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Öğe Acute Normovolemic Hemodilution in Coronary Artery Bypass Surgery: Effects on Inflammatory Response(2003) Durmuş M.; Karaaslan K.; But A.K.; Do?an Z.; Sezgin N.; Ersoy M.Ö.Acute normovolemic hemodilution is the removal of the blood from patients before or shortly after induction of anesthesia, and simultaneous replacement with acellular fluid, that is crystalloid or colloid and retransfusion of removed blood if needed. In this study we aimed to evaluate the effects of acute normovolemic hemodilution on and enflammatory response in patients undergoing coronary artery bypass surgery. After Ethics Committee approval 40 patients undergoing coronary artery bypass surgery were divided into two groups randomly. After induction of anesthesia, one or two units of blood were drawn from the Group I (n=20) until the hematocrit values became lesser than < 35%. At the same time, volume replacement was achieved with same amount of colloid infusion from peripheral vein. Any additional procedure was not done to the control group (Group II, n=20). Alanine transaminase, aspartate transaminase, lactate dehydrogenase, creatine kinase MB, creatine phosphokinase, ?-glutamyl transferase, complement 3a, complement 4a, ferritin, transferrin, nitric oxide, C-reactive protein and haptoglobulin levels were measured before induction, after operation, postoperative 6th and 24th hours. The amount of transfused allogenic blood was lower in Group I compared to group II (p<0.05). It was detected that complement system was not induced in two groups; lactate dehydrogenase, creatine kinase MB and nitric oxide levels were higher in Group II at postoperative 6 th, ferritin level was higher in group I at postoperative 24 th hours statistically (p<0.05). It was concluded that the effect of acute normovolemic hemodilution regarding to complement system was not different from control group and lower levels in lactate dehydrogenase, creatine kinase MB and nitric oxide can show that organ functions can be better prevented with acute normovolemic hemodilution.Öğe Comparison of the antioxydant enzyme levels with the degree of dysfunction in patients with myocardial dysfunction(2004) Sezgin N.; Sezgin A.T.; Karabulut A.; Topal E.; Barutçu I.; Gözükara E.M.Objective: Myocardial dysfunction in patients with cardiomyopathy is proposed to occur due to membrane changes caused by oxidative stress. In our study we evaluate whether there is any relation between the degree of myocardial dysfunction and antioxicant enzymes. Methods: We studied superoxide dismutase (SOD), glutathione peroxidase (GSHPx) and catalase (CAT) enzyme activities from blood samples of 60 patients (30 patients had ejection fraction (EF) <%35 and 30 patients had EF= %35-50) who have myocardial dysfunction according to clinical findings and two dimensional echocardiography, and 20 healthy volunteers. Results: We found erythrocyte SOD enzyme activities of patients with EF <%35 (group 3) were significantly lower than in control subjects (group 1) (p=0.01). However in group 2 patients (EF=%35-50), erythrocyte SOD activities were found to be lower than in control subjects but this difference was not significant. Erythrocte CAT and GSHPx enzyme activities of group 3 were also significantly lower than in control group (p=0.04 and p=0.02 respectively). Conclusion: In conclusion, reactive oxygen species play a significant role in the initiation and the progression of congestive heart failure. Increased free radicals levels may cause myocardial muscle dysfunction.Öğe Complexity and irregularity analysis of the output data of a cortical network(2013) Tekin R.; Emin Tagluk M.; Ertugrul Ö.F.; Sezgin N.Depending on the complex interconnection of billions of neurons forming cortical network excitation times and the emergence of action potentials or spike trains becomes complex and irregular. The effect of various parameters such as synaptic connections, conductivity and voltage dependent channels on the output of the network has become of research issues. In this study, based on Hodgkin-Huxley neuron model an artificial cortical network that simulates a local region of cortex was designed and the effect of probabilistic values of network parameters used in this model on irregularity and complexity of the spike trains at the neurons' output were investigated. Approximation Entropy, Spectral Entropy and Magnitude Squared Coherence methods were used for irregularity analysis. © 2013 IEEE.