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PubMed2006

Imaging prostate cancer with 11C-choline PET/CT.

UNLABELLED: The ability of 11C-choline and multimodality fusion imaging with integrated PET and contrast-enhanced CT (PET/CT) was investigated to delineate prostate carcinoma (PCa) within the prostate and to differentiate cancer tissue from normal prostate, benign prostate hyperplasia, and focal chronic prostatitis. METHODS: All patients with PCa gave written informed consent. Twenty-six patients with clinical stage T1, T2, or T3 and biopsy-proven PCa underwent 11C-choline PET/CT after intravenous injection of 1,112 +/- 131 MBq 11C-choline, radical retropubic prostatovesiculectomy, and standardized prostate tissue sampling. Maximal standardized uptake values (SUVs) of 11C-choline within 36 segments of the prostate were determined. PET/CT results were correlated with histopathologic results, prostate-specific antigen (PSA), Gleason score, and pT stage. RESULTS: The SUV of 11C-choline in PCa tissue was 3.5 +/- 1.3 (mean +/- SD) and significantly higher than that in prostate tissue with benign histopathologic lesions (2.0 +/- 0.6; P < 0.001 benign histopathology vs. cancer). Visual and quantitative analyses of segmental 11C-choline uptake of each patient unambiguously located PCa in 26 of 26 patients and 25 of 26 patients, respectively. A threshold SUV of 2.65 yielded an area under the receiver-operating-characteristic (ROC) curve of 0.89 +/- 0.01 for correctly locating PCa. The maximal 11C-choline SUV did not correlate significantly with PSA or Gleason score but did correlate with T stage (P = 0.01; Spearman r = 0.49). CONCLUSION: 11C-Choline PET/CT can accurately detect and locate major areas with PCa and differentiate segments with PCa from those with benign hyperplasia, chronic prostatitis, or normal prostate tissue. The maximal tumoral 11C-choline uptake is related to pT stage.

Aged↗
PubMed1985

Regulation of choline kinase activity and phosphatidylcholine biosynthesis by mitogenic growth factors in 3T3 fibroblasts.

The regulation of choline kinase activity by fetal bovine serum and the regulation of phosphatidylcholine biosynthesis by choline kinase have been investigated in 3T3 fibroblasts. Treatment of quiescent 3T3 fibroblasts with serum was shown in previous work to increase phosphocholine pool size and phosphatidylcholine biosynthesis. We now report that treatment of 3T3 cells with serum increased intracellular choline kinase activity by 2-3-fold with a concomitant 2-3-fold decrease of intracellular free choline concentrations. Initial rates of choline transport were the same in quiescent and serum-treated cells, whereas choline kinase activity was 2-3-fold higher in serum-treated cells. As a consequence, free choline concentrations were 2-3-fold lower in serum-stimulated cells than in control quiescent cells. Phosphocholine turnover rates were increased 2-fold by serum treatment both as a consequence of a serum-dependent increase of phosphocholine pools and as a result of a serum-dependent lowering of the phosphocholine half-life. Thus, the overall response of 3T3 cells to serum stimulation included decreased choline pools and increased choline kinase activity, phosphocholine pool size, phosphocholine turnover, and phosphatidylcholine biosynthesis.

Animals↗
PubMed1985

Evidence for the existence of isozymes of choline kinase and their selective induction in 3-methylcholanthrene- or carbon tetrachloride-treated rat liver.

New evidence is provided that rat liver choline kinase exists in several distinct forms (choline kinases I, II and III) which differ in isoelectric point, molecular size and antigenicity against anti-rat kidney choline kinase IgG. Remarkable and selective induction of the choline kinase II and choline kinase III forms of choline kinase was caused similarly by the administration of polycyclic aromatic hydrocarbon carcinogen, 3-methylcholanthrene or hepatotoxic carbon tetrachloride (CCl4). The immunochemical approach further indicated that the elevation in the activity of choline kinase in the 3-methylcholanthrene- or CCl4-treated rat liver was not accompanied by a parallel increase in the amount of choline kinase II enzyme protein, compatible with the induction of either a small amount of new enzyme protein(s) with very high specific activity or another enzyme which might catalyze post-translational modification of choline kinase.

