Abstract: Maghemite (gamma-Fe2O3) nanoparticles were obtained by the coprecipitation of Fe(II) and Fe (III) salts with ammonium hydroxide followed by oxidation with sodium hypochlorite. Solution radical polymerization of N,N-dimethylacrylamide (DMAAm) in the presence of maghemite nanoparticles yielded poly(N,N-dimethylacrylamide) (PDMAAm)-coated maghemite nanoparticles. The presence of PDMAAm on the maghemite particle surface was confirmed by elemental analysis and ATR FTIR spectroscopy. Other methods of nanoparticle characterization involved scanning and transmission electron microscopy, atomic adsorption spectroscopy (AAS), and dynamic light scattering (DLS). The conversion of DMAAm during polymerization and the molecular weight of PDMAAm bound to maghemite were determined by using gas and size-exclusion chromatography, respectively. The effect of ionic 4,4'-azobis(4-cyanovaleric acid) (ACVA) initiator on nanoparticle morphology was elucidated. The nanoparticles exhibited long-term colloidal stability in water or physiological buffer. Rat and human bone marrow mesenchymal stem cells (MSCs) were labeled with uncoated and PDMAAm-coated maghemite nanoparticles and with Endorem as a control. Uptake of the nanoparticles was evaluated by Prussian Blue staining, transmission electron microscopy, T-2-MR relaxometry, and iron content analysis. Significant differences in labeling efficiency were found for human and rat cells. PDMAAm-modified nanoparticles demonstrated a higher efficiency of intracellular uptake into human cells in comparison with that of dextran-modified (Endorem) and unmodified nanoparticles. In gelatin, even a small number of labeled cells changed the contrast in MR images. PDMAAm-coated nanoparticles provided the highest T-2 relaxivity of all the investigated particles. In vivo MR imaging of PDMAAm-modified iron oxide-labeled rMSCs implanted in a rat brain confirmed their better resolution compared with Endorem-labeled cells.

Abstract: Our study followed the changes in thalamic nuclei metabolism, hindlimb sensitivity to thermal stimulation, and locomotor function after spinal cord injury (SCI). MR spectroscopy (MRS) was used to examine the thalamic nuclei of rats 1 day before and 1, 3, 6, and 15 days after SCI or sham surgery. All animals were tested before MRS measurements for motor performance and thermal sensitivity. SCI induced by balloon compression caused complete paraplegia from the first to third day, followed by partial functional recovery during the second week. MRS revealed an increase in N-acetylaspartate (NAA) concentration in the thalamic nuclei on the first day after SCI, which decreased by the third day. The data also showed an increase in inositol (Ins), glutamate, and creatine (Cr) concentrations on the third day postinjury; the Ins concentration remained elevated on the sixth day. In sham-operated animals an increase in NAA concentration was observed on the sixth and fifteenth days after surgery and an increase in Cr concentration on the third day. A positive correlation between Ins concentration and hindlimb sensitivity in both SCI and sham-operated animals suggests changes in glial activity, while changes in NAA levels may indicate the response of thalamic neuronal cells to injury. (c) 2008 Wiley-Liss, Inc.

Abstract: Neurogenic pulmonary edema is an acute life-threatening complication following central nervous system injury. The exact pathogenic mechanism leading to its development is still unclear. We introduce a new hypothesis that high levels of anesthesia might protect the organism against the development of neurogenic pulmonary edema due to a more pronounced inhibition of the hypothalamic, brainstem and spinal vasoactive sympathetic centers. On the basis of a more pronounced neuronal inhibition of the vasoactive centers, a severe sympathetic discharge does not occur and neurogenic pulmonary edema does not develop. In contrast, an insufficient anesthesia level is not able to inhibit the sympathetic nervous system during an injury of the central nervous system and thus neurogenic pulmonary edema develops. During experiments with central nervous system injury, low-anesthesia-induced neurogenic pulmonary edema might negatively influence the overall recovery of the animal. More importantly, during a neurosurgical intervention, insufficient anesthesia might similarly lead to neurogenic pulmonary edema development in operated patients. Our hypothesis indicates the necessity of precisely monitoring of the level anesthesia during experimental manipulations of the central nervous system in animals or neurosurgical interventions in humans.

Abstract: We describe a new model of neurogenic pulmonary edema in spinal cord injured Wistar male rats. The pulmonary edema was elicited by an epidural thoracic balloon compression spinal cord lesion, performed under a low concentration of isoflurane (1.5 or 2%) in air. Anesthesia with 1.5% isoflurane promoted very severe interstitial and intraalveolar neurogenic pulmonary edema with a significantly increased thickness of the alveolar walls and massive pulmonary hemorrhage. In this group, 33% of animals died. Anesthesia with 2% isoflurane promoted severe interstitial and intraalveolar neurogenic pulmonary edema with less thickening of the alveolar walls and pulmonary hemorrhage. For evoking severe neurogenic pulmonary edema in spinal cord injured rats, 2% isoflurane anesthesia would be more suitable. However, if very severe neurogenic pulmonary edema needs to be evoked, spinal cord injury under 1.5% isoflurane anesthesia could be used, but one-third of the animals will be lost.

