Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Magnetic resonance spectroscopy (MRS) measurements of the lactate methyl proton in rat brain C6 glioma tissue acquired in the presence of an off-resonance irradiation field, analyzed using coupled Bloch equation formalism assuming two spin pools, demonstrated the occurrence of magnetization transfer. Quantitative analysis revealed that a very small fraction of lactate (f = 0.0012) is rotationally immobilized despite a large magnetization transfer effect. Off-resonance rotating frame spin-lattice relaxation studies demonstrated that deuterated lactate binds to bovine serum albumin and the proteins present in human plasma, thereby providing a possible physical basis for the observed magnetization transfer effect. These results demonstrate that partial or complete saturation of the motionally restricted lactate pool (as well as other metabolites) by the application of an off-resonance irradiation field, such as that used for water presaturation, can lead to a substantial decrease in resonance intensity by way of magnetization transfer effects, resulting in quantitation errors.
 ...
PMID:In vivo observation of lactate methyl proton magnetization transfer in rat C6 glioma. 1033 42

The mechanisms leading to rapid invasive growth of malignant gliomas are poorly understood. Expression of the hyaluronic acid (HA) receptor CD44 and adhesion to HA are involved in invasive properties. Our previous studies have shown that malignant glioma cells are able to adhere to extracellular HA. Here we investigated expression of the hyaluronic acid receptor CD44 protein in five human (T98G, A172, U87MG, 86HG39, 85HG66) and two rat (C6, 9L) glioma cell lines. Influence of anti-CD44 antibody and hyaluronidase-preincubation on the HA-binding was determined using HA/BSA (bovine serum albumin)-coated culture plates. While all gliomas were highly positive for CD44 with no differences in the number of positive staining cells, median fluorescence intensity decreased as follows: C6>T98G>9L>85HG66> 86HG39>A172>U87MG. Using HA/BSA coated culture plates the relative levels of specific adhesion to HA were determined as T98G>A172>9L>86HG39>U87MG> 85HG66. C6 cells failed to bind HA specifically. Incubation with anti-human-CD44 MAb significantly decreased HA-adhesion of T98G, A172, 85HG66 and U87MG human glioma cells. However the binding capacity was completely blocked only in 85HG66 cells. The three other cell lines kept a specific HA-adhesion after saturation of the receptor. Hyaluronidase pretreatment markedly enhanced HA-adhesion of C6 and 9L rat glioma cells. These results suggest that (i) HA-adhesion of malignant glioma cells is mainly, but not only, mediated by CD44, (ii) expression of CD44 does not correspond with adhesion capacity and (iii) cell-bound glycosaminoglycans may influence glioma cell adhesion to extracellular HA.
 ...
PMID:CD44 expression and hyaluronic acid binding of malignant glioma cells. 1039 Jan 50

We investigated whether the simultaneous use of paramagnetic contrast medium and 3D on-resonance spin lock (SL) imaging could improve the contrast of enhancing brain tumors at 0.1 T. A phantom containing serial concentrations of gadopentetate dimeglumine (Gd-DTPA) in cross-linked bovine serum albumin (BSA) was imaged. Eleven patients with histologically verified glioma were also studied. T1-weighted 3D gradient echo images with and without SL pulse were acquired before and after a Gd-DTPA injection. SL effect, contrast, and contrast-to-noise ratio (CNR) were calculated for each patient. In the glioma patients, the SL effect was significantly smaller in the tumor than in the white and gray matter both before (p = 0.001, p = 0.025, respectively), and after contrast medium injection (p < 0.001, p < 0.001, respectively). On post-contrast images, SL imaging significantly improved tumor contrast (p = 0.001) whereas tumor CNR decreased slightly (p = 0.024). The combined use of SL imaging and paramagnetic Gd-DTPA contrast agent offers a modality for improving tumor contrast in magnetic resonance imaging (MRI) of enhancing brain tumors. 3D gradient echo SL imaging has also shown potential to increase tissue characterization properties of MR imaging of human gliomas.
 ...
PMID:3D spin-lock imaging of human gliomas. 1046 51

