Positron emission tomography PET studies

An additional benefit of COMT inhibitors can be found in positron emission tomography (PET) studies. In PET, using 6-[18F]-fluoro-L-dopa (6-FD) to visualize the brain dopamine metabolism, the peripheral formation of 3-0-methyl-6-[18F]-fluoro-L-dopa (3-OMFD) by COMT is harmful. 3-OMFD contaminates the brain radioactivity analysed since it is easily transported like 3-OMD to the... 

The validity of this concept, in which Cb,u is used to project RO accurately across species, was evaluated for a dual-pharmacology antagonist (1) simultaneously targeting the synaptic transmembrane proteins SerT and 5-HT2A [37]. Briefly, SerT RO was determined in rats and humans by ex vivo binding and positron emission tomography (PET) studies,... 

Rosenberg NL, Myers JA, Martin WRW. 1989. Cyanide-induced parkinsonism clinical MRI and 6 fluorodopa Fd positron emission tomography pet studies. Neurology 39 142-144. 

Although studies of resting brain metabolism in adults with schizophrenia have produced conflicting results, studies during activation tasks have more consistently revealed frontal hypometabolism. Patients with COS were noted to have somewhat similar (but not more severe) abnormalities in a positron emission tomography (PET) study, although interpretation was limited as these severely ill patients could not adequately perform the activation task (Jacobsen et ah, 1997b). 

A recent positron emission tomography (PET) study in which the radiolabeled serotonin precursor alpha C methyl tryptophan was used provides empirical evidence of decreased 5-HT synthesis in frontal and thalamic regions and increased 5-HT synthesis in contralateral cerebellar dentate regions (Chugani et al., 1997). These findings are consistent with findings of increased 5-HTm inhibitory autoreceptor sensitivity in adult autistic patients (Hollander et al., 2000 Novotny et al., 2000), since these receptors are prevalent in frontal and thalamic, but not cerebellar, regions. 

Because clozapine may block specific DA receptors, its antipsychotic activity could be consistent with an antidopaminergic mechanism of action. Conversely, clozapine does not typically induce extrapyramidal symptoms, which are presumably subserved by the A-9 system. Thus, while clozapine is known to block striatal DA receptors, in positron emission tomography (PET) studies, resolution is not sufficient to clarify effects on other tracts. Furthermore, low doses of metoclopramide, which significantly decrease the number of DA neurons spontaneously active in A-9, do not have antipsychotic effects (except at high doses) but can induce tardive dyskinesia (TD), as well as acute extrapyramidal side effects (EPS). 

Renewed interest in the fluorination of quaternary ammonium salts is prompted by the need for rapid fluorination techniques to incorporate 18F (t /f 110 mm) in positron emission tomography (PET) studies One promising approach is displacement of trimethylammomum ion, bound directly to an aromatic ring, by fluoride ion This technique was initially developed with substituted phenyltnmeth-ylammomum perchlorates and unlabeled cesium fluoride in dimethyl sulfoxide or acetonitrile [73] (equation 14)... 

Indeed, there is a correlation between impaired NE transmission and depressive behavior. Postmortem studies demonstrated increased NE levels in the brains of unipolar and bipolar suicide victims (Juckel et al., 2000 Wiste et al., 2008). One positron emission tomography (PET) study suggested that depressive patients have an increased activity of MAO-A, which might result in reduced catecholamine levels (Meyer et al., 2006). Another imaging study showed correlation between the degree of loss of limbic NE innervation and severity of depressive symptoms in Parkinson patients (Brooks and Piccini 2006 Remy et al., 2005). 

Dimitrakopoulou-Strauss A, Strauss LG, Mikolajczyk K, et al. (2003) On the fractal nature of dynamic positron emission tomography (PET) studies. World JNucl Med 2, 306-313. 

Rosenberg, N.L., Myers, J.A., and Marin, W.R.W., Cyanide-induced Parkinsonism clinical, MRI and 6-fluorofops Fd positron emission tomography pet studies. Neurology, 39, 142-144, 1989. 

Increasing evidence supports the presence of a DA-receptor defect in schizophrenia. Numerous positron emission tomography (PET) studies have shown regional brain abnormalities, including increased glucose metabolism in the caudate nucleus, and decreased blood flow and glucose metabolism in the frontal lobe and left temporal lobe. ... 

No consistent evidence from positron emission tomography (PET) studies or genetic association studies to suggest a constitutional change in D2 receptors in schizophrenia. 

I Dowmegulation/reduced numbers of postsynaptic 5-HTia receptors (neu-roendocrine studies prolactin response to tryptophan infusion buspirone-induced hypothermia positron emission tomography (PET) studies of brain 5-HTia receptor binding). 

Another important clinical application of HPAE-PAD is the determination of 2-deoxy-2-[ F]fluoro-D-glucose (FDG), which is the most widely used radiopharmaceutical for positron emission tomography (PET) studies. This approach is used in the diagnosis of a number of diseases and disorders including cancer, cardiovascular disease, and dementia [582,583]. In addition, it is an important tool in neuroscience to enable the study of brain regional activation [584] and in drug research where it is used to evaluate drug biodistribution. FDG is a... 

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