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Radiopharmaceuticals for Diagnostics
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Jim Ballinger, Jacek Koziorowski
The function of the dopamine transporter is reuptake of dopamine released into the synapse into vesicles in the presynaptic nerve terminal. The dopamine transporter can be imaged with an 123I-labelled analogue of cocaine, ioflupane (fluoropropyl carbomethoxy iodophenyl nortropane, FP-CIT, Datscan, Striascan). Ioflupane binds to the transporter to give an indication of the density of presynaptic nerve terminals. SPECT imaging is performed at a fixed time, 3-6 h after injection [16]. In normal individuals there is bilateral homogeneous accumulation of activity in the basal ganglia (striatum; caudate nucleus and putamen). Parkinson’s disease involves degeneration of the nigrostriatal pathway with loss of dopaminergic nerve terminals. Thus, dopamine transporter imaging can be used to diagnose Parkinson’s disease and to differentiate it from other causes of Parkinsonian tremor, such as essential tremor (i.e. non-degenerative) or that caused by certain neuroleptic drugs. In early Parkinson’s disease there tends to be asymmetry, particularly in the putamen, while in advanced disease there is bilateral degeneration. Ioflupane is also useful in diagnosis of Lewy body disease [17].
High Information Content Physiological Biosensors
Published in George K. Knopf, Amarjeet S. Bassi, Smart Biosensor Technology, 2018
Guenter W. Gross, Joseph J. Pancrazio, Kamakshi Gopal
Attention-deficit hyperactivity disorder (ADHD) is thought to result from a disturbance in catecholaminergic neurotransmission with emphasis on dopamine (DA) and norepinephrine (NE) neurotransmitters (Pliszka et al., 1996). D,L-Methylphenidate (MPH) is a psychostimulant, which is commonly administered to treat ADHD. Subjects with ADHD are reported to have increased expression of dopamine transporters in the brain, leading to greater removal of dopamine from the extracellular space and decreasing the levels of dopamine at the synapses (Dougherty et al., 1999; Krause et al., 2000). MPH seems to preferentially block these transporters and inhibit the presynaptic uptake of dopamine (Volkow et al., 2001, 2003; Kuczenski and Segal 2002; Overtoom et al., 2003), thus decreasing the spontaneous neuronal activity in the postsynaptic neurons and leading to enhanced attention and motivation for specific tasks.
Improved Classification Accuracy for Diagnosing the Early Stage of Parkinson’s Disease Using Alpha Stable Distribution
Published in IETE Journal of Research, 2023
The DaTscan image has 91 image slices from bottom to top of the brain. The pattern of the striatum would change based on the binding level of radiotracer to the dopamine transporter (DAT). As the density of DaT decreases in the striatum, the comma-shaped pattern is reduced into dot. Therefore, striatum is the region where DaT content should be looked for. Based on the recommendation of the Society of Nuclear Medicine (SNM) [18], consecutive image slices, which have high striatal uptake region (slices from 36 to 47), are taken for the analysis. The remaining slices are not included in our investigation as the striatal uptake region gets reduced gradually (which has not shown significant dopamine) to make the analysis as simple as possible and to progress the diagnostic accuracy [19]. The sample input SPECT image for HC is shown in Figure 3. As the selected slices (36–47) provide volume information of the striatum in the two-dimensional image, they are called VRI slices [29]. The VRI slices offer continuity of the striatum shape than single image slice. It is highly recommended for displaying SPECT images in nuclear medicine.
Kinetic modeling and statistical optimization of submerged production of anti-Parkinson’s prodrug L-DOPA by Pseudomonas fluorescens
Published in Preparative Biochemistry & Biotechnology, 2022
Ananya Naha, Santosh Kumar Jha, Hare Ram Singh, Muthu Kumar Sampath
Levodopa is an amino acid and a precursor of dopamine. It can easily cross the blood-brain barrier and convert to dopamine by Dopa Carboxylase by a single enzymatic step, thus increasing the store of dopamine in the brain. Unlike dopamine, L-DOPA can be taken orally or intravenously. It is rapidly taken up by dopaminergic neurons and converted to dopamine.[4] The conversion of L-DOPA to dopamine mainly occurs in the periphery as well as in Central Nervous System (CNS) thus facilitating the reuptake of dopamine by the dopamine transporter (DAT) and vesicular monoamine transporter (VMAT). DAT helps to transport dopamine from extracellular to intracellular space, and VMAT reloads dopamine into the vesi hcles. The whole process is energy-dependent and uses Na-K ions for ATP hydrolysis to create a concentration gradient of ions across the presynaptic membrane. This drive opens the transporter and cotransport Na and Cl ions and dopamine from the synaptic cleft. The released K ions in the synaptic cleft help in the equilibration of the ionic gradient across the presynaptic membrane. Metabolism of dopamine by monoamine oxidase (MAO) and catechol-O-methyl transferase (COMT) is one of the effective mechanisms for dopamine inactivation. This includes several pathways like oxidative deamination by MAO, conjugation by glucuronidase or sulfotransferases, and O-methylation by COMT. MAO acts intracellularly and is located at the external membrane of mitochondria, whereas COMT acts extracellularly and is located within the external cell membrane.[5]
Experimental models of chemically induced Parkinson’s disease in zebrafish at the embryonic larval stage: a systematic review
Published in Journal of Toxicology and Environmental Health, Part B, 2023
Paola Briñez-Gallego, Dennis Guilherme da Costa Silva, Marcos Freitas Cordeiro, Ana Paula Horn, Mariana Appel Hort
Two investigators (P.B.G. and D.G.C.S.) independently extracted the following information from each study: (1) first author and year of publication; (2) neurotoxin type and concentrations; (3) behavioral outcomes (ex: locomotor activity: total swimming distance, swimming velocity, among others); (4) dopaminergic damage markers (TH, dopamine transporter (DAT), and dopamine (DA) levels); (5) other relevant outcomes (PD-specific, mitochondrial, cell proliferation, cell death, oxidative stress, and inflammation markers); and 6) mortality rate and morphological abnormalities were also extracted (Table 1).