Biomedical subjects

Ljubisav Rakic

Publications and source records attributed to Ljubisav Rakic.

7 recordsLinked to original sources

PubMed2006

Immunolocalization of ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) in the rat forebrain.

Immunohistochemical study was performed to determine distribution of ecto-nucleotide pyrophosphatase/phosphodiesterase1 (NPP1) in adult rat forebrain. The study revealed widespread distribution of NPP1 in rat forebrain, yet with regional differences in the expression pattern and abundance. Strong NPP1 immunoreaction was detected in pyramidal cell layer of cerebral cortex and hippocampus, and in the midline regions of hypothalamus and thalamus. In many immunopositive forebrain areas, NPP1 was mainly localized at neuronal cell bodies. However, prominent immunoreaction was also detected at ependymal cells, tanycytes, endothelial cells of the capillaries and cells of the choroid plexus, suggesting that NPP1 could be involved in some highly specialized transport process.

Animals↗

PubMed2006

Enhancement of AP-1 DNA-binding activity during amphetamine- and phencyclidine-mediated behaviour in rats.

Amphetamine (AMPH) and phencyclidine (PCP) induce a variety of behavioural and synaptic changes in the brain, many of which are believed to involve the regulation of gene expression. In this study, we examined the effects of AMPH (5mg/kg), PCP (5mg/kg) and their combination (5mg/kg each) on rat motor activity as well as on the activation of the AP-1 transcription factor in rat brains. AMPH administration, followed by PCP, led to a statistically significant elevation of locomotor activity. It was found that the behavioural response of rats was more pronounced when the two drugs were administered together. The electrophoretic mobility shift assay (EMSA) revealed a significant increase in AP-1-binding activity after treatments with AMPH, PCP or their combination. Super shift/shift inhibition analysis demonstrated the presence of c-Fos and c-Jun protein families in the transcriptional complex bound to AP-1 sequences. Further, our results suggest that the enhanced behavioural changes after AMPH and PCP administration were associated with increased expression of AP-1 proteins (Fos and Jun) in the cortex, striatum and hippocampus and that their binding to AP-1 sites on the DNA contributes to long-term changes in rat brain.

Amphetamine↗

PubMed2006

Up-regulation of ectonucleotidase activity after cortical stab injury in rats.

The objective of this study was to examine the changes in the activity and expression of ectonucleotidase enzymes in the model of unilateral cortical stab injury (CSI) in rat. The activities of ecto-nucleoside triphosphate diphosphohydrolase 1 (NTPDase 1) and ecto 5'-nucleotidase were assessed by measuring the levels of ATP, ADP and AMP hydrolysis in the crude membrane preparations obtained from injured left cortex, right cortex, left and right caudate nucleus, whole hippocampus and cerebellum. Significant increase in NTPDase and ecto 5'-nucleotidase activities was observed in the injured cortex following CSI, whereas in other brain areas only an increase in ecto 5'-nucleotidase activity was seen. Immunohistochemical analysis performed using antibodies specific to NTPDase 1 and ecto 5'-nucleotidase demonstrated that CSI induced significant changes in enzyme expression around the injury site. Immunoreactivity patterns obtained for NTPDase 1 and ecto 5'-nucleotidase were compared with those obtained for glial fibrillary acidic protein, as a marker of astrocytes and complement receptor type 3 (OX42), as a marker of microglia. Results suggest that up-regulation of ectonucleotidase after CSI is catalyzed by cells that activate in response to injury, i.e. cells immunopositive for NTPDase 1 were predominantly microglial cells, whereas cells immunopositive for ecto 5'-nucleotidase were predominantly astrocytes.

5'-Nucleotidase↗

PubMed2004

Alpha-synuclein is expressed in different tissues during human fetal development.

Alpha-synuclein is a small presynaptic protein associated with both normal synaptic plasticity and neurodegenerative processes. Its normal cellular function, however, remains unknown. Even though it is highly enriched in the brain, its presence was reported in other human adult tissues. In the present study, we examined tissue expression of alpha-synuclein in human and rat prenatal development. Using Western blot analysis, various peripheral tissues from 15 to 23 gestational weeks, human and E19 rat fetuses, along with human and rat adult tissues, were assayed. alpha-Synuclein expression was observed in all fetal human organs examined. In adult human tissues the high expression of alpha-synuclein was maintained in the brain, whereas in other organs the expression was greatly reduced. In contrast, both in fetal and adult rat tissues, alpha-synuclein was only detected in the brain. In addition to a 19-kDa alpha-synuclein band, 36- and 52-kDa immunoreactive bands were observed in all fetal and adult human organs, with the exception of the brain, but their identity remains to be determined. These findings suggest that apart from its function in development of the nervous system, alpha-synuclein has an important function in peripheral tissues as well during normal human prenatal development.