Öğe Diagnostic estimation of OSAS using binary mixture logistic regression(2012) Kaya Y.; Ta?luk M.E.; Sezgin N.Binary (Binomial) Logistic Regression is a statistical model that can be used for classification. Concerning the targeted outcome, if the variance of observations is higher than the variance of expectations, because of overdispersion the success rate of the method in classification goes down. This overdispersion is thought as arising from the unobserved heterogen samples in the data set. In Composite models, the overdispersion is minimized by clustering the data into homogeneous subsets and performing a subset based process. In this study a composite binary logistic regression was used for estimating the sleep apnea. Through this model, snoring signals were classified and with a 98.16% success rate the apnea was diagnosed. © 2012 IEEE.Öğe The effects of acute normovolemic hemodilution on coagulation parameters in coronary artery bypass surgery(2003) Durmuş M.; Karaaslan K.; But A.K.; Erdem T.B.; Sezgin N.; Ersoy M.Ö.Acute normovolemic hemodilution reduces allogenic blood transfusion requirements during surgery. We aimed to investigate the effects of acute normovolemic hemodilution on hemostasis after cardiopulmonary bypass by comparing routine coagulation tests, thrombin-antithrombin III complex, fibrinogen, D-dimer, protein C and S levels. After Ethics Committee approval 40 patients undergoing coronary artery bypass surgery were divided into two groups randomly. After induction of anesthesia, one or two units of blood were drawn from the Group I (n=20) until the hematocrit values became less than < 35% (Htc < 35%). At the same time, volume replacement was achieved with same amount of colloid infusion from peripheral veins. No additional procedure was done to Group II (n=20). All coagulation tests were measured before induction, at the end of surgery, at postoperative 6th and 24th. In addition to this time periods, thrombin-antithrombin III complex, fibrinogen and D-dimer levels were measured before cardiopulmonary bypass. The amount of transfused allogenic blood was lower in Group I compared to Group II (p<0.05). Routine coagulation tests remained within normal limits. Before cardiopulmonary bypass, fibrinogen, thrombin-antithrombin III complex and D-dimer levels were higher in Group I compared to Group II statistically (p<0.05). Protein C level was less at the end of surgery in Group I (p<0.05). Fragmentation ratio was detected lower in Group I than Group II (P<0.01). We concluded that, although acute normovolemic hemodilution reduces allogenic blood transfusion requirement and fragmentation ratio, it may activate coagulation and fibrinolysis in patients undergoing coronary artery bypass surgery.Öğe Effects of intrathecal fentanyl or meperidine addition to bupivacaine on hemodynamic variables, postoperative analgesic requirements, levels of histamine, IgE, basophiles and eosinophiles(2003) Köro?lu A.; Erdem S.; Çiçek M.; Do?an Z.; Sezgin N.; Ersoy M.O.The aim of our study is to compare the effects of intrathecal fentanyl and meperidine with bupivacaine on hemodynamics, postoperative analgesic requirement, side effects and levels of histamine, IgE, basophiles, eosinophiles and to investigate a possible relationship between itching and levels of basophiles and eosinophiles. Heart rate, mean arterial pressure, SpO2 values, respiration rates of 45 cases were recorded before and after spinal anesthesia. Intrathecal 10mg bupivacaine heavy was used in combination with 0.5 mL 0.9% NaCl in group B, 25 ?g fentanyl in group F, 25 mg meperidine in group M were given. Blood samples were collected to determine the plasma levels of histamine, IgE, basophiles and eosinophiles 30 min before spinal anaesthesia, and at the 8th, 60th minutes of spinal anaesthesia. Analgesic requirement was evaluated for postoperative 24 hours by using VAS. Although plasma levels of histamine and basophiles were significantly higher in group M and F at the 8th, 60th min of spinal anaesthesia, levels of histamine were significantly higher in group M than other two groups at the 8th min of spinal anaesthesia. VAS scores and analgesic requirements were significantly lower in group M than the other two groups at late postoperative period. Itching and vomiting incidences were higher in group F and there was no relationship between itching and levels of eosinophiles and basophiles. In conclusion, we determined that intrathecal fentanyl and meperidine did not effect hemodynamics, and meperidine provided better analgesia in the postoperative period. Although, histamine release increased with both opioids, it was more in meperidine than fentanyl, however fentanyl caused more vomiting and itching. There was no relationship between levels of eosinophiles, basophiles and itching.