Experimental magnesium depletion in adult rabbits caused by blast overpressure.

The complex pressure wave (blast) generated by some explosions causes pulmonary pathological changes which resemble the histological findings of the adult respiratory distress syndrome (ARDS). The development of indirect neurotrauma following experimental pulmonary blast injury has been shown previously. The purpose of this study was to evaluate lung and brainstem total tissue magnesium concentrations in adult rabbits following pulmonary blast injury. In order to assess the interrelationship between magnesium and other secondary injury factors, total calcium and high energy phosphate (phosphocreatine, PCr; adenosine triphosphate, ATP) contents were simultaneously measured. Twenty adult male rabbits were divided into two groups. Group C (n = 10) served as control, while group B (n = 10) was subjected to a focused blast wave, generated in laboratory conditions using an air-driven shock tube. Moderate pulmonary blast injury was verified by histological examination in group B. Total tissue magnesium and calcium contents were measured by atomic absorption spectrophotometry in the lungs and brainstem of adult rabbits 30 min following blast overpressure and in their uninjured controls. Simultaneously, PCr and ATP contents were measured by fluorimetric enzymatic analyses in same structures. Lung and brainstem water contents were determined by wet weight to dry weight ratio. Blast overpressure to the lungs induced significant magnesium depletion, increased calcium and decreased the Mg/Ca ratio in lung tissue of injured animals. Increases in water content and PCr/ATP ratio were also observed. Significant correlations between these Mg/Ca and PCr/ATP and between Mg and ATP parameters confirmed the functional relationship between magnesium depletion and impaired bioenergetic state in indirect neurotrauma in adult rabbits through blast overpressure.

[The effect of sodium benzyl-penicillin on the mean quantal levels of released acetylcholine]. / Uticaj natrijumbenzil-penicilina na srednji kvantalni iznos oslobodenog acetilholina.

Examined are effects of different doses of potassium (2.500 IU/ml) and sodium (5.000 IU/ml) (10.000 IU/ml) of benzylpenicillin on the mean quantum content (MQC) of the released acetylcholine in the phrenicus-hemidiaphragm specimens in rats. Very significant MQC decrease depending on the given antibiotic doses was found. Presented was hypothesis that the MQC decrease could result in the decreased Ca++ ion entering the terminal axoplasm under the benzylpenicillin molecule effect.

Inhibition of leukotriene formation by diethylcarbamazine modifies the acid-base balance in the rabbits with blast injuries of the lungs.

Our previous investigations have shown that leukotrienes are important mediators/modulators in local response of the lungs to the blast injury. The aim of the present study was to investigate the effects of diethylcarbamazine (DEC), an 5-lipoxygenase inhibitor, on the acid-base balance following pulmonary blast injury. The experiments were performed on rabbits (n = 16) subjected to focused blast over-pressure on the middle thoracic region. Immediately prior to blast injury one group was treated with DEC (50 mg/kg, i.v.), and the other with the same volume of saline. Parameters of acid-base balance were measured in arterial and venous blood before and 30 minutes after injury. Obtained results indicated that DEC treatment reduced some disturbances induced by blast injury (prevents edema formation in the lungs, permits respiratory compensation of metabolic acidosis in general circulation, normalization of respirations and slightly improves the oxygen saturation of hemoglobin), in spite of intensified hemodynamic insufficiencies associated with increased hypotension and acidosis in the peripheral circulation.

[The effect of short-chain aliphatic alcohols on electrophysiologic characteristics of muscle cells and neuromuscular transmission in the rat diaphragm]. / Uticaj kratkolancanih alifaticnih alkohola na elektrofizioloske karakteristike misicnih celija i neuromisicnu transmisiju dijafragme pacova.

Effects of short-chain aliphatic alcohols C1-C3 on the rest potential, entrance membranous resistance and spontaneous activity of the neuromuscle synapse of the muscle cells of the diaphragm of the Wistar rats have been studied. The standard electrophysiologic method of intracellular recording was used. Taking into account effects of the increased chain length on the studied parameters, the equimolar alcohol concentrations (0.2 M) were used. The studied alcohols have caused increased rest potential as well as the entrance membranous resistance of the muscle cell. They cause increased spontaneous activity of the neuromuscular synapse and later the shape of the postsynaptic signals. The effects are more manifested if the alcohol chain is longer.

[Neuromodulation of synaptic transmission with thymopentin]. / Neuromodulacija sinapticke transmisije timopentinom.

