MRI quantitation of edema in focal cerebral ischemia in cats: correlation with cytochrome aa3 oxidation state

1H MRI permits detection of edema in the brain. In a middle cerebral artery stroke model in the cat, we found a significant correlation between an edema index based on MRI and a sensitive metabolic index of ischemia, the in vivo oxidation status of mitochondrial cytochrome aa3 determined by near-infrared reflectance spectrophotometry (r = -0.70, alpha = 0.001). This result suggests that a simple, noninvasive study using MRI can provide an index of the extent of ischemic damage in an experimental acute stroke model.

Inducible ornithine decarboxylase expression in brain subject to vasogenic oedema after transient ischaemia: relationship to C-fos gene expression

Ornithine Decarboxylase (ODC) is the rat controlling enzyme of polyamine biosynthesis and has been shown to be produced in a delayed fashion in response to cerebral ischaemia. Its appearance has been linked to the development of vasogenic brain oedema. To understand the genetic control of this protein, Mongolian gerbils were studied for the possible expression of the ODC gene as compared to that of the inducible proto oncogenes c-fos and c-jun after transient bilateral carotid artery occlusion. Total cellular RNA was isolated from gerbil brains by guanidine-thiocyanate extraction and characterized by northern blot analysis for c-fos, c-jun, and ODC mRNA over reperfusion times. c-fos and c-jun expression rose rapidly with peak level reached at 60 min of reperfusion (70 x control, p less than or equal to 0.01). Peak levels of ODC mRNA induction were seen at 4 hrs reperfusion (2.83 x control, p less than or equal to 0.01) consistent with the period of maximum of brain oedema as measured by specific gravity (1.0386 +/- 0.0009, p less than or equal to 0.05). These data indicate the differential timing of genetic expression during the reperfusion period after transient ischaemia. Such studies suggest that potential therapies may be possible by addressing the delayed ODC component of ischaemic oedema formation and allow a greater understanding of the role of gene induction in the multifaceted cerebral response to ischaemia.

Ischaemic brain oedema and xanthine-xanthine oxidase system

The formation of oxygen-derived free radicals in cerebral ischaemia has been implicated in altering the BBB permeability, cause oedema and tissue damage. However little attention has been paid regarding the involvement of xanthine oxidase in the cerebral ischaemic events. Recently we demonstrated that cerebral ischaemia promotes the conversion of xanthine oxidase type D (nicotinamide adenine dinucleotide-dependent dehydrogenase) to type 0 (oxygen-dependent superoxide-producing oxidase). This investigation was concerned with elucidating the relationship between the conversion of xanthide oxidase and the duration of brain ischaemia. Four vessel-occlusion served as a model for the induction of cerebral ischaemia in rats. Xanthine oxidase was assayed by high pressure liquid chromatography using ultraviolet and electrochemical detection. The enzymatic conversion of xanthine oxidase from type D to type O increased with time from 7.6-15% during 5 min ischaemia to 27% and 36% at 15 min and 30 min after ischaemia, respectively. These results support the contention that xanthine oxidase may participate in free radical-induced ischaemic brain oedema.

Inhibition by H-7 of the protein kinase C prevents formation of brain edema in Sprague-Dawley CFY rats

The effect of the protein kinase C enzyme inhibitor H-7 was examined on the brain edema formation evoked by bilateral occlusion of the common carotid arteries in Sprague-Dawley rats of CFY strain. Brain edema was assessed by measurement of water and electrolyte contents of the brain. The results showed that pretreatment with H-7 reduced the extent of brain edema formation in a dose-dependent manner. The fact that H-7 treatment prevented the accumulation of water and certain electrolytes in the brain indicates that the protein kinase C may be activated not only in the neuronal structures but also in the microvessels during ischemia, which can lead directly or via certain calcium-mediated mechanisms to the opening of tight junctions resulting in the development of brain edema.

Phosphatases and cathepsin D activities after vasogenic oedema: an experimental study

The role of two phosphatases (acid and alkaline phosphatase) and a lysosomal aspartyl endopeptidase (cathepsin D) in producing rat brain oedema was studied in 3 different rat cerebral areas (i.e. frontal cortex, hippocampus and striatum) at 1, 2 and 3 d after vasogenic brain oedema induction. The percentage of water content in the frontal cortex increased immediately, 1 d after oedema induction and remained high for 2 and 3 d after oedema induction. In the hippocampus and the striatum the water content only increases 3 d after oedema induction. In the oedematous hemisphere (right), when compared to the contralateral hemisphere (left), the acid phosphatase activity decreases in the hippocampus, while the alkaline phosphatase increases in the frontal cortex and striatum; cathepsin D increases only in the striatum. The changes caused by the enzymatic activities were significant only 2 and 3 d after oedema induction. The results of this study show that: (i) the vasogenic oedema induced in experimental conditions was not sufficient to cause a massive liberation of lysosomal enzymes and (ii) brain areas adjacent (below) to the site of the experimental oedematous lesion (frontal cortex) were influenced by oedema induction.

