Iranian Biomedical Journal
Year:2011 | Volume:15 | Issue:1-2|Papers Count:8

Background: During antigen capture and processing, mature dendritic cells (DC) express large amounts of peptide-MHC complexes and accessory molecules on their surface. DC are antigen-presenting cells that have an important role in tolerance and autoimmunity. The transforming growth factor-beta1 (TGF-b1) cytokine has a regulatory role on the immune and non-immune cells. The aim of this study is to evaluate the effect of TGF-b1 on the induction of human leukocyte antigen-G (HLA-G) expression on the DC which is derived from monocyte.Methods: In this study, we evaluated the effect of TGF-b1 in induction HLA-G expression on the monocyte-derived DC by flowcytometry and then CD4+ T cell proliferative responses in the presence of DC-treated TGF-b1 was studied.Results: The results of this study showed that DC bearing HLA-G downregulated activation of CD4+ T cells and production of IL-6 and IL-17 in comparison with control (P<0.05).Conclusion: It is concluded that TGF-b1 has an important regulatory role in CD4+ T cell proliferation by increasing HLA-G on DC and these cells can probably prevent unexpected immune responses in vivo.

Background: Surface properties of a biomaterial could be critical in determining biomaterial’s biocompatibility due to the fact that the first interactions between the biological environment and artificial materials are most likely occurred at material’s surface. In this study, the surface properties of a new nanocomposite (NC) polymeric material were modified by combining plasma treatment and collagen immobilization in order to enhance cell adhesion and growth.Methods: NC films were plasma treated in reactive O2 plasma at 60 W for 120 s. Afterward, type I collagen was immobilized on the activated NC by a safe, easy, and effective one-step process. The modified surfaces of NC were characterized by water contact angle measurement, water uptake, scanning electron microscopy (SEM), and Fourier transformed infrared spectroscopy in attenuated total reflection mode (ATR-FTIR). Furthermore, the cellular behaviors of human umbilical vascular endothelial cells (HUVEC) such as attachment, growth and proliferation on the surface of the NC were also evaluated in vitro by optical microscopy and 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide test.Results: The outcomes indicated that plasma treatment and collagen immobilization could improve hydrophilicity of NC. SEM micrograph of the grafted film showed a confluent layer of collagen with about 3-5 mm thicknesses. In vitro tests showed that collagen-grafted and plasmatreated surfaces both resulted in higher cell adhesion and growth state compared with untreated ones.Conclusion: Plasma surface modification and collagen immobilization could enhance the attachment and proliferation of HUVEC onto NC, and the method would be usefully applied to enhance its biocompatibility.

Background: In the previous study, we have shown that the presence of A allele at position -588 in Ag-globin gene was highly frequent and closely associated with fetal hemoglobin elevation among b-thalassemia intermedia patients. Therefore, we decided to investigate whether this allele (A allele at -588) could result in an increase in Ag-globin gene expression to ameliorate the severity of the disease in thalassemia patients. Methods: Three constructs containing μ locus control region, Ag-globin and b-globin genes were designed and employed in the transient expression assay. The difference among constructs was in the promoter region of Ag-globin gene (A and G alleles at -588). A construct with T to C base substitution at -175 of Ag-globin, created by site-directed mutagenesis, was selected as positive control. The K562 cell line was transfected with the above constructs. Subsequently, the expression of Ag-globin gene was determined by quantitative real-time reverse transcription-PCR.Results: There was not a significant increase in the expression of Ag-globin gene in the construct containing A allele comparing the one with G allele at -588.Conclusions: -588 (A>G) mutation does not play a major role in regulation of Ag-globin gene, suggesting that other factors may be involved.

Background: Nitric oxide synthase (NOS) activity is increased during hypertension and cerebral ischemia. NOS inactivation reduces stroke-induced cerebral injuries, but little is known about its role in blood-brain barrier (BBB) disruption and cerebral edema formation during stroke in acute hypertension. Here, we investigated the role of NOS inhibition in progression of edema formation and BBB disruptions provoked by ischemia/reperfusion injuries in acute hypertensive rats.Methods: Rats were made acutely hypertensive by aortic coarctation. After 7 days, the rats were randomly selected for the recording of carotid artery pressure, or regional cerebral blood flow (rCBF) using laser Doppler. Ishcemia induced by 60-min middle cerebral artery occlusion (MCAO), followed by 12-h reperfusion. A single i.p. dose of L-NAME (1 mg/kg) was injected before MCAO. After evaluation of neurological disabilities, rats were slaughtered under deep anesthesia to assess cerebral infarction volume, edema, or BBB disruption.Results: A 75-85% reduction in rCBF was occurred during MCAO which returned to pre-occluded levels during reperfusion. Profound neurological disabilities were evidenced after MCAO alongside with severe cerebral infarctions (628±98 mm3), considerable edema (4.05±0.52%) and extensive BBB disruptions (Evans blue extravasation, 8.46±2.03 mg/g). L-NAME drastically improved neurological disabilities, diminished cerebral infarction (264±46 mm3),reduced edema (1.49±0.47%) and BBB disruption (2.93±0.66 mg/g). Conclusion: The harmful actions of NOS activity on cerebral microvascular integrity are intensified by ischemia/reperfusion injuries during cute hypertension. NOS inactivation by L-NAME preserved this integrity and diminished cerebral edema.

