Glutathione deficiency induced in newborn rats by giving buthionine sulfoximine, a selective inhibitor of y-glutamylcysteine synthetase, led to markedly decreased cerebral cortex glutathione levels and striking enlargement and degeneration ofthe mitochondria. These effects were prevented by giving glutathione monoethyl ester, which relieved the glutathione deficiency, but such effects were not prevented by giving glutathione, indicating that glutathione is not appreciably taken up by the cerebral cortex. Some of the oxygen used by mitochondria is known to be converted to hydrogen peroxide. We suggest that in glutathione deficiency, hydrogen peroxide accumulates and damages mitochondria. Glutathione, thus, has an essential function in mitochondria under normal physiological conditions. Observations on turnover and utilization of brain glutathione in newborn, preweaning, and adult rats show that (i) some glutathione turns over rapidly (t ., -30 min in adults, ==8 min in newborns), (ii) several pools of glutathione probably exist, and (iii) brain utilizes plasma glutathione, probably by y-glutamyl transpeptidase-initiated pathways that account for some, but not all, of the turnover; thus, there is recovery or transport of cysteine moieties. These studies provide an animal model for the human diseases involving glutathione deficiency and are relevant to oxidative phenomena that occur in the newborn.Studies in which glutathione (GSH) deficiency was induced in animals by administering L-buthionine (S,R)-sulfoximine (BSO) (1, 2), a transition-state inhibitor of y-glutamylcysteine synthetase (3,4), showed that GSH deficiency leads to myofiber degeneration in skeletal muscle (5), damage to type 2-cell lamellar bodies and capillary endothelial cells in the lung (6), and epithelial-cell damage to jejunum and colon (7) in adult mice, and to lens epithelial-cell degeneration and cataract formation in newborn mice (8, 9) and rats (9). These effects, which were invariably accompanied by markedly decreased mitochondrial GSH levels, were associated with mitochondrial swelling with vacuolization and rupture of cristae and mitochondrial membranes as seen by EM. The isolated mitochondria exhibited decreased citrate synthase activity.It should be emphasized that these effects occurred without application of stress (e.g., increased oxygen, drugs, radiation) and that they were completely prevented by administration of GSH monoesters (10-13). In the absence of evidence that BSO itself exerts a separate type of toxicity other than its effect on the enzyme that catalyzes the first step of GSH synthesis, it may be concluded that a major effect of GSH deficiency is mitochondrial damage. Although mitochondria have long been known to contain GSH, only recently was mitochondrial GSH found to originate from the cytosol and to be imported into mitochondria by a system that contains a high-affinity transporter (14,15). Not all oxygen used by mitochondria is reduced to water, but a significant fraction of it is converted, apparently throu...

It is crucially important to detect subarachnoid haemorrhage (SAH) in all patients in whom it has occurred to select patients for angiography and preventative surgery. A computerized tomography (CT) scan is positive in up to 98% of patients with SAH presenting within 12 h, but is positive in only 50% of those presenting within one week. Cerebrospinal fluid (CSF) bilirubin spectrophotometry can be used to determine the need for angiography in those few CT-negative patients in whom clinical suspicion of SAH remains high; it may remain positive up to two weeks after the event. A lumbar puncture (LP) should only be performed .12 h after the onset of presenting symptoms. Whenever possible collect sequential specimens. Always ensure that the least blood-stained CSF sample taken (usually the last) is sent for bilirubin analysis. Protect the CSF from light and avoid vacuum tube transport systems, if possible. Always use spectrophotometry in preference to visual inspection. All CSF specimens are precious and should always be analysed unless insufficient sample is received. Centrifuge the specimen at .2000 rpm for 5 min as soon as possible after receipt in the laboratory. Store the supernatant at 48C in the dark until analysis. An increase in CSF bilirubin is the key finding, which supports the occurrence of SAH but is not specific for this. In most positive cases, bilirubin will occur with oxyhaemoglobin.

The shorter half-life of betamethasone in twin pregnancy than in singleton pregnancy may cause the level of betamethasone to be subtherapeutic for lung maturation in twin pregnancy.

A model for oxidative stress is described in which glutathione (GSH) synthesis is selectively blocked in newborn rats by administration of L-buthionine-(SR)-sulfoxipuine (BSO). In this model, the normal endogenous physiological formation of reactive oxygen species is largely unopposed, and therefore oxidative tissue damage occurs; because GSH is used for reduction of dehydroascorbate, tissue ascorbate levels decrease. In lung there are decreased numbers of Isieflar bodies and decrease of intraalveolar surfactant. Proximal renal tubular, hepatic, and brain damage also occur. A diastereolsomer of BSO that does not inhibit GSH synthesis, L-buthiflR-sulfoximine, does not produce toxicity; this control experiment renders it unlikely that the observed effects of BSO are produced by the sulfoximine moiety itself. There is correlation between the decrease of mitochondrial GSH levels and mitochondrial and cell damage. Oxidative stress as evaluated by mitochondrial damage and mortality can be prevented by treatment with GSH esters or ascorbate. There is apparent inkage between the antioxidant actions of GSH and ascorbate. This model, which may readily be applied to evaluation of the efficacy of other compounds in preventing oxidsative stress, offers an approach to study of other effects of GSH deficiency (e.g., on lipid metabolim, hematopoiesis), and closely resembles oxidative stress that occurs in certain human newborns and in other clinical states.Glutathione (GSH), the ubiquitous peptide thiol that provides cells with their reducing environment, is a key component of the antioxidant system (which includes ascorbate, a-tocopherol, and other compounds) that defends cells against the toxic effects ofoxygen (1-3). GSH is synthesized within cells; its export by many cells is a step in a recycling pathway that seems to protect cell membrane components against oxidative damage (4-6). The functions of GSH may be probed by examining the effects of decreasing cellular GSH. Cellular GSH may be decreased by administering compounds that react with GSH to form conjugates or that oxidize GSH to GSSG; however, these approaches are limited by lack of specificity of the reagents available and, because the effects obtained are transient, are associated with major perturbations of metabolism, or both. Inhibition of GSH synthesis by inhibition of -glutamylcysteine synthetase [rather than of GSH synthetase, whose blockage leads to metabolic acidosis (7,8)] is the preferred approach to a sustained decrease in cellular GSH (9). L-Buthionine-(S,R)-sulfoximine (BSO) and related sulfoximines are highly selective inactivators of -glutamylcysteine synthetase, and their administration to animals turns off cellular GSH synthesis effectively (10-13). BSO does not react with GSH, and there is no evidence that the sulfoximine moiety itself exerts toxicity, a conclusion supported by studies reported here on a diastereoisomer, L-buthionine-(R)-sulfoximine, that does not inhibit GSH synthesis. The effects observed after treatment with BSO, which ...