The effect of thymopentin (TP-5; 1 x 10(-5) and 1 x 10(-4) M), the active center of the thymic hormone thymopoietin was examined upon spontaneous and induced neuromuscular synaptic activity (N-MS) in the isolated diaphragm of Wistar-strain rat. Standard electrophysiological method of intracellular registration was used. Analysis of original experimental microphysiologic results revealed clear depressant neuromodulative effect of TP-5 upon skeletal N-MS in vitro. Effect of TP-5 is expressed in decreased amount of the released median quantal value of neurotransmitter acetylcholine at orthodromic stimulation of the alpha-motor nerve. TP-5 also reduces chemiosensitivity of postsynaptic nicotinic acetylcholine receptors.

Relationship between early neuroendocrine response and severity of war injury according to the Red Cross Classification.

The hypothesis that neuroendocrine response to military gunshot/missile (MG/M) wounds reflect the severity and type of wounds given by the Red Cross Wound Classification (RCWC), has been tested on 82 casualties of war in former Yugoslavia. Adrenaline (A), noradrenaline (N), Cortisol, triiodothyronine (T3), testosterone (TES) and prolactin (PRL) levels have been measured in blood samples taken on admission (2-18 hr after wounding) at Military Medical Academy. Neuroendocrine response to MG/M wounds has clearly reflected severity but not the type of wounds and it has been bidirectional, i.e. A, NA and cortisol levels positively related to, while T3 and TES levels were negatively related to severity of MG/M wounds. With regard to high compatibility between RCWC and Injury severity score (ISS) and the fact that magnitude of the neuroendocrine response is related to severity given by RCWC we have concluded that the RCWC is a good method of grading wound severity on the battlefield.

Oxidative and antioxidative activity in the patients with disseminated demyelinating disease of central nervous system.

Considering the basic pathologic process and current knowledge of the physiopathologic mechanisms in the active phase of disseminated demyelinating disease of central nervous system, the increase of oxidative processes was assumed in the patients with that disease in the phase of clinical impairment. The aim of the research was to study some indices of oxidative processes and activity of antioxidative enzymes in such patients. The research was performed on blood samples (erythrocyte hemolysate and plasma) and cerebrospinal fluid of 30 patients with disseminated demyelinating disease of central nervous system during the clinical impairment and during the increase of immunologic activity in intrathecal space. The patients were of younger age, in the acute phase or with the shorter disease duration (up to 3 years). Control group was formed of 12 patients examined for lesions of intervertebral disks in lumbosacral region. The research results demonstrated the increase of superoxide anion production, the elevation of lipid peroxidation followed by the increase of superoxide dismutase and glutathione reductase activation. It was concluded that the signs of simultaneous increase of oxidative processes and antioxidative activity, but also the oxidative impairment of lipid structures existed in the studied patients during the acute phase.

Pulmonary blast injury increases nitric oxide production, disturbs arginine metabolism, and alters the plasma free amino acid pool in rabbits during the early posttraumatic period.

Plasma nitrate + nitrite (nitrates), as final NO products, and free amino acid pool (FAAP) characteristics, as indicators of protein/amino acid metabolism, were analyzed in the early (30 min) period following blast injury. The experiments were performed on 27 rabbits subjected to pulmonary blast injury (experimental group) or not exposed to overpressure (controls). We report that pulmonary blast injury (PBI) induces prompt NO overproduction within a very early period. Increased arginine utilization via NO synthase, presumably associated with its cleavage by arginase, leads to the depletion of the arginine level in arterial plasma 30 min following PBI. Impaired balance between arginine utilization and release/resynthesis from endogenous sources causes disturbed nutritional status and urea cycle activity. Early identification and appropriate management of the changes in amino acid metabolism should be included in the evaluation of patients with blast injury. Furthermore, the results suggest that depleted arterial levels of arginine and NO overproduction may be helpful in diagnosis and prognosis of blast injury.

Involvement of the central nervous system in the general response to pulmonary blast injury.

