Hakan Emmez

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.

Intracranial Meningiomas of Childhood and Adolescence

Meningiomas are rare intracranial neoplasms in childhood and adolescence, representing 0.4–4.1% of the pediatric-age tumors and 1.5–1.8% of all intracranial meningiomas. The goal of this study was to determine epidemiology, clinical and radiological features, and long-term outcome of childhood and adolescence meningiomas. Patients operated for intracranial meningiomas of childhood and adolescence between 1983 and 2003 at Gazi University School of Medicine, Department of Neurosurgery, were evaluated retrospectively. This study presents 11 cases (6 male, 5 female), ranging in age from 14 months to 17 years. Age and sex distribution, presenting symptoms, neurological examination results, location of meningiomas, radiological and histopathological findings, and prognosis were reviewed. The results were compared with those reported in the existing literature. Atypical and malignant meningiomas seem to be more common in childhood and adolescence with respect to adult meningiomas. Tumor location, completeness of tumor removal, and pathological grade are the most important prognostic factors.

ROLE OF ANTIFIBROTIC CYTOKINE INTERFERON-γ IN THE PREVENTION OF POSTLAMINECTOMY PERIDURAL FIBROSIS IN RATS. Commentary

OBJECTIVE Extensive peridural fibrosis after spinal surgery may be the underlying cause of failed-back syndrome in some cases. There is increasing evidence that generation of specific cytokine patterns by immune and structural cells and interactions among these cells mediate many of the key events involved in fibrogenesis. Interferon-gamma (IFN-gamma) has several potential antifibrotic actions, including inhibition of fibroblast proliferation and collagen deposition, promotion of fibroblast apoptosis, and inhibition of production and action of the fibrogenic cytokine, transforming growth factor-beta. We conducted a study to determine the effectiveness of IFN-gamma in preventing postlaminectomy peridural fibrosis in rats. To the best of our knowledge, this is the first study testing immunotherapy in peridural fibrosis. Type 2 cytokine hypothesis of fibrogenesis is emphasized. METHODS Laminectomies were performed in 30 rats. We administered 2000 U/d IFN-gamma, 20,000 U/d IFN-gamma, or 0.2 ml/d saline to the laminectomy site through a silicone catheter for 3 days in blinded fashion. The amount of scar tissue, fibroblast density, inflammatory cell density, arachnoidal involvement, and bone regeneration were analyzed histologically. RESULTS Histopathological examination showed a significantly reduced amount of scar tissue and fibroblast density in the low-dose IFN-gamma group compared with the control and high-dose IFN-gamma groups. A significant increase was detected in inflammatory cell density in the high-dose IFN-gamma group compared with the control and low-dose IFN-gamma groups. CONCLUSION Cytokines play a critical role in wound healing, tissue repair, and fibrogenesis. This study suggests that topical application of low-dose IFN-gamma is an effective and safe method of preventing peridural fibrosis, but further studies with different doses, durations, and intervals are required to achieve better results.

Neuroprotective effects of gabapentin on spinal cord ischemia-reperfusion injury in rabbits.

OBJECT Extensive research has been focused on neuroprotection after spinal cord trauma to alleviate the effects of secondary injury. This study aims to investigate the neuroprotective effects of gabapentin in an experimental spinal cord ischemia reperfusion injury. METHODS Thirty-two adult male New Zealand white rabbits received spinal cord ischemic injury using the aortic occlusion model. Animals were divided into 4 groups (sham, control, low-dose, and high-dose treatment groups; 8 rabbits in each group). High (200 mg/kg) and low (30 mg/kg) doses of gabapentin were administered to the animals in the treatment groups after spinal cord ischemic injury. Neurological status of the animals, ultrastructural findings in injured tissue samples, and levels of tissue injury markers in these 2 groups were compared with findings in the animals that did not receive the ischemic procedure (sham-operated group) and those that received normal saline after administration of ischemia. RESULTS Regarding levels of tissue injury marker levels after ischemic injury, animals in the gabapentin-treated groups demonstrated better results than animals in the other groups. The ultrastructural findings and caspase-3 activity were similar. The treatment groups demonstrated better results than the other groups. CONCLUSIONS Gabapentin demonstrated significant neuroprotection after early phases of ischemic injury. Further studies with different experimental settings including neurological outcome are required to achieve conclusive results.

Effectiveness of FK506 on lipid peroxidation in the spinal cord following experimental traumatic injury.