To delineate the tumor margins of malignant gliomas laser-induced fluorescence detection technique was applied using 5-aminofluorescein-albumin as the fluorescent dye. The 5-aminofluorescein was linked to serum albumin (= AFlc-SA) as a cumulative protein label using residualizing markers. In a C6-glioma model the biodistribution and pharmacokinetics of the injected dye were investigated by labeling the protein conjugate with 111In-DTPA. Twenty-four hours after intravenous injection of the dye, fluorescence was activated by an argon laser and inspected in the C6-gliomas. Histological examinations were performed to compare the microscopic margins of the fluorescence-stained tumors with hematoxylin/eosin. The tumor uptake 24 h after dye injection was 23-fold higher than in the surrounding brain. Fluorescence inspection under laser activation demonstrated clearly stained and sharply demarcated tumors. The microscopic borders of the tumors corresponded exactly with the fluorescence, also demonstrating intracellular tumor uptake of the dye. In a preliminary study, three patients with malignant gliomas were operated using laser-induced fluorescence detection technique after injection of AFlc-SA. In all patients, the borders of the malignant gliomas were clearly stained by AFlc-SA during surgery. Laser-induced fluorescence imaging using the albumin conjugate AFlc-SA may be a promising method for delineating tumor margins which are hard to detect under the operating microscope alone.
 ...
PMID:Laser-induced fluorescence detection of malignant gliomas using fluorescein-labeled serum albumin: experimental and preliminary clinical results. 1093 21

Antiproliferative properties of molecular regulators of lipid metabolism have been increasingly studied during recent years. Discussion is ongoing concerning optimal treatment conditions and assays used for monitoring proliferation and cytotoxicity. The objective of the present work was to optimize methods and treatment conditions used for studying antiproliferative effects of fatty acids and analogs, represented by palmitic acid (PA) and the beta-oxidation-restricted fatty acid analog tetradecylthioacetic acid (TTA), in rat (BT4Cn) and human (D54Mg and GaMg) glioma cell lines. Changes in [3H]thymidine incorporation preceded changes in cell number in TTA-treated glioma cell cultures, and the growth inhibition was more significantly expressed by [3H]thymidine incorporation than cell number. Addition of bovine serum albumin decreased cellular fatty acid uptake and reduced the effects of TTA and PA on [3H]thymidine incorporation. Determination of the antiproliferative effect of TTA in BT4Cn cells by MTT conversion and [3H]thymidine incorporation yielded concordant results. TTA-mediated reduction in cell number corresponded to reduction in cellular protein and total DNA content in BT4Cn cells. Reduced growth potential in TTA-treated multicellular D54Mg and GaMg spheroids supported the findings from monolayer cultures. In conclusion, cell density, treatment period, fatty acid administration, and methods for growth determination may profoundly influence the outcome of cell growth experiments. Thus, experimental conditions should be carefully controlled when performing cell growth experiments, and effects on cell growth should preferably be confirmed by different methods.
 ...
PMID:Optimization of methods and treatment conditions for studying effects of fatty acids on cell growth. 1133 87

