AIM: Puromycin has played an important role in our understanding of the eukaryotic ribosome and protein synthesis. It has been known for more than 40 years that this antibiotic is a universal protein synthesis inhibitor that acts as a structural analog of an aminoacyl-transfer RNA (aa-tRNA) in eukaryotic ribosomes. Due to the role of enzymes and their synthesis in situations of need (DNA damage, e.g., after chemo- or radiation therapy), determination of protein synthesis is important for control of antitumor therapy, to enhance long-term survival of tumor patients, and to minimize side-effects of therapy. Multiple attempts to reach this goal have been made through the last decades, mostly using radiolabeled amino acids, with limited or unsatisfactory success. The aim of this study is to estimate the possibility of determining protein synthesis ratios by using (68)Ga-DOTA-puromycin ((68)Ga-DOTA-Pur), [(3)H]tyrosine, and 2-fluoro-[(3)H]tyrosine and to estimate the possibility of different pathways due to the fluorination of tyrosine. METHODS: DOTA-puromycin was synthesized using a puromycin-tethered controlled-pore glass (CPG) support by the usual protocol for automated DNA and RNA synthesis following our design. (68)Ga was obtained from a (68)Ge/(68)Ga generator as described previously by Zhernosekov et al. (J Nucl Med 48:1741-1748, 2007). The purified eluate was used for labeling of DOTA-puromycin at 95°C for 20 min. [(3)H]Tyrosine and 2-fluoro-[(3)H]tyrosine of the highest purity available were purchased from Moravek (Bera, USA) or Amersham Biosciences (Hammersmith, UK). In vitro uptake and protein incorporation as well as in vitro inhibition experiments using cycloheximide to inhibit protein synthesis were carried out for all three substances in DU145 prostate carcinoma cells (ATCC, USA). (68)Ga-DOTA-Pur was additionally used for μPET imaging of Walker carcinomas and AT1 tumors in rats. Dynamic scans were performed for 45 min after IV application (tail vein) of 20-25 MBq (68)Ga-DOTA-Pur. RESULTS: No significant differences in the behavior of [(3)H]tyrosine and 2-fluoro-[(3)H]tyrosine were observed. Uptake of both tyrosine derivatives was decreased by inhibition of protein synthesis, but only to a level of 45-55% of initial uptake, indicating no direct link between tyrosine uptake and protein synthesis. In contrast, (68)Ga-DOTA-Pur uptake was directly linked to ribosomal activity and, therefore, to protein synthesis. (68)Ga-DOTA-Pur μPET imaging in rats revealed high tumor-to-background ratios and clearly defined regions of interest in the investigated tumors. SUMMARY: Whereas the metabolic pathway of (68)Ga-DOTA-Pur is directly connected with the process of protein synthesis and shows high tumor uptake during μPET imaging, neither [(3)H]tyrosine nor 2-fluoro-[(3)H]tyrosine can be considered useful for determination of protein synthesis.
- MeSH
- experimentální nádory metabolismus MeSH
- heterocyklické sloučeniny monocyklické chemie MeSH
- krysa rodu rattus MeSH
- pozitronová emisní tomografie MeSH
- proteosyntéza * účinky léků MeSH
- puromycin diagnostické užití MeSH
- radiofarmaka chemická syntéza diagnostické užití MeSH
- radioizotopy galia diagnostické užití izolace a purifikace MeSH
- tritium diagnostické užití MeSH
- tyrosin metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Organophosphorus poisoning manifests as a cholinergic syndrome due to an inhibition of acetylcholinesterase. It is treated symptomatically by anticholinergics and oxime reactivators are used as causal antidotes. Reactivators possess a complex mechanism of action and interact at various levels of the cholinergic transmission. The aim of this study was to investigate the effect of standard oxime reactivators (HI-6, obidoxime, trimedoxime, methoxime and pralidoxime) on the hemicholinium-3 sensitive carriers, which are involved in the high-affinity choline uptake (HACU) transport, a key regulatory step in the synthesis of acetylcholine. The activity of the carriers was estimated in vitro on hippocampal synaptosomes using the substrate (3H)-choline and the competitive inhibitor (3H)-hemicholinium-3. Furthermore, the effect of the reactivators on the fluidity of hippocampal membranes was assessed. All tested compounds, except methoxime, showed an acute inhibitory effect on the carriers, however, only at μM concentrations. Trimedoxime showed the highest potency to inhibit HACU among all tested compounds (I(max) 62%, IC(50)=3 μM). All compounds, except HI-6, influenced also a membrane fluidity in the region of the hydrophilic heads of phospholipid bilayer, nevertheless, only methoxime was able to penetrate more deeply into the hydrocarbon core. We suggest that the direct interaction of oxime reactivators with the carrier protein (HI-6 and trimedoxime) and/or the changes in carrier conformation mediated by alterations in membrane fluidity (trimedoxime, obidoxime and pralidoxime) could occur here. The influence of reactivators on the carriers could be unfavorable in the case of their prolonged administration in vivo. From this point of view, the application of methoxime appears to be the best.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- anizotropie MeSH
