Search results for "Radioisotope"
showing 10 items of 300 documents
68Ga-BPAMD: PET-imaging of bone metastases with a generator based positron emitter
2012
Abstract Purpose Bone metastases are a serious aggravation for patients suffering from cancer. Therefore, early recognition of bone metastases is of great interest for further treatment of patients. Bisphosphonates are widely used for scintigraphy of bone lesions with 99m Tc. Using the 68 Ge/ 68 Ga generator together with a macroyclic bisphosphonate a comparable PET-tracer comes into focus. Procedures The bisphosphonate DOTA-conjugated ligand BPAMD was labelled with 68 Ga. [ 68 Ga]BPAMD was evaluated in vitro concerning binding to hydroxyapatite and stability. The tracer's in vivo accumulation was determined on healthy rats and bone metastases bearing animals by μ-PET. Results BPAMD was lab…
Radiolabelling and preliminary evaluation of 68Ga-tetrapyrrole derivatives as potential tracers for PET
2013
article i nfo Tetrapyrroles are multisided natural products which are of relevance in clinical medicine. Owing to their specific accumulation in tumour tissue, porphyrins, metalloporphyrins and chlorins have been used as in photodynamic therapy and optical imaging. Moreover, their specific uptake into inflammatory atheromatous plaques via LDL endocytosis has been reported. The present study is concerned with the synthesis of 68 Ga labelled porphyrin derivatives and an in vitro assessment of the utility of radiotracers in positron emission tomography. A set of five porphyrin derivatives were labelled using 68 Ga from a commercially obtained radionuclide generator. Dedicated post-processing o…
On the mechanism of action of phenylephrine in rat atrial heart muscle
1994
Both in rat left atrial heart and in aortic smooth muscle preparations, phenylephrine (PE) caused a concentration-dependent increase in force of contraction (FC) in the presence of atenolol (10 mumol/l), which was antagonized by phentolamine, prazosin and WB 4101 in a competitive manner. The pA2 values of the antagonists in the cardiac tissue were 10-20fold lower than those in the rat thoracic aorta. In the spontaneously beating right atrium, PE exerted a positive chronotropic action, which was not significantly antagonized by phentolamine or prazosin. It is therefore assumed that the effects of phenylephrine in the left atrium and in the aorta are mediated by different subtypes of alpha 1-…
Production, regeneration and biochemical precursors of the major components of the defensive secretion of Eurycotis floridana (Dictyoptera, polyzoste…
2000
0965-1748 (Print) Journal Article; The defensive secretion of the cockroach Eurycotis floridana contains three main components, (E)-2-hexenal, (E)-2-hexenol and (E)-2-hexenoic acid, which represented about 98% of the organic phase. The quantity of the aldehyde, alcohol, and acid present in the defensive secretion increased rapidly for 60 days from the imaginal moult. Following artificial discharge, the males were able to regenerate their initial volume of secretion over a 30 day period. To investigate the possible routes of biosynthesis of the three components, E. floridana was injected with 14C-labeled fatty acids and acetate, and the incorporation of 14C into the three components were qua…
Fate of Linear and Branched Polyether-Lipids In Vivo in Comparison to Their Liposomal Formulations by 18F-Radiolabeling and Positron Emission Tomogra…
2015
In this study, linear poly(ethylene glycol) (PEG) and novel linear-hyperbranched, amphiphilic polyglycerol (hbPG) polymers with cholesterol (Ch) as a lipid anchor moiety were radiolabeled with fluorine-18 via copper-catalyzed click chemistry. In vivo investigations via positron emission tomography (PET) and ex vivo biodistribution in mice were conducted. A systematic comparison to the liposomal formulations with and without the polymers with respect to their initial pharmacokinetic properties during the first hour was carried out, revealing remarkable differences. Additionally, cholesterol was directly labeled with fluorine-18 and examined likewise. Both polymers, Ch-PEG27-CH2-triazole-TEG-…
Ex vivo and in vivo evaluation of [18F]PR04.MZ in rodents: a selective dopamine transporter imaging agent.