The abilities of 19 analogues of palmitoylethanolamide and two analogues of oleoylethanolamide to affect the Ca(2+) influx into human embryonic kidney cells expressing the human vanilloid receptor (hVR1-HEK293 cells) in response to anandamide (AEA) have been investigated using a FLIPR assay and a bovine serum albumin-containing assay medium. Only palmitoylethanolamide produced any effect in the absence of AEA. The ability of palmitoylethanolamide to potentiate the response to AEA was retained when the N-CH(2)CH(2)OH group was replaced by N-CH(2)CH(2)Cl,whereas replacement with N-alkyl substituents [from -H up to -(CH(2))(12)CH(3)] resulted either in a reduction or in a complete loss of this activity. The tertiary amide N-(CH(2)CH(3))(2) (19) and N-morpholino (20) analogues of palmitoylethanolamide potentiated the response to 1 microM AEA to a greater degree than the parent compound, whereas the N-(CH(3))(2) analogue was inactive. 19 and 20 produced leftward shifts in the dose-response curve for AEA activation of Ca(2+) influx into hVR1-HEK293 cells. EC(50) values for AEA to produce Ca(2+) influx into hVR1-HEK293 cells were 1.1, 1.1, 0.54 and 0.36 microM in the presence of 0, 1, 3 and 10 microM 19, respectively. The corresponding values for 20 were 1.5, 1.3, 0.77 and 0.17 microM, respectively. The compounds did not affect the dose-response curves to capsaicin. The ability of oleoylethanolamide to potentiate AEA is retained by the N-CH(2)CH(3) and N-CH(CH(3))(2) analogues (22 and 23, respectively). 22 and 23 produced a small ( approximately 25%) inhibition of the binding of [(3)H]-CP55,940 and [(3)H]-WIN 55,212-2 to CB(1) and CB(2) receptors, respectively, expressed in CHO cells. The compounds inhibited the metabolism of 2 microM [(3)H]-AEA by rat brain fatty acid amidohydrolase with IC(50) values of 5.6 and 11 microM, respectively. In contrast, 19 and 20 were without effect on either binding to CB receptors or fatty acid amidohydrolase activity. Minor reductions in the accumulation of 10 microM [(3)H]-AEA into C6 glioma cells were seen at 10 microM concentrations of 19 and 20. It is concluded that 19 and 20 selectively enhance AEA effects upon VR1 receptors without potentially confounding effects upon CB receptors or fatty acid amidohydrolase activity.
 ...
PMID:N-Morpholino- and N-diethyl-analogues of palmitoylethanolamide increase the sensitivity of transfected human vanilloid receptors to activation by anandamide without affecting fatty acid amidohydrolase activity. 1261 67

Relatively little is known about the process whereby the endocannabinoid anandamide (AEA) is released from cells. A simple way of studying this process is to sample the appearance in the medium of tritium following preloading of cells with [(3)H]AEA under conditions where its metabolism is prevented. However, this approach may be complicated by the ability of AEA to be adsorbed reversibly to the cell culture wells. In the present study, it is found that cell culture wells adsorb almost half of the added AEA in a manner prevented by fatty acid-free bovine serum albumin, and by the prototypical uptake inhibitors AM404 and VDM11 with IC(50) values of 3 and 1 microM, respectively. After incubation followed by washing of the plates, AEA is released into the medium from the wells by a first order process (K approximately 0.1 min(-1)) that is temperature-dependent and increased by AM404 and fatty acid-free bovine serum albumin. When assays were run with 0.15% fatty acid-free bovine serum albumin during the loading, washing and release phases of the assay, the release from the well was greatly reduced and a first order, temperature-sensitive release from C6 glioma cells could be unmasked. It is concluded that the reversible adsorption of AEA by cell culture wells can be a confounding factor in release experiments.
 ...
PMID:Reversible, temperature-dependent, and AM404-inhibitable adsorption of anandamide to cell culture wells as a confounding factor in release experiments. 1515 3

