Adding 11C-methionine PET to the EORTC prognostic factors in grade 2 gliomas.

PURPOSE: The management of adult patients with grade 2 gliomas remains a challenge for the clinical neuro-oncologist. Several clinical prognostic factors appear to be as important as treatment factors in determining outcome. From the European Organisation for Research and Treatment of Cancer (EORTC) trials 22844 and 22845, a prognostic scoring system has been proposed based on the presence of unfavourable prognostic factors. The aim of the present study was to assess the additional prognostic value of (11)C-methionine (MET) measured by positron emission tomography (PET) in the setting of the EORTC prognostic scoring system. METHODS: In this retrospective review, 129 patients with supratentorial grade 2 gliomas were subjected to a PET study as part of the pre-treatment tumour investigation. One hundred and three cases were classified as low-risk patients (0-2 unfavourable factors) and 26 cases as high-risk patients (3-5 unfavourable factors) according to the EORTC criteria. MET PET was evaluated as an extra prognostic factor in both groups. RESULTS: In the high-risk group, patients with high MET uptake had a worse outcome than patients with low MET uptake. A similar trend was found for the low-risk group in patients with oligodendrocytic tumours. CONCLUSIONS: Our findings further strengthen the role of MET PET as an important prognostic tool in the management of this group of patients.

Effect of alpha-trinositol on carrageenan-induced rat paw edema and lowering of interstitial fluid pressure.

Alpha-trinositol attenuates edema formation and capillary albumin extravasation and lowering of interstitial fluid pressure (Pif) in several acute inflammatory reactions in rat skin or trachea. The lowering of Pif is an important driving force required to explain the rapid edema formation in acute inflammatory reactions. The lowering of Pif and edema formation are attenuated by alpha-trinositol, which is suggested to act on the cellular adhesion receptor for extracellular matrix components. This would represent a novel therapeutic strategy for acute inflammation. To further clarify the mechanisms behind the anti-inflammatory effects of alpha-trinositol, the effects of pre- and post-treatment with alpha-trinositol on edema formation and lowering of Pif were studied after subdermal injection of carrageenan in the rat. The experiments measuring Pif showed that the lowering of Pif induced by carrageenan was abolished by 10 mg alpha-trinositol when administered either prior to or after injection of 5 microl 1% (w/v) lambda carrageenan in the dorsum of the paw. Edema formation after injection of lambda carrageenan (100 microl, 1.5% w/v) into the foot pad was studied in a separate series. In control animals receiving saline vehicle, the volume of the paw injected with carrageenan increased by approximately 30% after 3-4 h. The only significant effect of infusion of 20 mg kg(-1) h(-1) alpha-trinositol was a reduction of edema to approximately 20% when treatment was started 1 h before carrageenan injection. Therefore, the plasma concentration of alpha-trinositol must already be high when carrageenan is injected in order to prevent edema in the late phase. In conclusion, the present results indicate that the mechanisms involved in the lowering of Pif in the early phase of edema development are different from those responsible for the manifest edema measured 3-4 h after carrageenan.

The effect of alpha-trinositol on cholera toxin-induced fluid accumulation in pig (Sus scrofa domesticus) jejunum in vivo.

The effect of alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate) on cholera toxin-induced fluid accumulation (i.e., net fluid secretion) was studied in the pig jejunum in vivo. Cholera toxin caused a dose-dependent fluid accumulation in control experiments. Intravenous injection of alpha-trinositol produced a reduction of the response to cholera toxin with a significant maximal inhibition of 36%. However, in high concentrations of alpha-trinositol this inhibition was absent.

alpha-Trinositol prevents increased negativity of interstitial fluid pressure in rat skin and trachea induced by dextran anaphylaxis.

