Publications by authors named "Yasin Ozturk"

12 Publications

  • Page 1 of 1

Rapid fabrication of teflon apertures by controlled high voltage pulses for formation of free standing planar lipid bilayer membrane.

Biomed Microdevices 2021 Feb 27;23(1):12. Epub 2021 Feb 27.

Department of Biomedical Engineering, Ankara Yıldırım Beyazıt University, Ankara, Turkey.

Free standing artificial lipid bilayers are widely used in the study of biological pores. In these types of studies, the free standing planar lipid bilayer is formed over a micron-sized aperture consisting of either polymer such as Polytetrafluoroethylene (PTFE, Teflon) or glass. Teflon is chemically inert, has a low dielectric constant, and has a high electrical resistance which combined allow for obtaining low noise recordings. This study investigates the reproducible generation of micropores in the range of 50-100 microns in diameter in a Teflon film using a high energy discharge set-up. The discharger set-up consists of a microprocessor, a transformer, a voltage regulator, and is controlled by a computer. We compared two approaches for pore creation: single and multi-pulse methods. The results showed that the multi-pulse method produced narrower aperture size distributions and is more convenient for lipid bilayer formation, and thus would have a higher success rate than the single-pulse method. The bilayer stability experiments showed that the lipid bilayer lasts for more than 33 h. Finally, as a proof-of-concept, we show that the single and multi-channel electrophysiology experiments were successfully performed with the apertures created by using the mentioned discharger. In conclusion, the described discharger provides reproducible Teflon-pores in a cheap and easy-to-operate manner.
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http://dx.doi.org/10.1007/s10544-021-00553-4DOI Listing
February 2021

Clinical outcomes of COVID-19 in hemodialysis patients in the city of Zonguldak, Turkey.

Int Urol Nephrol 2021 Jan 15. Epub 2021 Jan 15.

Division of Nephrology, Department of Internal Medicine, Sivas Cumhuriyet University Medical Faculty, Sivas, Turkey.

Purpose: Patients on maintenance hemodialysis are vulnerable to viral infections like COVID-19 because of the low chance of obedience and complying with rules besides the need for transfer to distant dialysis facilities. We investigated the impact and clinical effect of treatment of COVID-19 in dialysis patients.

Methods: We included patients on maintenance hemodialysis at different healthcare facilities in Zonguldak city. With the diagnosis of the first infected HD case, all other patients who shared the same session were screened. Hospitalized and clinically confirmed cases were included. COVID-19 diagnosis was made based on clinical, biochemical along radiologic findings.

Results: 34 (F/M:19/15, mean age 62 ± 13.2 years, dialysis duration 66.9 ± 57.7 months, length of hospital stay 16.2 ± 7.9 days) were diagnosed with COVID-19 infection. The prevalence of COVID-19 was found to be 18.4% of our exposed population. 38.2% of our patients were initially diagnosed by CT screening while asymptomatic. 35.3% had a fever as the first presenting symptom. Lymphopenia was the most common laboratory finding. Except for one, all had at least one comorbidity. Out of 12 (35.3%) patients admitted to ICU 6(17.6%) died. The deceased patients were older, presented with lower serum albumin and lymphocyte count, and had higher CRP and fibrinogen levels. High CRP level on admission was the only significant predictor of mortality.

Conclusion: Early detection will lower mortality. In this study, with a low prevalence of COVID-19, the importance of early screening of both symptomatic and asymptomatic patients was shown to be highly important. Further studies are still needed to find out the most appropriate medical management.
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http://dx.doi.org/10.1007/s11255-020-02781-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7809887PMC
January 2021

Investigation of the Effect of Channel Structure and Flow Rate on On-Chip Bacterial Lysis.

IEEE Trans Nanobioscience 2021 Jan 30;20(1):86-91. Epub 2020 Dec 30.