Animals↗
PubMed1983

Biosynthesis of phosphatidylcholine from serum phospholipids in Chinese hamster ovary cells deprived of choline.

We report that Chinese hamster ovary cells assemble membrane phospholipids from choline-linked lipid present in fetal calf serum. This was examined by testing the ability of various serum preparations to satisfy the choline requirement of the cells. Chinese hamster ovary cells divided in growth medium containing lipoprotein-deficient serum and approximately 8 microM lysolecithin. Identical results were obtained in growth medium supplemented with solvent-extracted (delipidated) serum reconstituted with purified egg lysolecithin and the uptake of lipid was inhibited by the addition of bovine serum albumin. Analysis of the phospholipid composition of cells incubated with 32Pi and egg lysolecithin in place of choline revealed that approximately 30% of the phosphorus moieties of the cellular phospholipids were derived from the added lipid, while in the presence of choline less than 10% arose in this fashion. Choline starvation enhanced the formation of lecithin from [32P]lysolecithin without affecting phospholipid turnover and labeled lecithin was converted to other phospholipids, especially sphingomyelin and phosphatidylserine. Unlike endogenous serum lysolecithin, lipoproteins obtained from human and fetal calf sera failed to satisfy the choline requirement of Chinese hamster ovary cells, even though 95% of the lipoprotein phospholipid was phosphatidylcholine and sphingomyelin. Together, these results demonstrate that animal cells can derive all of the choline required for membrane phospholipid synthesis from serum lysolecithin and that its conversion to lecithin within the cell is regulated by the availability of choline. In contrast, serum lipoproteins do not normally serve as a major source of choline moieties.

Animals↗
PubMed1983

Formation of methylamines from ingested choline and lecithin.

Humans ingest substantial amounts of choline and lecithin as part of common foods. Physicians have recently begun administering large doses of these compounds to individuals with neurological diseases. A significant fraction of ingested choline is destroyed by enzymes within gut bacteria, forming trimethylamine (TMA), dimethylamine (DMA) and monomethylamine (MMA). Some of these methylamines are eventually excreted into the urine, presumably after being absorbed and carried to the kidneys via the bloodstream. The methylamines formed after choline is eaten could be substrates for the formation of nitrosamines, which have marked carcinogenic activity. Twenty-seven millimoles of choline chloride, choline stearate or lecithin were administered to healthy human subjects. It was found that these treatments markedly increased the urinary excretion of TMA, DMA and MMA, with choline chloride having the greatest effect. Rats were treated with 2 mmol/kg b.wt. of choline chloride or lecithin, and it was found that these treatments significantly increased urinary TMA excretion and did not alter DMA or MMA excretion. Our choline chloride preparation contained no MMA, DMA or TMA; however, it was found that our choline stearate and all the commercially available lecithins tested were contaminated with methylamines. Prior removal of methylamines from our lecithin preparation minimized the effect of oral administration of this compound on methylamine excretion in urine of rats and humans.

Administration, Oral↗
PubMed1994

Effects of CDP-choline on cognition and cerebral hemodynamics in patients with Alzheimer's disease.

CDP-choline (cytidine-5-diphosphate-choline) is an acetylcholine precursor frequently used in cerebrovascular disorders and psychoorganic syndromes. Furthermore, several authors have demonstrated the positive effects of CDP-choline on cognitive disorders and memory deficits. In the present study, the effects of CDP-choline (1000 mg/day, p.o. for 1 month) on cognition, evaluated by the Mini-Mental State Examination (MMSE) of Folstein et al., and on blood flow velocities, measured by transcranial Doppler ultrasonography (TCD), were investigated in patients with Alzheimer's disease: (AD, n = 20, age: 66.75 +/- 6.73 years, range: 57-78 yr). Cognitive function was measured by means of the MMSE in basal conditions (A) and after 1 month of treatment with CDP-choline (C). TCD measures were taken through the temporal window for right (MCA-R) and left (MCA-L) middle cerebral arteries with a 2 MHz pulsed transducer using a TC-2000S in basal conditions (A), 1 h after the administration of CDP-choline (B) and after 1 month of treatment with CDP-choline (C). MMSE scores were significantly increased (p < 0.005) in patients with early-onset Alzheimer's disease (EOAD) after CDP-choline treatment. Moreover, the orientation subtest significantly increased in the global group of AD patients (p < 0.01) and in EOAD patients (p < 0.02). Significant differences (p < 0.05) were also found in MCA-Land MCA-R measures between recordings. These results suggest that CDP-choline influences cognitive and cerebrovascular function in Alzheimer's disease, probably through a mechanism linked to an immunogenic and/or neurotrophic effect at the microvascular niche.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

CDP-choline-induced blood histamine changes in Alzheimer's disease.