The new anti-inflammatory agent alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate), is suggested to act on the cellular adhesion receptor towards extracellular matrix components, the beta1-integrins, and may therefore represent a novel principle for therapy of the phenomena associated with acute inflammation. Increased negativity of interstitial fluid pressure (p(if)) is a major driving force for the rapid edema formation in trachea and skin associated with dextran anaphylaxis in the rat. We therefore used this experimental model to study the effect of alpha-trinositol in skin and trachea of pentobarbital anesthetized rats. p(if) was measured with sharpened glass capillaries (3-7 microm) connected to a servocontrolled counterpressure system. alpha-Trinositol (10 mg) was given before or after dextran. Circulatory arrest was induced 2 min after i.v. dextran to limit the increased capillary fluid filtration associated with the anaphylactic reaction. This increased filtration will otherwise raise interstitial volume and thereby p(if) and cause an underestimation of a potential increased negativity of p(if). In the trachea, p(if) was 0.0 +/- 1.0 mmHg (S.D.) and -1.4 +/- 0.5 mmHg in controls given saline vehicle and alpha-trinositol (P > 0.05), respectively, and fell to -8.5 +/- 2.7 mmHg after dextran (P < 0.01). alpha-Trinositol given 2 min prior to or after dextran resulted in p(if) of -1.7 +/- 1.2 mmHg (P > 0.05 versus control, P < 0.01 versus dextran) and -4.7 +/- 3.0 mmHg (P < 0.01 versus control and dextran), respectively. In skin, i.v. dextran caused p(if) to fall from -0.6 +/- 0.5 to -4.6 +/- 1.9 mmHg (P < 0.001). When alpha-trinositol was given prior to dextran the corresponding figures were -0.4 +/- 0.8 and -0.9 +/- 1.1 mmHg, respectively (P > 0.05). Subdermal administration of alpha-trinositol after i.v. dextran and circulatory arrest normalized p(if) in concentration of 100, 10 and partly at 1 mg/ml. Thus, alpha-trinositol prevented the increased negativity of p(if) induced by dextran anaphylaxis when administered prior to as well as after dextran showing that the alpha-trinositol also could influence an already started inflammatory reaction.

Lowering of interstitial fluid pressure will enhance edema in trachea of albumin-sensitized rats.

Interstitial fluid pressure (Pif) has recently been found to play an important role in edema formation in acute airway inflammation. Because airway inflammation is important in the pathogenesis of asthma, Pif was measured in rat trachea after albumin challenge to rats previously sensitized to chicken egg albumin. In pentobarbital anesthesia (50 mg/kg intraperitoneally) sensitized rats received an intravenous infusion of either saline or albumin, which circulated for 4 min. Circulatory arrest was then induced with saturated KCl intravenously to prevent further edema formation, which will increase Pif and thereby possibly cause an underestimation of an increased negativity of Pif. Pif was measured with sharpened glass capillaries (diameter 3-6 micrometer) connected to a servo-controlled counter pressure system. Pif was -1.3 +/- 0.4 mm Hg in controls and -5.8 +/- 0.5 mm Hg in sensitized rats (p < 0.01) after allergen challenge. Airway resistance was measured to verify the occurrence of airway narrowing and increased significantly in sensitized rats after allergen challenge but did not change in controls. The experimental anti-inflammatory drug, alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate, 10 mg), given before or after allergen challenge abolished the increased negativity of Pif (p < 0.05), while hydrocortisone (6.25 mg) had no effect. Thus, allergen challenge is associated with a lowering of Pif, which was abolished by alpha-trinositol.

Binding sites for alpha-trinositol (inositol 1,2,6-trisphosphate) in porcine tissues; comparison with Ins(1,4,5)P3 and Ins(1,3,4,5)P4-binding sites.