The local, general, and cerebral responses of rabbits exposed to pulmonary blasts were examined to define the role of vagal afferentation in cardiorespiratory as well as metabolic control after a blast injury. Two series of experiments were conducted on rabbits to analyze the general, local, and cerebral responses to pulmonary injury caused by blast overpressure, and to evaluate the effects of bilateral vagotomy on the general, local, and cerebral responses to local (pulmonary) blast injury. The blast wave was generated in laboratory conditions using an air-driven shock tube that was able to cause moderate pulmonary blast injury, i.e., four pulmonary contusions characterized as confluent ecchymoses involving 30 to 60% of the lungs. One group of animals was subjected to pulmonary deafferentation, performed by bilateral transections of the vagus, glossopharyngeal, and hypoglossal nerves. Numerous hemodynamic as well as biochemical parameters were observed in systemic circulation and in lung and brain (medulla oblongata) tissues. After observation during the early posttraumatic period, rabbits were sacrificed by decapitation 30 minutes after the blast injury. On the basis of obtained results, it was concluded that vagal afferents have an important role in the modification of general and local responses to a pulmonary blast injury. Furthermore, it was suggested that functional changes in medulla oblongata may be the consequences of afferent neural impulses from the injured region (lungs) rather than consequences of ischemia, energy transfer to the brain, or both.

Leukotrienes in the pathogenesis of pulmonary blast injury.

Our previous studies demonstrate a significant increase of sulfidopeptide leukotriene concentrations in animals exposed to a free air blast. The aim of this study was to analyze the role of leukotrienes in the local response of lung tissue as well as in the general response of organisms to blast overpressure. The study was conducted on adult rabbits exposed to moderate blast overpressure (four pulmonary contusions characterized as confluent ecchymoses involving 30 to 60% of the lungs), generated in laboratory conditions. One group of experimental animals was treated with 5-lipoxygenase (5-LO) inhibitor, diethylcarbamazine (DEC, Sigma, St. Louis, Missouri) (50 mg/kg, i.v.), immediately before blast. The early posttraumatic period was observed (30 minutes after blast). Hemodynamic parameters (mean arterial pressure, heart rate, blood gases) as well as arterial plasma levels of conjugated dienes were observed. The myeloperoxidase activity, lipid peroxidation products levels, and water contents were measured in the lung tissue of injured rabbits. We observed that 5-LO inhibition reduced edema formation, accumulation of neutrophils, and generation of lipid peroxidation products in injured lungs. In this study, we demonstrated that treatment with DEC inhibits the increased systemic generation of conjugated dienes after blast injury. Although DEC exerts local antioxidant activity with beneficial effects on lung tissue, this 5-LO inhibitor intensifies the blast overpressure caused hemodynamic insufficiency.

Index of lipid peroxidation and glucose utilization in the cerebrospinal fluid in patients with cerebral infarction.

Cerebral ischemia could be observed as acute metabolic crisis, when oxygen and glucose supply is compromised and synthesis of energy is insufficient. Apart from the excitotoxicity, increased production of reactive oxygen species with consequent lipid peroxidation is also included in neuronal cell damage. Furthermore, these toxic compounds could also be produced during the process of secondary inflammation of ischemic tissue. In the early stage of ischemia, as a systemic response to acute stress, there is an increase in glucose level in cerebrospinal fluid (CSF) and peripheral blood. According to the metabolic crisis and acidosis in ischemic brain tissue we investigated index of lipid peroxidation (ILP) and glucose utilization (IGU) in CSF of 53 patients of both sexes, aged 55-70 years with cerebral infarction. Control group comprised 15 patients with sudden onset of motor deficit subjected to diagnostic lumbar radiculography and suspected on discal genesis. ILP in CSF, as the indicator and sequela of neuronal cell membranes damage, was two fold increased in the acute period of cerebral infarction and maximal values (3.5 times) were noticed 24 hours after the ischemic episode compared to controls. Besides the increase in glucose concentration in peripheral blood and CSF of patients with cerebral infarction, IGU was decreased (37%) with minimal values (32%) 24 hours after the ischemia. These changes indicate that glucose is available but cells are incapable to metabolize it. We concluded that ILP and IGU in CSF of patients with cerebral infarction could be indicators of metabolic dysfunction and neuronal cell damage. Also, these results suggest the significance of polyvalent therapy including antioxidative and antiinflammatory agents in acute phase of cerebral ischemia.

Effects of nerve growth factor on antioxidative system in the thalamus of MPTP treated Wistar rats.

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced parkinsonism is one of the most useful models for the study of that disease. It has been suggested that MPTP-induced neurotoxicity may involve the production of reactive oxygen species. MPTP was applied intracerebrally, unilaterally, in the striatum in single dose of 0.09 g/kg b.w. The second group was treated both with MPTP and nerve growth factor (NGF) in dose of 7 ng/ml. NGF was applied immediately after the neurotoxin. Control group was treated with 0.9% saline solution in the same manner. Animals were decapitated 7 days after the treatment. In the group treated with MPTP, the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) was decreased in ipsilateral thalamus, compared to control values as well as to the contralateral thalamus. In the same structures superoxide anion production was increased, compared to controls. Following the application of both MPTP and NGF, the activity of SOD and GSH-Px remained on control values, while the superoxide anion content was decreased, compared to controls. These results indicate a temporal and spatial propagation of oxidative stress and spread protective effects of NGF on the thalamus, the structure that is distant, but very tightly connected with striatum, the place of direct neurotoxic damage.