Successful lysis of cells/microorganisms is a key step in the sample preparation in fields like molecular biology, bioengineering, and biomedical engineering. This study therefore aims to investigate the lysis of bacteria on-chip and its dependence on both microfluidic channel structure and flow rate. Effects of temperature on lysis on-chip were also investigated. To perform these investigations, three different microfluidic chips were designed and produced (straight, zigzag and circular configurations), while the length of the channels were kept constant. As an exemplary case, Mycobacterium smegmatis was chosen to represent the acid-fast bacteria. Bacterial suspensions of 1.5 McFarland were injected into the chips at various flow rates (0.6- [Formula: see text]/min) either at room temperature or 50° C. In order to understand the on-chip lysis performance fully, off-chip experiments were carried out at durations which are equal to those bacteria spent in the channel from inlet to the outlet at different flow rates. We also performed COMSOL multiphysics program simulations to evaluate further the effect of the applied parameters. As a result, we found that the structure and the flow rate do not affect lysis over all in all investigated channel types, however on-chip experiments at room temperature produced more effective lysis compared to the on-chip and the off-chip samples performed at higher temperatures. Interestingly on-chip experiments at higher tempratures do not result in effective lysis.
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http://dx.doi.org/10.1109/TNB.2020.3031346DOI Listing
January 2021

Label-free molecular detection of antibiotic susceptibility for Mycobacterium smegmatis using a low cost electrode format.

Biotechnol Appl Biochem 2020 Sep 25. Epub 2020 Sep 25.

Department of Metallurgical and Materials Engineering & Cellular Therapy and Stem Cell Research Center, Eskisehir Osmangazi University, Eskisehir, Turkey.

Today, the emergence of antibiotic resistance in pathogenic bacteria is considered an important problem for society. Excessive consumption of antibiotics, long-term treatments, and inappropriate prescriptions continually increase the severity of the problem. Improving antibiotic stewardship requires improved diagnostic testing, and, therefore, in vitro antibiotic susceptibility testing is becoming increasingly important. This research details the development of an antibiotic susceptibility test for Mycobacterium smegmatis using streptomycin as antibiotics. This strain was selected because it is a member of the slow growing Mycobacterium genus and serves as a useful surrogate organism for M. tuberculosis. A commercially available and low-cost screen-printed gold electrode in combination with a specifically developed nucleic acid probe sequence for the 16SrRNA region of the mycobacterial genome was employed to monitor M. smegmatis nucleic acid sequences using the techniques of square-wave voltammetry and electrochemical impedance spectroscopy. The results show that it was possible to detect M. smegmatis sequences and distinguish antibiotic-treated cells from untreated cells with a label-free molecular detection. As a result, the in vitro antibiotic susceptibility test revealed that M. smegmatis showed sensitivity to streptomycin after a 24-H incubation, with the developed protocol representing a potential approach to determining antibiotic susceptibility more quickly and economically than current methods.
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http://dx.doi.org/10.1002/bab.2037DOI Listing
September 2020

Assessment of Farmers' Knowledge, Attitudes and Practices on Antibiotics and Antimicrobial Resistance.

Animals (Basel) 2019 Sep 4;9(9). Epub 2019 Sep 4.

Department of Microbiology, Faculty of Veterinary Medicine, University of Firat, 23119 Elazig, Turkey.

The aim of this study was to determine knowledge, attitudes, and behaviors of farmers dealing with animal husbandry in eastern Turkey with regard to antibiotic knowledge, use, and resistance. A face to face questionnaire survey, consisting of five sections with 42 questions in total, was applied to 360 farmers located in the region. The questions in the first and fifth sections were closed-ended while those in other sections were prepared using the Likert scale. It was determined that knowledge of the farmers about antibiotic use, duration, storage, and resistance was well below desired levels. This was particularly remarkable in the participants with a low level of education, living in rural areas, and those at 48 years of age or over. In contrast, younger and highly educated participants living in urban areas were more knowledgeable about antibiotic use and they were well aware of the fact that resistance might pose a great risk for public health. Providing appropriate antibiotic use in animals through systematic training of livestock farmers is crucial in tackling the resistance problem.
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http://dx.doi.org/10.3390/ani9090653DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770244PMC
September 2019

Resveratrol Enhances Apoptotic and Oxidant Effects of Paclitaxel through TRPM2 Channel Activation in DBTRG Glioblastoma Cells.

Oxid Med Cell Longev 2019 7;2019:4619865. Epub 2019 Mar 7.

Centre for Healthy Brain Ageing, School of Psychiatry, University of New South Wales, Sydney, Australia.

