Latar belakang: Untuk menganalisis hubungan antara stres oksidatif pada sel glioma manusia dengan derajat keganasan, sehingga dapat mengeksplorasi peranan stress oksidatif sebagai petanda tumor dalam menentukan progresi tumor. Metode: Sampel terdiri dari 21 jaringan tumor dan 5 jaringan otak normal dari penderita glioma. Stres oksidatif dianalisis melalui pengukuran Malondyaldehida (MDA) yang menggambarkan kerusakan lipid dan kadar karbonil untuk kerusakan protein, serta 8-hydroxy-2'-deoxyguanosine/ 8-OHdG untuk kerusakan DNA. Selain itu, dilakukan analisis terhadap ekspresi Manganese Superoxide Dismutase (MnSOD) sebagai enzim antioksidan utama yang berperan dalam stres oksidatif. Ekspresi MnSOD dianalisis melalui pengukuran mRNA MnSOD menggunakan Real Time PCR dan aktivitas spesifik enzim MnSOD menggunakan inhibisi xantin oksidase (kit RanSOD). Derajat keganasan ditentukan berdasarkan pemeriksaan histopatologis. Analisis statistik dengan menggunakan t-test dan uji korelasi Pearson. Hasil: Kadar MDA, karbonil dan 8-OHdG sebagai parameter stres oksidatif pada glioma lebih tinggi bermakna dibandingkan dengan otak normal. Kadar MDA dan karbonil ini meningkat sesuai dengan derajat keganasan. Ekspresi relatif mRNA MnSOD dan aktivitas spesisifik enzim MnSOD pada glioma lebih tinggi bermakna dibandingkan dengan otak normal. Ekspresi relatif mRNA MnSOD tersebut meningkat bermakna sesuai dengan derajat keganasan. Namun, aktivitas spesifik enzim MnSOD pada glioma derajat tinggi lebih rendah bermakna dibandingkan glioma derajat rendah, dengan demikian terdapat ketidak sesuaian antara sintesis mRNA MnSOD dengan aktivitas spesifiknya. Terdapat korelasi positif antara mRNA MnSOD dengan kadar MDA.
Background: In a hypoxic state, fatty acid breakdown reaction may be inhibited due to a lack of oxygen. It is likely that the fatty acids will be stored as triacylglycerol. The aim of this study was to analyse triacylglycerol synthesis in the liver after intermittent hypobaric hypoxia (HH) exposures. Methods: Samples are liver tissues from 25 male Wistar rats were divided into 5 groups: control group (normoxia), group I (once HH exposure), group II (twice HH exposures), group III (three-times HH exposures) and group IV (four-times HH exposures). The triacylglycerol level, mRNA expression of HIF-1α and PPAR-γ were measured in rat liver from each group. Results:We demonstrated that triacylglycerol level, mRNA expression of HIF-1α and PPAR-γ is elevated in group I significantly compared to control group. In the intermittent HH groups (group II, III and IV), mRNA expression of HIF-1α and PPAR-γ tends to downregulate near to control group. However, the triacylglycerol level is still found increased in the intermittent HH exposures groups. Significant increasing of triacylglycerol level was found especially in group IV compared to control group. Conclusions: We conclude that intermittent HH exposures will increase the triacylglycerol level in rat liver, supported by the increasing of HIF-1α and PPAR-γ mRNA expression that act as transcription factor to promote triacylglycerol synthesis.
Background: High altitude can cause hypobaric hypoxia (HH), resulted from the lower barometric pressure and hence partial pressure of oxygen. Hypoxia can lead to a lot of deleterious molecular and cellular changes, such as generation of free radicals or reactive oxygen species (ROS). Increasing of ROS can cause oxidative stress if the antioxidant enzyme does not increase simultaneously. Oxidative damage in brain has toxic effect on cognitive functions.Objective: In this study, we investigate effect of acute intermittent HH on oxidative stress and antioxidant enzyme activity in rat brain.Method: Wistar rats divided into 5 groups, consisting control group and four experimental groups which treated to HH. Rats were exposed to simulated HH equivalent to 35.000 feet in hypobaric chamber for 1 minute, repeated once a week.Results: Level of malondialdehyde and carbonyl in rat brain under acute HH increased at HH exposure (group I) compare to control group. These levels decreased afterward at intermittent HH exposure (group II-IV). Specific activity of superoxide dismutase (SOD) shows increasing level at intermittent HH exposure, especially group IV was increasing of SOD level significantly. The increasing pattern of specific activity of catalase was inversely from SOD pattern, but it still has higher activity in intermittent HH compare to control group.Conclusion: Brain tissue seems to be able to perform an adequate adaptive response to hypobaric hypoxia after the training, shown by its significantly decreased MDA and carbonyl level and also increased specific activity of SOD and catalase.
This study aimed to enhance the mechanical properties of PMMA composites by introducing various types of fillers, including ZrO2, SiO2, and a mixture of ZrO2-SiO2 nanoparticles, which were prepared as prototypes for an endodontic implant. The ZrO2, SiO2, and mixed ZrO2-SiO2 nanoparticles were synthesized using the sol–gel method and the precursors Tetraethyl Orthosilicate, Zirconium Oxychloride, and a mixture of both precursors, respectively. Before polymerization, the as-synthesized powders were subjected to the bead milling process to obtain a well-dispersed suspension. Two scenarios for the fillers were implemented in the preparation of the PMMA composite: a mixture of ZrO2/SiO2 and ZrO2-SiO2 mixed with two different types of silane: (3-Mercaptopropyl) trimethoxysilane (MPTS) and 3-(Trimethoxysilyl) Propyl Methacrylate (TMSPMA). The observation of the characteristics of all of the investigated fillers included the use of a particle-size analyzer (PSA), a Zeta-potential analyzer, FTIR, XRF, XRD, and SEM. The mechanical properties of the MMA composites, as prepared under various scenarios, were observed in terms of their flexural strength, diametrical tensile strength (DTS), and modulus of elasticity (ME). These levels of performance were compared with a PMMA-only polymer. Each sample was measured five times for flexural strength, DTS, and ME. The results showed that the best PMMA composite was SiO2/ZrO2/TMSPMA, as revealed by measurements of the flexural strength, DTS, and ME corresponding to 152.7 ± 13.0 MPa, 51.2 ± 0.6 MPa, and 9272.8 ± 2481.4 MPa, which are close to the mechanical properties of dentin. The viability of these PMMA composites, as measured up to day 7, was 93.61%, indicating that they are nontoxic biomaterials. Therefore, it was concluded that the PMMA composite created with SiO2/ZrO2/TMSPMA can be considered to be an acceptable endodontic implant.
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