Modeling the Catalytic Activity and Kinetics of Lipase(Glycerol-Ester Hydrolase)

Demirer, Goksel N.,Duran, Metin,Tanner, Robert D. The Korean Society for Biotechnology and Bioengine 1996 Biotechnology and Bioprocess Engineering Vol.1 No.1

In order to design industrial scale reactors and proceises for multi-phase biocatalytic reactions, it is essential to understand the mechanisms by which such systems operate. To il-lustrate how such mechanisms can be modeled, the hydrolysis of the primary ester groups of triglycerides to produce fatty acids and monoglycerides by lipased (glycerol-ester hydrolase) catalysis has been selected as an example of multiphase biocatalysis. Lipase is specific in its behavior such that it can act only on the hydrolyzed (or emulsified) part of the substrate. This follows because the active center of the enzyme is catalytically active only when the substrate contacts it in its hydrolyzed form. In other words, lipase acts only when it can shuttleback and forth between the emulsion phase and the water phase, presumably within an interphase or boundary layer between these two phases. In industrial applications lipase is employed as a fat splitting enzyme to remove fat stains from fabrics, in making cheese, to flavor milk products, and to degrade fats in waste products. Effective use of lipase in these processes requires a fundamental understanding of its kinetic behavior and interactions with substrates under various environmental conditions. Therefore, this study focuses on modeling and simulating the enzymatic activity of the lipase as a step towards the basic understanding of multi-phase biocatalysis processes.

Clinical and Prognostic Features of Erionite-Induced Malignant Mesothelioma

Ersin Demirer,Elamin M. Elamin,Christian F. Ghattas,Mohamed O. Radwan 연세대학교의과대학 2015 Yonsei medical journal Vol.56 No.2

This review analytically examines the published data for erionite-related malignantpleural mesothelioma (E-MPM) and any data to support a genetically predisposedmechanism to erionite fiber carcinogenesis. Adult patients of age ≥18 years with erionite-related pleural diseases and genetically predisposed mechanisms to erionite carcinogenesis were included, while exclusion criteria included asbestos- or tremolite-related pleural diseases. The search was limited to human studies though not limited to a specific timeframe. A total of 33 studies (31042 patients) including 22 retrospective studies, 6 prospective studies, and 5 case reports were reviewed. E-MPM developed in some subjects with high exposures to erionite, though not all. Chest CT was more reliable in detecting various pleural changes in E-MPM than chest X-ray, and pleural effusion was the most common finding in E-MPM cases, by both tests. Bronchoalveolar lavage remains a reliable and relatively less invasivetechnique. Chemotherapy with cisplatin and mitomycin can be administered either alone or following surgery. Erionite has been the culprit of numerous malignantmesothelioma cases in Europe and even in North America. Erionite has a higher degree of carcinogenicity with possible genetic transmission of erionite susceptibilityin an autosomal dominant fashion. Therapeutic management for E-MPM remains very limited, and cure of the disease is extremely rare.

Effects of postoperative parenteral nutrition with different lipid emulsions in patients undergoing major abdominal surgery

Seher Demirer,Ali Sapmaz,Ahmet Serdar Karaca,Ilknur Kepenekci,Semih Aydintug,Deniz Balci,Pinar Sonyurek,Kenan Kose 대한외과학회 2016 Annals of Surgical Treatment and Research(ASRT) Vol.91 No.6