Ultracytochemical study of capillary Ca2+-ATPase activity in brain edema

To investigate the functional relationship between astrocytes and Ca2+-ATPase of cerebral capillary endothelial cells (capillary Ca2+-ATPase), cold lesions were produced and the cytochemical reaction (CR) for Ca2+-ATPase activity and morphological changes of astrocytes were chronologically studied. Under normal conditions, CR for capillary Ca2+-ATPase activity was mild. However, at 20 min after the operation, astrocytic end-feet embracing the capillaries were swollen, and CR was moderate. Deposits of slightly coarsened reaction product (RP) appeared and accumulated on the abluminal surface. CR became stronger as edema fluid accumulated. At 4, 7 and 15 days, detachment of the astrocytic processes from the capillary wall was observed and in the uncovered capillaries, CR was intense, especially on the abluminal surface. It could be thus possible that the enzyme was related to the blood-brain barrier (BBB). At 2 months, reactive astrocytes had recovered lesion-resistant capillaries. CR was mild and its associated deposits were coarser, the number decreasing on both surfaces. The nature and localization of the deposits of RP in the scar were different from those under normal conditions, possibly due to the functional differences between normal and reactive astrocytes in the BBB. CR was mild in association with astrocytes embracing the capillary wall and was intense without astrocytes. Therefore, it might be possible that astrocytes exerted certain effects on capillary Ca2+-ATPase activity in relation to BBB function.

Ornithine decarboxylase activity and immunohistochemical location in postischemic brain

Ornithine decarboxylase, rate-limiting in polyamine formation, has been found to be necessary for the development of vasogenic edema after cryogenic cerebral injury and is postulated to be of importance in late ischemic brain edema formation. Ornithine decarboxylase activity and accompanying edema was studied after transient cerebral ischemia in Mongolian gerbils. Bilateral carotid artery occlusion was utilized to produce dense forebrain ischemia. After 4 h of reperfusion a significant elevation in ornithine decarboxylase activity was present (72.5 +/- 24.7 vs 8.5 +/- 2 pmoles/mg protein/h, p less than 0.05). Immunohistochemical localization of ornithine decarboxylase indicated its presence in cortical neurons of ischemic gerbils. This was typically located in the perinuclear cytoplasm and extended into proximal dendrites. Nonischemic animals did not contain ornithine decarboxylase immunoreactivity. These studies show the presence and location of ornithine decarboxylase in cerebral tissue subjected to transient ischemia. The increase in this marker of polyamine activity paralleled previous studies in this model of cerebral edema formation and reperfusion deficit in blood flow and evoked potential, suggesting that ornithine decarboxylase is a marker for and may be associated with those late metabolic events leading to progressive functional deterioration after incomplete cerebral ischemia.

Brain ornithine decarboxylase activity following transient cerebral ischaemia: relationship to cerebral oedema development

Ornithine decarboxylase (ODC) activity, the first and generally rate-limiting enzyme for polyamine synthesis, is stimulated in permanent focal cerebral ischaemia in areas of incomplete ischaemia which are developing ischaemic brain oedema. As polyamines are ubiquitous ornithine-derived molecules which are obligatory in cold-induced vasogenic oedema, we studied the effect of transient dense cerebral ischaemia with reperfusion on ischaemic oedema development and ODC activity. Fifty-nine Mongolian gerbils were anaesthetized with ketamine hydrochloride (160 mg/kg i.p. plus supplementation as needed). Both common carotid arteries were isolated and a tracheotomy placed in position. EEG was monitored with needle electrodes and temperature maintained at 37-38 degrees C. Twenty-nine gerbils underwent 40 min of bilateral carotid artery occlusion followed by reperfusion times of 10 min, 1, 2, 4, 6 or 8 h. Non-ischaemic control groups were monitored for equal intervals. At sacrifice, the brain was rapidly removed and forebrain samples analysed for ODC activity (enzymatic assay) and cerebral oedema (gravimetric determination). Marked loss of EEG amplitude was noted in all gerbils subjected to bilateral carotid artery occlusion. Ischaemia produced significant levels of cortical oedema throughout the reperfusion period (maximal decrease in specific gravity at 4 h postischaemia; control: 1.0456 +/- 0.0013; ischaemia: 1.0355 +/- 0.0021, mean +/- SD; p less than 0.0001). Significant subcortical oedema was produced at 10 min, 2 and 4 h postischaemia. A biphasic response was observed in brain ODC activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasminogen activator activity and molecular weight patterns in human brain tumors