1. The molecular mechanism of action of the inositol trisphosphate isomer, alpha-trinositol (Ins(1,2,6)P3) which has potential therapeutic use in treatment of inflammation and burn oedema, is still unclear. Therefore we have studied binding sites for alpha-trinositol in different tissues. 2. In membranes from pig cerebellum, liver, kidney, heart, and spleen, the density of specific [3]-alpha-trinositol binding sites was maximal at pH 5.0. Cerebellum and spleen showed only one binding site (cerebellum KD = 9.1 microM, spleen KD = 7.3 microM). In the other tissues, there were a high-affinity site (heart KD = 70 nM, liver KD = 790 nM and kidney KD = 1800 nM), besides a low-affinity site with a KD ranging between 32 and 120 microM. In cerebellar membranes, the affinity and density (107 pmol mg-1 protein) of alpha-trinositol binding sites were not affected by phosphate (0 to 25 mM). 3. Binding of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 to membranes from different porcine tissues was also determined. Ins(1,3,4,5)P4, the isomer stereochemically related to alpha-trinositol, binds with an affinity of 1.2 nM in cerebellum, but in the other tissues the binding site density was too low to determine the affinity. With cerebellar membranes heterologous displacement of [3H]-Ins(1,3,4,5)P4 by alpha-trinositol yielded a K1 of 11 microM. The Ins(1,4,5)P3 receptor displayed an affinity of 15 nM in cerebellum and of 5 to 7 nM in the other tissues investigated. 4. The solubilized Ins(1,3,4,5)P4 receptor preparation from cerebellum did not show Ins(1,2,6)P3 binding. Ins(1,2,6)P3 binding was found in the pellet obtained after solubilization of the membranes with the detergent Brij 58. 5. Thus, in different tissues alpha-trinositol binds to proteins with different affinity. They are obviously not related to binding sites for Ins (1,4,5)P3 or for Ins(1,3,4,5)P4. Future experiments have to unravel the identity of the binding protein(s) for alpha-trinositol.

The effect of alpha-trinositol on cholera toxin-induced hypersecretion and morphological changes in pig jejunum.

alpha-Trinositol (D-myo-inositol 1,2,6-trisphosphate, PP56) is a novel antiinflammatory drug. This study elucidates the effect of intravenous alpha-trinositol on basal and acute fluid transport and morphological changes following cholera toxin administration in pig jejunum in vivo. Using isolated jejunal tied-off loops, the fluid hypersecretory (accumulation) effect of different doses of cholera toxin was studied in pigs treated intravenously with saline added different doses (0, 4, 8, 16 and 32 mg x kg-1 x hr-1) of alpha-trinositol. Levels of alpha-trinositol, as well as stereomicroscopical, light microscopical and scanning electron microscopical morphological studies were performed. Cholera toxin evoked a dose-dependent fluid hypersecretion. Treatment with alpha-trinositol caused a dose-dependent inhibition of the cholera toxin-induced fluid hypersecretion and did not affect basal fluid absorption. The 16 mg x kg-1 x hr-1 alpha-trinositol dose gave a maximal inhibition of 36%. Morphological studies showed only minor changes following 6 hr of exposure to 20 micrograms x loop-1 cholera toxin. These changes consisted of dilation of the villus capillaries, an increase of apical membrane blebbing and a reduction of the intercellular space. Treatment with 16 mg x kg-1 x hr-1 alpha-trinositol alone did not induce any morphological changes, and did not alter the morphological changes induced by cholera toxin, which caused fluid hypersecretion and only minor acute morphological changes. In conclusion, alpha-trinositol treatment reduced cholera toxin-induced fluid hypersecretion without altering basal fluid absorption, basal morphology, or cholera toxin-induced morphological changes in pig jejunum in vivo.

Effects of ischemia on regional ligand binding to adrenoceptors in the rat brain.