Purpose: This study was designed to investigate the effects of total parenteral nutrition (PN) using different lipid emulsions in patients undergoing major abdominal surgery. Methods: Fifty-two patients were randomized to receive soybean oil + medium chain triglycerides (MCT) (group I), soybean oil + olive oil (group II), soybean oil + olive oil + fish oil (group III) as a lipid source. PN was started on postoperative day 1 and patients were maintained on PN for a minimum period of 4 days. Laboratory variables (CRP, prealbumin, transferrin) were measured before surgery and on postoperative days. Results: Three treatment groups were included in the study. Patients in group I received long chain triglycerides (LCT) + LCT/MCT emulsion (%75 LCT + %25 LCT/MCT); Patients in group II received olive oil based emulsion (80% olive oil + 20% soybean oil, ClinOleic); Patients in group III received fish oil in addition to olive oil based emulsion (%85 ClinOleic + %15 Omegaven; Fresenius Kabi). The following 14 parameters were assessed: body weight, CRP, prealbumin, transferrin, tumor necrosis factor-α, interleukin-6, total antioxidant status, thiobarbituric acid reactive substances, oxidized low density lipoprotein-2, complete blood cell, international normalized ratio, D-dimer, activated partially thromboplastin time, prothrombin time. All other parameters showed no differences among the groups. Conclusion: The results of our trial demonstrate a potential beneficial effect of soybean oil/olive oil based lipid emulsions for use in PN regarding inflammatory response and oxidant capacity in the treatment of patients.

Evaluation of Quality of Life with the Chronic Obstructive Pulmonary Disease Assessment Test in Chronic Obstructive Pulmonary Disease and the Effect of Dyspnea on Disease-Specific Quality of Life in These Patients

OguzhanOkutan,Dilaver Tas,Ersin Demirer,ZaferKartaloglu 연세대학교의과대학 2013 Yonsei medical journal Vol.54 No.5

Purpose: The chronic obstructive pulmonary disease (COPD) assessment test (CAT) was recently introduced for use in assessing disease-specific quality of life and follow-up of patients with COPD. The purpose of this study was to evaluate the effect of the dyspnea on disease-specific quality of life detected by CAT score in patients with COPD. Materials and Methods: In this study, 90 stable patients with COPD as defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria were included. The level of dyspnea was assessed with the Medical Research Council (MRC) dyspnea scale, and disease-specific quality of life was assessed with CAT score. Results: The mean±SD age was 68.5±10.9 (range 41-97) years. A significant relationship was established between CAT score, MRC dyspnea scale score and GOLD stage in patients with COPD. There was also a positive correlation between dyspnea scale scores and GOLD stage in the patients (p<0.001), as well as positive correlation between CAT score and dyspnea scale score (p<0.001). CAT score showed a significant correlation with hospitalization and exacerbations (p<0.05). Conclusion: Dyspnea is an important symptom that may impact quality of life in patients with COPD. CAT was shown to be a simple, fast and intelligible measurement of disease-specific quality of life, and was correlated with levels of dyspnea in patients with COPD.

Periodontal Status of Chronic Renal Failure Patients Receiving Hemodialysis

Ismail Marakoglu,Ulvi Kahraman Gursoy,Serhat Demirer,Hafize Sezer 연세대학교의과대학 2003 Yonsei medical journal Vol.44 No.4

Host factors such as systemic diseases, genetic polymorphism or drug usage play a major role in the pathogenesis of periodontal disease by modifying the host response to periodontal infection or altering the susceptibility to infection by periodontal organisms. This study was designed to evaluate the clinical response of patients receiving hemodialysis to existing microbial dental plaque. Gingival Index (GI) and Plaque Index (PI) scores and probing depths (PD) were recorded for the entire dentition on 36 chronic renal failure patients receiving hemodialysis (H) and 36 systemically healthy individuals (C), matched with the patient group, based on age and extent of plaque accumulation. No statistically significant difference was observed in the clinical parameters between the two groups (PI: t=1.69 p= 0.096; GI: t=1.057 p=0.294; PD: t=0.01 p=0.99). In the present study, H patients revealed a similar response to existing bacterial plaque and their periodontal status was comparable to that of the control group. Although patients receiving hemodialysis have been suggested to present a certain degree of immunosuppression, based on the findings of the present study chronic renal failure does not seem to be an additional risk factor for more severe periodontal destruction. Host factors such as systemic diseases, genetic polymorphism or drug usage play a major role in the pathogenesis of periodontal disease by modifying the host response to periodontal infection or altering the susceptibility to infection by periodontal organisms. This study was designed to evaluate the clinical response of patients receiving hemodialysis to existing microbial dental plaque. Gingival Index (GI) and Plaque Index (PI) scores and probing depths (PD) were recorded for the entire dentition on 36 chronic renal failure patients receiving hemodialysis (H) and 36 systemically healthy individuals (C), matched with the patient group, based on age and extent of plaque accumulation. No statistically significant difference was observed in the clinical parameters between the two groups (PI: t=1.69 p= 0.096; GI: t=1.057 p=0.294; PD: t=0.01 p=0.99). In the present study, H patients revealed a similar response to existing bacterial plaque and their periodontal status was comparable to that of the control group. Although patients receiving hemodialysis have been suggested to present a certain degree of immunosuppression, based on the findings of the present study chronic renal failure does not seem to be an additional risk factor for more severe periodontal destruction.