Fresh human brain-tumor samples were assayed for their plasminogen activator (PA) content. Specific molecular weight patterns were identified for each of five common brain tumors and for normal brain, suggesting a cell-specific origin of the various PA forms. Malignant tumors contained higher PA activity and a larger number of molecular weight patterns than benign tumors, with the exception of acoustic neurinomas. Irradiated tumors contained lower PA activity than nonirradiated tumors. Finally, a slight but definite correlation between brain edema and PA activity was detected. The future role of brain-tumor PA's for diagnostic and therapeutic purposes is discussed.

Analysis of hyperamylasemia in patients with severe head injury

To evaluate the influence of severe head injury (SHI) on amylase activity, we studied the amylase profile of 60 patients with SHIs and Glasgow Coma Scores less than 10. Fourteen additional multiple trauma patients without head injuries were studied as a control group. We excluded patients with pancreatic injury and abdominal trauma. Total serum amylase (TA), pancreatic isoamylase (PA), and nonpancreatic isoamylase (NPA) levels were measured on Days 0, 2, 4, 7, and 14 postinjury. Values greater than 2 SD above the normal mean were considered elevated. All SHI patients were comatose; 14 died. In the SHI group, TA increased in 23 patients, PA increased in 40, and NPA increased in 14. The source of hyperamylasemia was PA in 14, NPA in one, and mixed in 8 patients. While PA increases occurred throughout the study, NPA elevations occurred early. These increases did not correlate with shock (BP less than 80 mm Hg; 17 patients), facial trauma (24 patients), or associated injury (29 patients). On Day 7 postinjury, the mean TA (215 du%) and the mean PA (203.8 du%) were significantly elevated in the SHI patients compared to controls (122.1 du%, P less than 0.05, Wilcoxon's rank sum test). These data indicate that serum amylase is not a reliable index of pancreatic injury in patients with SHI. Severe head injury and multiple trauma activate pathways that increase amylase levels in the blood, suggesting a central nervous system regulation of serum amylase levels.

Na+-K+-ATPase activity of glial, neuronal, and synaptosomal enriched fractions from normal and freezing-injured rabbit cerebral cortex

This paper investigates the kinetic parameters of Na+-K+-ATPase in glial, neuronal, and synaptosomal enriched fractions isolated from rabbit cerebral cortex. Under normal conditions, kinetic parameters-Vmax and KK+0.5- of Na+-K+-ATPase are the same in the three fractions, suggesting that this enzyme behaves as the same molecular entity. Following a cryogenic lesion, the alterations of these parameters appear to be different in the different fractions. These data suggest that the same enzyme exhibits various responses when exposed to the same pathological event. The dissimilar lipid composition of the Na+-K+-ATPase environment, and/or different adaptative responses to abnormal ion concentrations in glial, neuronal, and synaptosomal fractions could account for these different responses.

Effects of an extract of Ginkgo biloba on the 3',5'-cyclic AMP phosphodiesterase activity of the brain of normal and triethyltin-intoxicated rats

For clarification of the beneficial effects of the extract of Ginkgo biloba (EGB) on triethyltin (TET) toxicity in rats, the phosphodiesterase (PDE) activities of the cerebral tissue were measured under in vitro and ex vivo conditions. Under in vitro conditions, low concentrations of EGB (0.25-4.0 mg/L) activated the enzyme, whereas after higher concentrations (5-250 mg/L), dose-dependent inhibition of the enzyme activity was observed. In the lower concentration range, the extract also partially restored the high-affinity PDE activity (measured with 0.25 microM cyclic AMP) of the particulate fraction of the brain inhibited by TET in vitro. In contrast, the inhibitory influence of TET on the low-affinity PDE activity (measured with 50 microM cyclic AMP) of the particulate fraction was enhanced by the extract. Although treatment with a single large dose of EGB lowered the particulate PDE activities of the brain of normal rats, no effects of the extract could be detected in animals after repeated daily administrations of EGB during a 4-day period. Curative treatment of the TET-intoxicated rats with EGB during a 7-day period accelerated the recovery of the edematous state of the white matter caused by the intoxication and also normalized the lowered PDE activity of the particulate fraction of the edematous brain tissue. Furthermore, when preventively administered, EGB counteracted both the edema formation and the fall in PDE activity observed with treatment by TET alone. These observations strongly suggest that some beneficial effects of EGB might be due to its modulating influences on cellular cyclic AMP levels via activation of membrane-bound PDE.

