Magnetic Resonance Imaging in Stroke Study
Yanlin Wang-Fischer in Manual of Stroke Models in Rats, 2008
Nuclear magnetic resonance (NMR) refers to the ability of certain nuclei to emit useful signals when these nuclei are subjected to a strong static magnetic field and then excited by another strong but varying magnetic field. This signal is then recorded during a session and decoded into valuable information. Organic material is made up of a wide variety of molecules that comprise a large number of hydrogen and carbon atoms. There are also intermediate numbers of other atoms like oxygen, nitrogen, phosphorous, iron, and sulfur as well as numerous trace elements such as selenium, chromium, and others. To be useful in NMR, nuclei must be magnetic, that is, have a nuclear magnetic moment. Of all of the atoms within the body, the 1H atom is of the most interest. It generates the largest signal and is therefore the most valuable for in vivo NMR experiments.
Miscellaneous Methods of Analysis
Joseph Chamberlain in The Analysis of Drugs in Biological Fluids, 2018
Nuclear magnetic resonance spectroscopy is a powerful technique for examining the behavior of suitable atomic nuclei in a magnetic field. In its most familiar form, the technique separates signals due to single hydrogen nuclei depending on their chemical situation in the molecule, and the signal is further split depending on the immediate molecular environment of the hydrogen atom. Thus, Figure 9.5 shows the NMR spectrum of ethanol; three main signals are shown corresponding to the three types of hydrogen atom in the molecule: a hydrogen atom which is part of the methyl group, a hydrogen atom which is part of a methylene group, and a hydrogen atom which is part of a hydroxyl group. In this molecule, the methyl and methylene hydrogens are affected by the proximity of the other group and the signal is further subdivided. The methyl hydrogens are affected by two methylene hydrogens and are therefore split into a characteristic triplet pattern, the signals being in the ratio 1:2:1. The methylene hydrogens are similarly affected by the proximity of three methyl hydrogens and are split into a characteristic quartet, the signals being in the ratio 1:3:3:1. Integrating the groups of signals shown gives the the relative number of each type of hydrogen atom.
Early Diagnosis and Staging of Prostate Cancer Using Magnetic Resonance Imaging
Ayman El-Baz, Gyan Pareek, Jasjit S. Suri in Prostate Cancer Imaging, 2018
In the past few years, the use of magnetic resonance imaging (MRI) was proposed by the CaP research community as the most accurate noninvasive screening tool for prostate cancer diagnosis and staging [8]. Especially in the case of active surveillance, MRI can greatly assist doctors in disease monitoring and treatment management [9]. MRI is an imaging technique that uses the fundamentals of nuclear magnetic resonance (NMR) phenomenon to produce images that describe internal physical and chemical characteristics of an object [10]. By nature, some atoms such as hydrogen (H) possess a random nuclear spin (Figure 11.1a). However, when exposed to an external magnetic field (B0), these spins are aligned to produce a net magnetic moment (Figure 11.1b). The MRI technique depends on measuring the time needed by these spins to return to their original orientations after turning off the aligning magnetic field B0 as in Figure 11.1c.
The applications of metabolomics in the molecular diagnostics of cancer
Published in Expert Review of Molecular Diagnostics, 2019
Pro Kit Cheung, Man Hin Ma, Hing Fung Tse, Ka Fai Yeung, Hin Fung Tsang, Man Kee Maggie Chu, Chau Ming Kan, William Chi Shing Cho, Lawrence Bo Wah Ng, Lawrence Wing Chi Chan, Sze Chuen Cesar Wong
The principle of NMR is that the interaction of magnetic spins of nuclei of various atoms in magnetic fields leads to the generation of signals following radiofrequency excitation. By Fourier analysis, a spectrum of the frequencies of the signal is generated [3]. The interpretation of spectrum in NMR spectroscopy by the characteristic of the chemical shift and spin–spin coupling of the various nuclei under the magnetic field. Chemical shift is the effect observed that nuclei of the same species resonate at slightly different frequencies. These differences are mainly because of the shielding effect of electrons. Resonance frequencies of nuclei decrease in different degrees under various chemical environment and thus it can characterize the specific structural fragments of organic compounds and their substituents. Spin–spin coupling effect is responsible for splitting spectroscopic lines into multiplets. Depending on the number of neighboring nuclei, different splitting patterns are observed. The spectroscopic line intensity in the NMR spectrum is directly proportional to the number of spins associated with the particular resonance. This means the signal intensity is proportional to the molar concentration of metabolomics. Thus, NMR can be used for quantification in metabolomics [12].
Stimuli-responsive nanoscale drug delivery systems for cancer therapy
Published in Journal of Drug Targeting, 2019
Li Li, Wu-Wei Yang, Dong-Gang Xu
Lee et al. engineered a supramolecular nanoparticle which contained beta-cyclodextrin grafted with polyethylenimine (CD-PEI), adamantine-modified PEG (Ad-PEG) and adamantane modified polyamines amine dendrimer (Ad-PAMAM). Then adamantane grafted Zn0.4Fe2.6O4 magnetic nanoparticle (Ad-MNP) was embedded in it to form a block polymer. It was approved that the polymer described above could be used to encapsulate DOX [102]. Guisasola et al. [103] prepared an iron oxide MNP embedded in a mesoporous silica matrix, which can provoke the release of anti-tumour drug DOX trapped inside the silica pores. In vivo and in vitro experiments showed that significant tumour growth inhibition was achieved in 48 h after treatment [103]. Moreover, magnetic materials could also be applied into nuclear magnetic resonance imaging to realise the integrated diagnosis and treatment of diseases [104–109].
Omics of antimicrobials and antimicrobial resistance
Published in Expert Opinion on Drug Discovery, 2019
Vladislav M. Chernov, Olga A. Chernova, Alexey A. Mouzykantov, Leonid L. Lopukhov, Rustam I. Aminov
Similarly to proteomics, the progress in metabolomics has been largely driven by the development of mass spectrometry [109] (Figure 1). Contemporary methods use nuclear magnetic resonance (NMR), as well as various types of chromatography, spectrometry, and electrophoresis. Combined analytical tools include gas chromatography coupled to mass spectrometry (GC-MS), liquid chromatography coupled to mass spectrometry (LC-MS), capillary electrophoresis coupled to mass spectrometry (CE-DM), ultra-high performance liquid chromatography coupled to mass spectrometry (UPLC-MS), high-performance liquid chromatography-electrospray ionization coupled to mass spectrometry (HPLC-ESI-MS), high-performance liquid chromatography-diode array detection-electrospray ionization tandem mass spectrometry (HPLC/DAD/ESI-MS), and others. LC-MS and its variants became popular in metabolomic research because of the large amount of information it provides as well as due to its flexibility and versatility [110].
Related Knowledge Centers
- Crystallography
- Hyperpolarization
- Magnetometer
- Magnetic Resonance Imaging
- Atomic Nucleus
- Near & Far Field
- Molecular Physics
- Medical Imaging
- Larmor Precession
- Low Field Nuclear Magnetic Resonance