Numerous studies have reported a strong association between increased production of reactive oxygen species (ROS) and the pathobiology of several diseases, and cancer in particular. Therefore, manipulation of cellular oxidative stress levels represents an important therapeutic target. Recently, resveratrol (RESV), a naturally occurring phytochemical, has been shown to sensitize several cell lines to the anticancer effects of other chemotherapeutic agents, including paclitaxel (PAX). However, the molecular mechanisms of action of RESV through oxidative sensitive TRPM2 channel activation remain unclear. The aim of this study was to evaluate the effect of combination therapy of RESV and PAX on activation of TRPM2 in DBTRG glioblastoma cells. DBTRG cells were divided into four treatment groups: control, RESV (50 M), PAX (50 M), and PAX + RESV for 24 hours. Our data shows that markers for apoptosis, mitochondrial membrane depolarization and mitochondrial function, intracellular steady-state ROS levels, caspase 3 activity, TRPM2 current density, and Ca florescence intensity were significantly increased in DBTRG cells following treatment with PAX and RESV, respectively, although cell viability was also decreased by these treatments. These biochemical markers were further increased to favor the anticancer effects of PAX in DBTRG cells in combination with RESV. The PAX and RESV-mediated increase in current density and Ca florescence intensity was decreased with a TRPM2 blocker. This suggests that for this combination therapy to have a substantial effect on apoptosis and cell viability, the TRPM2 channel must be stimulated.
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http://dx.doi.org/10.1155/2019/4619865DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6431513PMC
July 2019

Ischemic modified albumin as a new biomarker in predicting oxidative stress in alopecia areata

Turk J Med Sci 2019 Feb 11;49(1):129-138. Epub 2019 Feb 11.

Background/aim: Results show that oxidative stress is a pathophysiologic factor for alopecia areata (AA); however, the markers used can be confounding. Thus, we aimed to investigate the role of oxidative stress in the pathogenesis of AA through an evaluation of ischemia-modified albumin (IMA); other markers of the oxidant/antioxidant system, such as SOD, CAT, GSH-ST, and MDA; and contributing clinical risk factors.

Materials And Methods: The usefulness of IMA as a new marker for oxidative stress was compared with that of other markers and evaluated in patients with AA.

Results: The mean serum level of IMA was of higher statistical significance in AA patients than in the control group (IMA: 0.57 ± 0.01 vs. 0.52 ± 0.02 ΔABSU, P < 0.0001). IMA (P = 0.03, OR = 25.8, 95% CI = 1.4–482.7) was found to be an independent predictor of oxidative stress in patients with AA. Increased severity of AA was found as an independent risk factor for IMA.

Conclusion: Long-lasting disease, male sex, >1 site of involvement of disease, and increased severity of disease were correlated with increased oxidation. Presence of AA, male sex, and severe disease were determined to be independent risk factors for antioxidant and oxidant systems. IMA has great potential as a biomarker of oxidative stress in AA when compared to other studied biomarkers.
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http://dx.doi.org/10.3906/sag-1708-35DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7350867PMC
February 2019

Usefulness of ischemia-modified albumin in predicting oxidative stress in patients with vitiligo.

Biomark Med 2017 May 9;11(6):439-449. Epub 2017 Jun 9.

Gazi University, Faculty of Medicine, Biochemistry, Ankara, Turkey.

Aim: To investigate the emphasis of oxidative stress in the pathogenesis of vitiligo through an evaluation of ischemia-modified albumin (IMA). Results/methodology: IMA was of higher statistical significance in patients than in the control group (IMA: 0.57 ± 0.2 vs 0.52 ± 0.2 ΔABSU; p < 0.0001). IMA (p < 0.0001; OR: 8.9; 95% CI = 3.1-26.1) was found as an independent predictor of oxidative stress. Increases in affected body surface area and age were found to be independent risk factors for IMA. The sensitivity, specificity and positive and negative predictive values and capacity of IMA were higher than other studied biomarkers.

Discussion/conclusion: IMA can be detected in the condition of oxidative stress in vitiligo; it has great potential as a biomarker of said condition, when compared with other studied biomarkers.
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http://dx.doi.org/10.2217/bmm-2016-0259DOI Listing
May 2017

Should every region use the same gastric cancer scanning and treatment approaches? let's reconsider: a northeastern turkey example.