Adrenal Glands↗

PubMed2003

Ribavirin reduces clinical signs and pathological changes of experimental autoimmune encephalomyelitis in Dark Agouti rats.

The effect of ribavirin on development of experimental autoimmune encephalomyelitis (EAE) was investigated. The disease was induced in genetically susceptible Dark Agouti rats with syngeneic spinal cord homogenate in complete Freund's adjuvant (SCH-CFA). Depending on the amount of mycobacteria in CFA, the animals developed either moderate or severe EAE. Ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) was applied i.p. at a daily dosage of 30 mg/kg in two treatment protocols: from the start of immunization (preventive treatment) or from the onset of the first EAE signs after the induction (therapeutic treatment). Signs of EAE began between 7 and 9 days after induction and peaked at days 11-13. In moderate EAE (mean maximal severity score 3.33 +/- 0.21), the recovery was completed by days 23-26, whereas, in severe EAE (mean maximal severity score 4.5 +/- 0.23), obvious recovery was not detected. Preventive ribavirin treatment significantly decreased clinical signs after both moderate (score 1.75 +/- 0.25, P < 0.05) and severe (score 3.62 +/- 0.31, P < 0.015) immunization. Also, disease manifestations were reduced by therapeutic treatment of ribavirin (mean maximal severity score 2.5 +/- 0.2 vs. 3.33 +/- 0.21 in controls, P < 0.005) but less so in comparison with preventive treatment. Analysis of the effects of ribavirin on histopathologic changes in the spinal cord tissue revealed a reduction of mononuclear cell infiltrates, composed of T cells and macrophages/microglia, and the absence of demyelination, which were pronounced in control EAE animals. Beneficial effects of preventive and therapeutic treatment with ribavirin on development of EAE suggest this nucleoside analogue as a useful candidate for therapy in multiple sclerosis.

Adjuvants, Immunologic↗

PubMed2003

Characterization of 9L glioma model of the Wistar rat.

The aim of our study was to develop and characterize solid brain tumors in Wistar rats, which could be used in investigations concerning the molecular mechanisms that lay beneath the genesis of the gliomas as well as in the testing of curative potentials of various therapeutics. The tumors were induced by intracerebral inoculation of 9L glioma cells and characterized by morphometrical, histological and immunohistochemical analysis after 7, 14 and 21 postimplantation days. Immunohistochemical characterization included detection of the nuclear antigene Ki-67 as the proliferative cell marker, GFAP as a tracer of reactive gliosis surrounding the tumor mass, and CD4/CD8 and ED1 antigens, as markers of the immunological response. Our results showed that after 7 days all experimental animals developed solid, well-circumcised tumors, which were clearly separated from the surrounding brain tissue. Tumors showed progressive growth from the 7th to the 21st day despite the observed immunological response starting after 14 days. Histologically tumors were hypercellular with neovascularization and necrosis. These results indicate that reproducible morphometric evaluation can be performed on 9L tumors growing in immunocompetent Wistar rats, enabling its use as an animal tumor model for the evaluation of various therapeutic approaches.

Animals↗

PubMed2002

8-Cl-cAMP affects glioma cell-cycle kinetics and selectively induces apoptosis.

8-Chloro-cyclic-adenosine-3',5'-monophosphate (8-Cl-cAMP), a site-selective synthetic cyclic adenosine 3',5'-monophosphate (cAMP) analog exhibits growth inhibition in a broad spectrum of human cancer lines. However, detailed studies on the effects exerted by cAMP analogs on cell-cycle kinetics have been lacking. We have examined and compared the effect of 8-Cl-cAMP on cell-cycle kinetics in two human glioma cell lines, U87MG (p53wt) and U251MG (p53mt). A flow cytometric analysis of cell-cycle distribution as well as apoptosis evaluation were performed by univariate DNA analysis after 24-72 hr of treatment with 10-50 M concentrations of 8-Cl-cAMP. Longer incubation with 8-Cl-cAMP induced dose related accumulation of cells in S phase and a subsequent decrease in the proportion of cells in G0/G1 phase of cell cycle in both cell lines. Time-dependent suppression of cyclin B1 was detected in both glioma cell lines and could be associated with observed G2 delay. However, 8-aCl-cAMP selectively induced apoptotic cell death only in U87MG, but not in U251MG cells. Induction of apoptosis was revealed both by flow cytometry and apoptotic cell morphology. These results provide an insight into the mechanism of 8-aCl-cAMP action, suggesting that the disturbance of cell-cycle kinetics and induction of apoptosis might contribute to its growth-inhibitory effect on cancer cells.

8-Bromo Cyclic Adenosine Monophosphate↗