Histamine (HA) is a known neurotransmitter with a wide spectrum of biological actions at the central and peripheral levels. Recently, it has been found that HA is involved in the regulation of immune cell function, acting as an immunomodulator. A hyperactivation in the histaminergic system has been demonstrated in Alzheimer's disease (AD), including increased levels of HA in brain, serum, and cerebrospinal fluid of AD patients. In addition, changes in phospholipid metabolism and neuroimmune function have been reported in AD. CDP-choline (cytidine-5-diphosphate-choline) participates in the phospholipid metabolism pathway incorporating free choline into phosphatidyl-choline and choline plasmalogens in several tissues, including the central nervous system. In this study we have measured the concentration of HA in blood from patients with early-onset AD (EOAD) and late-onset AD (LOAD) under treatment with CDP-choline (1000 mg p.o. x30 days). HA was measured by high performance liquid chromatography (HPLC) with fluorometric detection. CDP-choline reduced the basal levels of blood HA in both EOAD and LOAD by 2-fold. The reduction in blood HA content was observed 2 h after CDP-choline administration and gradually progressed for 30 days of treatment. These results confirm the potential immunogenic effects of CDP-choline and also that an excess of HA might influence some etiopathogenic events in AD.

Administration, Oral↗
PubMedDate not supplied

A placebo controlled trial of two dosages of LPC antagonist--choline in the management of bronchial asthma.

The present study was conducted to compare choline with a placebo for its dose-effect relationship in management of bronchial asthma. Three groups: Group A: taking placebo (sorbitol), Group B: low dose choline (500 mg TDS), and Group C: high dose choline (1000 mg TDS) were assessed after a trial of four months. A decrease in symptoms score and increase in percent asymptomatic days was observed in all the three groups but was statistically significant only in the groups taking choline (Group B and C). Further, it was more significant in the group taking higher dose of choline (Group C). Average drug-requirement decreased in all the three groups but was significant only in the high dose choline group (Group C) Specific airway conductance (SGaw) at FRC and RV improved significantly only in group taking higher dose of choline (Group C), while no significant change in percent fall in SGaw at RV was observed in any group. It is, thus, concluded that choline is a useful prophylactic drug in the management of bronchial asthma. The improvement was more significant at a higher dose. Further studies are required to establish optimal dose of choline in the management of bronchial asthma.

Adolescent↗
PubMed1986

Change of choline metabolism in rat liver on chronic ethionine-feeding.

On chronic ethionine-feeding (0.1% DL-ethionine in 0.5% sucrose solution) for 2, 4 or 6 months, choline metabolism in rat hepatic cells was altered considerably, although RNA contents were virtually unchanged. Choline dehydrogenase activity in the hepatic mitochondrial fraction was suppressed by about 1/2 or 1/3, compared to its normal level, whereas choline kinase activity, which existed in the cytoplasmic fraction, was elevated more than 1.5-fold. The normal value for choline-metabolizing enzymes in terms of the choline dehydrogenase/choline kinase activity ratio was estimated to be about 70 under the defined conditions, while the average value of the activity ratio drastically changed to about 10-20 on chronic ethionine-feeding. The present results suggest that an alteration of hepatic choline-flux occurred, due both to an increase in choline kinase activity and to a counteractive decrease in choline dehydrogenase activity.

Alcohol Oxidoreductases↗
PubMed2000

Enhanced tolerance of transgenic Brassica juncea to choline confirms successful expression of the bacterial codA gene.