- buněčná membrána účinky léků metabolismus MeSH
- cholin metabolismus MeSH
- fluidita membrány účinky léků fyziologie MeSH
- hemicholinium 3 metabolismus MeSH
- hipokampus účinky léků metabolismus MeSH
- krysa rodu rattus MeSH
- membránové transportní proteiny účinky léků metabolismus MeSH
- potkani Wistar MeSH
- reaktivátory cholinesterázy metabolismus farmakologie MeSH
- synaptozomy účinky léků metabolismus MeSH
- tritium diagnostické užití MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Microdialysis has been utilized for nutritive blood flow measurements, but both the advantages and disadvantages of various approaches have not been evaluated in parallel in the stomach yet. Our aim was to compare the (3)H(2)O efflux technique with biochemical monitoring during temporary celiac artery occlusion in anesthetized rats. Microdialysis probes were implanted in the gastric submucosa and perfused with (3)H(2)O; samples were analyzed for β-activity, glucose, lactate, pyruvate and glycerol. Gastric mucosa and plasma were subjected to morphometry and analysis of myeloperoxidase, total thiols and lactatdehydrogenase. The most dramatic responses to ischemia were observed in lactate/pyruvate and lactate/glucose (%) ratios (6.1-9.3×, p < 0.0001); the changes in (3)H(2)O efflux and glycerol were less pronounced (1.1-1.7×, p < 0.0001 and < 0.01, respectively). (3)H(2)O efflux correlated best with the lactate/glucose ratio and glucose alone (r = 0.693 and -0.681, respectively, p < 0.0001). A correlation was also found between plasma lactatdehydrogenase and relative glycerol release (r = 0.600, p < 0.05). Myeloperoxidase, lactatdehydrogenase and histology score were increased by ischemia/reperfusion (0.06-0.12 nkat g(-1), p < 0.05, 0.26-0.44 nkat g(-1), p < 0.05 and 1.79-2.33, p < 0.05, respectively), macroscopy and plasma thiols remained unchanged. Microdialysis is useful in monitoring gastric ischemia, metabolic monitoring being superior to the (3)H(2)O efflux technique. The results question the efficacy of the utilized model to produce standardized major gastric damage.
- MeSH
- ischemie diagnóza metabolismus MeSH
- krysa rodu rattus MeSH
- mikrodialýza metody MeSH
- potkani Wistar MeSH
- tritium diagnostické užití MeSH
- voda diagnostické užití MeSH
- žaludeční sliznice krevní zásobení metabolismus patologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- MeSH
- biologický transport fyziologie účinky léků MeSH
- cytosin aplikace a dávkování farmakologie MeSH
- fungální proteiny metabolismus MeSH
- transportní proteiny metabolismus MeSH
- Trichoderma metabolismus MeSH
- tritium diagnostické užití MeSH
- uracil farmakokinetika MeSH
- Publikační typ
- srovnávací studie MeSH
- MeSH
- Alzheimerova nemoc metabolismus MeSH
- cholin metabolismus MeSH
- dospělí MeSH
- hemicholinium 3 metabolismus MeSH
- lidé středního věku MeSH
- lidé MeSH
- multiinfarktová demence metabolismus MeSH
- pitva MeSH
- senioři MeSH
- tritium diagnostické užití MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- senioři MeSH
- MeSH
- autoradiografie metody využití MeSH
- barvení a značení metody využití MeSH
- cytologické techniky metody využití MeSH
- DNA biosyntéza metabolismus MeSH
- histocytochemie metody využití MeSH
- krysa rodu rattus MeSH
- myši MeSH
- RNA biosyntéza metabolismus MeSH
- statistika jako téma MeSH
- thymidin aplikace a dávkování diagnostické užití MeSH
- tritium aplikace a dávkování diagnostické užití MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- myši MeSH
- zvířata MeSH
- MeSH
- autoradiografie metody využití MeSH
- barvení a značení metody využití MeSH
- biochemie metody MeSH
- cytologické techniky metody využití MeSH
- elektronová mikroskopie metody využití MeSH
- histocytochemie metody využití MeSH
- izotopové značení metody trendy využití MeSH
- lidé MeSH
- proteosyntéza fyziologie účinky léků MeSH
- radionuklidy aplikace a dávkování diagnostické užití MeSH
- rentgenové filmy normy využití MeSH
- thymidin aplikace a dávkování diagnostické užití MeSH
- tritium aplikace a dávkování diagnostické užití MeSH
- Check Tag
- lidé MeSH