Because of a possible role of astrocytes in trialkyltin-induced neurotoxicity in vivo various studies have been performed using cultures of astrocytes or glioma cells in vitro. With respect to cytotoxic potencies of trialkyltins these studies gave rather divergent results. Therefore the aim of the present study was to clarify whether variations of experimental conditions could be responsible for the differences of the cytotoxic activities of trimethyltin (TMT), triethyltin (TET) and tributyltin (TBT). Experiments were performed with rat C6 glioma cells. Toxicity was determined by measuring the reduction of the cell protein content. Cultures of proliferating and growth-arrested cells did not differ in their sensitivity. Exposure duration (1-72 h) had a strong but differing influence on the cytotoxic potency of the trialkyltins. After short exposure times the potencies differed largely (TMT < TET < TBT), whereas they became more and more similar with increasing exposure duration. The potency-time relationships for TMT and TET could be described by the equation: EC50 = k x t(-n), while for TBT an incipient value (EC50, infinity) had to be included: EC50 = EC50, infinity + k x t(-n). Addition of serum albumin to the culture medium decreased the cytotoxic potency of the trialkyltins. However, the impact of protein binding on their bioavailability was relatively low. The cytotoxic potency of the alkyltins was not dependent on the concentration of C6 cells. Taken together, neither differences in exposure conditions nor in the proliferative status of the cells are sufficient to account for the discrepancies in published results for trialkyltin cytotoxicity to astrocytes. Instead they may--at least partially--be explained by differing sensitivities of the endpoints used. Furthermore, C6 glioma cells respond considerably more sensitively to trialkytins than primary astrocytes, which questions their applicability as models for astrocyte toxicity.
 ...
PMID:Cytotoxic potency of trialkyltins to C6 glioma cells in vitro: impact of exposure conditions. 1568 30

Estrogen-mediated neuroprotection is well established; however, no single mechanism of action for this effect has yet been established. As glial cells are integral for both the intact and injured nervous system, we hypothesized that estrogen-mediated neuroprotection may partly be attributed to attenuation of glial cell apoptosis, allowing them to protect neurons following injury. To assess the protective effects of estrogen on glia, C6 rat glioma cells were treated for 24 h with 500 microM glutamate. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and apoptosis was confirmed by cell morphology and DNA fragmentation. Pretreatment with 10 nM 17beta-estradiol (estrogen) increased cell viability and attenuated apoptosis. Treatment with the stereoisomer 17alpha-estradiol, or estrogen plus estrogen receptor antagonist ICI 182,780, was significantly less effective, indicating that cytoprotection was receptor-mediated. Estrogen treatment upregulated expression of estrogen receptor alpha. Cell impermeable bovine serum albumin-conjugated estrogen was also protective, indicating activation of estrogen receptors on the cell membrane. Intracellular free [Ca2+] was increased after glutamate treatment. This increase was attenuated in cells pretreated with estrogen. Glutamate increased the activity of pro-apoptotic proteases, such as calpain and caspase-3, and these protease activities were significantly attenuated by estrogen. The mechanism by which estrogen decreased intracellular Ca2+ was examined by assaying cell viability after using inhibitors that either blocked extracellular Ca2+ influx or prevented the release of intracellular Ca2+ stores. While several inhibitors increased cell viability in glutamate-treated cells, none were as protective as estrogen, and estrogen co-treatment significantly increased cell viability. These findings indicate that estrogen-mediated cytoprotection may be related to effects on Ca2+ entry but that these effects are not limited to any one of these Ca2+ entry points alone.
 ...
PMID:Estrogen prevents glutamate-induced apoptosis in C6 glioma cells by a receptor-mediated mechanism. 1628 85

Biomaterial surface modification is an efficient way of improving cell-material interactions. In this study, sub-micrometer laser-induced periodic surface structures (LIPSS) were produced on polystyrene by laser irradiation. FT-IR analysis confirmed that this treatment also led to surface oxidation and anisotropic orientation of the produced carbonyl groups. As a consequence, the surface energy of the laser-treated polystyrene was 1.45 times that of the untreated polystyrene, as measured by contact-angle goniometry. Protein adsorption and rat C6 glioma cell behavior on the two substrates were investigated, showing that the changed physicochemical properties of laser-modified polystyrene surface led to an increase in the quantity of adsorbed bovine serum albumin and significantly affected the behavior of rat C6 glioma cells. In the early stages of cell spreading, cells explored their microenvironment using filopodium as the main sensor. Moreover, cells actively aligned themselves along the direction of LIPSS gradually and cell attachment and proliferation were significantly enhanced.
 ...
PMID:Influence of physicochemical properties of laser-modified polystyrene on bovine serum albumin adsorption and rat C6 glioma cell behavior. 1673 77


<< Previous 1 2 3 4 5 6 7 Next >>