Changes in ligand binding to adrenoceptors ([3H]prazosin to alpha 1-receptors, [3H]idazoxan to alpha 2-receptors and [125I]cyanopindolol to beta-receptors) following transient cerebral ischemia were investigated using autoradiographic methods. The binding was quantified in brain sections from control rats, rats subjected to 15 min of 2-vessel occlusion ischemia, and rats with recirculation times of 1 h, 1 week or 4 weeks after ischemia. No significant change in alpha 1-receptor binding was observed during and immediately following ischemia, but a decrease was noted in the vulnerable hippocampal CA1 region following 1 week's survival. In the parietal cortex, the ligand binding to alpha 1-receptors increased at 4 weeks. A reduced [3H]idazoxan binding was observed 1 h after ischemia in the temporal cortex and amygdala. No change in ligand binding to beta-receptors was seen in the early phase postischemia, but a marked increase had occurred in the hippocampal CA1 region at 1 and 4 weeks after ischemia (+163% and +142%, respectively), presumably due to accumulation of macrophages expressing beta-receptors. The early postischemic changes in receptor binding may represent downregulation of the adrenoceptors by processes activated during ischemia, while neuronal degeneration, compensatory mechanisms in surviving neurons and proliferation of non-neuronal cells may account for the subsequent changes.

Extracellular brain cortical levels of noradrenaline in ischemia: effects of desipramine and postischemic administration of idazoxan.

Using microdialysis, extracellular noradrenaline (NA) levels in the rat cerebral cortex were studied under isoflurane/N2O anaesthesia before, during and for 6 hours following 10 min of forebrain ischemia in a 2-vessel occlusion model. A microdialysis probe was introduced into the parietal cortex and dorsal hippocampus in anaesthetized rats and continuously perfused with Krebs-Ringer-bicarbonate buffer with or without the NA uptake inhibitor desipramine (DMI, 5 microM). Twenty min fractions were collected and the extracellular NA levels were measured in the dialysates using HPLC with electrochemical detection. The basal NA concentration in the dialysate was 10.5 +/- 1.8 (mean +/- SEM) pg/20 min fraction and increased to 39.3 +/- 4.8 pg/20 min fraction after local administration of DMI. During ischemia, NA increased to 38 times the basal level without DMI, and 6 times with DMI included during two hours' perfusion prior to ischemia. After recirculation NA levels returned to, or even transiently decreased below, preischemic values. With DMI present in the dialysis buffer, administration of idazoxan immediately following ischemia delayed the return to preischemic NA levels in the recirculation phase. In the absence of DMI, no effect of idazoxan on postischemic levels of NA was found. Local administration of DMI increases basal extracellular NA levels and reduces the ischemia-induced NA release. The latter effect may be a due to inhibition of the NA uptake system working in a reversed mode, or as a result of decreased synthesis of NA due to activation of presynaptic alpha 2-receptors by the increased synaptic NA levels. Postischemic treatment with the alpha 2-adrenoceptor antagonist idazoxan in combination with DMI prolongs the period of elevated extracellular NA levels, which may be of importance for the protective properties of idazoxan against ischemic cell injury.

Protection against ischemia-induced neuronal damage by the alpha 2-adrenoceptor antagonist idazoxan: influence of time of administration and possible mechanisms of action.

The protective effect of the alpha 2-receptor antagonist idazoxan against neuronal damage in the neocortex and in the hippocampal CA1 region was studied in rats exposed to 10 min of incomplete forebrain ischemia. When administered i.v. immediately after ischemia (0.1 mg/kg) and subsequently for 6 h (10 micrograms/kg/min), idazoxan significantly reduced neuronal damage in the hippocampus (from 84 to 26%) and in the vulnerable parts of the neocortex (from 15 to 1%). The bolus dose alone provided no significant protection. When idazoxan administration was delayed for 30 min, no significant protection was noticed in the neocortex, and the effect in the hippocampus was ambiguous. A transient elevation of plasma corticosterone levels was induced during ischemia. Idazoxan administration for 2 h did not affect postischemic changes in corticosterone levels compared with saline infusion. Idazoxan (10(-7)-10(-4) M) did not influence the in vitro binding to glutamate receptors in brain slices. Thus, the protective effect of idazoxan cannot be explained by suppression of the plasma corticosteroid levels or via an antagonistic effect on glutamate receptors. Idazoxan apparently protects neurons when given during the first hours of postischemic reperfusion, while histopathological necrosis of neurons becomes visible 48-72 h after ischemia. Detrimental processes causing delayed neuronal death occur in the early postischemic phase and can be influenced by adrenoceptor ligands. Idazoxan may protect by several mechanisms but probably exerts its protective postischemic effect mainly through an increased noradrenergic neuronal activity and an elevation of extracellular noradrenaline (NA) levels in the brain. The favorable effects of NA may either be due to inhibition of excitotoxic neurotransmission or activation of survival-promoting and trophic processes.

