocardiographic Services (20.15).

Get all the coding and reimbursement information you need to integrate the CAM heart monitor patch into your medical practice.

Ambulatory electrocardiography (ECG) allows for extended monitoring of arrhythmias in a real-world setting. This article reviews the currently available ambulatory ECG devices and their differences in design, function, indications, efficacy, cost, and optimal use in clinical practice.

Ambulatory electrocardiography (ECG) allows for extended monitoring of arrhythmias in a real-world setting. This article reviews the currently available ambulatory ECG devices and their differences in design, function, indications, efficacy, cost, and optimal use in clinical practice.

Ambulatory electrocardiography (ECG) allows for extended monitoring of arrhythmias in a real-world setting. This article reviews the currently available ambulatory ECG devices and their differences in design, function, indications, efficacy, cost, and optimal use in clinical practice.

Ambulatory electrocardiography (ECG) allows for extended monitoring of arrhythmias in a real-world setting. This article reviews the currently available ambulatory ECG devices and their differences in design, function, indications, efficacy, cost, and optimal use in clinical practice.

Ambulatory electrocardiography (ECG) allows for extended monitoring of arrhythmias in a real-world setting. This article reviews the currently available ambulatory ECG devices and their differences in design, function, indications, efficacy, cost, and optimal use in clinical practice.

Ambulatory electrocardiography (ECG) allows for extended monitoring of arrhythmias in a real-world setting. This article reviews the currently available ambulatory ECG devices and their differences in design, function, indications, efficacy, cost, and optimal use in clinical practice.

Ambulatory electrocardiography (ECG) allows for extended monitoring of arrhythmias in a real-world setting. This article reviews the currently available ambulatory ECG devices and their differences in design, function, indications, efficacy, cost, and optimal use in clinical practice.

For the most up-to-date version of CFR Title 21, go to the Electronic Code of Federal Regulations (eCFR).

Almost 13 million American adults require drug therapy to meet the low-density lipoprotein goals set by the National Cholesterol Education Program. Attempts to achieve these goals through diet and exercise are often unsuccessful. Major studies in recent years have demonstrated that statins decrease low-density lipoprotein levels, coronary events and overall mortality. Statins are the most commonly prescribed lipid-lowering agents because they are effective, well tolerated and easy to administer. Niacin has beneficial effects on all of the main lipid components, and new extended-release tablets have fewer adverse effects. Fibrates remain the most effective agents in lowering triglyceride levels and should be limited to this use. Bile acid sequestrants are seldom prescribed because of their adverse gastrointestinal effects and cumbersome administration.