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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The metabolism of Ca2+ was studied in a neuronal model system, the clonal mouse neuroblastoma x rat glioma hybrid cell line 108CC5. 1. Homogenates of the hybrid cells exhibit a specific activity of Ca2+-ATPase considerably higher than that of homogenates of the parental cells. 2. Uptake and release of 45Ca2+ by the hybrid cells display two and three distinct phases, respectively, and indicate that 40--50% of the cell-associated Ca2+ is located at the cell surface. 3. The influx of 45Ca2+ is insignificantly affected by Mg2+ or Na+, slightly diminished by Ba2+ or Sr2+, strongly inhibited by La3+, Co2+ or prenylamine, and considerably enhanced by high (i.e., depolarizing) concentrations of K+. The efflux of 45Ca2+ is reduced by La3+. 4. The hybrid cells tend to maintain Ca2+ homeostasis with an overall cellular Ca2+ concentration of 0.5--0.7 mM. At 1.8 mM Ca2+ in the medium this implies the necessity of an extrusion pump in the plasma membrane. 5. A reduction in the hybrid cells of the level of ATP is paralleled by a decline in the content of Ca2+. This can only be explained by the existence of energy-dependent intracellular Ca2+ stores that effectively compete for Ca2+ with a Ca2+ pump located in the plasma membrane. The internal stores are not identical with the mitochondria because mitochondrial inhibitors hardly change Ca2+ metabolism. 6. Micromolar concentrations of the ionophore A23187 can switch off the internal Ca2+ stores without affecting considerably the influx of Ca2+ through the plasma membrane. 7. With switched-off Ca2+ stores it is possible to increase the cellular Ca2+ content distinctly and to bring it back again to the control values in an ATP-dependent manner, i.e. to demonstrate the action of a Ca2+-extrusion pump in the plasma membrane. 8. Under some conditions active extrusion of Ca2+ depends not only on ATP but also on the presence of extracellular Na+. 9. Similar results as with hybrid cells are also obtained with rat glioma cells. The methodology of combining energy deprivation with the application of the ionophore A23187 is possibly generally applicable to obtain insight into the Ca2+ metabolism of various cell types.
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PMID:Uptake and energy-dependent extrusion of calcium in neural cells in culture. 644 79

From October 1978 to June 1981, 35 consecutive patients with grade III-IV malignant glioma were treated with a concentrated course of radiotherapy (two cycles of 17 Gy in two sessions over a 3-day period) with a cobalt unit, followed by chemotherapy with vincristine and BCNU. In the 30 evaluable patients, no complete remission, seven partial remissions, 23 stable disease, and no progression were encountered. Median duration of response was 6 months (range 4-11+). Median survival time was 9 months (range 7-19); radically resected patients survived longer than those with inoperable tumor. Toxicity of treatment was acceptable; however, two patients with brain stem tumors had acute neurologic toxicity following the first radiotherapy session.
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PMID:Treatment of grade III and IV astrocytoma with high-dose irradiation: schedule and chemotherapy. 673 47

Reticulum cell sarcoma involving the vitreous and the brainstem occurred in a 45-year-old man. He initially was seen with diplopia from a partial left-sided third cranial nerve palsy, which is rare. Later, a typical uveitis developed in the right eye. An initial diagnosis of brainstem glioma, based primarily on the computed tomographic scan findings and clinical history, was ultimately proved erroneous when the correct diagnosis was shown by the results of a cytologic examination of vitreous aspirate. Excellent visual response to a moderately high oral dose of steroids occurred, which has not been usual in other reported cases. Definitive cobalt (gamma) radiation therapy (6,000 rad to the brainstem and 4,000 rad to the vitreous) has produced a one-year remission at this time.
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PMID:Update of ocular reticulum cell sarcoma. 701 95

The term "radiosurgery" was defined by Lars Leksell, a Swedish neurosurgeon, as the closed-skull destruction of a precisely defined intracranial target using high-dose radiation with stereotactic technique in a single session. For this purpose, the Gamma Knife was developed in 1968. It was equipped with multiple cobalt 60 sources and delivered collimated narrow radiation beams precisely concentrated to the focus. The dose gradient in the periphery of the treatment volume is extremely steep, so a high dose can be delivered to the small target volume sparing the surrounding normal tissue. Treatment planning was directed using a computer program developed for Gamma Knife and stereotactically obtained imaging database. The treatment procedure may be completed in only one day. The Gamma Knife makes it possible to treat deep-seated and surgically inaccessible lesions with low mortality and morbidity, and to control conventionally radioresistant lesions. Up to now, over 10,000 patients have undergone radiosurgery with a Gamma Knife around the world. The indications were primarily functional disorders, then expanded to include arterio-venous malformation (AVM), benign and a few malignant brain tumors. Excellent results were noted in the treatment of AVM. The two-year total obliteration rate of the nidus was 71-87%, and the adverse effect rate was 3-12%. The control rates of acoustic tumors was reportedly 85-89% with a lower incidence of facial nerve injury and a higher rate of hearing preservation. Gamma Knife radiosurgery has also been used to treat meningioma, pituitary adenoma and metastatic brain tumors. Its application for the treatment of malignant glial tumors or other tumors is developing. The capability of this technique is growing, and radiosurgery will be one of the important treatment modalities for selected neurosurgical or other pathological conditions.
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PMID:[Gamma knife]. 823 77

