Emin Umit Bagriacik

Sevoflurane and isoflurane preconditioning provides neuroprotection by inhibition of apoptosis-related mRNA expression in a rat model of focal cerebral ischemia.

Background: This study aimed to examine the effects of sevoflurane or isoflurane preconditioning on cerebral ischemia/reperfusion–induced inflammation, oxidative stress, and lipid peroxidation and test the hypothesis that the underlining mechanism of the protective effect of preconditioning involves changes in the apoptotic gene expression profiles in an experimental model of middle cerebral artery occlusion in rats. Methods: Twenty-four adult male rats were randomly divided into 3 groups: control (n=8), sevoflurane (n=8), and isoflurane (n=8). For preconditioning, these 3 groups were exposed to 40% O2, 2% sevoflurane, and 1.5% isoflurane, respectively, for 60 minutes, followed immediately by 1 hour of middle cerebral artery occlusion and then 6 hours of reperfusion. Blood and brain tissue samples were collected for determination of blood gas tension, tumor necrosis factor-&agr;, interleukin-6, and interleukin-1&bgr;. Brain tissue samples were collected for determination of the wet/dry ratio, myeloperoxidase, malondialdehyde, and total RNA and also for histologic examinations. Results: Tumor necrosis factor-&agr;, interleukin-1&bgr;, and myeloperoxidase levels decreased and antioxidant enzyme levels increased in the sevoflurane group compared with the control and isoflurane groups. Proapoptotic genes (Tnf, Tnfrsf10b, and Tp53) downregulated and antiapoptotic genes (Aven, Bcl2, Bcl2l2, and Prok2) upregulated with sevoflurane treatment compared with the isoflurane and control groups. Both isoflurane and sevoflurane pretreatment decreased malondialdehyde, Dffb, the wet/dry ratio, and injury score and upregulated Bax and Apaf 1 compared with the control group. Conclusions: Sevoflurane and isoflurane preconditioning ameliorates inflammation, cerebral lipid peroxidation, and histologic injury. Downregulation of proapoptotic molecules and upregulation of antiapoptotic molecules may be associated with this effect.

A Shift in the Balance of Regulatory T and T Helper 17 Cells in Rheumatic Heart Disease

Background Autoimmunity plays an essential role in the pathogenesis of rheumatic heart disease (RHD); however, cellular mechanisms of autoimmune response are unclear. Whereas T helper 17 (TH17) and regulatory T cells (Treg) cells share a common differentiation pathway, they play opposite roles in the immune tolerance and autoimmune diseases. Although high TH17/Treg ratio has been shown in several autoimmune diseases, no data are available in RHD. This study investigated the balance between TH17 and Treg in rheumatic mitral valve disease (MVD). Methods Forty patients with rheumatic MVD and 23 control subjects were enrolled into the study. All subjects underwent clinical, electrocardiographic, and echocardiographic evaluation. The percentages of circulating TH17 and Treg cells were analyzed by flow cytometry. Serum levels of high-sensitivity C-reactive protein (hs-CRP) and cytokines were assessed by enzyme-linked immunosorbent assay. Results As compared with control subjects, rheumatic MVD patients showed significant increase in peripheral TH17 percentage, high serum levels of TH17-related cytokine interleukin 17A, and an obvious decrease in the percentage of Treg cells. T helper 17/Treg ratio was significantly high in rheumatic MVD patients compared with control subjects (P = 0.0001). Serum concentrations of hs-CRP in rheumatic MVD group were higher than those of the control subjects, and hs-CRP levels correlated with the TH17/Treg ratio (r = 0.71, P = 0.0001). Serum levels of transforming growth factor β1 were increased in rheumatic MVD group compared with those of the control subjects. Conclusions The results indicated that high TH17/Treg ratio exists inrheumatic MVD. This imbalance may play a role in the pathogenesis, and TH17/Treg balance may be a promising therapeutic approach in RHD.

TSH-induced gene expression involves regulation of self-renewal and differentiation-related genes in human bone marrow-derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells are pluripotent cells that are capable of differentiating into a variety of cell types including neuronal cells, osteoblasts, chondrocytes, myocytes, and adipocytes. Despite recent advances in stem cell biology, neuroendocrine relations, particularly TSH interactions remain elusive. In this study, we investigated expression and biological consequence of TSH receptor (TSHR) interactions in mesenchymal stem cells of cultured human bone marrow. To the best of our knowledge, we demonstrated for the first time that human bone marrow-derived mesenchymal stem cells expressed a functional thyrotropin receptor that was capable of transducing signals through cAMP. We extended this study to explore possible pathways that could be associated directly or indirectly with the TSHR function in mesenchymal stem cells. Expression of 80 genes was studied by real-time PCR array profiles. Our investigation indicated involvements of interactions between TSH and its receptor in novel regulatory pathways, which could be the important mediators of self-renewal, maintenance, development, and differentiation in bone marrow-derived mesenchymal stem cells. TSH enhanced differentiation to the chondrogenic cell lineage; however, further work is required to determine whether osteoblastic differentiation is also promoted. Our results presented in this study have opened an era of regulatory events associated with novel neuroendocrine interactions of hypothalamic-pituitary axis in mesenchymal stem cell biology and differentiation.