Öğe Kortikal spindle salinim aktivitesinin oluşumunda ve senkronizasyonunda talamik projeksiyonlarin rolünün model temelli incelenmesi(Institute of Electrical and Electronics Engineers Inc., 2017) Tekin R.; Kaya Y.; Sezgin N.; Ta?luk M.E.In this study, mechanisms of formation of thalamocortical spindle oscillations, which are critical for various functions of the brain, have been examined on a model basis. For this, both spike activity and spectral characteristics were investigated by isolating the cortex and thalamus and then connecting them with thalamo-cortical projections. In order to determine the spindle activity in the LFP signal of each cell group, it has been tried to determine slow-wave and spindle frequency components which can coexist with each other on the basis of superposition. For this purpose, power spectral densities of LFP signals were analyzed. According to the results of this study, spindle activity can be seen in thalamus without cortex. It can be said that thalamo-cortical projections provided by the thalamic TC cells enable the spindle activity to be transferred into the cortex and thus display itself in LFP / EEG. At the same time, it has been observed that thalamo-cortical projections increase spike activity, equalize the dominant frequency in the whole system, and also cortico-thalamic projections strengthen spindle activity. © 2017 IEEE.Öğe Plasma D-lactic acid level: A useful marker to distinguish perforated from acute simple appendicitis(Elsevier (Singapore) Pte Ltd, 2004) Demircan M.; Cetin S.; Uguralp S.; Sezgin N.; Karaman A.; Gozukara E.M.Early diagnosis of perforated appendicitis is important for reducing morbidity rates. The aim of this study was to determine the value and utility of plasma D-lactic acid levels in identifying the type of appendicitis. In this clinical study, plasma D-lactic acid levels were assessed in 44 consecutive paediatric patients (23 with acute appendicitis, 21 with perforated appendicitis) before laparotomy. D-lactic acid levels were determined by an enzymatic spectrophotometric technique using a D-lactic acid dehydrogenase kit. Patients with perforated appendicitis had higher D-lactic acid levels (3.970 ±0.687 mg/dL) than patients in the control group (0.478 ± 0.149 mg/dL) and patients with acute appendicitis (1.409 ±0.324 mg/dL; p < 0.05). For a plasma D-lactic acid level greater than 2.5 mg/dL, the sensitivity and specificity of the D-lactic acid assay were 96% and 87%, respectively. The positive predictive value was 87%, the negative predictive value was 96%, and the diagnostic value was 91%. These results suggest that the measurement of plasma D-lactic acid levels may be a useful adjunct to clinical and radiological findings in distinguishing perforated from acute non-perforated appendicitis in children.Öğe Separation of EEG signals by using independent component analysis(2012) Sezgin N.; Ta?luk M.E.; Tekin R.Independent Component Analysis (ICA) is a statistical method used for separating nongaussian independent components of a mixture signal. In this study, by separating the signal into its possible independent components, the simplification and comprehension of analysis of EEG signals was aimed. Through such an analysis it was thought that early diagnosis of some neurological disease such as epilepsy, parkinson's disease, sleep disorders as well as information regarding the location and size of problematic zone may become possible. © 2012 IEEE.Öğe Using bispectral analysis in OSAS estimation(2010) Sezgin N.; Tagluk M.E.; Akin M.In this study the possibility of estimation of Obstractive Sleep Apnea Syndrome (OSAS) through electroensephalographic (EEG) signals using higher order spectra was investigated. Biological structures usually exhibit nonlinear and non-Gaussian distributed characteristics which consequently generate signals embracing nonlinear components as well as phase relations occurring between componets oscillating in different frequencies whose phase couples together over a limited period of time, so called Quadratic Phase Coupling (QPC). In this case the second order power spectrum may not reflect the real characteristics of the biological system. Therefore, the bispectrum analysis was achieved to characterize the nonlinearities and QPCs in OSAS and normal EEGs. Through this analysis the differences in OSAS EEG and normal EEG were comparatively uncovered. From the analysis it was understood that the bispectrum can be used for estimation of OSAS from patients' EEG signals. ©2010 IEEE.