Extracellular levels of quinolinic acid are moderately increased in rat neostriatum following severe insulin-induced hypoglycaemia.

Extracellular concentrations of the brain metabolite quinolinic acid, an endogenous excitotoxin, were monitored by microdialysis in rat neostriatum and hippocampus/cortex during and following a 30-min period of insulin-induced hypoglycaemia. During hypoglycaemia-induced isoelectricity, extracellular levels of quinolinic acid in the striatum (basal value, 1.1 +/- 0.3 pmol per 30-microliters fraction) were elevated 1.7 times as compared to the control period. Thirty to ninety minutes following hypoglycaemia a significant increase in extracellular quinolinic acid to 2.2 times basal level was noted. After 2 h recovery, the beginning of neuronal necrosis was observed in the dorsolateral striatum. Implantation of the dialysis probe did not influence the extent of neuronal damage. No changes in extracellular quinolinic acid levels were observed in the hippocampus/cortex. The data indicate that following a severe hypoglycaemic insult vulnerable striatal cells are exposed to hyperphysiological extracellular quinolinic acid concentrations over an extended period of time. Considering the pronounced susceptibility of rat striatal neurons to the toxin, the small but prolonged elevation in the extracellular levels of quinolinic acid could be of significance for the development of delayed neuronal death in hypoglycaemia.

Changes in excitatory amino acid receptor binding in the intact and decorticated rat neostriatum following insulin-induced hypoglycemia.

An involvement of excitatory amino acid (EAA) transmitter-receptor interactions in the development of hypoglycemia-induced neuronal damage has been suggested. We report here on the binding to EAA receptors in the rat caudate nucleus and cerebral cortex, during and following severe insulin-induced hypoglycemia with an isoelectric EEG of 10 or 30 min duration. The binding of alpha-[3H]amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [( 3H]AMPA) to quisqualate receptors, [3H]kainic acid (KA) to kainate receptors, and [3H]glutamate to N-methyl-D-aspartate (NMDA)-sensitive sites was determined by quantitative autoradiography. During EEG isoelectricity, AMPA binding was reduced by approximately 40%, which could represent quisqualate receptor desensitization. One hour following glucose-induced recovery, AMPA binding was no longer different from control level. As the recovery period was prolonged to 1 or 4 weeks, AMPA binding decreased. The decrease was more pronounced in the dorsolateral than in the ventromedial part of the striatum. This correlates with the distribution of neuronal damage, and probably reflects loss of receptor binding sites due to cell death. During the period of EEG silence there was a tendency toward an increase in NMDA displaceable glutamate binding. Following 4 weeks of recovery, binding to NMDA receptors was significantly decreased. Glutamate binding to NMDA-sensitive sites was remarkably resistant to neuronal necrosis and was not significantly different from control values in the dorsolateral caudate 1 week following the hypoglycemic coma. No changes in KA binding were found until 1 week posthypoglycemia, when a significant reduction in binding was noted in the lateral striatum.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic changes of excitatory amino acid receptors in the rat hippocampus following transient cerebral ischemia.