Abstract: Anesthetics can either promote or inhibit the development of neurogenic pulmonary edema (NPE) after central nervous system (CNS) injury. The influence of isoflurane was examined in male Wistar rats using 1.5%, 2%, 2.5%, 3%, 4%, or 5% isoflurane in air. Epidural balloon compression of the thoracic spinal cord was performed. The development of NPE was examined in vivo and on histologic sections of lung tissue. Animals anesthetized with 1.5% or 3% isoflurane were behaviorally monitored using the BBB and plantar tests for 7 weeks post-injury. The spinal cord was examined using MRI and morphometry of the spared white and gray matter. All animals from the 1.5% and 2% groups developed NPE. Almost 42% of the animals in the 1.5% group died of severe pulmonary hemorrhage and suffocation; x-rays, the pulmonary index, and the histological picture revealed a massive NPE. More than 71% of the animals from the 2.5% and 3% groups did not develop any signs of NPE. Blood pressure after spinal cord compression rose more in the 1.5% group than in the 3% one. In the 1.5% group, the sympathetic ganglionic blockade prevented the neurogenic pulmonary edema development. Animals from the 3% group recovered behaviorally more rapidly than did the animals from the 1.5% group; morphometry and MRI of the lesions showed no differences. Thus, low levels of isoflurane anesthesia promote NPE in rats with a compressed spinal cord and significantly complicates their recovery. The optimal concentration of anesthesia for performing a spinal cord compression lesion is 2.5-3% isoflurane in air.

Abstract: Carnosine, a specific constituent of excitable tissues of vertebrates, exhibits a significant antioxidant protecting effect on the brain damaged by ischemic-reperfusion injury when it was administered to the animals before ischemic episode. In this study, the therapeutic effect of carnosine was estimated on animals when this drug was administered intraperitoneally (100 mg/kg body weight) after ischemic episode induced by experimental global brain ischemia. Treatment of the animals with carnosine after ischemic episode under long-term (7-14 days) reperfusion demonstrated its pronounced protective effect on neurological symptoms and animal mortality. Carnosine also prevented higher lipid peroxidation of brain membrane structures and increased a resistance of neuronal membranes to the in vitro induced oxidation. Measurements of malonyl dialdehyde (MDA) in brain homogenates showed its increase in the after brain stroke animals and decreased MDA level in the after brain stroke animals treated with carnosine. We concluded that carnosine compensates deficit in antioxidant defense system of brain damaged by ischemic injury. The data presented demonstrate that carnosine is effective in protecting the brain in the post-ischemic period.

Abstract: In vivo magnetic resonance spectroscopy (MRS) studies of glial brain tumours reported that higher grade of astrocytoma is associated with increased level of choline-containing compounds (Cho) and decreased levels of N-acetylaspartate (NAA) and creatine and phosphocreatine (Cr). In this work, we studied the metabolism of glioma tumours by in vitro proton magnetic resonance spectroscopy (1H-MRS). 1H-MR spectra were recorded in vitro from perchloric acid extracts of astrocytoma (WHO II) and glioblastoma multiforme (WHO IV) samples. We observed differences between astrocytoma and glioblastoma multiforme in the levels of Cho, alanine, lactate, NAA, and glutamate/glutamine. In astrocytoma samples, we found higher MR signal of NAA and lower signal of Cho and alanine. MR spectra of glioblastoma samples reported significantly higher levels of lactate and glutamate/glutamine. In contrast, levels of Cr were the same in both tumour types. We also determined NAA/Cr and Cho/Cr ratios in the tumour samples. The NAA/Cr ratio was higher in astrocytomas than in glioblastomas multiforme. Conversely, the Cho/Cr ratio was higher in glioblastoma multiforme. The results indicate that MRS is a promising method for distinguishing pathologies in human brain and for pre-surgical grading of brain tumours.

Abstract: Alterations in phospholipid content and Cu/Zn superoxide dismutase (SOD) activity were examined in rat brain after 15 min of global ischemia (four-vessel occlusion) followed by 2-, 24- or 48-h reperfusion. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE), the main brain phospholipids, were markedly decreased in ischemic rats and remained decreased during the whole reperfusion period. Concentrations of phosphatidylinositol (PI) and sphingomyelin (SM) were also significantly reduced during ischemia but recovered during reperfusion period. In contrast, phosphatidylserine (PS) and lysophospholipids (LysoPL) were unchanged during ischemia but were elevated after 24 h of reperfusion. Significant reductions in blood plasma phospholipids were also demonstrated. 24-48 h of reperfusion markedly decreased PE, PC and PS contents, while the concentrations were almost unchanged by ischemia alone. Brain SOD activity decreased significantly during ischemia and was recovered to control value already after 2 h of reperfusion. These results suggest that ischemia/reperfusion is accompanied by a significant and selective degradation of brain phospholipids that may be attributable to oxidative stress and activation of phospholipases.