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

In order to clarify the influence of induced hyperglycemia upon antitumor effects of chemotherapy we studied some animal and human tumors. We observed that hyperglycemia enhances the antitumor effects of some cytostatic drugs several fold, due in part to the changes in the microphysiology induced by the hyperglycemia. Time doubling of some transplanted rat tumors and survival time of rats, rabbits and dogs bearing the transplanted and spontaneous tumors increased two to ten fold when the chemotherapy was used under hyperglycemia. Remission duration in patients with malignant brain glioma was enhanced by an average of six months; two years survival increased two-fold and the three years survival in patients with ovarian carcinoma in Stage III-IV increased two-fold; five years survival, 1.5-fold. The number of complications due to the combination of hyperglycemia and chemotherapy were not increased significantly. The problems of combination chemotherapy and hyperglycemia for oncologic patients' treatment are under discussion.
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PMID:Induced hyperglycemia and tumor chemotherapy: experimental and clinical studies. 212 86

Surface coil NMR spectroscopy was used to monitor the hyperglycemia-induced alterations in pH and blood flow in vivo in C6 gliomas implanted both subcutaneously and intracerebrally in rats. Tumor pH was calculated from the chemical shift difference between PCr and Pi in the 31P NMR spectra. Subcutaneous glioma pH decreased 0.8 units by 1 h after intraperitoneal administration of an aqueous 50% glucose solution (6 g glucose per kg body weight). In contrast, hyperglycemia failed to significantly alter the pH of intracerebral gliomas which were monitored for 90 min following administration of glucose. Tumor blood flow (TBF) was determined both pre- and post-glucose administration using deuterium NMR by monitoring the time course of D2O washout following intratumoral injection of saline D2O. Subcutaneous and intracerebral TBF were found to have an average change of -78.1% (range -47.4 to -93.3%, n = 5) and -21.1% (range +6.0 to -37.8%, n = 9), respectively. In addition, laser Doppler blood flow measurements of rat skin and subcutaneous glioma revealed a dramatic reduction in blood flow in both tissues following glucose administration. These results indicate that the effects of acute hyperglycemia are site dependent and that hyperglycemia alone is not beneficial for inducing intracellular acidosis in intracerebral tumors.
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PMID:In vivo 31P and 2H NMR [corrected] studies of rat brain tumor pH and blood flow during acute hyperglycemia: differential effects between subcutaneous and intracerebral locations. 255 87

The authors studied the content of lactic acid in glial tumors of the brain and brain tissue of rats in short-term artificial hyperglycemia. In short-term artificial glycemia the lactic acid content in glial tumors of animals was almost twice the level of this metabolite in the brain tissue, which is due to the high potential rate of glucose consumption by the tumor and the increased glycolytic activity in it in these conditions. The lactate content in the glial brain tumors significantly increases when the sugar concentration in the blood of animals is artificially increased. It is suggested that accumulation of lactic acid in brain gliomas of experimental animals contributes to diminution of tumor cell viability, which will increase sensitivity of the tumor to irradiation.
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PMID:[Concentration of lactate concentration in experimental glial tumors and brain tissue during brief artificial hyperglycemia]. 400 55

Experiments were staged on rats with transplantable anaplastic cerebral right hemisphere astrocytomas. Hyperglycemia was induced by means of intraperitoneal fractional administration of 40% glucose solution. Single local x-ray tumor irradiation followed on the 4-5th, 7-8th and 10-12th days after strain transplantation at the doses of 30 and 40 Gy without hyperglycemia and in combination with it. The irradiation effect was assessed by the mean survival time of the animals. Hyperglycemia was shown to increase significantly radiation injury of highly resistant experimental malignant cerebral glial tumors.
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PMID:[Enhancement of ionizing radiation effects on transplantable cerebral gliomas using short-term hyperglycemia]. 406 40

The glucose content in the tissues of rat brain glial tumors and in the brain tissue during short-term induced hyperglycemia was studied. It was shown that in artificial increase of the concentration of glucose in blood, its content in the tumor grows sharply and exceeds considerably the level of this metabolite in the brain tissue. In distinction from the brain tissue, the tumor was marked by a high rate of glucose consumption and utilization under these conditions. It is concluded that brain glial tumors are also capable of increasing glucose consumption in artificial hyperglycemia. It is suggested the the accumulation of glucose by the tumor creates the preconditions for improving the efficacy of radiotherapy combined with short-term artificial hyperglycemia in the management of brain glial tumors.
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PMID:[Concentration of glucose in the tissues of glial tumors of the brain in rats with artificial hyperglycemia of short duration]. 671 Dec 21

In vivo 1H MRS can be used to detect and quantify the lactate resonance at 1.3 ppm provided that overlapping lipid resonances are eliminated. A homonuclear spectral editing method was developed to acquire uncontaminated 1H spectra of lactate with adiabatic pulses. An advantage of the adiabatic pulse sequence is the ability to induce uniform flip angles and to maximize sensitivity in applications employing surface coil transmitters which produce highly inhomogeneous B1. Glycolytic activity in an intracerebral C6 glioma in rats was monitored by using adiabatic editing sequences to observe [3-13C]lactate produced from infused [1-13C]glucose. Acute hyperglycemia (serum glucose > 22 mM, n = 10) had no significant effect (P = 0.08) on the total ([12C] + [13C]) tumor lactate signal intensity.
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PMID:Localized detection of glioma glycolysis using edited 1H MRS. 837 70

