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    Chemoresistance in Malignant Intracranial Tumors: Longer Survival with Negative MDR1 Expression
    (Turkish Neurosurgical Soc, 2021) Ezgu, Mehmet Can; Kural, Cahit; Simsek, Gulcin Guler; Kaygin, Pinar; Oguztuzun, Serpil; Kirik, Alparslan; Yasar, Soner
    AIM: To analyze the Glutathione S-transferase (GST)-P, GST-M, cytochrome p450 (CYP)1-A1, CYP1-B1, and multidrug resistance (MDR)-1 expressions in malignant intracranial tumor (ICT)s, and to elicit their role on patient survival. MATERIAL and METHODS: GST-P, GST-M, CYP1-A1, CYP1-B1, and MDR-1 expressions were analyzed using immunostaining in 149 samples from 141 patients with preoperative ICT diagnosis. The case characteristics were reviewed, and the enzyme expressions were equated based on the age, gender, and tumor type. Then, 77 of 141 patients with malignant ICT and complete medical records postoperative were also investigated in detail for the relationship between the diagnosis, enzyme expression, and overall survival. RESULTS: The average age was 49.44 years, with 83 (58.45%) male patients. Among the 77 malignant ICTs, 38 (49.3%) and 29 were glial tumors and metastases, respectively, with a 13.35-month overall survival. Patients with metastatic tumor have approximately threefold higher GSTP level than those with glial tumors. MDR-1 expression was approximately twofold higher in > 60-year-old patients. No statistically significant association was found between patients' smoking behaviors, alcohol consumption, and overall survival. Only MDR-1 expression was correlated with overall survival. Better overall survival was observed in patients with a negative MDR-1 expression than those with a positive one. CONCLUSION: MDR-1 is an important indicator of survival in malignant intracranial tumor patients. Longer survival is associated with negative MDR-1 expression.
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    Expression of Sigma-Class Glutathione-S-Transferase in Fetal and Pediatric Filum Terminale Samples: A Comparative Study
    (Mdpi, 2019) Kural, Cahit; Ogurtuzun, Serpil; Simsek, Gulcin Guler; Guresci, Servet; Kaygin, Pinar; Yasar, Soner; Izci, Yusuf
    Background and objectives: The pathophysiology of tethered cord syndrome (TCS) in children is not well elucidated. An inelastic filum terminale (FT) is the main factor underlying the stretching of the spinal cord in TCS. Our study aimed to investigate the expression of glutathione-S-transferase (GST) in children and fetal FT samples in order to understand the relationship between this enzyme expression and the development of TCS. Materials and Methods: FT samples were obtained from ten children with TCS (Group 1) and histological and immunohistochemical examinations were performed. For comparison, FT samples from fifteen normal human fetuses (Group 2) were also analyzed using the same techniques. Statistical comparison was made using a Chi-square test. Results: Positive GST-sigma expression was detected in eight (80%) of 10 samples in Group 1. The positive GST-sigma expression was less frequent in nine (60%) of 15 samples from Group 2. No statistically significant difference was detected between the two groups (p = 0.197). Conclusions: Decreased FT elasticity in TCS may be associated with increased GST expression in FT. More prospective studies are needed to clarify the mechanism of the GST-TCS relationship in children.