Brassica juncea cv. Pusa Jaikisan was transformed with the codA gene for choline oxidase from Arthrobacter globiformis with an aim to introduce glycine betaine biosynthetic pathway, as it lacks any means to synthesize glycine betaine. Western blot analysis revealed the presence of choline oxidase in the protein extract from the codA transgenic lines, demonstrating that the bacterial codA gene had been successfully transcribed and translated in transgenic lines. Good activity of choline oxidase indicated its presence in fully functional form in the transformed lines. This was further confirmed by the presence of glycine betaine only in the transformed lines of B. juncea. The shoots of both wild type and transformed lines were exposed to various concentrations of choline in order to evaluate if the introduction of the codA gene in any way enhances the potential of B. juncea to tolerate high levels of choline. The growth (in terms of fresh weight and dry weight) of the shoots of transformed lines exposed to high levels of choline was significantly superior to those of wild type. Moreover, the loss in chlorophyll content and the activity of photosystem II in shoots of the transformed lines exposed to high concentration of choline were significantly lower than that observed in wild type. These results showed that shoots of B. juncea transformed with the codA gene, most probably had the potential to readily convert choline to glycine betaine. Therefore, choline tolerance can be used as an efficient marker for the identification of the lines transformed with the codA gene.

Journal Article↗
PubMed1986

Brain and serum levels of choline and lecithin resulting from long-term administration.

Choline and phosphatidylcholine tissue concentrations were examined in mice treated with long-term (18-22 month) dietary choline enrichment, choline deficiency, or phosphatidylcholine enrichment. There were no significant differences found in choline levels among the dietary groups in any of the tissues examined: plasma, erythrocytes, cortex, hippocampus, and striatum. In contrast, the concentration of phosphatidylcholine in both the choline enriched and phosphatidylcholine enriched groups were significantly increased in the cortex, compared to the choline deficient group, and in the striatum, compared to control. No differences in phosphatidylcholine concentration were found in the hippocampus or plasma between any of the dietary groups. These results are in contrast to the reported effects of acute or short-term choline and phosphatidylcholine treatment and indicate that there may be differences between the effects of short-term and long-term administration on the blood and brain levels of choline and phosphatidylcholine.

Animals↗
PubMed1984

Ethanolamine inhibits choline uptake in the isolated hamster heart.

The effect of exogenous ethanolamine on phosphatidylcholine biosynthesis in the isolated hamster heart was investigated. Hamster hearts were perfused with [Me-3H]choline in the presence of 0.05-0.5 mM ethanolamine. Incorporation of label into phosphatidylcholine was decreased 26-63% at 0.1-0.5 mM ethanolamine. Similar decreases in the labelling of the metabolites of the CDP-choline pathway were observed at these ethanolamine concentrations. The observed decrease in phosphatidylcholine labelling at 0.1-0.5 mM ethanolamine was attributed to an inhibition of labelled choline uptake by ethanolamine. The inhibitory role of ethanolamine to choline uptake was examined by comparison to hemicholinium-3. Both compounds inhibited choline uptake in a competitive manner. Intracellular choline, phosphocholine and CDP-choline concentrations were not altered under all experimental conditions. It can be concluded that exogenous ethanolamine has no immediate effect on the rate of phosphatidylcholine biosynthesis in the isolated hamster heart. The reduced labelling of phosphatidylcholine in the presence of ethanolamine is a direct result of the reduction of labelled choline taken up by the heart.

Animals↗
PubMed1994

Regulation of CTP: phosphocholine cytidylyltransferase in HepG2 cells: effect of choline depletion on phosphorylation, translocation and phosphatidylcholine levels.

We studied the effect of choline depletion on the biosynthesis of phosphatidylcholine (PC) and the distribution and phosphorylation of cytidylyltransferase (CT) in HepG2 cells. Phosphocholine concentrations decreased within 24 h of choline depletion to values less than 2% of controls. The incorporation of [3H]glycerol into PC was reduced in choline-depleted (CD) cells. The apparent turnover of PC was similar in CD and choline-supplemented (CS) cells (T1/2 = 20 h). The methylation pathway for PC synthesis increased nearly 10-fold in CD cells. Cell growth was similar in CD and CS cells. Over 95% of CT activity in CS cells was in the soluble pool. Choline depletion resulted in a progressive decrease in CT activity and immunodetected enzyme in the soluble pool and a corresponding increase in membrane CT over a 48-h period. Choline supplementation of CD cells caused a rapid release of membrane CT (complete release by 3 h). Two phosphorylated forms of CT were identified. One form contained a higher level of phosphorylation (HPCT) than the other form (LPCT). HPCT migrated slightly slower than LPCT on SDS gels. CD cells contained only LPCT in both soluble and membrane pools. CS cells contained only HPCT. During choline depletion PC content decreased nearly 20% but CT binding did not occur until LPCT was generated in cytosol. Conversely, choline supplementation released LPCT into cytosol and HPCT was formed only after the release. We conclude that both the induction of binding sites, perhaps by depletion of PC and dephosphorylation of HPCT to LPCT, are required for CT translocation to membranes. The release of CT from membranes is initiated by changes in membrane binding sites followed by trapping of the CT in the soluble pool by phosphorylation of LPCT to HPCT.

