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Öğe Association of cardiac changes with serum adiponectin and resistin levels in obese and overweight children(Lippincott Williams & Wilkins, 2013) Akinci, Aysehan; Karakurt, Cemsit; Gurbuz, Sibel; Elkiran, Ozlem; Nalbantoglu, Ozlem; Kocak, Gulendam; Guldur, TayfunObjectives To investigate serum adiponectin and resistin levels in childhood obesity and their relationship with cardiac changes and insulin resistance. Methods Seventy-one obese and 24 overweight children and 40 healthy children and adolescents were selected for the study. Height and weight measurements, BMI values and BMI SD score values were obtained for each individual. After blood pressure measurement, left ventricular wall thickness, left ventricular mass, stroke volume, cardiac output, systolic and diastolic functions of the left ventricle were measured using an M-mode, two dimensional color-coded echocardiography device. Blood samples of the individuals were obtained for fasting blood sugar, total blood cholesterol, triglyceride, low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, insulin, C-peptide, adiponectin and resistin values. Results Cholesterol and LDL values, homeostasis model assessment of insulin resistance, fasting insulin and fasting C-peptide values of the obese and overweight groups were higher (P<0.01). Adiponectin level (P<0.001) and resistin level (P<0.05) of the obese and overweight groups were lower than those of the control group (P<0.05). Echocardiographic evaluation showed diastolic dysfunction in addition to increased left ventricular wall thickness and left ventricle mass values in the obese and overweight children. We also detected a significant positive correlation among left ventricular mass, interventricular septum systolic diameter and resistin in obese children. Among the factors, resistin level was determined as an independent predictor of left ventricular mass in obese children. Conclusion In this study, even in asymptomatic obese and overweight children, cardiac structural and functional changes, such as increased left ventricular mass and diastolic dysfunction, were demonstrated. Although decreased adiponectin level was not related to cardiac changes, it was shown that decreased serum resistin levels in the obese cases lead to left ventricle hypertrophy.Öğe Circadian rhythm in mammals: time to eat & time to sleep(Taylor & Francis Ltd, 2017) Guldur, Tayfun; Otlu, Husniye GulCircadian rhythm is defined as rhythmic fluctuations in physiological processes which enable living organisms to make necessary arrangements for upcoming changes in the environment thereby optimizing their metabolism. Mammalian circadian clock consists of feedback(negative) and feedforward (positive) loops consisting of transcription, translation and posttranslational events. It is believed that there are two kinds of clock functioning in the body. The master clock residing in hypothalamus oscillating in conjunction with light/dark cycle whereas peripheral clocks occur in peripheral tissues and influenced by other environmental factors such as feeding. The rhythmic alterations in activities of metabolic pathways are provided by the coordinated expressions of clock genes and consequently by clock-controlled genes. The current studies indicate that consumption of food at inappropriate times as well as sleep restrictions lead to metabolic dysfunctions due to disruption of circadian rhythm which result in diabetes, obesity and heart diseases. To this end, it is aimed, in this review, to examine interactions among food or sleep, metabolism and circadian rhythm with an insight into metabolomic profiling studies of circadian disturbances by sleep restrictions following an overview of working mechanisms of circadian rhythms in mammals.Öğe Comparison of stereochemical structures of cholesterol from different sources by HPLC(Marmara Univ, Fac Pharmacy, 2012) Satilmis, Basri; Guldur, Tayfun; Karakurt, Arzu; Buyuktuncel, Ebru; Ertan, MevlutIt is known that only one stereoisomeric form, nat-cholesterol, naturally occurs. Nat-cholesterol and its enantiomer, ent-cholesterol, sometimes show enantiospecific interactions with biological molecules. If cholesterol is naturally found only one form, then the question of why does cholesterol show an enantiomeric selectivity? arises. For this purpose, stereoisomer analysis of cholesterol obtained from porcine liver and wool wax were carried out with three different high performance liquid chromatography (HPLC) systems including reversed-phase, reversed-phase with different cyclodextrins as a mobile phase modifier, and chiral. Results from HPLC analysis of both cholesterol samples by permethylated gamma-cyclodextrin and amylose tris-(3,5-dimethylphenylcarbamate) chiral columns showed that there was no stereoisomer of cholesterol present. However reversed-phase HPLC analysis of cholesterol samples from porcine liver carried out with various cyclodextrins as mobile phase modifiers presented a peak which was not observed in the analysis of cholesterol samples from wool wax. On the other hand, different storage conditions of cholesterol samples and addition of cyclodextrins as mobile phase modifiers produced almost identical alterations in chromatograms of fresh samples by reversed-phase HPLC. This could be attributed to catalytic properties of cyclodextrins. Cyclodextrins may not be suitable as a mobile phase modifier in the stereoisomer analysis of cholesterol with high performance liquid chromatography.