Biocompatible thermoresponsive PEGMA nanoparticles crosslinked with cleavable disulfide-based crosslinker for dual drug release

Smart materials have been attracting much attention because of their stimuli responsive nature. We have synthesized biocompatible thermoresponsive crosslinked poly(ethylene glycol) methyl ether methacrylate (PEGMA)-co-vinyl pyrrolidone nanoparticles (PEGMA NPs) using disulfide-based crosslinker by surfactant-free emulsion polymerization method. Particle characterization studies were carried out by dynamic light scattering, and scanning electron microscopy. Polymerization kinetics, effect of crosslinker and initiator concentrations on both average hydrodynamic diameter and polydispersity index were investigated. Hydrodynamic diameters of thermoresponsive PEGMA NPs were decreased from 210 nm to 90 nm upon heating over the lowest critical solution temperature (LCST). Disulfide crosslinked PEGMA NPs were demonstrated as a dual delivery system. Rhodamine B, a model of small-sized drug molecule, and poly(ethylene glycol) (PEG)-alizarin yellow, a model of large drug molecule, were loaded into PEGMA NPs where LCST of these NPs was tuned to 37°C, the body temperature. The rhodamine B was released from PEGMA NPs upon heating to 39°C. Then, PEG-alizarin content was released by subsequent degradation of nanoparticles using dithiothreitol (DTT), which reduces disulfide bonds to thiols. Furthermore, cytotoxicity studies of PEGMA NPs were carried out in 3T3 cells, which resulted in no toxic effect on the cells.

A Cannabinoid Ligand, Anandamide, Exacerbates Endotoxin-Induced Uveitis in Rabbits

PURPOSE This study aimed to investigate the effects of anandamide or arachidonylethanolamide (AEA), an endogenous cannabinoid receptor agonist, on intraocular inflammation in an endotoxin-induced uveitis (EIU) model in rabbits. METHODS Forty New Zealand albino male rabbits were used (5 groups, 8 animals in each). After establishment of sufficient anesthesia, animals were taken under surgery for intravitreal injections. A maximum amount of 50 μL of solution was injected into the central vitreous with a 30-gauge needle. In the control group, sterile saline was injected into the right eyes of the animals. Likewise, AEA (10(-5) M) in the second group, lipopolysaccharide (LPS; 100 ng) in the third group, and AEA (10(-5) M) and LPS (100 ng) in the fourth group were administered. Fifth group received 0.1 mL subtenon injection of AM251 (10(-5) M), a CB(1)-receptor antagonist, 30 min prior to intravitreal LPS (100 ng) and AEA (10(-5) M) injection. At 24 h after the surgical intervention, clinical evaluation was performed and animals were then euthanized with 100 mg/kg intravenous pentobarbital injections. Immediately after the induction of pentobarbital anesthesia, the anterior chamber of the eyes was quickly punctured using a 30-gauge needle to drain aqueous humor (AH) and obtained specimens were used for cell count, protein measurement, and microbiological contamination tests. After AH collection, enucleation was performed and enucleated material was kept for the pathological evaluation. RESULTS AEA caused an overall worsening of EIU in studied eyes. It significantly increased the detrimental effects of endotoxin, as assessed by clinical investigation of ocular inflammation, AH leukocyte content, and AH protein concentrations. CB(1)-receptor antagonist AM251 administration reversed some components of this AEA-induced exacerbation to significant extents. CONCLUSION AEA exacerbated EIU in rabbit eyes. AM251 has been found beneficial to prevent AEAs aggravating impact on EIU. As AEA is a treatment choice for lowering intraocular pressure in ophthalmology practice, concurrent use of CB(1)-receptor antagonists may be a questionable strategy in cases of secondary glaucoma, to avoid aggravation of the present inflammation.

Establishment of a primary pleomorphic xanthoastrocytoma cell line: in vitro responsiveness to some chemotherapeutics.