Binding Sites↗
PubMed1985

Dietary choline affects response to acetylcholine by isolated urinary bladder.

Age-related increases occur in the response of isolated urinary bladders to the parasympathetic neurotransmitter acetylcholine (ACh). Experiments were carried out to determine whether long-term elevation or diminution in the amount of ingested choline can also affect the response of the urinary bladder to ACh. Female C57BL/6J mice were maintained on a choline-deficient chow and on drinking water supplemented with either 0, 1.5, or 4.0 mg/ml choline chloride from 8 to 20 months of age. Isolated bladders from choline deficient animals showed a 46% increase in the maximum response to ACh as compared to those from normal choline animals, while bladders from animals on choline enriched diets showed a 15% decrease in maximum contractile response. Radioligand binding experiments suggested that the functional changes result from alterations in the density of muscarinic receptors in the bladder. The results are consistent with the hypothesis that muscarinic receptors are down-regulated to compensate for increased parasympathetic activity associated with choline-enriched diets and up-regulated to compensate for decreased parasympathetic activity associated with choline-deficient diets.

Acetylcholine↗
PubMed1991

Nicotine improves cognitive disturbance in rodents fed with a choline-deficient diet.

The effect of nicotine on learning disturbances was tested in rats. Rats were fed either a choline-enriched or a choline-deficient diet. Concentration of acetylcholine in the whole brain was significantly lower in rats fed with choline-deficient diet than rats fed with choline-enriched diet. Passive avoidance learning shows that rats on a choline-deficient diet showed significantly impaired learning compared to rats on a choline-enriched diet. Nicotine (0.04 mg/kg) administered intraperitoneally significantly potentiated learning in rats on a choline-deficient diet, as well as in rats on a choline-enriched diet. We, therefore, suggest that nicotine may potentiate learning in an acetylcholine-deprived brain.

Acetylcholine↗
PubMed1991

Regional differences in extracellular choline dependency of acetylcholine synthesis in the rat brain.

Acetylcholine (ACh) synthesis under conditions of restricted extracellular choline uptake was investigated in order to clarify the procurement of choline for ACh synthesis using slices of several regions of the rat brain. Extracellular choline-independent ACh synthesis was observed in the hippocampus, frontal cortex and caudate putamen, which contain cholinergic nerve terminals, whereas little or no synthesis was observed in the medial septum or basal nucleus of Meynert, which contain cholinergic cell bodies. These results indicate that cholinergic nerve terminals, but not the cell bodies, may be able to synthesize choline for ACh biosynthesis. Extracellular choline-dependent ACh synthesis was observed in all regions examined. In the presence of 10 microM choline, the highest content of newly synthesized ACh and the proportionate increase in ACh compared with the unreleasable fraction (basal level) were observed in the caudate putamen. In the frontal cortex, although the level of synthesized ACh was low, the proportionate increase in ACh was high. In contrast, in the medial septum and basal nucleus of Meynert, high levels of ACh with a low proportionate increase compared with basal levels were observed. In the presence of hemicholinium-3, extracellular choline was also taken up for ACh synthesis in all regions examined, the level being especially high in the frontal cortex and medial septum. The present results indicate that the manner of choline procurement for ACh synthesis is heterogeneous among the various regions of the rat brain.

Acetylcholine↗
PubMed1985

Membrane-bound choline acetyltransferase in Torpedo electric organ: a marker for synaptosomal plasma membranes?

