Brain cell death following ischemia and reperfusion: a proposed biochemical sequence

Brain nuclear DNA survives cardiac arrest and reperfusion

Iron-mediated peroxidation of brain lipids is known to occur during reperfusion following cardiac arrest. Since in vitro damage to DNA is caused by similar iron-dependent peroxidation, we tested whether free radical damage to genomic DNA also develops during reperfusion following cardiac arrest and resuscitation. Genomic DNA was isolated from the cerebral cortex in (i) normal dogs, (ii) dogs subjected to a 20-min cardiac arrest, and (iii) dogs resuscitated from a 20-min cardiac arrest and then allowed to reperfuse for 2 or 8 h. DNA strand nicks were evaluated by in vitro labeling of newly created 3' and 5' termini. DNA base damage was evaluated utilizing reaction with piperidine prior to labeling of 5' termini. The 3' DNA termini were labeled before and after digestion with exonuclease III, and the 5' DNA termini were labeled before and after treatment with piperidine. In vitro experiments with genomic DNA damaged by oxygen radicals verified that these labeling methods identified radical damage. In the experimental animal groups, terminal incorporation and electrophoretic mobility of brain nuclear DNA are not significantly changed either by 20 min of complete brain ischemia or during the first 8 h of reperfusion. We conclude that genomic DNA is not extensively damaged during cardiac arrest and early reperfusion, and therefore such DNA damage does not appear to be an important early aspect of the neurologic injury that accompanies cardiac arrest and resuscitation.

Cerebrovascular regulation and neonatal brain injury

Neuropathology occurring as a result of hemodynamic injury occurs in up to 25% of preterm newborns of less than 1,500 gm birth weight and in a much smaller, but nonetheless meaningful, proportion of more mature infants. Abnormalities in cerebrovascular regulation have been proposed as major contributing factors to both ischemic and hemorrhagic injuries in the newborn brain. In this review we explore several factors that play a role in cerebrovascular regulation in the immature brain and relate them to what is known about vascular regulation in the mature brain and to the types of pathology that occur in the newborn brain. One goal in this "decade of the brain" should be to increase our basic and clinical knowledge about the cerebrovasculature of the newborn in order to enhance our ability to predict and prevent perinatal brain injury.

Determination of lipoperoxide in animal tissue by ion-pair reversed phase high performance liquid chromatography

An ion-pair reversed phase high performance liquid chromatographic method was developed for the quantitative determination of lipoperoxide (as malondialdehyde, MDA) in animal tissue using a ODS column and a mobile phase of methanol + phosphate buffer (53:47 v/v, pH 6.5). Tetrabutylammonium bromide was used as an ion-pair reagent and the detection wavelength was set at 532 nm. The method was sensitive, accurate and simple. A linear relationship was obtained between the peak height and the amount of MDA from 50 nmol/L to 1200 nmol/L and the lower limit of detection of MDA was 15 nmol/L (signal-to-noise ratio greater than 2), and the coefficient of variation at the 200 nmol/L level was 3.7% (n = 7). The results correlated well with those from the 2-thiobarbituric acid colorimetric method. The method has been used in the pathogenic studies of cerebral ischemia and acute renal failure for the determination of trace lipoperoxide.

Management of massive hemorrhage associated with abdominal trauma

Control of massive hemorrhage from intra-abdominal organs and major vascular structures may tax the ingenuity of the trauma surgeon. It is emphasized, however, that total blood loss and the amount of transfused blood are far less critical than the duration and severity of shock.

[Study of cerebral energy metabolism and development of postanoxia coma]

An open prospective study of brain energy metabolism was carried out in 20 consecutive cases of coma occurring after cardiopulmonary arrest (CPA) of various causes. Mean age was 54 years and mean duration of CPA 2.75 min, with a mean of 11 min for resuscitation. Brain energy metabolism was compared with clinical course, electroencephalogram (EEG), and neurological outcome. All the patients were given the usual intensive care: intermittent positive pressure ventilation, haemodynamic control, sedation with benzodiazepines, neuromuscular paralysis, anticonvulsants, mannitol. A clinical examination and an EEG were carried out daily, 4 h after all drugs which might interfere with these investigations or brain energy metabolism had been stopped (except for anticonvulsants). Successive measurements of the cerebral arteriovenous oxygen (C (a - v) O2) and glucose (C (a - v)gluc) contents were made. The oxygen glucose index (OGI) was calculated according to Cohen's formula. The first set of measurements were carried out within the first 30 h after CPA. The last measurements were made a few hours before death or recovery, or stabilization of the coma. Patients were assigned to 2 groups according to their neurological outcome: group R (n = 8), patients who recovered consciousness; group D (n = 12), patients who developed brain death or a vegetative state - Safar's cerebral performance category 4. During the first 30 h, there was no relationship between clinical course, EEG and cerebral outcome. Half of the patients died or recovered within 72 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoxia/hypotension evoked release of glutamate and aspartate from the rat cerebral cortex

Glutamate and aspartate levels in cerebral cortical superfusates rose rapidly after introduction of artificial cerebrospinal fluid into cortical cups to reach stable levels within 5-10 min. These equilibrated levels (glutamate 1.33 +/- 0.1 microM; aspartate 0.29 +/- 0.04 microM), which are very similar to those in fourth ventricular CSF (glutamate, 1.5 +/- 0.2 microM; aspartate, 0.27 +/- 0.03 microM), are likely to reflect basal interstitial amino acid levels in the superficial layers of the cortex. During and following brief (5 min) hypoxemic/hypotensive episodes, release of both excitatory amino acids into the cortical superfusates was enhanced. The finding of an hypoxia/hypotension-evoked release of excitatory amino acids is consistent with recent speculation that these agents may play an important role in the destruction of neurons in ischemic regions of the brain.

Brain resuscitation

Optimal neurological outcome after cardiac arrest requires careful attention to the details of both intracranial and extracranial homeostasis. A high index of suspicion regarding the potential causes and complications of cardiac arrest facilitates discovery and treatment of problems before they adversely impact upon neurological outcome. The future is bright for resuscitation research since our fundamental understanding of cerebral ischemia and its consequences has dramatically improved. This knowledge can hopefully be transferred to clinical useful modes of therapy.

Acidosis and ischemic brain damage

It is now widely accepted that acidosis is an important component of the pathogenetic events that lead to ischemic brain damage. The objective with this article is to recall the evolution of the concept, to describe the conditions under which tissue acidosis arises and causes enhanced brain damage, and to probe into the cellular and molecular mechanisms involved.