Citrate inhibition of snake venom proteases.

Thirty snake venoms had a citrate content of 2.3 to 12.9%, dry basis, by an aconitase isocitric dehydrogenase coupled enzyme assay. This is a venom concentration range of approximately 30 to 150 mM citrate assuming 25% venom solids content. Inhibition of snake venom protease activity by the addition of exogenous citrate was obtained using azure blue hide powder and azocasein as substrates. Protease inhibitions of 7.5% for Crotalus atrox venom to 78% for Bothrops picadoi venom were observed with citrate. Complete inhibition of snake venom protease activity by citrate was not observed. Bothrops asper (Pacifico) venom showed a 41% protease inhibition by citrate with azocasein as the substrate and 46% inhibition of Bothrops asper (Alantico) venom protease with azure blue hide power as a substrate. Trypsin was not inhibited in this system. Citrate may inhibit some venom protease activity by forming a complex with the zinc of zinc-dependent enzymes. reserved.

Neurologic sequelae of open-heart surgery in children. An 'irritating question'.

As pediatric cardiac surgical techniques have improved in recent years, mortality rates have dropped and attention has turned to residual morbidity, especially neurologic sequelae. Although the majority of children undergoing open-heart surgery for correction of congenital heart defects apparently emerge with no adverse consequences, a small percentage suffer permanent neurologic injury (seizures, motor disorders). Another small and not well-defined population may be left with disorders of higher cortical function, such as mental retardation or learning disabilities. A survey of six major pediatric cardiac surgery units in North America was undertaken in 1988-1989 to ascertain current approaches to the detection and management of neurologic sequelae of pediatric open-heart surgery. All units reported seeing a small but definite incidence of postoperative neurologic symptoms, including alterations of consciousness, seizures, and localized abnormalities such as hemiparesis or delayed choreoathetoid syndromes. Postoperative neuroimaging procedures have shown a disturbing incidence of hypoxic-ischemic encephalopathy, unsuspected cerebral atrophy, and subdural hematomas. Pathogenesis may include factors related to preoperative brain anomalies and/or hypoxic insults, altered cerebral blood flow and metabolism during hypothermic cardiopulmonary bypass with or without total circulatory arrest, embolization, and low cardiac output states postoperatively. Further studies are needed to examine the mechanisms of injury and to develop techniques to minimize the occurrence of these sequelae, as they may be associated with life-long neurologic disability and reduced quality of life.

Neurologic sequelae of cardiac surgery in children.

Major advances in surgical and cardiopulmonary bypass technology have occurred in the past 30 years. Total correction of previously inoperable congenital cardiac defects is being performed with increasing frequency and in children at progressively younger ages. While the majority of children undergoing cardiac surgery survive without incident, increasing concern is being raised about neurologic sequelae seen in some survivors. Complications such as embolization, hypoxia, inadequate cerebral perfusion, and biochemical disturbances may all lead to brain damage following cardiac surgery. Acute postoperative neurologic problems include seizures, impaired levels of consciousness, focal motor deficits, and movement disorders. Long-term sequelae include language and learning disorders, mental retardation, seizures, and cerebral palsy. Intraoperative cerebral monitoring techniques are as yet imperfect, but their use in combination with meticulous intraoperative and postoperative care currently provides the best means of reducing neurologic morbidity. Future studies should explore other methods of preserving neurologic integrity in children undergoing open heart surgery.

Unusual acute neurologic presentations with Epstein-Barr virus infection.

We describe two patients with serologic evidence of active Epstein-Barr virus infection who presented with unusual neurologic manifestations and minimal systemic findings of infectious mononucleosis. One girl developed an acute hemiplegic migraine syndrome followed by acute psychosis, and the other patient had severe, generalized chorea. The wide spectrum of presenting central nervous system findings associated with Epstein-Barr virus infections underscores the need to suspect this agent in a variety of acute neurologic syndromes.

Computed cranial tomography in children.

The CT head scan is a valuable new device for the diagnosis of intracranial pathology in children. It is especially useful in detection of cerebral tumors, hydrocephalus, blood-fluid collections, and congenital anomalies. Because of its expense, it cannot be recommended for use in screening of children with seizures, headaches, or nonprogressive focal neurologic signs. Other new ultrasonic and tomographic techniques are being developed, making it advisable to use the radiologist as a clinical consultant in selection of appropriate neuroradiologic procedures in children.