Browsing by Author "Özel H.F."
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Item A physical model of the thermodilution method: Influences of the variations of experimental setup on the accuracy of flow rate estimation(2011) Özbek M.; Özel H.F.; Ekerbiçer N.; Zeren T.The thermodilution method has been widely used to estimate cardiac output by injecting a cold solution into circulating blood. It is uncertain if radial heat transfer from the vascular/cardiac wall to circulating injectate can cause inaccurate results with this method. In this study, we have introduced a physical experimental model of the thermodilution method without recirculation of the cold solution. To test the accuracy of the thermodilution method, the experimental setup included an aluminum tube to allow radial heat transfer. Variations of the following parameters were conducted: (i) the real flow rate, (ii) the distance between injection point of cold solution and the temperature sensor, (iii) the volume of injectate, and (iv) the temperature of injectate. By following the above variations, we have calculated different correction factors eliminating the influence of radial heat transfer on the estimation of flow rate by the thermodilution method. The results indicate that changes in both injectate temperature and volume have no influence on the estimation of flow rates. The experimental variations, which can cause greater radial heat transfer, seem to be responsible for the result of the smaller estimation of the flow rate than the real value. These variations include (i) a decreased real flow rate and (ii) increased distances between the injection point of cold fluid and the thermosensor. Such an incorrect estimation could be eliminated by using correction factors. The correction factor seems to be a function of the area of the thermodilution curve, assuming no recirculation. © 2011 by Walter de Gruyter Berlin New York.Item Therapeutic effects of Lacosamide in a rat model of traumatic brain injury: A histological, biochemical and electroencephalography monitoring study(Elsevier Ltd, 2021) Mete M.; Alpay S.; Aydemir I.; Unsal U.U.; Collu F.; Özel H.F.; Duransoy Y.K.; Kutlu N.; Tuglu M.İ.Objective: Traumatic Brain Injury (TBI) is a major cause of death and disability worldwide, especially in children and young adults. TBI can be classified based on severity, mechanism or other features. Inflammation, apoptosis, oxidative stress, and ischemia are some of the important pathophys-iological mechanisms underlying neuronal loss after TBI. Lacosamide (LCM) is an anticonvulsant compound approved for the adjunctive treatment of partial-onset seizures and neuropathic pain. This study aimed to investigate possible neuroprotective effects of LCM in a rat model of TBI. Material and methods: Twenty-eight adult male, Wistar albino rats were used. The rats were divided into 4 groups. Group 1 was the control group (n=7). Group 2 was the trauma group (n=7) where rats were treated with 100 mg/kg saline intraperitoneally (IP) twice a day. Groups 3 and 4, rats were treated with 6 (group 3, n=7) or 20 (group 4, n=7) mg/kg Lacosamide IP twice a day. For each group, brain samples were collected 72 hours after injury. Brain samples and blood were evaluated with histopathological and biochemical methods. In addition, electroencephalograpy monitoring results were compared. Results: The immunoreactivity of both iNOS and eNOS (oxidative stress markers) were decreased with LCM treatment compared to trauma group. The results were statistically significant (***P<0.001). The treatments of low (56,17±9,69) and high-dose LCM (43,91±9,09) were decreased the distribution of HIF-1α compared to trauma group (P<0.01). The number of apoptotic cells were decreased with LCM treatment the difference between the trauma group and 20mg/kg LCM treated group (9,55±1,02) was statistically significant (***P<0.001). Malondialdehyde level was reduced with LCM treatment. MDA level was significantly higher in trauma group compared to LCM treated groups (***P<0.001). The level of Superoxide dismutase in the trauma group was 1,86 U/ml, whereas it was 36,85 U/ml in 20mg/kg LCM treated group (***P<0.001). Delta strength of EEG in 20mg/kg LCM treated group were similar to control group values after LCM treatment. Conclusion: No