Reduced brain Na+, K+-ATPase activity in rats with galactosamine-induced hepatic failure: relationship to encephalopathy and cerebral oedema

Previously we have shown that sera from patients with fulminant hepatic failure (FHF) will inhibit partially purified rat brain Na+, K+-ATPase and sodium efflux from human leucocytes in vitro. Similar inhibition may be involved in the pathogenesis of encephalopathy and cerebral oedema in these patients. In the present study we have attempted to establish whether the activity of brain Na+, K+-ATPase is decreased in vivo in rats with D-galactosamine induced hepatic failure using homogenates of snap-frozen brains. Na+, K+-ATPase activity was significantly reduced in the forebrain region at the stage of mild encephalopathy (43 h after injection), while at the deeper stage of coma (43-53 h after injection) enzyme activity was further reduced in the forebrain region and was also significantly reduced in the hindbrain region. Ouabain insensitive ATPase activity was not significantly altered at any time. While a significant increase in the water content (0.5%) of the hindbrain region was found 43 h after galactosamine, there was no clear correlation between the development of cerebral oedema and the reduction of Na+, K+-ATPase activity. The activity of partially purified normal rat brain Na+, K+-ATPase was 15% lower when incubated with sera from rats in the deep stage of coma compared with control sera. These data support other evidence that the reduction in brain Na+, K+-ATPase is likely to be due to toxic substance circulating in serum which have been shown to inhibit this enzyme in vitro and to cause coma when administered to normal animals.

[A study of the optimum dose of a glucocorticoid, methylprednisolone sodium succinate, before and after neurosurgical major operations--relationship between beta-glucuronidase level and post operative brain edema]

The effects of pre- and postoperative administration of methylprednisolone (5, 10, 15 mg/kg/day) was studied on 50 cases of major neurosurgical operation. The serum level of beta-glucuronidase was also analyzed in 20 cases so as to determine whether it could be useful as an indicator of post operative brain edema. Methylprednisolone seemed to be effective in the cases administrated in the dosage of 10, 15 mg/kg/day. However, several kinds of postoperative infections were seen in the cases administrated 15 mg/kg/day. The results may suggest that the dosage tested, 10 mg/kg/day, causes little side effects while it is clinically effective. The serum level of beta-glucuronidase tended to increase from the second postoperative day to the seventh day. Those increase were remarkably in the cases with brain edema. Recovery of beta-glucuronidase level was earlier in the cases with 10 mg/kg/day administrated rather than in the cases with 5 mg/kg/day administrated. These results suggest that the measurement of serum beta-glucuronidase level may be useful for evaluating the degree of brain edema.

Creatine kinase in the serum of patients with acute infections of the central nervous system

Serum creatine kinase was assessed in 94 consecutive patients without convulsions admitted to hospital due to suspicion of infection of the central nervous system. No reliable discrimination between patients with aseptic and those with bacterial meningitis was obtained. Patients with bacterial meningitis and brain oedema, as well as patients with encephalitis, had significantly higher values (P less than 0.01) than patients with meningism, aseptic meningitis and bacterial meningitis without cerebral oedema. Very high values, above 2500 U/1, were encountered in only the most severe cases of bacterial meningitis. The highest serum CK value found in patients with encephalitis was 725 U/l. Reference values for control patients with meningism were 16-269 U/1. In a subset of 9 patients creatine kinase isoenzyme analysis was performed. In all cases only muscle type (MM) isoenzyme was found.

Hyperammonemia

A symptomatic elevation in plasma ammonium concentration, termed hyperammonemia, is associated with numerous congenital and acquired conditions (Table 11). In some cases, such as urea cycle disorders, ammonia is the principal toxin. In other instances, such as portal systemic encephalopathy, it is but one of a number of metabolic disturbances, However, in either case hyperammonemic episodes should be treated aggressively to prevent coma, subsequent brain damage, or death. This involves restricting protein intake, providing adequate calories, and giving agents that remove accumulated nitrogen. Long-term therapy relies on diagnosing the specific disease rate. This rarely requires invasive procedures such as liver biopsy. In most cases measurement of plasma amino acids and urinary organic acids will identify the defect. Treatment involving restriction of nitrogen intake, vitamin supplementation, or stimulation of alternative pathways of waste nitrogen excretion can then be instituted. Early therapy, especially in patients with neonatal-onset hyperammonemia, is imperative to avoid severe brain damage. On this basis, the plasma ammonium level should be determined in virtually every newborn with lethargy, hypotonia, poor feeding, seizures, and/or respiratory distress of unclear origin (Table 12).

