Inhibition of glycolysis alters potassium ion transport and mitochondrial redox activity in rat brain.

To examine the relationships between brain glycolysis, ion transport, and mitochondrial reduction/oxidation (redox) activity, extracellular potassium ion activity (K+0) and redox shifts of cytochrome oxidase (cytochrome a,a3) were recorded previous to and during superfusion of rat cerebral cortex with the glycolytic inhibitor iodoacetic acid (IAA). IAA produced oxidation of cytochrome a,a3, increased local oxygenation, increased K+0, and, in response to neuronal activation, slowed rates of K+0 reaccumulation. Rates of rereduction of cytochrome a,a3, after the oxidation of this cytochrome by stimulation, were also slowed by IAA. These effects of IAA demonstrate the dependence of K+0 reaccumulation on the integrity of glycolysis, support the concept that active processes are involved in brain ion transport, and suggest a link between ATP supplied by glycolysis and ion transport activity. These data are also compatible with the suggestion that residual dysfunctions after brain ischemia result from derangements in glycolytic functioning rather than from limitations in oxygen availability or oxidative metabolic activity.

Potassium ion homeostasis and mitochondrial redox activity in brain: relative changes as indicators of hypoxia.

This study was directed at relating ion transport and mitochondrial redox activity during hypoxia, as a step toward definition of brain oxygen sufficiency. To accomplish this, extracellular potassium ion activity (K+o) was recorded by ion-selective microelectrodes while reduction/oxidation (redox) ratios of cytochrome oxidase (cytochrome a,a3) were monitored by reflection spectrophotometry in cerebral cortex of rats anesthetized with pentobarbital. In normoxia, neuronal activation by direct cortical stimulation produced transient oxidation of cytochrome a,a3 and elevation of K+o. Moderate hypoxia (PaO2 above 50 mm Hg) resulted in reduction of cytochrome a,a3 but only slight elevation of K+o. At this level of hypoxia, cytochrome a,a3 continued to respond to neuronal activation with transient shifts toward oxidation and rates of K+o reaccumulation were unchanged from control. When PaO2 was further decreased below a critical threshold, stimulus-provoked oxidative responses of mitochondrial reactants were replaced by shifts toward reduction, but rates of reaccumulation of K+, spilled into the extracellular space by neuronal activation, remained unchanged. Only during severe hypoxia (PaO2 less than 20 mm Hg) was it possible in some animals to record a slowing in the reaccumulation of K+o without provocation of spreading cortical depression. These data indicate that ion transport activity in cerebral cortex is more refractory to hypoxia than is mitochondrial redox functioning. They suggest an in vivo parallel to the "cushioning" effect of mitochondria in vitro, in which oxygen consumption remains constant despite fluctuations in oxygenation and redox ratios, and also that there may be a greater anaerobic capacity to provide energy for ion transport in mammalian brain than has previously been appreciated.

Glycolysis, oxidative metabolism, and brain potassium ion clearance.

Studies were directed toward defining relationships between brain ion transport, glycolysis, and oxidative phosphorylation. This was done by examining the relative sensitivity to hypoxemia and to iodoacetate (IAA)-induced inhibition of glycolysis in rats anesthetized with pentobarbital. Both insults had minimal effects on K+o baseline. In response to neuronal activation, IAA increased the time required for K+o clearance from maximal values to half-recovery of baseline. Hypoxemia slowed the later phase of K+o clearance, when K+o was approaching "resting" levels. Hypoxemia produced greater declines in high-energy intermediates than did IAA, which indicated that the IAA effect was not due to a greater overall insult to metabolism and suggested a direct link between ATP produced by glycolysis and ion transport activity. These data demonstrate that K+o clearance requires energy from glycolysis and oxidative phosphorylation for different phases of the recovery process and that inhibition specific to glycolysis or oxidative phosphorylation may be temporally resolved within a single stimulus.

EEG suppression and anoxic depolarization: influences on cerebral oxygenation during ischemia.

Cerebral ischemia provokes sequential changes that include EEG suppression, anoxic depolarization (AD) with maximal increases in extracellular potassium ion activity (K+o), and anoxia with maximal decreases in tissue oxygen tension (tPO2) and increases in the reduction/oxidation (redox) ratios of the mitochondrial electron transport carriers. Studies were directed toward relationships among these events during cerebral ischemia ("four-vessel occlusion model") in pentobarbital anesthetized rats. Results demonstrate that EEG suppression and anoxic depolarization do not occur as a simple function of progressive oxygen decline during cerebral ischemia. Rates of K+ elevation, tPO2 decline, and cytochrome a,a3 reduction were decreased in the immediate period following EEG suppression. Latency to EEG suppression was inversely correlated with latency to maximal cytochrome reduction. In contrast, AD was associated with increased rates of tPO2 decline and cytochrome a,a3 reduction. Latency to AD was related to latency of subsequent maximal cytochrome a,a3 reduction. These data suggest that EEG suppression spares oxygen while AD accelerates the progression to energy failure by accelerating the decline in oxygen stores in brain following global ischemia.

Mitochondrial hyperoxidation signals residual intracellular dysfunction after global ischemia in rat neocortex.