Serum Soluble Urokinase Plasminogen Activator Receptor Levels in Chronic Hepatitis B and C Patients and Relationship with Clinical Parameters

( Ali Pekcan Demiröz ),( Reyhan Öztürk ),( Şener Barut ),( Salih Cesur ),( Semanur Ayyıldız ),( Vildan Fidancı ),( Osman Demir ),( Ferdi Güneş ),( Laser Şanal ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: Chronic hepatitis B (CHB) and C (CHC) are leading causes of liver cirrhosis and hepatocellular cancer. Defining of inflammatory activity and severity of disease is important for commencing antiviral treatment and monitoring the patient. Currently noninvasive serological markers to define disease activity are of great interest. In this study we aimed to determine soluble urokinase plasminogen activator receptor (suPAR) levels of patients with CHB and CHC, compare its levels with those of controls and to find if suPAR levels correlated with some laboratory parameters, histologic activity index (HAI) and fibrosis stage. Methods: Twenty-eight patients with CHB, 11 patients with CHC and 41 healthy subjects, eighty subjects in total, were included in the study. suPAR levels of all subjects were determined using commercial ELISA kits according to manufacturer’s instructions. Correlation between suPAR levels and parameters including AST, ALT, leukocyte count, thrombocyte count and liver histology scores were statistically analyzed. Results: Fifty percent of CHB patients were on oral antiviral treatment. Serum suPAR levels of both CHB and CHC patients were higher than controls (p< 0,001). Age, suPAR, HAI, AST, ALT, leukocyte and thrombocyte counts of subjects in different groups (CHB, CHC patients and controls) were shown in table 1. When we divided patients into two groups according to HBV DNA, suPAR levels were not different between patients with HBV DNA >1000 IU/ml and those with HBV DNA<1000 IU/ml. suPAR levels were not found to be correlated with AST, ALT levels, thrombocyte and leukocyte counts or histologic findings. Conclusions: In both CHB and CHC patients, suPAR levels were determined to be higher than healthy controls although suPAR was not found to be correlated with diseae activity or severity related parameters. However new wide scale studies are needed to investigate the relation between suPAR and disease activity or fibrosis stage.

Effects of ultrasound coupled with potassium permanganate pre-treatment of sludge on aerobic digestion

Demir, Ozlem Techno-Press 2016 Advances in environmental research Vol.5 No.4

The biodegradability and decomposition efficiencies increase with the pre-treatment of sludge in a digestion process. In this study, the feasibility of ultrasound coupled with potassium permanganate oxidation as a disintegration method and digestibility of aerobic reactor fed with disintegrated sludge with ultrasound coupled potassium permanganate were investigated. The first stage of the study focused on determining the optimum condition for ultrasonic pre-treatment for achieving better destruction efficiency of sludge. The second part of the study, the aerobic digestibility of sludge disintegrated with ultrasound and potassium permanganate oxidation alone and combined were examined comparatively. The results showed that when 20 min of ultrasonic pre-treatment applied, the specific energy output was 49384 kJ/kgTS with disintegration degree of 58.84%. During the operation of aerobic digester, VS/TS ratios of digesters fed with disintegrated sludge decreased indicating that disintegration methods could obviously enhance aerobic digestion performance. The highest reduction in volatile solids was 75% in the digester fed with ultrasound+potassium permanganate disintegrated sludge at the end of the operation compared to digester fed with raw sludge. Total Nitrogen (TN) and Total Phosphorus (TP) levels in sludge supernatant increased with this combined method significantly. Besides, it promoted the production of ${\bullet}OH$, thus enhancing the release of Carbon (C), Nitrogen (N) and Phosphorus (P) from the sludge. Disintegration with all methods used in this study could not improve Capillary Suction Time (CST) reduction in disintegrated digesters during the operation. The results demonstrated that the combined ultrasound treatment and potassium permanganate oxidation method improves the biodegradability compared to control reactor or their single application.