BACKGROUND Anaplastic pleomorphic xanthoastrocytoma is an aggressively growing, malignant, and eventually fatal tumor of the central nervous system. Testing chemotherapeutic drug sensitivity under in vitro conditions would be a useful strategy to determine sensitive or resistant drugs for fatal brain cancers. OBJECTIVE To establish primary cell cultures of excised tumor tissue from pleomorphic xanthoastrocytoma–bearing patients and to test their sensitivity against various anticancer chemotherapy drugs. METHODS Prepared suspensions of the excised tumor tissue from a patient who had a recurrent grade 3 pleomorphic xanthoastrocytoma was cultured in culture dishes until cells began to grow. Immunofluorescent and immunohistochemical visualizations were performed using confocal and light microscopy. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay in comparison with 3H-thymidine incorporation assay was used to test cellular toxicity of several anticancer drugs. RESULTS We established vigorously growing primary cells of the tumor. Drug sensitivity testing was conducted successfully. CONCLUSION Primary cell cultures of surgically removed tumor tissues may be useful in studies of cancer biology and chemotherapeutic drug sensitivity for recurrent malignant brain tumors, particularly for anaplastic pleomorphic xanthoastrocytoma.

Production of Toxoplasma gondii in Vero cell culture

OBJECTIVE To investigate parasite-host dynamics in cultures of Toxoplasma gondii (T. gondii). METHODS T. gondii tachyzoites were incubated in Vero-E6 cell cultures at 37°C, 5％CO₂. Tachyzoites and host cells were characterized by light microscopy. Growth kinetics of the parasite were determined. RESULTS Doubling time of tachyzoites and viability of host cells were determined by comparing tachyzoite cultures and control Vero cell cultures that were free of parasites. Tachyzoites harvested from cell cultures were established as a line for future studies. Purified tachyzoit line was named as GPK-001, a catalog name for the line. CONCLUSION In this study, we showed that an intracellular parasite, T. gondii can be produced in cell cultures under sterile conditions. We believe that the tachyzoite line established in this study would be useful in many other studies and provide answers to questions regarding biology and treatment of T. gondii infections.

Sevoflurane exerts brain-protective effects against sepsis-associated encephalopathy and memory impairment through caspase 3/9 and Bax/Bcl signaling pathway in a rat model of sepsis:

Objective We compared the effects of sevoflurane and isoflurane on systemic inflammation, sepsis-associated encephalopathy, and memory impairment in a rat sepsis model of cecal ligation and puncture (CLP)-induced polymicrobial peritonitis. Methods Twenty-four rats were assigned to sham, CLP, CLP + sevoflurane, and CLP + isoflurane groups. At 72 hours after CLP, the rats underwent behavior tests. Serum cytokines were evaluated. Brain tissue samples were collected for determination of glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase; the wet/dry weight ratio; myeloperoxidase (MPO) and malondialdehyde (MDA); apoptotic gene release; and histologic examinations. Results The MPO level, wet/dry weight ratio, and histopathology scores were lower and the Bcl2a1 and Bcl2l2 expressions were upregulated in both the CLP + sevoflurane and CLP + isoflurane groups compared with the CLP group. The interleukin-6, interleukin-1β, MDA, and caspase 3, 8, and 9 levels were lower; the GPX, SOD, Bax, Bcl2, and Bclx levels were higher; and non-associative and aversive memory were improved in the CLP + sevoflurane group compared with the CLP + isoflurane group. Conclusion Sevoflurane decreased apoptosis and oxidative injury and improved memory in this experimental rat model of CLP. Sevoflurane sedation may protect against brain injury and memory impairment in septic patients.

The Effect of Endothelin Receptor Antagonists in the Endotoxin-Induced Uveitis Rabbit Model

Abstract Purpose: To investigate the effect of Bosentan (non-selective endothelin receptor antagonist) and BQ123 (ETA receptor antagonist) on intraocular inflammation in an endotoxin-induced uveitis (EIU) rabbit model. Methods: Uveitis was induced by intravitreal injection of lipopolysaccharide (LPS). The animals were divided into 7 groups and there were six rabbits in each group (saline, saline and ethanol, bosentan, BQ123, lipopolysaccharide (LPS), bosentan and LPS, BQ123 and LPS-injected groups). Bosentan and BQ123 were applied before LPS injection. Aqueous humour was collected at 24th hour post-injections and enucleation was performed for the evaluation of histopathological changes. Results: BQ123 decreased clinical score, cell counts and protein amount more than bosentan and it was significant for cell counts (p = 0.018). Bosentan significantly diminished inflammatory reactions more than BQ123 as shown in histopathological specimens (p = 0.002). Conclusions: ETA receptor blockage is effective on uveitis treatment by its protective effect on blood aqueous barrier.