Elevated tissue lactate concentrations typically found in tumors can be measured by in vivo nuclear magnetic resonance (NMR) spectroscopy. In this study, lactate turnover in rat C6 glioma was determined from in vivo 1H NMR measurements of [3-13C]lactate buildup during steady-state hyperglycemia with [1-13C]glucose. With this tumor model, a narrow range of values was observed for the first-order rate constant that describes lactate efflux, k2 = 0.043 +/- 0.007 (n = 12) SD min-1. For individual animals, the standard error in k2 was small (< 18%), which indicated that the NMR data fit the kinetic model well. Lactate measurements before and after infusing [1-13C]glucose showed that the majority of the tumor lactate pool was metabolically active. Signals from 13C-labeled glutamate in tumors were at least 10-fold smaller than the [3-13C]lactate signal, whereas spectra of the contralateral hemispheres revealed the expected labeling of [4-13C]glutamate, as well as [2-13C] and [3-13C]glutamate, which indicates that label cycled through the tricarboxylic acid cycle in the brain tissue. Lack of significant 13C labeling of glutamate was consistent with low respiratory metabolism in this glioma. It is concluded that lactate in rat C6 glioma is actively turning over and that the kinetics of lactate efflux can be quantified noninvasively by 1H NMR detection of 13C label. This noninvasive NMR approach may offer a valuable tool to help evaluate tumor growth and metabolic responsiveness to therapies.
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PMID:Lactate turnover in rat glioma measured by in vivo nuclear magnetic resonance spectroscopy. 982 16

S100B is an astrocyte calcium-binding protein that plays a regulatory role in the cytoskeleton and cell cycle. Moreover, extracellular S100B, a marker of glial activation in several conditions of brain injury, has a trophic or apoptotic effect on neurons, depending on its concentration. Hyperglycemic rats show changes in glial parameters, including S100B expression. Here, we investigated cell density, morphological and biochemical alterations in primary cortical astrocytes from rats and C6 glioma cells cultured in high-glucose medium. Astrocytes and C6 glioma cells have a reduced content of S100B and glial fibrillary acidic protein when cultured in a high-glucose environment, as well as a reduced content of glutathione and cell proliferation rate. Although these cells have been used indistinctly to study S100B secretion, we observed a contrasting profile of S100B secretion in a high-glucose medium: a decrease in primary astrocytes and an increase in C6 glioma cells. Based on the in vitro neurotrophic effects of the S100B protein, our data suggest that chronic elevated glucose levels affect astrocyte activity, reducing extracellular secretion of S100B and that this, in turn, could affect neuronal activity and survival. Such astrocyte alterations could contribute to cognitive deficit and other impairments observed in diabetic patients.
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PMID:S100B content and secretion decrease in astrocytes cultured in high-glucose medium. 1735 Jan 41

(1)H MRS is evolving into an invaluable tool for brain tumor classification in humans based on pattern recognition analysis, but there is still room for improvement. Here we propose a new approach: to challenge tumor metabolism in vivo by a defined perturbation, and study the induced changes in MRS pattern. For this we recorded single voxel (1)H MR spectra from mice bearing a stereotactically induced GL261 grade IV brain glioma during a period of induced acute hyperglycemia. A total of 29 C57BL/6 mice were used. Single voxel spectra were acquired at 7 T with point resolved spectroscopy and TE of 12, 30 and 136 ms. Tumors were induced by stereotactic injection of 10(5) GL261cells in 17 mice. Hyperglycemia (up to 338 +/- 36 mg/dL glucose in the blood) was induced by intraperitoneal bolus injection. Maximal increases in glucose resonances of up to 2.4-fold were recorded from tumors in vivo. Our observations are in agreement with extracellular accumulation of glucose, which may suggest that glucose transport and/or metabolism are working close to their maximum capacity in GL261 tumors. The significant and specific MRS pattern changes observed when comparing euglycemia and hyperglycemia may be of use for future pattern-recognition studies of animal and human brain tumors by enhancing MRS-based discrimination between tumor types and grades.
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PMID:Perturbation of mouse glioma MRS pattern by induced acute hyperglycemia. 1760 Aug 47

MR spectroscopic Imaging (MRSI), with PRESS localization, is used here to monitor the effects of acute hyperglycemia in the spectral pattern of 11 mice bearing GL261 gliomas at normothermia (36.5-37.5 degrees C) and at hypothermia (28.5-29.5 degrees C). These in vivo studies were complemented by ex vivo high resolution magic angle spinning (HR-MAS) analysis of GL261 tumor samples from 6 animals sacrificed by focused microwave irradiation, and blood glucose measurements in 12 control mice. Apparent glucose levels, monitored by in vivo MRSI in brain tumors during acute hyperglycemia, rose to an average of 1.6-fold during hypothermia (p < 0.05), while no significant changes were detected at normothermia, or in control experiments performed at euglycemia, or in normal/peritumoral brain regions. Ex vivo analysis of glioma-bearing mouse brains at hypothermia revealed higher glucose increases in distinct regions during the acute hyperglycemic challenge (up to 6.6-fold at the tumor center), in agreement with maximal in vivo blood glucose changes (5-fold). Phantom studies on taurine plus glucose containing solutions explained the differences between in vivo and ex vivo measurements. Our results also indicate brain tumor heterogeneity in the four animal tumors investigated in response to a defined metabolic challenge.
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PMID:1H-MRSI pattern perturbation in a mouse glioma: the effects of acute hyperglycemia and moderate hypothermia. 1967 Feb 63


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