Alterations in tissue Mg++, Na+ and spinal cord edema following impact trauma in rats

Alterations in water content and total tissue Na+ and Mg++ of rat spinal cord tissue were followed over time after a 100 g-cm impact injury to the T-9 spinal cord segment. Rats subjected to laminectomy but not trauma served as controls. In the injured segment there was a progressive increase in water content with increased Na+ and decreased Mg++ at 1 hour and 24 hours after trauma. At seven days, water and Na+ content remained elevated, whereas Mg++ levels had returned to preinjury baseline values. Because of its important role in many metabolic and physiological regulatory processes the early decline in Mg++ concentration after trauma may contribute to the development of secondary tissue damage after spinal cord injury.     

Decline in intracellular free Mg2+ is associated with irreversible tissue injury after brain trauma

Much of the tissue damage resulting from trauma to the central nervous system appears to result from secondary, delayed biochemical changes that follow primary mechanical injury. However, the early biochemical events remain to be elucidated. In the present studies, we have used phosphorus (31P) magnetic resonance spectroscopy (MRS) to examine in vivo, the temporal changes in brain intracellular free Mg2+ concentration following fluid percussion head injury in rats. We report that injury caused a profound and rapid decrease in intracellular free Mg2+ which was significantly correlated with the severity of injury. At high levels of injury, the decrease in intracellular free Mg2+ concentration was associated with a decrease in total Mg2+ concentration as determined by atomic absorption spectrophotometry. Prophylactic treatment with MgSO4 prevented the post-traumatic decrease in intracellular free Mg2+ and resulted in a significant improvement in acute neurological outcome. Because magnesium is essential for a number of critical enzyme reactions, including those of glycolysis, oxidative and substrate level phosphorylation, protein synthesis, and phospholipid synthesis, changes in free Mg2+ after brain trauma may represent a critical early factor leading to irreversible tissue damage.     

Phospholipids of normal and experimentally injured spinal cord of the miniature pig

Experimental spinal cord trauma was produced in 3-month-old SS-1 minature pigs by dropping a 25 g weight from a height of 20 cm upon the exposed spinal cord. The histological lesion consisted of edema and hemorrhage. Phospholipid concentration and composition, cholesterol concentration and phospholipid fatty acid composition were determined in whole spinal cord 3 hours after injury, and in spinal cord myelin 5 hours after injury. Three hours after injury phospholipid and cholesterol concentration were decreased by about 14% in the whole spinal cord. Trauma had no effect on the phospholipid composition of whole spinal cord and myelin. Fatty acid composition of myelin also did not change after injury, and changed very slightly in the whole spinal cord. It is concluded that edema following spinal cord trauma is much more extensive than previously assumed. Furthermore, peroxidation of membrane lipid fatty acids does not appear to be a significant factor in spinal cord pathology 3 hours after injury.     

Effects of Methylprednisolone and the Combination of α-Tocopherol and Selenium on Arachidonic Acid Metabolism and Lipid Peroxidation in Traumatized Spinal Cord Tissue

Traumatic injury of the spinal cord leads to a series of pathological events that result in tissue necrosis and paralysis. Among the earliest biochemical reactions are hydrolysis of fatty acids from membrane phospholipids, production of biologically active eicosanoids, and peroxidation of lipids. This study examines the effect of agents purported to improve recovery following spinal cord trauma, methylprednisolone sodium succinate (MPSS) and the combination of alpha-tocopherol and selenium (Se), on the posttraumatic alterations of membrane lipid metabolism. Pretreatment with either MPSS or alpha-tocopherol and Se reduced the trauma-induced release of total FFA including arachidonate in the injured spinal cord tissue. In addition, these agents decreased the postinjury levels of prostanoids. Pretreatment with either MPSS or alpha-tocopherol and Se also completely prevented the trauma-induced loss of cholesterol while inhibiting the increase of a cholesterol peroxidation product, 25-hydroxycholesterol. These data suggest that: perturbation of membrane lipid metabolism may contribute to the tissue necrosis and functional deficit of spinal cord injury and MPSS or the combination of alpha-tocopherol and Se may protect injured spinal cord tissue, at least in part, by limiting these posttraumatic membrane lipid changes.     

Decrease in total and free magnesium concentration following traumatic brain injury in rats

31P magnetic resonance spectroscopy was used to determine the intracellular free Mg2+ concentration prior to and following fluid percussion induced traumatic brain injury in rats. Prior to injury, cerebral intracellular free Mg2+ concentration in the rat was 0.93 +/- 0.19 mM (mean +/- SE; n = 5). Following injury, free Mg2+ in the injured cortex declined by 70% within the first hour, and did not recover over the next 3 hours. Total Mg2+ also declined by 10% over this time period; however, there were no changes in brain Na+ or tissue water content. Because of its primary role in cellular metabolism, the early decline in tissue Mg2+ following brain trauma may be a critical factor in the development of irreversible tissue injury.     

