The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Reingard Senekowitsch-schmidtke - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Choline Uptake in prostate cancer cells following bicalutamide and docetaxel treatment.
European Journal of Nuclear Medicine and Molecular Imaging, 2009Co-Authors: Sebastian Müller, Korbinian Holzapfel, Christof Seidl, Uwe Treiber, Bernd J. Krause, Reingard Senekowitsch-schmidtkeAbstract:Purpose Choline derivatives labelled with positron emitters are successfully used for PET imaging of prostate cancer patients. Since little is known about Uptake mechanisms, the aim of this study was to characterize Choline Uptake in prostate cancer cells, also following anti-androgen treatment or chemotherapy.
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Effects of irradiation on the [Methyl-3H]Choline Uptake in the human prostate cancer cell lines LNCaP and PC3.
Strahlentherapie und Onkologie : Organ der Deutschen Rontgengesellschaft ... [et al], 2008Co-Authors: Korbinian Holzapfel, Sebastian Müller, Christof Seidl, Anca-ligia Grosu, Markus Schwaiger, Reingard Senekowitsch-schmidtkeAbstract:BACKGROUND AND PURPOSE: Choline positron emission tomography (PET) can help to optimize radiation treatment strategy of prostate cancer. Therefore, the aim of this study was to elucidate the effects of ionizing radiation on the Choline Uptake in an androgen-dependent (LNCaP) and an androgen-independent (PC3) prostate cancer cell line. MATERIAL AND METHODS: Uptake of [methyl-(3)H]Choline chloride was investigated between 4 and 96 h after irradiation with 6 Gy. Dose dependence of Choline Uptake was examined following irradiation with 2-12 Gy, and cell survival was analyzed via the clonogenic assay. Michaelis-Menten kinetics was determined 24 h (PC3) and 48 h (LNCaP) after irradiation with 6 Gy. RESULTS: PC3 cells showed a significant transitory increase of [methyl-(3)H]Choline Uptake with a maximum at 24 h after irradiation. In LNCaP cells irradiation induced a significant decrease with a minimum at 48 h. Changes in Choline Uptake in both cell lines were almost dose-independent up to 12 Gy. Following irradiation with 6 Gy, transport capacity (v(max)) increased and Michaelis-Menten constant (K(M)) decreased in PC3 cells, while in LNCaP cells the two parameters behaved vice versa. CONCLUSION: Changes in Choline Uptake following irradiation might be due to metabolic changes associated with initiation of processes that finally cause cell death. Thus, changes in tumor Choline Uptake monitored by PET after radiotherapy might not exclusively reflect therapeutic success but also altered tracer Uptake as a consequence of irradiation.
Sebastian Müller - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Choline Uptake in prostate cancer cells following bicalutamide and docetaxel treatment.
European Journal of Nuclear Medicine and Molecular Imaging, 2009Co-Authors: Sebastian Müller, Korbinian Holzapfel, Christof Seidl, Uwe Treiber, Bernd J. Krause, Reingard Senekowitsch-schmidtkeAbstract:Purpose Choline derivatives labelled with positron emitters are successfully used for PET imaging of prostate cancer patients. Since little is known about Uptake mechanisms, the aim of this study was to characterize Choline Uptake in prostate cancer cells, also following anti-androgen treatment or chemotherapy.
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Effects of irradiation on the [Methyl-3H]Choline Uptake in the human prostate cancer cell lines LNCaP and PC3.
Strahlentherapie und Onkologie : Organ der Deutschen Rontgengesellschaft ... [et al], 2008Co-Authors: Korbinian Holzapfel, Sebastian Müller, Christof Seidl, Anca-ligia Grosu, Markus Schwaiger, Reingard Senekowitsch-schmidtkeAbstract:BACKGROUND AND PURPOSE: Choline positron emission tomography (PET) can help to optimize radiation treatment strategy of prostate cancer. Therefore, the aim of this study was to elucidate the effects of ionizing radiation on the Choline Uptake in an androgen-dependent (LNCaP) and an androgen-independent (PC3) prostate cancer cell line. MATERIAL AND METHODS: Uptake of [methyl-(3)H]Choline chloride was investigated between 4 and 96 h after irradiation with 6 Gy. Dose dependence of Choline Uptake was examined following irradiation with 2-12 Gy, and cell survival was analyzed via the clonogenic assay. Michaelis-Menten kinetics was determined 24 h (PC3) and 48 h (LNCaP) after irradiation with 6 Gy. RESULTS: PC3 cells showed a significant transitory increase of [methyl-(3)H]Choline Uptake with a maximum at 24 h after irradiation. In LNCaP cells irradiation induced a significant decrease with a minimum at 48 h. Changes in Choline Uptake in both cell lines were almost dose-independent up to 12 Gy. Following irradiation with 6 Gy, transport capacity (v(max)) increased and Michaelis-Menten constant (K(M)) decreased in PC3 cells, while in LNCaP cells the two parameters behaved vice versa. CONCLUSION: Changes in Choline Uptake following irradiation might be due to metabolic changes associated with initiation of processes that finally cause cell death. Thus, changes in tumor Choline Uptake monitored by PET after radiotherapy might not exclusively reflect therapeutic success but also altered tracer Uptake as a consequence of irradiation.