Oxidative stress in the thalamus of Wistar rats treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

Experimental parkinsonism was induced in adult Wistar rats by selective nigrostriatal neurotoxine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in a single dose of 0.09 g/kg, by unilateral intrastriatal application using stereotaxic instrument. Control group included rats treated with 0.9% saline solution in the same manner. Animals were sacrificed by decapitation seven days after the treatment. Total glutathione was measured in the crude mitochondrial fraction of thalamus and striatum. Total glutathione content, as a measure of reduced cell atmosphere, was mutually decreased in the thalamus and striatum of MPTP-treated animals, compared to controls: thalamus ipsi- = 24.8 +/- 3.11, contralateral = 26.81 +/- 5.31; striatum ipsi- = 19.96 +/- 4.13, contralateral = 17.3 +/- 4.09 nmol/mg prot. Mutually depleted glutathione content in the thalamus and contralateral striatum, the structures distant from ipsilateral treated striatum, could indicate on spatial propagation of oxidative stress, not only in the selective vulnerable dopaminergic nigrostriatal neurons, but in the structures included in the motor and cognitive loops of basal ganglia.

Cytochrome C oxidase activity and total glutathione content in experimental model of intracerebral aluminum overload.

Treatment of Wistar rats with aluminum chloride causes astroglial and neuronal cell damage in the selective brain regions of association cortex and hippocampus, seen in patients with Alzheimer's disease. Adult Wistar rats were treated with unilateral intrahippocampal injection of AlCl3 in one single dose of 3.7 g/kg b.w. Control group of animals was treated with 0.9% saline solution likewise. Animals were sacrificed by decapitation seven days after the treatment. Activity of cytochrome C oxidase (COX) and total glutathione content were measured in the ipsi- and contralateral hippocampus and forebrain cortex. Activity of COX was mutually decreased in the hippocampus (ipsi- 30%, contra- 34%), as well as in the forebrain cortex (ipsi- 44%, contra- 47%), compared to controls. These decrease could indicate a deficiency in reducing equivalents with concomitant altered proton gradient and function of electron transport chain, as well as decreased ATP synthesis. Content of glutathione, a clue antioxidative factor, was decreased for about 50% in all examined structures, primary suggesting an impaired regeneration of reduced glutathione. Such distribution of diminished antioxidative defense could be the consequence of the specific brain distribution of transferrin receptors, which was also a main protein carrier for Al. Furthermore, at the cellular level Al could impede glycolysis with consequent decreased production of reducing equivalents which were necessary for glutathione synthesis/reduction, as well as for proton gradient and functionality of electron-transport chain.

Oxidative damage and metabolic dysfunction in experimental Huntington's disease: selective vulnerability of the striatum and hippocampus.

The etiology of neuronal death in neurodegenerative diseases, including Huntington's disease (HD), is still unknown. There could be a complex interplay between altered energy metabolism, excitotoxicity and oxidative stress. Unilateral administration of quinilonic acid (QA), NMDA agonist, in rat striatum in a single dose of 150 nM was used as a model of HD. The other two groups of animals were pretreated immediately before QA application with nerve growth factor (NGF) and fibroblast growth factor (FGF), respectively. Control group was treated with 0.9% NaCl in the same manner. Content of total glutathione was not altered in the striatum and hippocampus of QA-treated animals, as well as in the groups pretreated with neurotrophic factors (NF), compared to controls. Content of reduced glutathione, a key antioxidant, was mutually depleted in the striatum and hippocampus of each experimental group. The reduced/total glutathione ratio was decreased in the QA-treated animals, but nearby or over the controls in each structure of the NF-treated groups. These results support the hypothesis that oxygen-free radicals contribute to the excitotoxic neuronal injury, and also that NF could be the potential neuroprotective agents in HD. Moreover, activity of cytochrome c oxidase, the last component in the mitochondrial respiratory chain, was mutually increased in each structure of QA-treated animals. This increase was less pronounced in the NF-treated groups. Striatal lesions led to the loss of tonic inhibitory inputs to the globus pallidus with consequent increase in the activity of GABAergic efferent pallidal neurons, suggesting that NF could functionally repair the altered striopallidal pathway.