We studied the cerebral effects of oxygen-derived free radicals generated from the xanthine oxidase/hypoxanthine/ADP-Fe3+ system. Xanthine oxidase/hypoxanthine/ADP-Fe3+ solution (0.1 ml) was infused into caudate putamen, and brain was frozen rapidly in situ. Brain water and sodium content increased concomitant with decreased potassium content at 24 hours and 48 hours after the infusion. The degree of brain edema and injury depended on the dose of xanthine oxidase. Spongy neuropil and neuronal cytoplasmic vacuoles were seen at 2 hours, with an infiltration by polymorphonuclear leukocytes at 24 hours, followed by lipid-laden macrophages and reactive astrocytes. Leakage of fluorescent dye into neuropil was seen at 2 hours, but not later. These data suggest that oxygen-derived free radicals damage endothelial cells of the blood-brain barrier; the brain injury is characterized by edema and by structural damage of neurons and glia.

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We identified and characterized the glucose transporter in the human cerebral cortex, cerebral microvessels, and choroid plexus by specific D-glucose-displaceable [3H]cytochalasin B binding. The binding was saturable, with a dissociation constant less than 1 microM. Maximal binding capacity was approximately 7 pmol/mg protein in the cerebral cortex, approximately 42 pmol/mg protein in brain microvessels, and approximately 27 pmol/mg protein in the choroid plexus. Several hexoses displaced specific [3H]cytochalasin B binding to microvessels in a rank-order that correlated well with their known ability to cross the blood-brain barrier; the only exception was 2-deoxy-D-glucose, which had much higher affinity for the glucose transporter than the natural substrate, D-glucose. Irreversible photoaffinity labeling of the glucose transporter of microvessels with [3H]cytochalasin B, followed by solubilization and polyacrylamide gel electrophoresis, labeled a protein band with an average molecular weight of approximately 55,000. Monoclonal and polyclonal antibodies specific to the human erythrocyte glucose transporter immunocytochemically stained brain blood vessels and the few trapped erythrocytes in situ, with minimal staining of the neuropil. In the choroid plexus, blood vessels did not stain, but the epithelium reacted positively. We conclude that human brain microvessels are richly endowed with a glucose transport moiety similar in molecular weight and antigenic characteristics to that of human erythrocytes and brain microvessels of other mammalian species.

The effects of polyunsaturated fatty acids on brain edema formation have been studied in rats. Intracerebral injection of polyunsaturated fatty acids (PUFAs), including linolenic acid (18:3) and arachidonic acid (20:4), caused significant increases in cerebral water and sodium content concomitant with decreases in potassium content and Na+- and K+- dependent adenosine triphosphatase activity. There was gross and microscopic evidence of edema. Saturated fatty acids and monounsaturated fatty acid were not effective in inducing brain edema. The [125I]-bovine serum albumin spaces increased twofold and threefold at 24 hours with 18:3 and 20:4, respectively, indicating vasogenic edema with increased permeability of brain endothelial cells. Staining of the brain was observed five minutes after injection of Evans blue dye followed by arachidonic acid perfusion. A major decrease in brain potassium content was evidence of concurrent cellular (cytotoxic) edema as well. The induction of brain edema by arachidonic acid was dose dependent and maximal between 24 and 48 hours after perfusion. Dexamethasone (10 mg/kg) was effective in ameliorating the brain edema, whereas a cyclooxygenase inhibitor, indomethacin (10 mg/kg), was not. These data indicate that arachidonic acid and other PUFAs have the ability to induce vasogenic and cellular brain edema and further support the hypothesis that the degradation of phospholipids and accumulation of PUFAs, particularly arachidonic acid, initiate the development of brain edema in various disease states.

Progressive ascending myelitis was the presenting feature of the acquired immune deficiency syndrome (AIDS) in a homosexual man who also had Kaposi's sarcoma, Pneumocystis pneumonia, and disseminated cytomegalovirus (CMV) infection. Neuropathological studies showed profuse cytomegalic cells throughout the brain and spinal cord, but no inflammatory response. At postmortem examination, CMV and herpes simplex virus, type 2 (HSV-2), were recovered from multiple sites throughout the central nervous system (CNS). HSV-2 was isolated from the anus, but from no other extraneural site; in contrast, pathology typical of CMV was also seen in the liver, gastrointestinal tract, adrenals, and lungs. Although histopathological evidence suggesting prior CMV infection has been seen in the brains of AIDS patients, the virus has never been cultured from the CNS in these immunosuppressed hosts, nor has it been known to infect the spinal cord. The absence of an inflammatory response suggests that the pathogenesis of CNS viral infections is altered in AIDS patients. Evidence for CMV infection of the CNS in AIDS patients is no longer circumstantial.

We report a patient with delayed postanoxic demyelination who had pseudodeficiency of arylsulfatase A, reducing his enzyme activity to 10 to 30% of normal. This may have implications regarding the pathogenesis of postanoxic demyelination.

Six patients showed a transient and otherwise unexplained cerebrospinal fluid (CSF) pleocytosis following a flurry of generalized convulsions. Each had an obvious cause for repeated seizures. No evidence was found for an infectious, inflammatory, neoplastic, or other cause for the pleocytosis. All CSF specimens were clear and colorless, under normal pressure, and bacteriologically sterile. The maximal leukocyte count ranged from 9 to 80 per cubic millimeter and reached a maximum on the day after cessation of convulsions. No specimen contained more than 650 erythrocytes. Two patients initially had a mildly increased CSF protein; glucose values were unremarkable. We propose that the pleocytosis in these patients was a result of frequently repeated generalized convulsions. The mechanism of postictal pleocytosis is uncertain. It may result from transient breakdown of the blood-brain barrier, which has been demonstrated after seizures in experimental animals. Although infectious causes must first be considered and rigorously searched for, it appears that seizures alone may cause a transient CSF pleocytosis.