Immunotropic and immunogenic properties of Burkholderia pseudomallei surface and membrane antigens

The immunotropic and immunogenic properties of some chromatographic fractions of B. pseudomallei surface antigenic complex, as well as the preparations of B. pseudomallei outer and cytoplasmic membranes, were studied. The difference between the biopolymers under study in cytotoxicity, humoral and cell-mediated immunity characteristics, phagocytic activity were established. Some antigenic fractions (B, C, C1, H) showed perceptible protective activity (25-60%) in experiments on mice infected with B. pseudomallei virulent strain. One of the preparations of cytoplasmic membrane (CM-1) was also found to have protective properties (30%). Complex immunization with the antigenic complexes under study, introduced in combination with the immunomodulating agent Bromantan, was shown to enhance the protective effect.     

Mechanical damage to murine neuronal-enriched cultures during harvesting: Effects of free fatty acids,diglycerides, Na+, K+-ATPase,and lipid peroxidation

Summary The most commonly used procedure to harvest cultured cells from petri dishes is to scrape the cells off the plates with a rubber or Teflon policeman. However, the results reported herein demonstrate that this technique, with its associated mechanical trauma, significantly perturbed cell membranes in neuronal-enriched cultures derived from the ventral half of fetal murine spinal cords. This is evidenced by liberation of free fatty acids and diglycerides, partial inhibition of Na⁺K⁺-ATPase activity, and increased malondialdehyde production. Harvesting the cells by freezing, either on liquid nitrogen or dry ice, significantly attenuated these effects. This important observation indicates that mechanical manipulation of cultured cells during harvesting significantly affects subsequent biochemical analyses, particularly those associated with the cell membrane (e.g., membrane lipid metabolism and assay of intrinsic membrane enzymes).     

Effects of plasmenylethanolamine on the dynamic properties of the hydrocarbon region of mixed phosphatidylcholine-phosphatidylethanolamine aqueous dispersions. A spin label study

Spin-labeled aqueous dispersions of total phospholipid extracts from whole brains of hibernating hamsters and rats chronically consuming ethanol were compared with dispersions from control animals. Order parameter values and approximate rotational correlation times for the nitroxide spin labels indicated that ethanol consumption results in an adaptive decrease in bilayer membrane fluidity, while hibernation produces increases in fluidity. Since it has been proposed that changes in plasmenylethanolamine such as those seen with hibernation play a role in the homeoviscous adaptation of brain membranes, electron spin resonance studies using aqueous phospholipid dispersions containing equimolar mixtures of rat brain phosphatidylethanolamine and phosphatidylcholine, or synthetic dioleylphosphatidylcholine and dioleylphosphatidylethanolamine, and brain plasmenylethanolamine were performed. The molar amount of plasmenylethanolamine was varied within the ethanolamineglycerophospholipid fraction of each dispersion. Order parameter values of spin labels in liposomes containing brain phosphatidylcholine and phosphatidylethanolamine increased in parallel with increases in plasmenylethanolamine concentrations, indicating that fluidity was decreasing. Liposomes composed of synthetic dioleyl phospholipids exhibited biphasic changes in order parameter (S) values as plasmenylethanolamine replaced the diacyl form. Below 30% (mol%) plasmenylethanolamine, S values decreased, while above 30%, S values were seen to increase; indicating an initial fluidization, followed by a decrease in fluidity.     

Effects of chronic consumption of ethanol and low-thiamin, low-protein diets on the lipid composition of rat whole brain and brain membranes

Four groups of rats were used in a nutritionally-controlled study of effects of chronic ethanol consumption on brain membrane lipid composition. Rats chronically consuming ethanol were fed high-nutrient or low-thiamin, low-protein diets. After 4 months, lipid analyses were performed on brains, brain microsomes and myelin from each group and from pair-fed, non-ethanol controls. Among the effects of ethanol was an increase of the relative proportion of cholesterol in microsomal lipids while there was decrease of it in myelin. Ethanol also increased plasmenylethanolamine while decreasing phosphatidylethanolamine proportions in myelin and in whole brain lipids, decreased the total lipid phosphorus of whole brain, and elevated the proportion of phosphatidylserine in microsomal and whole brain lipids. Effects of poor diet generally did not interfere with ethanol effects except in the case of microsomal lipids, where it apparently prevented an ethanol-induced increase in proportion of cholesterol. These changes may be adaptive responses to the fluidizing effect of ethanol on membranes.