The enzyme choline-O-acetyltransferase catalyses the biosynthesis of acetylcholine from acetyl coenzyme A and choline and is considered as one of the best markers for cholinergic nerve endings. The distribution of this enzymatic activity was analysed during the purification of plasma membranes of purely cholinergic nerve endings isolated from the electric organ of the fish Torpedo marmorata. This tissue, which receives a profuse and purely cholinergic innervation, can be considered as being a "giant" neuromuscular synapse. The isolated nerve endings (synaptosomes) were first osmotically disrupted and their plasma membranes isolated by equilibrium density centrifugation (discontinuous followed by continuous sucrose gradients). Choline acetyltransferase activity was found to exist in three forms: (1) a soluble form (the major one) present in the cytoplasm of the nerve endings, (2) a form which is ionically associated with membranes and which can be solubilized by washing exhaustively the membrane fraction with solutions of high ionic strength (0.5 M NaCl) and (iii) a form which is non-ionically bound to membranes and cannot be solubilized with high salt solution. The soluble and the non-ionically bound activities exhibited very similar affinities for choline (1.34 and 1.64 mM, respectively). The non-ionically membrane-associated form of choline acetyltransferase was found to "copurify" with the cholinergic synaptosomal plasma membranes of Torpedo, its specific activity being increased from 122 (crude fraction) to 475 (purified membrane fraction) nmol/h/mg protein. An enrichment was also observed for another cholinergic marker, the enzyme acetylcholinesterase, but not for the nicotinic receptor to acetylcholine, a marker for postsynaptic membranes. No choline acetyltransferase activity could be detected in preparations of synaptic vesicles that were highly purified from the electric organ. Also, the non-ionically associated form of choline acetyltransferase activity was hardly detectable (2.4 nmol/h/mg protein) in fractions enriched in axonal membranes prepared from the cholinergic electric nerves innervating the electric organ. The partition into soluble and membrane-bound activity was also analysed for choline acetyltransferase present in human placenta, a rich source for the enzyme but a non-innervated tissue. In this case the great majority of the enzyme appeared as soluble activity. Very low levels of non-ionically membrane-bound activity were found to be present in a crude membrane fraction from human placenta (2.8 nmol/h/mg protein).(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylation↗
PubMed1986

Amphiphilic and hydrophilic forms of choline-O-acetyltransferase in cholinergic nerve endings of the Torpedo.

In the purely cholinergic nerve endings isolated (i.e. synaptosomes) from the electric organ of the fish Torpedo, the enzyme choline acetyltransferase was found to exist not solely in its well-known soluble form but also in a form which is non-ionically bound to the plasma membrane; this activity could not be solubilized in solutions of high ionic strength (0.5 M NaCl). The non-ionic detergent Triton X-114 was used to solubilize synaptosomes isolated from either the electric organ of Torpedo or rat brain. This detergent allows to separate hydrophilic from amphiphilic proteins of cells or subcellular fractions. Twelve per cent of the synaptosomal choline acetyltransferase partitioned as amphiphilic and 80-97% as hydrophilic activity. The percentage of amphiphilic activity present in synaptosomes was significantly higher than that of the form of activity (4.4%) extracted from samples containing only the soluble form of choline acetyltransferase but was significantly lower than the percentage of amphiphilic enzyme present in preparations of synaptosomal plasma membrane (20-22%) which were enriched in the non-ionically membrane-bound form of choline acetyltransferase. These results indicate that the soluble and the non-ionically membrane-bound enzymes differ in their capacity to interact with non-ionic detergents. The preparations of synaptosomal plasma membranes contained significantly higher proportions of detergent-insoluble choline acetyltransferase activity than did the whole synaptosomes; the difference was more striking for the Torpedo than for the rat enzyme. This detergent-insoluble activity was not due to aggregates of the enzyme. Some properties of the hydrophilic and amphiphilic choline acetyltransferase of Torpedo were analyzed. The two forms of the enzyme did not exhibit different affinities for their substrates; they were found to differ with respect to their sensitivity to inhibition by increasing concentrations of the two products of the reaction, acetylcholine and coenzyme A and heat inactivation at 45 degrees C. Most probably the hydrophilic and amphiphilic activities correspond to what was referred to as soluble and non-ionically membrane-bound choline acetyltransferase, respectively. The amphiphilic form may be an integral enzyme of the plasma membrane of cholinergic nerve endings or may be tightly bound to a specific protein in this membrane which may act as a "receptor" for choline acetyltransferase.

Animals↗