Debomoy K. Lahiri - One of the best experts on this subject based on the ideXlab platform.
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high affinity Choline Uptake hacu and Choline acetyltransferase chat activity in neuronal cultures for mechanistic and drug discovery studies
Current protocols in protein science, 2012Co-Authors: Balmiki Ray, J. R. Simon, Jason A Bailey, Debomoy K. LahiriAbstract:AcetylCholine (ACh) is the neurotransmitter used by Cholinergic neurons at the neuromuscular junction, in parasympathetic peripheral nerve terminals, and in important memory-related circuits in the brain, and takes part in other critical functions. ACh is synthesized from Choline and acetyl coenzyme A by the enzyme Choline acetyltransferase (ChAT). The formation of ACh in Cholinergic nerve terminals requires the transport of Choline into cells from the extracellular space and the activity of ChAT. High-affinity Choline Uptake (HACU) represents the majority of Choline Uptake into the nerve terminal and is the acutely regulated, rate-limiting step in ACh synthesis. HACU can be differentiated from nonspecific Choline Uptake by inhibition of the Choline transporter with hemicholinium. Several methods have been described previously to measure HACU and ChAT activity simultaneously in synaptosomes, but a well-documented protocol for cultured cells is lacking. We describe a procedure for simultaneous measurement of HACU and ChAT in cultured cells by simple radionuclide-based techniques. Using this procedure, we have quantitatively determined HACU and ChAT activity in Cholinergically differentiated human neuroblastoma (SK-N-SH) cells. These simple methods can be used for neurochemical and drug discovery studies relevant to several disorders, including Alzheimer's disease, myasthenia gravis, and cardiovascular disease.
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Determination of high-affinity Choline Uptake (HACU) and Choline acetyltransferase (ChAT) activity in the same population of cultured cells
Brain research, 2009Co-Authors: Balmiki Ray, J. R. Simon, Debomoy K. LahiriAbstract:Cholinergic neurons are a major constituent of the mammalian central nervous system. AcetylCholine, the neurotransmitter used by Cholinergic neurons, is synthesized from Choline and acetyl CoA by the enzymatic action of Choline acetyltransferase (ChAT). The transport of Choline into the Cholinergic neurons, which results in synthesis of ACh, is hemicholinium-sensitive and is referred to as high-affinity Choline Uptake (HACU). Thus, the formation of acetylCholine in Cholinergic neurons largely depends on both the levels of Choline being transported into the cells from the extracellular space and the activity of ChAT. Several methods were described previously to measure HACU and ChAT simultaneously in synaptosomes, but the same for cultured cells is lacking. We describe a procedure to measure HACU and ChAT at the same time in cultured cells by simple techniques employing radionuclides. In this procedure, we determined quantitatively hemicholinium-sensitive Choline Uptake and ChAT enzyme activity in a small number of differentiated human neuroblastoma (SK-N-SH) cells. We also determined the kinetics of Choline Uptake in the SK-N-SH cells. We believe that these simple methods can be used for neurochemical and drug discovery studies in several models of neurodegenerative disorders including Alzheimer's disease.
Joseph T. Coyle - One of the best experts on this subject based on the ideXlab platform.
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Effects of calmodulin antagonists on sodium-dependent high-affinity Choline Uptake.
Brain research, 1991Co-Authors: Kiyofumi Yamada, Mario D. Saltarelli, Joseph T. CoyleAbstract:The effects of calmodulin (CaM) antagonists were investigated on the sodium-dependent high-affinity Choline Uptake (SDHACU) as assessed by the specific binding of [3H]hemicholinium-3 ([3H]HCh-3) and high-affinity [3H]Choline Uptake. Potassium depolarization caused a significant 2-fold increase in the specific binding of [3H]HCh-3 in slices of rat striatum in vitro. CaM antagonists, including trifluoperazine (TFP), W-5, W-7, promethazine and haloperidol, dose-dependently inhibited potassium depolarization-stimulated [3H]HCh-3 binding with IC50s of 20, 40, 70, 30 and 48 (microM), respectively. Scatchard analysis revealed that the inhibitory effect of TFP resulted from a decrease in Bmax but no change in Kd of [3H]HCh-3 binding. Potassium depolarization of slices also stimulated high-affinity [3H]Choline Uptake, which was completely inhibited by 10 microM TFP. These results are discussed in relation to the regulatory mechanisms of SDHACU.