Modifications of synaptosomal Na+ -K+ -ATPase activity during vasogenic brain edema in the rabbit

This study investigates the functioning of synaptosomal ouabain-sensitive Na+ -K+ -ATPase in cold-induced edema. During vasogenic brain edema development, the enzyme affinities for Na+ and K+ are progressively decreased paralleling the increase in the tissue water content, whereas maximal velocity of the reaction is not changed. On the basis of these data, it is likely that Na+ -K+ -ATPase impairment accounts for the intracellular uptake of water in this model of edema.

Phospholipid degradation and edema development in cold-injured rat brain

Development of brain edema following various pathological insults occurs after some delay. The mechanism of the delay is poorly understood. Using an in vivo model of cold-injury to study the time course of edema development, the present study indicates that the initiation of phospholipid degradation and rapid release of endogenous polyunsaturated fatty acids occurs within 1 min. Evans blue staining was slightly increased in the lesioned area at 1 min and was more profound at 30 min and at 24 h. The cerebral water content was unchanged at 1 min but was significantly increased at later times. The content of thiobarbituric acid-reactive malondialdehyde (MDA) was normal at 1 min but decreased at 30 min and at 24 h. The lipid-soluble fluorescence of MDA conjugates was also decreased concomitant with the degradation of membrane phospholipids at 24 h. Furthermore, Na+, K+-ATPase activities were consistently decreased in traumatized cortex from 24 h to 48 h after the cold-injury. These data indicate that the degradation of membrane phospholipids, the rapid release of polyunsaturated fatty acids and increased blood-brain barrier permeability are very early events underlying the subsequent development of vasogenic edema induced by cold-injury.

Enzyme cytochemistry of blood-brain barrier (BBB) disturbances

Alkaline phosphatase (AP) is one of the enzymes which is highly active in the plasmalemma of endothelial cells (ECs) of BBB-type microvessels. In the ECs of non-BBB type vessels, the reaction for AP (and other phosphatases) is negative (e.g. choroid plexus, area postrema, hypophysis). After BBB damage, the leakage of the vessels can be demonstrated by the use of horseradish peroxidase (HRP). Concomitantly, changes in polar distribution of AP in the ECs occur, paralleled by the appearance of numerous pinocytic vesicles, deep invaginations of the plasmalemma and channel-like structures. The delimiting membranes of these structures possess AP, 5'-nucleotidase, nucleoside diphosphatase and Na+, K+-ATPase activities. These observations suggest that the redistribution of plasmalemma bound enzymes from luminal to abluminal surface results from membrane flow associated with formation of pinocytic vesicles and channel-like structures in affected ECs. In the area of brain where the process of resolution of brain edema occurs, the shift of the enzymatic activity from luminal to abluminal plasmalemma of the ECs is observed probably because of the need to remove various solutes present in the edematous fluid. The appearance of positive reaction for AP in the abluminal side of the EC can be a reflection of the changed functional polarity of these cells associated with reverse transport of solutes from brain, back into the blood stream.

Lactate dehydrogenase and creatine kinase activities in isolated edema fluid and peripheral blood in cold-induced brain edema

A study of the alterations in lactate dehydrogenase and creatine kinase isoenzyme patterns in isolated grey and white matter edema fluid and in peripheral blood is described with a view to possible clinical use in severe brain-injury. The breakdown of the blood-brain barrier, caused by the infliction of a cold injury to the cerebral cortex of cats, resulted in a shift in the LD isoenzyme distribution in favour of the faster moving fractions and the appearance of brain-type CK in the peripheral blood. Total lactate dehydrogenase activity demonstrated no statistical significant changes during the experiment and total creatine kinase showed only slight increased values in the samples collected simultaneously with the infliction of a cold lesion. This strongly suggests that measurements of these parameters in peripheral blood are of little value as indicators of brain damage. Alterations in isoenzyme patterns observed in edema fluids are reflected in peripheral blood. The presence, therefore, of brain-type creatine kinase accompanied by a relative high amount of lactate dehydrogenase H-sub unit in peripheral blood, can be considered as adequate indices of severe brain damage.