Study design:An in vivo study in Wistar albino rats with injured spinal cord.SettingDepartment of Neurosurgery, Biochemistry and Pathology, Gazi University, Ankara, Turkey.Objectives:The aim of this study was to investigate and compare the effects of FK506 an immunosupressive agent with methylprednisolone (MP) on lipid peroxidation (LP) in injured spinal cord tissue.Method:A total of 28 adult healthy Wistar albino rats were subjected to traumatic spinal cord injuries (SCI) by using an aneurysmal clip compression technique, and they were divided into four groups. The G1 group (n=8) received FK506 (1 mg/kg); the G2 group (n=8) received FK506 (1 mg/kg) and MP (30 mg/kg); the G3 group (n=6) received only MP (30 mg/kg); and the G4 group (n=6) received no medication. The injured spinal cord tissue was studied by means of lipid peroxides, malondialdehyde (MDA), with thiobarbituric acid reaction and additionally the FK506 (G1); the MP (G3) groups were studied for histopathologic alterations 72 h after SCI with eight separate animals.Results:Although LP values of G1, G2, G3 showed no statistical difference between intergroup analyses (P=0.547), a histopathological examination revealed that in the group that received MP, the oedema pattern was more significant than the group that received FK506. Another interesting finding was the presence of polymorphonuclear leucocytes in the MP group, whereas no infiltration was found in the FK506 group.Conclusion:Analysis of the results indicated that FK506 is a valuable pharmacological agent that could be used to decrease the LP and polymorphonuclear leucocyte infiltration and inflamatory reactions in the injured spinal cord tissue.

Malignant intracerebral giant nerve sheath tumor in a 14-month-old girl with neurofibromatosis type 1: a case report

IntroductionMalignant intracerebral nerve sheath tumor (MINST) is extremely rare and the origin is still unclear. The authors present the clinical, radiological, and pathological features of a malignant intracerebral giant nerve sheath tumor.Case reportA giant tumor in the right frontotemporoparietal lobes causing a midline shift was detected in a 14-month-old girl who presented with developmental delay, vomiting, and lethargy. The physical examination was consistent with neurofibromatosis type 1 (NF-1). Subtotal resection was performed and the histopathological examination revealed the diagnosis of MINST.DiscussionThere are only six cases of malignant intracerebral nerve sheath tumor in the literature. The presented case is the youngest and the occurrence of MINST in a 14-month-old girl may support the hypothesis of multipotent mesenchymal stem cell origin; however, the tumors which arise from multipotent mesenchymal stem cells may be seen in later stages of life. Another important feature of the presented case is the occurrence of MINST in NF-1.ConclusionMINSTs are extremely rare tumors with unknown origin. The location, the degree, and the size of the tumor and the general condition of the patient are prognostic factors in MINSTs, like in other malignant tumors.

Neuroprotective effects of gabapentin in experimental spinal cord injury.

BACKGROUND Extensive research has focused on neuroprotection after spinal cord trauma to alleviate the effects of secondary injury. This study aims to investigate the neuroprotective effects of gabapentin in experimental spinal cord injury. METHODS Thirty-six adult, male Wistar rats received spinal cord injury using the clip compression method. Animals were divided into five groups. High (200 mg/kg) and low doses (30 mg/kg) of gabapentin were administered to the animals in the treatment groups after spinal cord trauma and ultrastructural findings and lipid peroxidation levels of these two groups were compared with the animals that received only laminectomy, only trauma, and trauma and 30 mg/kg methylprednisolone. RESULTS Regarding tissue lipid peroxidation levels after trauma, animals in gabapentin groups demonstrated better results than the trauma group. However, these results were no better than the methylprednisolone group. The results regarding the ultrastructural findings were similar. Treatment groups demonstrated better ultrastructural findings than the trauma group. In addition, the results of the high dose gabapentin group were significantly better than the low dose gabapentin group. CONCLUSIONS Gabapentin demonstrated similar neuroprotective effects as methylprednisolone in early phase of spinal cord injury. Further studies with different experimental settings including neurological outcome are required to achieve conclusive results.

Radiological and histopathological comparison of microporous polysaccharide hemospheres and oxidized regenerated cellulose in the rabbit brain: a study of efficacy and safety.

AIM Topical hemostatic agents are widely used in brain surgery but they have some disadvantages such as foreign body reaction, being a focus for infection and causing artifacts in radiological examinations. The purpose of this study is to compare the effectiveness and safety of microporous polysaccharide hemospheres (MPH) with a well known agent, oxidized regenerated cellulose (ORC), histopathologically and radiologically. MATERIAL AND METHODS Standard brain lesions (4x1mm) were created in 24 hemispheres in 12 New-Zealand rabbits. Animals were divided into three groups; control, ORC and MPH. Twenty-four hours later, all rabbits magnetic resonance brain imaging. After imaging, the animals were sacrificed and the brains were removed for histopathological analysis. RESULTS Histopathological analysis showed no significant difference between the groups. Radiological examination showed no significant difference between the MPH and ORC groups in terms of edema but the edema in control group was significantly prominent than MPH and ORC groups (p < 0.001). CONCLUSION A new agent (MPH) provides safe and effective hemostasis in the brain in this study. The most important advantage of microporous polysaccharide hemospheres is their rapid clearance from the surgical field and therefore having the potential of causing less imaging artifacts.

Hypothalamic lipoma adjacent to mamillary bodies.

Abstract Introduction. Intracranial lipomas are rare lesions of developmental origin. They are generally asymptomatic and localized in the midline. However, they may occasionally produce neurological symptoms such as seizures. Surgical treatment is rarely indicated. Case report. We report a child with a lipoma that is located on the ventral side of the mamillary bodies. The diagnosis was made using computerized tomography (CT) and magnetic resonance imaging (MRI). There have been no previous reports of lipomas in this location.

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.