BMC Gastroenterol 2016 Oct 4;16(1):120. Epub 2016 Oct 4.

Department of General Surgery, Erzurum Region Education and Research Hospital, Türkiye Sağlık Bilimleri University, Erzurum, Turkey.

Background: The rate for upper gastrointestinal (UGI) cancers, and especially the rate for gastric cancer, varies from country to country and from region to region within country. In Turkey, the incidence of gastric cancer varies widely among regions due to the diverse cultures and accompanying food habits of the population. This study aimed to determine the endoscopic frequency of esophageal and gastric cancers and the usefulness of alarm symptoms in diagnosing gastric cancer in subjects undergoing endoscopy in northeastern Turkey.

Methods: This retrospective study was based on hospital records, reviewing the records of patients who had underdone esophago-gastro-duodenal (EGD) video endoscopy at two general hospitals in Erzurum. From July 2010 to January 2013, 25,037 patients from Erzurum underwent EGD procedures under either intravenous sedation or local anesthesia. Classifications of UGI cancer, based on location of the tumor, were defined as esophageal, cardia, cardia and fundus or corpus or all of these, corpus, corpus and antrum, and antrum. Metastasis was studied in 659 patients diagnosed with cancer.

Results: Throughout the study, 1,007 biopsy samples were reported as malignant tumors (719 gastric, 276 esophageal, and 12 duodenal cancers). The study considered the gastric cancer population under age 46, which included 99 (13.8 %) patients. Among them, the distribution of UGI cancer by age was as follows: under age 26 years, 9 patients (0.9 %); age 26-35 years, 30 patients (3 %); and age 36-45 years, 60 patients (6 %). Overall, 298 patients (298/1007, 29.6 %) presented with localized disease, and 361 patients (35.9 %) had distant metastases at the time of diagnosis.

Conclusions: We determined that UGI cancer patients are observed more frequently in northeastern Turkey than in western Turkey, Europe, and the USA. We believe that alarm symptoms and endoscopic scanning programs require new, region-specific criteria to diagnose UGI cancers in this region. For the patient groups with these different characteristics, we believe that new scanning, follow-up, and treatment strategies are needed that take into consideration differences in the histopathology of the tumors, their localization, and the patients' ages.

Trial Registration: There is registration number. This study is "retrospective study". This study is "retrospectively registered".
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http://dx.doi.org/10.1186/s12876-016-0539-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5050616PMC
October 2016

Resistin: New serum marker for predicting severity of acute pancreatitis.

J Int Med Res 2016 Apr 8;44(2):328-37. Epub 2016 Feb 8.

Department of Internal Medicine, Education and Research Hospital, Erzurum, Turkey.

Objective: To assess the effectiveness of resistin in predicting the severity of acute pancreatitis.

Methods: Patients with acute pancreatitis who presented at the Gastroenterology Clinic, Erzurum Education and Research Hospital, Turkey were enrolled in this prospective study. White blood cell (WBC), C-reactive protein (CRP) and resistin levels were measured on admission and at 24 h, day 3 and day 7 following admission, along with other blood parameters. Patients were divided into two groups: mild acute pancreatitis and moderate/severe acute pancreatitis.

Results: Of 59 patients with acute pancreatitis (mild, n = 37; moderate/severe, n = 22), significant between-group differences were found in terms of resistin and CRP levels. Receiver operating curve analysis showed that resistin levels were better for predicting severe cases of acute pancreatitis than CRP or WBC levels on day 3 (area under the curve [AUC], 0.88 versus 0.81 and 0.63, respectively). Resistin levels on day 3 were better than CRP levels for predicting necrosis development (AUC, 0.70 versus 0.69, respectively).

Conclusions: Resistin may represent a new, effective indicator to predict the severity of acute pancreatitis and presence of necrosis in patients with acute pancreatitis.
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http://dx.doi.org/10.1177/0300060515605428DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5580057PMC
April 2016

Mean platelet volume in a patient with male hypogonadotropic hypogonadism: the relationship between low testosterone, metabolic syndrome, impaired fasting glucose and cardiovascular risk.

Blood Coagul Fibrinolysis 2015 Oct;26(7):811-5

Erzurum Regional Training and Research Hospital, Department of Endocrinology, Erzurum, Turkey.