existing study has produced results suggesting that different doses of LCM has therapeutic effect against TBI, using EEG recording in addition to histological and biochemical evaluations in rats. © 2021 Elsevier LtdItem Classical heart rate variability and nonlinear heart rate analysis in mice under Na-pentobarbital and ketamine/xylazine anesthesia(Turkiye Klinikleri, 2022) Kazdağli H.; Özel H.F.; Özbek M.; Alpay Ş.; Alenbey M.Background/aim: Anesthetics are often used in animal experiments to achieve immobilization and relieve pain. However, many anesthetics can alter the dynamics of cardiovascular systems. We aimed to compare the effects of two frequently used anesthetics agents on heart rate variability (HRV) parameters in mice. Materials and methods: This observational study was performed between May and June 2014 in 21 male BALB/c mice aged 16–20 weeks. The animals were divided into three groups: pentobarbital (P), (n = 7); pentobarbital+fentanyl (P+F), (n = 7); and ketamine+xylazine (K+X), (n = 7). Surface electrocardiography (ECG) electrodes were placed in lead II configuration. The tachogram of RR intervals was obtained after R waves were detected using the Pan-Tompkins real-time QRS recognition algorithm. Frequency-domain, time-domain, and nonlinear HRV analyses were performed. Results: The bradycardia effect was higher in the K+X group (p < 0.01). Time-domain indices were higher in group K+X compared to group P (p < 0.01) and group P+F (p < 0.001). Very low frequency (VLF) power was significantly lower in group K+X compared to group P and group P+F (p < 0.01). Low frequency (LF) power, low frequency/high frequency (LF/HF) ratio, and total power (TP) were higher in group K+X compared to group P (p < 0.01) and group P+F (p < 0.001). The detrended fluctuation analysis short-term parameter (DFAα1 ) was significantly higher in group K+X compared to group P+F (p < 0.05) and the long-term parameter (DFAα2 ) was lower in group K+X compared to group P (p < 0.05). Standard deviations SD1 and SD2 were higher in group K+X compared to group P (p < 0.001) and group P+F (p < 0.001), SD2/SD1 ratio was lower in group K+X compared to group P (p < 0.05) and group P+F (p < 0.05). Entropy measures did not differ between groups. Conclusion: HRV analyses, including nonlinear methods, indicated that a K+X combination reduces imbalance and disorder in the regulation of the autonomic nervous system (ANS) in comparison to both P and the P+F combination. © The Authors.Item Histological and electroencephalographic demonstration of probiotic effect for reduce of oxidative stress and apoptosis in experimental traumatic brain injury; [Deneysel travmatik beyin hasarında oluşan oksidatif stres ve apoptozun azalmasında probiotik etkisinin histolojik ve elektroensefalografik gösterilmesi](2023) Karakayalı E.M.; Kocamaz E.; Alpay Ş.; Önal T.; Öztatlıcı M.; Duruşma R.; Özel H.F.; Mete M.; Barutcuoglu M.; Kutlu N.; Tuğlu M.İ.BACKGROUND: The gut microbiota modulates nervous system function. In the literature, it has been shown that this modula-tion is used in many nervous system injuries through oxidative stress (OS) and apoptosis mechanisms. In this study, it was aimed to investigate the neuroprotective effects of probiotic (PB) treatment in a rat traumatic brain injury (TBI) model with histological and electroencephalographic (EEG) data. METHODS: Forty male Wistar albino rats were divided into four groups. Group 1 was the control group (CONTROL, n=10) and no trauma was applied. Group 2 was the trauma group with the weight-drop technique (TBH, n=10). Group 3 was the sham group (SHAM), (TBH+sterile saline [SS], n=10) rats were given 500 µL of SS per day by oral gavage. Group 4 was the PB treatment group, (TBH+PB, n=10) rats were treated daily for 7 days with 500 µL of PB oral gavage. Brain samples were collected 7 days after trauma. Histopathological evaluation of brain samples was done with HE. OS with Endothelial nitric oxide synthase, vascularization with Vas-cular Endothelial Growth Factor, gliosis with S100, and apoptosis with caspase 3 were evaluated immunohistochemically. Apoptotic index was determined with TUNEL. In addition, EEG and somatosensory evoked potential (SEP) recording findings were compared. RESULTS: It was determined by HE staining that there was a significant (P<0.001) damage in the TBI and sham groups compared to the control group. It was found that PB treatment provided a significant (P<0.01) improvement in the damage created. While OS (P<0.01), gliosis (P<0.01), and apoptosis (P<0.05) decreased with PB treatment, angiogenesis (P<0.01) increased. In support of these findings, in the software-mediated EEG and SUP examination; Delta wave power and theta/alpha ratio increased with TBI and de-creased with PB treatment. CONCLUSION: The results showed that PB treatment provided a significant improvement in rats by reducing OS, apoptosis, and gliosis and increasing vascularity. To the best of our knowledge in the literature, it was shown for the 1st time that histological results for the treatment of PB were supported by software-mediated EEG and SEP analysis.Item Effects of Ketamine/Xylazine and Urethane Anesthesia on Compound Muscle Action Potential Latency of Gastrocnemius Muscle in Rats(Wolters Kluwer Medknow Publications, 2023) Mentese B.; Özel H.F.; Özbek M.; Kutlu N.Objective: Anesthetic agents, which are used in appropriate doses for the application of the experimental procedure in animals, relieve pain when applied in sufficient amounts as well as muscle relaxation. However, many anesthetics can alter the dynamics of neuromuscular systems. We aimed to compare the effects of two frequently used anesthetic agents on electromyographic parameters in rats. Materials and Methods: This study was performed on male Wistar albino rats aged 22-24 months. The animals were divided into two groups: urethane (1.5 gkg-1, i.p; n = 6) and ketamine+xylazine (K+X) (80 mg/kg, i.p; n = 6). Under general anesthesia, rats were electrically stimulated with bipolar hook electrodes from both legs, and compound muscle action potential (CMAP) was recorded from the needle electrode of the gastrocnemius muscle. Motor nerve action potential latency (MNAPL) was measured from the sciatic nerve of the rats. Results: The results of electrodiagnostic findings related to two different anesthetics in the animals were compared, and CMAP parameters were found to differ between the groups. MNAPL in both the right and left legs was significantly reduced in the urethane group compared to the K+X group (P < 0.05). Conclusion: Urethane anesthesia may be a better choice than K+X anesthesia to evaluate nerve and muscle functions in animal electromyography studies. © 2023 Neurological Sciences and Neurophysiology.Item The effects of mechanical ventilation on heart rate variability and complexity in mice(Hellenic Veterinary Medical Society, 2023) Kazdağli H.; Özel H.F.; Özbek M.In a variety of diseases, altered respiratory modulation is often as an early sign of autonomic dysfunction. Therefore, understanding and evaluating the effects of mechanical ventilation on the autonomic nervous system is vital. The effects of mechanical ventilation on autonomic balance have been assessed by heart rate variability (HRV) using frequency domain and non-linear analysis including fractal complexity and entropy analysis in anesthetized mice. BALB/c mice (n=48) were divided into two groups: Spontaneous breathing and mechanical ventilation. The electrocardiograms were recorded. Four different types of analysis were employed: i. frequency domain analysis, ii. Poincaré plots, iii. Detrended Fluctuation Analysis (DFA) and iv. Entropy analysis. An unpaired t-test was used for statistical analysis. In a ventilated group, very low frequency (VLF) and low frequency (LF) parameters were not changed, whereas the high frequency parameter was decreased compared to spontaneous breathing mice. DFAa1 was significantly increased due to mechanical ventilation but DFAa2 was unchanged. In Poincaré plots analysis, standard deviation 2 (SD2) / standard deviation 1 (SD1) ratio was increased, however, SD1 and SD2 were not significantly affected. Also, Approximate Entropy and Sample Entropy remained unchanged. HF parameter, DFAa1, and SD2/SD1 were affected by mechanical ventilation. Decreased HF and increased DFAa1, further support the notion that HRV is dominated by respiratory sinus arrhythmia at high frequencies, this may be due to decreased vagal tone caused by mechanical ventilation. This novel results of HRV analysis are important considering increased usage of HRV techniques day by day