Extracellular ATP caused a dose-dependent accumulation of inositol phosphates and a rise in cytosolic free Ca2+ ([Ca2+]i) in C6 glioma cells with an EC50 of 60 +/- 4 and 10 +/- 5 microM, respectively. The threshold concentration of ATP (3 microM) for increasing [Ca2+]i was approximately 10-fold less than that for stimulating phosphoinositide (PI) turnover. The PI response showed a preference for ATP; ADP was about 3-fold less potent than ATP but had a comparable maximal stimulation (11-fold of the control). AMP and adenosine were without effect at concentrations up to 1 mM. ATP-stimulated PI metabolism was found to be partially dependent on extracellular Ca2+ and Na+ but was resistant to tetrodotoxin, saxitoxin, amiloride, ouabain, and inorganic blockers of Ca2+ channels (Co2+, Mn2+, La3+, or Cd2+). In Ca(2+)-free medium, ATP caused only a transient increase in [Ca2+]i as opposed to a sustained [Ca2+]i increase in normal medium. The ATP-induced elevation of [Ca2+]i was resistant to Na+ depletion and treatment with saxitoxin, verapamil and nisoldipine, but was attenuated by La3+. The differences in the characteristics of ATP-caused P1 hydrolysis and [Ca2+]i rise suggest that ATP receptors are independently coupled to phospholipase C and receptor-gated Ca2+ channels. Because of the robust effect of ATP in stimulating PI turnover and the apparent absence of P1-purinergic receptors, the C6 glioma cell line provides a useful model for investigating the transmembrane signalling pathway induced by extracellular ATP. The mechanisms underlying the unexpected finding of [Na+]o dependency for ATP-induced PI turnover require further investigation.
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PMID:Extracellular ATP stimulates inositol phospholipid turnover and calcium influx in C6 glioma cells. 838 91

Heterocyclic thiosemicarbazones, thioureas and 2-substituted pyridine N-oxides as well as representative nickel, cobalt and copper complexes were shown to be potent antineoplastic/cytotoxic agents. The cytotoxicity was demonstrated against single cell leukemia as well as cell lines derived from solid tissue (colon adenocarcinoma, HeLa, KB, skin, bronchogenic lung, bone osteosarcoma and glioma). In L1210 cells, DNA synthesis and subsequently RNA synthesis were particularly inhibited by the agents. IMP dehydrogenase activity and thus purine de novo synthesis was reduced significantly by the agents. Dihydrofolate reductase, ribonucleoside reductase, nucleoside kinase and DNA polymerase alpha activities were inhibited by the agents. d(NTP) pool levels were reduced by most of the agents. DNA strand scission was present with all of the derivatives; however, there was no evidence of intercalation, cross linking or alkylation/binding to bases of DNA. This new group of compounds may offer novel exploratory derivatives for future investigations in the treatment of cancer.
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PMID:The cytotoxicity of heterocyclic thiosemicarbazones and their metal complexes on human and murine tissue culture cells. 849 Feb 2

Since Leksell's description of the concept of radiosurgery in 1951, probably more than 20,000 patients worldwide have been treated with this technique. Initially designed as a tool for functional neurostereotaxis, it has found widespread applicability for conditions as diverse as vascular malformations, benign tumors such as acoustic neuroma, meningioma, pituitary adenoma, and also malignant tumors such as brain metastases and malignant glioma. From rudimentary knowledge of the ability to produce focal necrotic lesions, the biologic understanding of the process of single-fraction, small-volume, high-dose brain radiation has evolved into a multicompartmental model, with reasonable appreciation of the dose, volume, and time factors involved. With the explosion of technology on several fronts in the 1980s and 1990s, a multitude of devices for radiosurgery, ranging from cyclotron-generated particle beams to multisource cobalt-60 units to an immense variety of modified linear accelerators has become available. A parallel explosion of technology in the fields of imaging and computing will ensure that this is just the beginning; already, technologies for automated image segmentation and target identification, long the physician's monopoly, are around the corner; image fusion now allows simultaneous visualization of target and normal tissue anatomy, physiology, and other exciting possibilities such as chemical composition and vascular characteristics. Advances in physics and robotics have led to development of prototypical machines that will blur the distinction between radiosurgery and conformal radiotherapy. Already, several "first generation" devices to free stereotaxis from its fixation to frames are available. Substantial enthusiasm among clinicians has ensured that, unlike many fleetingly and momentarily exciting technologies of the last 2 decades, radiosurgery has made and will continue to make a strong commitment for clinical efficacy, safety, and cost-effectiveness through the process of thorough multiinstitutional clinical trials, as opposed to seeking validation from anecdotal experiences. In this regard, the Radiation Therapy Oncology Group (RTOG) and the Gamma Knife User's Group (GKUG) are to be commended; if the plethora of radiosurgery-related publications is evidence of scientific interest, the field will likely continue to expand. In the future, issues pertaining to appropriate regulatory review, patient selection, quality assurance, and training will need to be addressed. Major clinical and biological studies still need to be undertaken.
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PMID:The physical, biologic, and clinical basis of radiosurgery. 858 55