Isolated male hypogonadotropic hypogonadism (IHH) can be congenital or acquired. Mean platelet volume (MPV), determinant of platelet function, is an independent risk factor for cardiovascular disease (CVD). The aim of this study was to evaluate MPV values in male IHH and the relationships between MPV, low testosterone levels, metabolic syndrome, impaired fasting glucose (IFG) and cardiovascular risk. Thirty-one patients with untreated, normosmic, isolated, male IHH (mean age 22.5 ± 7.58 years) and 30 age and BMI-matched healthy individuals (mean 22.51 ± 4.94 years) were included in the study. All hormonal analyses were done by chemiluminesance assay. All study participants were evaluated by biochemical and platelet parameters. MPV were significantly higher in IHH than controls (8.6 ± 0.65 and 7.6 ± 0.54 fl, respectively; P = 0.000). MPV had a positive correlation between metabolic syndrome (r = 0.444; P = 0000), IFG (r = 0.371; P = 0.04), insulin (r = 0.820; P = 0.02), homeostasis model assessment (HOMA)-IR (r = 0.822; P = 0.0023) and BMI (r = 0.373; P = 0.012). MPV had a negative correlation between total testosterone (r =  -0.586; P = 0.0000), free testosterone (r =  -0.634; P = 0.0000), luteinizing hormone (r =  -0.471; P = 0.0000) and FSH (r =  -0.434; P = 0.0000). Although control patients did not have metabolic syndrome and IFG, IHH patients had metabolic syndrome and IFG significantly more often (P < 0.001, P = 0.003, respectively). Age, metabolic syndrome, IFG, BMI, fasting glucose, insulin, CRP and HOMA-IR were independent predictive factors of MPV in the multiple regression analysis. These results suggest that men with IHH are susceptible to increased platelet activation and increased MPV values that contribute to an increased risk of cardiovascular complications. From this study, it has been observed that IHH with low testosterone may be a feature of the metabolic syndrome, IFG, increased MPV levels and cardiovascular risk in young adult males.
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http://dx.doi.org/10.1097/MBC.0000000000000353DOI Listing
October 2015

The effects of iloprost on ischemia-reperfusion injury in skeletal muscles in a rodent model.

J Surg Res 2014 Mar 29;187(1):162-8. Epub 2013 Sep 29.

Department of Cardiovascular Surgery, Gazi University Medical Faculty, Ankara, Turkey.

Purpose: The aim of this study was to investigate the effects of iloprost (IL) on ischemia-reperfusion injury in a rodent model.

Materials And Methods: Twenty-four Wistar Albino rats were randomized into four groups (n = 6). Laparotomy was performed in all groups under general anesthesia. Only laparotomy was applied in group S (Sham). Ischemia-reperfusion group (group I/R) underwent ischemia and reperfusion performed by clamping and declamping of the infrarenal abdominal aorta for 120 min. The iloprost group (group IL) received intravenous infusion of IL 0.5 ng/kg/min, without I/R. Group I/R + IL received intravenous infusion of IL 0.5 ng/kg/min immediately after 2 h period of ischemia. At the end of the reperfusion period, all rats were killed under anesthesia and skeletal muscle samples of lower extremity were harvested for biochemical and histopathologic analyses.

Results: Tissue levels of endothelial nitric oxide were significantly higher in I/R groups than those in groups S and IL. The heat shock protein 60 levels were higher in group I/R than the other groups. But the heat shock protein 60 levels in group I/R + IL were found to be similar with the groups S and IL. Malondialdehyde levels were significantly higher in group I/R. On the other hand, in group I/R + IL, malondialdehyde levels were higher than those in groups S and IL but lower than those in group I/R. Superoxide dismutase (SOD) enzyme activities were found to be significantly lower in group I/R than the other groups. Also in group I/R/I, the SOD enzyme activities were higher than those in group I/R. But, in group I/R + IL, SOD levels were found to be higher than those in group I/R but lower than those in groups S and IL.

Conclusions: These results indicate that IL has protective effects on I/R injury in skeletal muscle in a rodent model.
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http://dx.doi.org/10.1016/j.jss.2013.09.031DOI Listing
March 2014