Background: Spinal cord injury (SCI) stimulates an inflammatory reaction that causes substantial secondary damage inside the injured spinal tissue. The purpose of this study was to determine the anti-inflammatory effects of epigallocatechin gallate (EGCG) on traumatized spinal cord.Methods: Rats were randomly divided into four groups of 12 rats each as follow: sham-operated group, trauma group, and EGCG-treatment groups (50 mg/kg, i.p., immediately and 1 hour after SCI). Spinal cord samples were taken 24 hours after injury and studied for determination of myeloperoxidase (MPO) activity, histopathological assessment and immunohistochemistry of tumor necrosis factor-a (TNF-a), interleukin-1b (IL-1b), Nitrotyrosine, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and poly(ADP-ribose) polymerase (PARP). Results: The results showed that MPO activity was significantly decreased in EGCG-treatment groups. Attenuated TNF-a, IL-1b, Nitrotyrosine, iNOS, COX-2, and PARP expression could be detected in the EGCG treated rats. Also, EGCG attenuated myelin degradation.Conclusion: On the basis of these findings, we propose that EGCG may be effective in protecting rat spinal cord from secondary damage by modulating the inflammatory reactions.

Background: The aim of the present study was to investigate the in vitro effects of mercury (Hg+2), lead (Pb+2), silver (Ag+2), tin (Sn+2), bismuth (Bi+3) and indium (In+3) ions on sperm creatine kinase.Methods: creatine kinase was isolated from human sperm homogenates after chromatography on a DEAE cellulose column.Results: At 60 mg ml-1 metal concentration, 70% of the creatine kinase activity was inhibited by Hg+2, while at the same concentration, Pb+2, Ag+2, Sn+2, Bi+3 and In+3 caused 68%, 66.5%, 65.7%, 64.7% and 62.7% inhibition, respectively. All six metal ions displayed a competitive type of inhibition mechanism for the isolated creatine kinase as analyzed by Lineweaver-Burk plot. Ki values of Hg+2, Pb+2, Ag+2, Sn+2, Bi+3 and In+3 were calculated and 8.34 mM, 5 mM, 4.54 mM, 3.45 mM, 3.12 mM and 2.63 mM values were obtained, respectively.Conclusion: All the studied metal ions, at levels of 60 mg ml-1, may reduce normal sperm metabolism by inhibition of sperm creatine kinase, which probably is an important cause of infertility in men. However, further investigations, as in vitro and in vivo, are needed to elucidate the exact mechanism of heavy metals on male reproductive functioning at the molecular level.

Background: Melatonin has receptors in substantia nigra pars compacta (SNc) and regulates development of dopaminergic (DA) neurons. This study was undertaken to determine ability of melatonin to protect SNc dopaminergic neuron loss induced by estrogen deficiency in ovariectomized rats.Methods: Female rats were randomized into four groups of seven each: control, ethanol sham, ovariectomy (ovx) and ovx with melatonin (ovx + m). In ovx, ovaries were removed. Ovx + m group was intraperitoneally injected with melatonin for 10 days, while the ethanol sham group received only ethanol. All rats were perfused with 4% paraformaldehyde, midbrains removed, fixed and paraffin embedded, then processed for Nissl and tyrosine hydroxylase staining (IHC). Ten sections of SNc in Nissl and IHC staining were analyzed in each animal, Nissl stained and tyrosine hydroxylase (TH) immunoreactive cells were counted in five experimental groups randomly. Data was analyzed using SPSS by ANOVA and t-test. Differences were considered significant for P<0.05.Results: There was less cell number in ovx compared to control and ethanol sham groups significantly (P<0.001). The ovx + m group had more cells than the ovx group in the SNc significantly (P<0.001). Furthermore, there was significant decrease of TH positive cell number in the ovx group compared to control and ethanol sham groups (P<0.05). The number of TH immunoreactive cells was higher in ovx + m compared to the ovx group (P<0.05).Conclusion: These findings can be compared with human and used in clinical application for prevention of DA neuron death of SNc after ovariectomy.

Background: Alzheimer’s disease (AD) is a neurodegenerative disorder with progressive loss of cognitive abilities and memory loss. The aim of this study was to compare neuropathological changes in hippocampus and brain cortex in a rat model of AD.Methods: Adult male Albino Wistar rats (weighing 250-300 g) were used for behavioral and histopathological studies. The rats were randomly assigned to three groups: control, sham and b-amyloid (Ab) injection. For behavioral analysis, Y-maze and shuttle box were used, respectively at 14 and 16 days post-lesion. For histological studies, Nissl, modified Bielschowsky and modified Congo red staining were performed. The lesion was induced by injection of 4 mL of Ab (1-40) into the hippocampal fissure.Results: In the present study, Ab (1-40) injection into hippocampus could decrease the behavioral indexes and the number of CA1 neurons in hippocampus. Ab injection CA1 caused Ab deposition in the hippocampus and less than in cortex. We observed the loss of neurons in the hippocampus and cerebral cortex and certain subcortical regions. Y-maze test and single-trial passive avoidance test showed reduced memory retention in AD group.Conclusion: We found a significant decreased acquisition of passive avoidance and alternation behavior responses in AD group compared to control and sham group (P<0.0001). Compacted amyloid cores were present in the cerebral cortex, hippocampus and white matter, whereas, scattered amyloid cores were seen in cortex and hippocampus of AD group. Also, reduced neuronal density was indicated in AD group.