1. The whole-cell patch-clamp technique was used to investigate the actions of substance P and other agonists at neurokinin (NK) receptors on voltage-gated K+ and Ca+ channel currents in undifferentiated mouse neuroblastoma x rat glioma NG 108-15 cells. 2. Both substance P (0.3-30 microM) and the NK1 receptor selective agonist GR73632 (10 nM-10 microM) caused concentration-dependent inhibition of K+ currents. GR64349 and senktide (agonists at NK2 and NK3 receptors respectively) also inhibited K+ currents, but only at concentrations which were several orders of magnitude greater than GR73632, suggesting that current inhibition was mediated via NK1 receptors. 3. Substance P and GR73632 were without effect on residual K+ currents recorded in the presence of extracellular Co2+ (4 mM) to abolish the Ca(2+)-sensitive component (IKca) of the K+ current. Ca2+ channel currents, recorded with either Ba2+ or Ca2+ as charge carrier, were unaffected by NK1, NK2 and NK3 receptor ligands. 4. Iontophoretic application of GR73632 produced a current-dependent reduction of K+ currents. In the presence of the non-peptide NK1 antagonists, CP-99,994 and RP67580, and the peptide antagonist, GR82334, the current-response relationship was reversibly shifted to the right. This indicates that the response is mediated by NK1 receptors. 5. Our results indicate that activation of NK1 receptors leads to the selective inhibition of IKca in undifferentiated NG 108-15 cells.
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PMID:Inhibition of Ca(2+)-sensitive K+ currents in NG 108-15 cells by substance P and related tachykinins. 888 15

Twenty-two patients with supratentorial malignant gliomas were treated postoperatively with concurrent intracarotid chemotherapy and radiation therapy. There were seven women and 15 men with a median age of 56 years (range, 22-69) and median performance status (Karnofsky score) of 70 (range, 40-90). In all except two cases, histologic studies confirmed malignant glioma. All patients were irradiated with a cobalt 60 equipment. They should have received 45 Gy to the whole brain plus a 15-Gy coned-down boost to the tumor area. Chemotherapy consisted of cisplatin infusion at a dose of 60 mg/m2 on days 2, 22, and 42. Treatment was interrupted in two patients because of progressive disease and voluntary withdrawal in one patient each. In all, 63 courses of cisplatin infusion were administered, all at full dose. Two patients achieved a partial response, and nine had stable disease. Toxicities included nausea/vomiting in nine patients (41%) and transient hemiparesis, confusion, diarrhea, and thrombophlebitis in one patient each. Median time to progression was 26 weeks (range, 4-226+), and median survival was 58 weeks (range, 14-226+). In conclusion, the present study suggests that intracarotid cisplatin administered concurrently with radiation does not improve the therapeutic index in malignant gliomas.
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PMID:Concurrent radiation and intracarotid cisplatin infusion in malignant gliomas: a feasibility study. 912 86

Antibody to galactocerebroside (GalC) evokes a Ca2+ response in cultured glioma U-87 MG cells. The rise in intracellular calcium [Ca2+]i occurs largely due to the influx of Ca2+ through a plasma membrane channel, though the release of Ca2+ from intracellular stores also contributes. We characterized the channel activated by anti-GalC. The channel activity was transient and the inactivation appeared to be Ca2+ dependent. The channel was impermeant to monovalent ions Na+ and K+ and also to Mn2+. Ni2+ and Co2+ neither permeate through the channel nor inhibit the Ca2+ influx. In contrast Cd2+ the most potent inorganic blocker of Ca2+ channels permeated through this channel. The Ca2+ influx was inhibited by verapamil with IC50 of 65 +/- 8 microM. The Ca2+ influx as well as the intracellular release were markedly inhibited by neomycin sulfate and phorbol dibutyrate, suggesting that the Ca2+ influx may be mediated by IP3 (1). Depletion of intracellular Ca2+ stores by thapsigargin was followed by Ca2+ influx. This represents the capacitative Ca2+ entry pathway and is distinct from the channel activated by anti -GalC.
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PMID:A novel type of Ca2+ channel in U-87 MG cells activated by anti-galactocerebroside. 944 38


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