Arthur J. Chu - One of the best experts on this subject based on the ideXlab platform.
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Lidocaine inhibits Choline Uptake and phosphatidylCholine biosynthesis in human leukemic monocyte‐like U937 cells
Cell biochemistry and function, 1994Co-Authors: Arthur J. Chu, Jack M. LeeAbstract:The effect of lidocaine on [3H]Choline Uptake and the incorporation of label into phosphatidylCholine (PC) in human monocyte-like U937 cells was investigated. Lidocaine inhibited the rate of Choline Uptake in a dose-dependent manner; at 3.2 mM it resulted in a drastic reduction, by as much as 65 per cent (n = 10; p < 0.0005) or 55 per cent (n = 10; p < 0.0006) in a 3- or 6-h incubation, respectively. Lidocaine also decreased the rate of Choline incorporation into PC in a dose-dependent manner. At the highest dose, nearly 70 per cent or 45 per cent reduction was seen in a 3- or 6-h incubation, respectively. Analysis of Choline-containing metabolites showed that the major label association with phosphoCholine and PC was reduced to a similar extent which was also parallel to the inhibition of Choline Uptake. At 3.2 mM lidocaine, the reduction of Choline Uptake was shown to follow a competitive inhibition. In the case of [3H] Choline incorporation into PC, the inhibitory pattern was shown to be of a mixed type. The pulse-chase study dissecting the effect on Choline metabolism from that on total Choline Uptake indicated that lidocaine exerted an additionally inhibitory effect on intracellular Choline metabolism into PC. In a separate protocol in which the labelled cells were first allowed to be chased until 3H-incorporation into PC reached a steady state, lidocaine no longer showed any effect. These results seem to exclude the possibility of enhanced PC breakdown and further suggest that the main inhibitory effect is on the CDP-Choline pathway for PC biosynthesis. After a 3-h treatment, CTP: Cholinephosphate cytidylyltransferase (CYT) in both the cytosolic and microsomal fractions was inhibited by approximately 20 per cent, while Choline kinase (CK) and Choline phosphotransferase (CPT) remain relatively unchanged. There was no evidence for translocation of CYT between cytosol and microsomes. Taken together, we have demonstrated a dual inhibitory function of lidocaine which inhibits PC biosynthesis in addition to its ability to block Choline Uptake profoundly in U937 cells.
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Stimulation of phosphatidylCholine biosynthesis by hemicholinium‐3, a potent inhibitor of Choline Uptake in human leukemic monocyte‐like U937 cells
Cell biochemistry and function, 1994Co-Authors: Arthur J. ChuAbstract:The effect of hemicholinium-3 (HC-3) on Choline Uptake and phosphatidylCholine (PC) biosynthesis was examined in human leukemic monocyte-like U937 cells. HC-3 inhibited [3H]Choline Uptake in a dose- and time-dependent manner. After a 3 h treatment, HC-3 (100 microM) decreased Choline Uptake by as much as 80 per cent (p < 0.0001; n = 4). Reduction of incorporation of label into PC was also detected in a dose-dependent manner; the extent of inhibition, however, was always 10-20 per cent less than that observed in the total Uptake. At 3 h HC-3 decreased the incorporation into PC by 65 per cent (p < 0.0001; n = 5). Kinetic studies in vivo showed that HC-3 inhibited total Uptake and incorporation into PC differently, suggesting that the labelling of PC is not simply dictated by [3H]Choline Uptake. In separate experiments, cells were pretreated with 100 microM HC-3 for 3 h. After washing, the inhibitory effect on total Uptake was no longer observed, while a 20 per cent stimulation of the incorporation into PC was obtained in these pretreated cells. In pulse-chase studies, the cells were prelabelled with [3H]Choline for 30 min and chased with HC-3 for up to 3 h; the results showed a significant stimulation of incorporation into PC in a longer chase with 100 microM HC-3. After a 3 h treatment, the cytosolic CTP:Cholinephosphate cytidylyltransferase (CT) was activated by 56 per cent, while Choline kinase (CK) was inhibited slightly. The stimulation of CT was not simply due to the intact HC-3 molecule, and there was no redistribution of CT between cytosol and microsomes. Taken together, the results suggest that HC-3 activates PC biosynthesis apart from the inhibitory effect on Choline Uptake.