Reperfusion after global ischemia (10-60 min in duration) in rat neocortex most commonly provoked transient hyperoxidation of mitochondrial electron carriers, tissue hyperoxygenation, and CBF hyperemia. These responses were normally accompanied by recovery of K+ homeostasis and EEG spike activity. Goals of this research were to understand putative relationships among these postreperfusion events with special emphasis on determining whether mitochondrial hyperoxidation results from intracellular changes that may modulate residual damage. The amplitude of postischemic mitochondrial hyperoxidation (PIMHo) did not increase when CBF increased above an apparent threshold during reperfusion, and tissue hyperoxygenation was not required for PIMHo to occur or to continue. These findings suggest that PIMHo is not merely a response to increased CBF and tissue hyperoxygenation; rather, PIMHo is modulated, at least in part, by residual intracellular derangements that limit mitochondrial electron transport. This suggestion was supported by observations that NAD became hyperoxidized after reoxygenation in anoxic hippocampal slices. Also, PIMHo occurred and subsequently resolved in many animals, but K+o never was cleared fully to baseline and/or EEG spike activity never was evident. One suggestion is that PIMHo signals or initiates residual intracellular derangements that in turn impair electrical and metabolic recovery of cerebral neurons after ischemia; an alternative suggestion is that PIMHo and tissue hyperoxygenation are not the sole factors modulating the immediate restoration of electrical activity after ischemia. Present data also support the following: Decreased oxygen consumption, despite adequate oxygen delivery, likely contributes to tissue hyperoxygenation after ischemia; and mitochondrial hyperoxidation is modulated by a limitation in the supply of electrons to the mitochondrial respiratory chain.

Trypanosoma cruzi meningoencephalitis and myocarditis in a patient with acquired immunodeficiency syndrome.

We report the case of a 52-year-old male heterosexual patient with acquired immunodeficiency syndrome (AIDS) and reactivation of Chagas' disease manifested by meningoencephalitis and myocarditis, diagnosed post-mortem. Unexplained reactivation of Chagas' disease should be included among the diagnostic criteria of AIDS in human immunodeficiency virus positive patients. On the other hand, AIDS should be considered in the differential diagnosis of patients with unexplained reactivation of Chagas' disease.

Genetic predisposition to febrile convulsions: a preliminary study.

The participation of genetic factors in the origin of convulsive disorders is a controversial matter. In an attempt to study the influence of heredity in a selected group of patients, we evaluated 128 subjects that presented febrile febrile convulsions. Of these, 18 (14,3% of the sample) had at least one relative affected by the same problem. Even though a more definite conclusion depends on sample enlargement and on setting up a control group, pedigree observation suggests the participation of an autosomal dominant gene, with incomplete and probably low penetrance, in the etiology of febrile convulsions.

[Paracoccidioidomycosis evidencing spinal cord involvement treated with success by fluconazole]. / Paracoccidioidomicose evidenciando comprometimento medular tratada com sucesso por fluconazol.

The involvement of central nervous system in paracoccidiodomycosis has rarely been described, with an incidence rate varying from 9.99% to 27.27%. There are two basic forms of clinical presentation: meningeal and tumor-like (abscesses, granulomas, nodules, and cysts). The Paracoccidioides brasiliensis is preferentially described in cerebral hemispheres, cerebellum, medulla oblonga and meninges, and exceptionally in the spinal cord. The authors present a case of paracoccidioidomycosis which diagnosis was achieved by microscopic examination of material from oral lesions and specific serology. The patient presented clinical signs of spinal cord involvement confirmed by lesions found in magnetic resonance imaging. They emphasize the inedit therapeutic response to a new antifungal agent (fluconazole) used for the first time in this kind of clinical manifestation, and the excellent prognosis when diagnosis is promptly made.

[Transverse myelitis as initial symptom of disseminated non-Hodgkin lymphoma and HIV-associated vacuolar myelopathy: case report]. / Mielite transversa como manifestação clínica inicial de linfoma não Hodgkin disseminado e mielopatia vacuolar associada ao HIV.

Non-Hodgkin lymphoma is frequently seen in AIDS patients usually affecting the central nervous system (CNS), especially the leptomeninges and the cerebral hemispheres. The epidural involvement is rarely described, ranging from 3.5% to 8.3% among the CNS sites. The authors present a case of disseminated non Hodgkin lymphoma associated to vacuolar myelopathy in a 27 years-old male patient with AIDS emphasizing the importance of this differential diagnosis in the myelopathies of AIDS.

Internal carotid artery pseudoaneurysm after tonsillectomy treated by endovascular approach. A case report.

SUMMARY: Surgery on the head and neck region may be complicated by vascular trauma, caused by direct injury on the vascular wall. Lesions of the arteries are more dangerous than the venous one. The traumatic lesion may cause laceration of the artery wall, spasm, dissection, arteriovenous fistula, occlusion or pseudoaneurysm. We present a case of a child with a giant ICA pseudoaneurysm after tonsillectomy, manifested by pulsing mass and respiratory distress, which was treated by endovascular approach, occluding the lesion and the proximal artery with Histoacryl. We reinforce that the endovascular approach is the better way to treat most of the traumatic vascular lesions.

Contribuicao ao estudo semiologico das convulsoes febris. / Semiologic study of febrile convulsions

Convulsao febril e um problema frequente na clinica pediatrica e a incidencia de crises generalizadas e nao-generalizadas varia na literatura conforme a definicao de convulsao febril utilizada. Com o objetivo de determinar os diversos tipos de crises epilepticas na vigencia de febre, 78 criancas foram avaliadas no Ambulatorio de Convulsao Febril do Hospital de Clinicas da Faculdade de Medicina da Universidade Federal de Uberlandia, no periodo de agosto de 1982 a setembro de 1983. Definimos convulsao febril como a crise epileptica que ocorre em criancas ate entao normais, na vigencia de febre, estando o foco infeccioso fora do sistema nervoso.Observamos que as crises generalizadas foram mais frequentes que a nao-generalizadas. Os principais tipos dentre as generalizadas foram as tonicas, tonica-clonicas e clonicas; nas nao-generalizadas, os tipos tonicos-clonicas, clonicas e tonicas assimetricas