The changes in excitatory amino acid receptor ligand binding induced by transient cerebral ischemia were studied in the rat hippocampal subfields. Ten minutes of ischemia was induced by common carotid artery occlusion combined with hypotension, and the animals were allowed variable periods of recovery ranging from 1 day to 4 weeks. The binding of 3H-AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) to quisqualate receptors, 3H-kainic acid (KA) to kainate receptors, and 3H-glutamate to N-methyl-D-aspartate (NMDA) receptors as determined by quantitative autoradiography. One week following ischemia the CA1 region of the hippocampus displayed a severe (90%) dendrosomatic lesion with preservation of presynaptic terminals. This was associated with a 60% decrease in AMPA binding and a 25% decrease in glutamate binding to NMDA receptors. At 4 weeks postischemia, both AMPA and NMDA sites were greatly reduced. Although the dentate gyrus granule cells are resistant to an ischemic insult of this magnitude, this region showed marked changes in receptor binding. One week following ischemia, the AMPA and NMDA binding decreased by approximately 40 and 20%, respectively. Following 2 weeks of recovery, the NMDA binding was not significantly different from control level, while the AMPA binding remained depressed up to 4 weeks postischemia. The high density of KA binding sites in the inner molecular layer of the dentate gyrus was unaffected by the ischemic insult, despite an extensive degeneration of cells in the hilus of dentate gyrus which projects glutamatergic afferents to this area.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional differences in arachidonic acid release in rat hippocampal CA1 and CA3 regions during cerebral ischemia.

Changes in the levels of arachidonic acid during ischemia in selectively vulnerable areas of the hippocampus were studied in the rat brain. Since neurons in the CA1 region are more vulnerable to ischemia than neurons in the adjacent CA3 region, the release of arachidonic acid in these two regions was measured during decapitation ischemia of 4- to 12-min duration. The concentration of free arachidonic acid increased with the duration of ischemia in both regions. However, the level was significantly higher in CA1 than in CA3 after 8 and 12 min of ischemia. This difference in arachidonic acid accumulation may reflect differences between the regions in agonist-dependent phospholipid breakdown as well as calcium-dependent phospholipase activity. The importance for the development of neuronal necrosis is discussed.

Excitatory amino acid receptors and ischemic brain damage in the rat.

The excitatory amino acid glutamate has been suggested to be an important mediator of the selective CA1 hippocampal damage which follows transient cerebral ischemia. In order to evaluate the possible involvement of altered glutamate receptor regulation in the expression of the delayed neuronal necrosis following ischemia, we have determined the density of glutamate receptor subtypes in the rat hippocampus following transient ischemia. We report a transient reversible decrease in [3H]AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) binding sites (presumably representing quisqualate receptors) followed by a long term loss of binding at 2 days postischemia which precedes neuronal loss. In contrast, no change was noted in the N-methyl-D-aspartate or kainic acid binding sites over this time period.

Effect of insulin-induced hypoglycemia on the concentrations of glutamate and related amino acids and energy metabolites in the intact and decorticated rat neostriatum.

The glutamate (Glu) terminals in rat neostriatum were removed by a unilateral frontal decortication. One to two weeks later the effects of insulin-induced hypoglycemia on the steady-state levels of amino acids [Glu, glutamine (Gln), aspartate (Asp), gamma-aminobutyric acid (GABA), taurine] and energy metabolites (glucose, glycogen, alpha-ketoglutarate, pyruvate, lactate, ATP, ADP, AMP, phosphocreatine) were examined in the intact and decorticated neostriatum from brains frozen in situ. The changes in the metabolite levels were examined during normoglycemia, hypoglycemia with burst-suppression (BS) EEG, after 5 and 30 min of hypoglycemic coma with isoelectric EEG, and 1 h of recovery following 30 min of isoelectric EEG. In normoglycemia Glu decreased and Gln and glycogen increased significantly on the decorticated side. During the BS period no significant differences in the measured compounds were noted between the two sides. After 5 min of isoelectric EEG Glu, Gln, GABA, and ATP levels were significantly lower and Asp higher on the intact than on the decorticated side. No differences between the two sides were found after 30 min of isoelectric EEG. After 1 h of recovery from 30 min of isoelectric EEG Glu, Gln, and glycogen had not reached their control levels. Glu was significantly lower, and Gln and glycogen higher on the decorticated side. The Asp and GABA levels were not significantly different from control levels. The results indicate that the turnover of Glu is higher in the intact than in decorticated neostriatum during profound hypoglycemia.