2009
N-4-Fluorobut-2-yn-1-yl-2beta-carbomethoxy-3beta-phenyltropane (PR04.MZ) has been developed as dopamine transporter (DAT) ligand for molecular imaging. It contains a terminally fluorinated, conformationally constrained nitrogen substituent that is well suited for the introduction of fluorine-18. The present report describes the pharmacological characterisation of [18F]PR04.MZ. The ligand shows an IC50 value of 2 nM against human DAT, whereas the IC50 value against human serotonin transporter and human noradrenalin transporter are lower (110 nM and 22 nM, respectively). Furthermore, its ex vivo organ distribution, its binding profile in the rat brain and reversibility of binding were examine…
In vivo biodistribution of amino-functionalized ceria nanoparticles in rats using positron emission tomography.
2012
A variety of nanoparticles have been proposed for several biomedical applications. To gauge the therapeutic potential of these nanoparticles, in vivo biodistribution is essential and mandatory. In the present study, ceria nanoparticles (5 nm average particle size) were labeled with F-18 to study their in vivo biodistribution in rats by positron emission tomography (PET). The F-18 isotope was anchored by reaction of N-succinimidyl 4-[F-18]fluorobenzoate (F-18-SFB) with a modified nanoparticle surface obtained by silylation with 3-aminopropylsilyl. Radiolabeled ceria nanoparticles accumulated mainly in lungs, spleen, and liver. Metabolic products of the radiolabeled nanoparticulate material w…
Pattern of occult nodal relapse diagnosed with 18F-fluoro-choline PET/CT in prostate cancer patients with biochemical failure after prostate-only rad…
2014
Abstract Introduction The purpose of this study was to describe the pattern of nodal relapse with 18 F-fluoro-choline (FCH) Positron Emission Tomography/Computerized Tomography (PET/CT) in prostate cancer patients after radiotherapy. Materials and methods Eighty-three patients had a FCH PET/CT at time of biochemical failure. Of 65 patients with positive findings, 33 had positive nodes. This analysis included 31 patients who had undergone prior prostate-only radiotherapy with or without a prior radical prostatectomy. Each FCH positive node was assigned to a lymph node station with respect to the CTV defined by the RTOG guidelines (CTV RTOG ). 3D mapping was performed after each node was manu…
Complement C1q is dramatically up-regulated in brain microglia in response to transient global cerebral ischemia.
2000
Abstract Recent evidence suggests that the pathophysiology of neurodegenerative and inflammatory neurological diseases has a neuroimmunological component involving complement, an innate humoral immune defense system. The present study demonstrates the effects of experimentally induced global ischemia on the biosynthesis of C1q, the recognition subcomponent of the classical complement activation pathway, in the CNS. Using semiquantitative in situ hybridization, immunohistochemistry, and confocal laser scanning microscopy, a dramatic and widespread increase of C1q biosynthesis in rat brain microglia (but not in astrocytes or neurons) within 24 h after the ischemic insult was observed. A marke…
Functional role of cholinoceptors and purinoceptors in human isolated atrial and ventricular heart muscle
1989
1. The effects of cholinergic and purinergic stimulation on action potential, force of contraction and 86Rb efflux were investigated in human atrial and ventricular heart muscle. 2. In atrial heart muscle, carbachol and (-)-N6-(R-phenyl-isopropyl)-adenosine (R-PIA) and 5'-(N-ethyl)-carboxamido-adenosine (NECA) evoked transient decreases of action potential duration and force of contraction; the steady-state effects on force of contraction were virtually identical to control values. In the presence of propranolol, steady-state values after carbachol, R-PIA or NECA amounted to about 50% of control values. 3. In ventricular heart muscle, carbachol, NECA and R-PIA did not significantly affect t…