in animal models and other medical practices. © 2023 H Kazdağli, HF Ozel, MA Özbek. All Rights Reserved.Item SGLT-2 inhibitors on cardiac autonomic function in individuals with and without type 2 diabetes mellitus(Elsevier Inc., 2025) Özel H.F.; Alpay; Asker E.; Gültekin E.S.; Kazdağlı H.Sodium-glucose cotransporter-2 (SGLT-2) inhibitors have emerged as key therapeutic agents in managing type 2 diabetes mellitus (T2DM) and obesity, offering benefits that extend beyond glycemic control. This review examines the role of SGLT-2 inhibitors in modulating cardiac autonomic function, with a particular focus on heart rate variability (HRV) as a biomarker of autonomic balance. These agents improve metabolic profiles through enhanced glucosuria, natriuresis, and weight loss, while concurrently reducing blood pressure. Importantly, they also attenuate sympathetic nervous system overactivity and promote parasympathetic modulation, which may lower the risk of adverse cardiovascular events. The underlying mechanisms include not only the metabolic effects but also anti-inflammatory and antioxidative actions, which together contribute to improved endothelial function and vascular health. Advanced HRV analyses, encompassing traditional time and frequency domain methods as well as nonlinear approaches, have proven valuable in detecting early autonomic dysfunction in high-risk populations. Some studies suggest that SGLT-2 inhibitors may be associated with improvements in HRV parameters, such as increased SDNN and RMSSD and a reduced LF/HF ratio. However, findings are inconsistent across studies, and further research is needed to determine the extent and mechanisms of these potential effects. Although these findings are promising, further standardized, long-term studies are essential to clarify the mechanisms and optimal therapeutic strategies involving SGLT-2 inhibitors in the management of autonomic dysfunction. Future research should also explore the synergistic potential of combining SGLT-2 inhibitors with other cardiometabolic therapies to enhance cardiovascular outcomes in individuals with and without T2DM. © 2025 Elsevier Inc.Item Cardioprotective effects of H3 receptor activation could be double-sided: insights from isoproterenol-induced cardiac injury(Springer Science and Business Media Deutschland GmbH, 2025) Özel H.F.; Özbek M.; Özden M.T.; Vatansever H.S.Histamine H3 receptors (H3Rs) are known to modulate neurotransmitter release in the nervous system, but their role in cardiac injury remains unclear. The present study aimed to investigate the cardioprotective role of H3Rs in a mouse model of myocardial injury. Forty BALB/c male mice were divided into four groups: Control (SF), Isoproterenol (ISO), Imetit (IMT), and IMT + ISO. The IMT and IMT + ISO groups were pretreated orally with 10 mg/kg imetit-dihydrobromide(imetit) for 7 days. In the last 2 days, the ISO and IMT + ISO groups received a subcutaneous injection of 85 mg/kg isoproterenol to induce myocardial ischemia. Electrocardiogram (ECG) recordings were obtained, and heart tissues were analyzed histopathologically. The results demonstrated that the administration of imetit resulted in the prolongation of the PR interval in the IMT group. QRS and QT intervals were prolonged in the ISO group. The J-wave area in the ISO group was significantly larger than in the other groups. Histopathological analyses revealed the presence of small vacuoles, inflammatory cell infiltration, and collagen aggregates in cardiomyocytes in the ISO group. No significant cellular changes were observed in the IMT group, in contrast. The IMT + ISO group exhibited fewer ischemic findings than the ISO group. Immunohistochemical analyses revealed positive H3R immunoreactivity in all groups. Imetit pretreatment increased the immunoreactivity of H3Rs in both the IMT and IMT + ISO groups. The findings of this study suggest that H3Rs may be present on the postsynaptic side in cardiac myocytes, in addition to adrenergic presynaptic nerve endings. Furthermore, imetit has been found to significantly reduce the effects of myocardial ischemia by activating H3Rs. The better characterization of the postsynaptic role of H3Rs offers potential for the development of new therapeutic strategies. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.