Determination of energy resolution for a NaI(Tl) detector modeled with FLUKA code

Demir, Nilgun,Kuluozturk, Zehra Nur Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11

In this study, 3" × 3" NaI(Tl) detector, which is widely used in gamma spectroscopy, was modeled with FLUKA code, and calculations required to determine the detector's energy resolution were reported. Photon beams with isotropic distribution with 59, 81, 302, 356, 511, 662, 835, 1173, 1275, and 1332 keV energy were used as radiation sources. The photon pulse height distribution of the NaI(Tl) without influence of its energy resolution obtained with FLUKA code has been converted into a real NaI(Tl) response function, using the necessary conversion process. The photon pulse height distribution simulated in the conversion process was analyzed using the ROOT data analysis framework. The statistical errors of the simulated data were found in the range of 0.2-1.1%. When the results, obtained with FLUKA and ROOT, are compared with the literature data, it is seen that the results are in good agreement with them. Thus, the applicability of this procedure has been demonstrated for the other energy values mentioned.

Clinical evaluation of efficacy of transcortical anesthesia for the extraction of impacted mandibular third molars: a randomized controlled trial

Demir, Esin,Ataoglu, Hanife The Korean Dental Society of Anesthsiology 2020 Journal of Dental Anesthesia and Pain Medicine Vol.20 No.1

Background: This study aimed to compare the pain levels during anesthesia and the efficacy of the QuickSleeper intraosseous (IO) injection system and conventional inferior alveolar nerve block (IANB) in impacted mandibular third molar surgery. Methods: This prospective randomized clinical trial included 30 patients (16 women, 14 men) with bilateral symmetrical impacted mandibular third molars. Thirty subjects randomly received either the IO injection or conventional IANB at two successive appointments. A split-mouth design was used in which each patient underwent treatment of a tooth with one of the techniques and treatment of the homologous contralateral tooth with the other technique. The subjects received 1.8 mL of 2% articaine. Subjects' demographic data, pain levels during anesthesia induction, tooth extractions, and mouth opening on postoperative first, third, and seventh days were recorded. Pain assessment ratings were recorded using the 100-mm visual analog scale. The latency and duration of the anesthetic effect, complications, and operation duration were also analyzed in this study. The duration of anesthetic effect was considered using an electric pulp test and by probing the soft tissue with an explorer. Results: Thirty patients aged between 18 and 47 years (mean age, 25 years) were included in this study. The IO injection was significantly less painful with lesser soft tissue numbness and quicker onset of anesthesia and lingual mucosa anesthesia with single needle penetration than conventional IANB. Moreover, 19 out of 30 patients (63%) preferred transcortical anesthesia. Mouth opening on postoperative first day was significantly better with intraosseous injection than with conventional IANB (P = 0.013). Conclusion: The IO anesthetic system is a good alternative to IANB for extraction of the third molar with less pain during anesthesia induction and sufficient depth of anesthesia for the surgical procedure.

THE SNOWFLAKE CURVE AS AN ATTRACTOR OF AN ITERATED FUNCTION SYSTEM

Demir, Bunyamin,Ozdemir, Yunus,Saltan, Mustafa Korean Mathematical Society 2013 대한수학회논문집 Vol.28 No.1

Although the snowflake curve, the boundary of the Koch snowflake, is one of the well-known fractals, there is no iterated function system (IFS) for it in the literature. In this study, we give an IFS for this familiar closed curve.