Öğe Effects of interactions between various fats and active/passive phases on postprandial inflammation in rats(Taylor & Francis Ltd, 2016) Otlu, H. Gul; Kayhan, Basak; Guldur, TayfunThe circadian clock controls number of behavioral and physiological processes during daily light/dark cycle including inflammation and vascular injury. However, how reciprocal interaction of dietary fats and light/dark cycle affects postprandial inflammation is currently unknown. To this end, effects of various dietary fats given to rats by gavaging either in light or dark phase on postprandial inflammation were compared. Sunflower oil load activated greater number of inflammatory CD markers in passive phase whereas the butter load in active phase compared to their counter phase. The inflammatory influence of fish oil load appeared to be mostly confined to passive phase. Differences found between the levels of some of the inflammatory markers in active and passive phases of normal fed rats were altered by fat/oil administrations. We conclude that influences of dietary fats/oils on postprandial inflammatory changes might depend not only on their fatty acid compositions but also on their ingestion times.Öğe Effects of reciprocal interactions between various dietary fats and circadian phases on postprandial hyperlipidemia in rats(Taylor & Francis Ltd, 2018) Satilmis, Basri; Kayhan, Basak; Guldur, TayfunExpression levels of various intestinal proteins involved in postprandial lipoprotein assembly as well as plasma triglyceride concentration exhibit daily oscillations indicating circadian control. The length of the carbon chain and degree and position of unsaturation of fatty acids influence triglyceride secretion by the enterocytes. To this end, effects of reciprocal interactions of various single fats/oil (olive oil, fish oil or butter) gavaging either in active or passive phase were investigated in rats. Fat/oil gavaged in the active phase of circadian rhythm resulted in higher postprandial serum triglyceride levels compared to that in the passive phase. Moreover, olive oil led to higher MTP activity and apo B-48 gene expression, while fish oil gavaging caused more prominent apo B-48 and MTP gene expression when they were given in the passive phase. The present results indicate that circadian time at which fat or oil gavaged once might exert influence on postprandial lipoprotein synthesis/assembly.Öğe Evaluation of changes in serum lipoprotein and apolipoprotein patterns in cows with ketosis(Amer Veterinary Medical Assoc, 2009) Ileri-Buyukoglu, Tulay; Sahinduran, Sima; Sezer, Kenan; Guldur, TayfunObjective-To detect changes in serum lipoprotein and apolipoprotein profiles via precipitation and electrophoresis in ketotic cows and in those cows treated with different methods. Animals-21 cows with clinical and subclinical ketosis, 7 healthy cows in the early lactation period, and 7 healthy cows in the nonlactation period. Procedures-Ketotic cows were allocated into 3 groups; the first group was treated with dextrose and dexamethasone, the second group with dextrose and prednisolone, and the third group with dextrose and insulin. The beta and alpha lipoproteins were precipitated with dextran sulfate-magnesium chloride in ketotic cows after treatment and healthy cows in the nonlactation and lactation periods. The serum samples, precipitates, and supernatants were examined via agarose gel electrophoresis for detection of alterations in serum lipoproteins. Subsequently, alterations in serum apolipoproteins were detected via SDS-PAGE of precipitates. Results-Compared with serum beta and alpha lipoprotein concentrations in healthy cows during nonlactation, those in cows during lactation were higher; however, those in cows with ketosis were lower. The SDS-PAGE analysis of serum beta lipoproteins revealed that apolipoprotein E (approx 36 and 40 kDa) decreased in ketotic cows, in comparison with healthy cows in the nonlactation and lactation periods, but increased after treatment. Decreases in apolipoprotein B (approx 222 kDa), apolipoprotein A-I(19 and 24 kDa), apolipoprotein A-IV (55 kDa), apolipoprotein C-III (8.8 and 10.2 kDa), and albumin (66 kDa) concentrations were detected in ketotic cows, in comparison with the healthy cows in the lactation period. Conclusions and Clinical Relevance-Serum lipoprotein and apolipoproteins may routinely be determined via precipitation and electrophoresis in the diagnosis and treatment of ketosis. (Am J Vet Res 2009;70:563-570)Öğe INVESTIGATION OF HYDROPHOBIC CHARACTERISTICS OF BIOFILM PRODUCER AND NON-PRODUCER STAPHYLOCOCCUS AUREUS CLINICAL ISOLATES(Ankara Microbiology Soc, 2010) Ay, Selma; Guldur, Tayfun; Tekerekoglu, Mehmet Sait; Otlu, BarisThe ability of staphylococcus to adhere certain structures and to form biofilm (slime) layer plays an important role in the pathogenesis of staphylococcal infections. Hydrophobic interactions and hydrogen bonds are important factors that play role in adherence This study was designed to compare the hydrophobic properties of slime positive and negative Staphylococcus aureus strains isolated from blood cultures. Ten methicillin-resistant S.aureus isolates (five of them being slime positive) obtained from blood cultures of patients at intensive care unit of a university hospital, between May 2006 and June 2007, were included in the study. Slime production of the isolates was determined by Christensen's method. Methicillin resistance was determined by cefoxitin disc test and oxacillin salt agar test It was determined that the test strains did not exhibit any autoaggregation The adherence of strains to the three different hydrocarbons as solid phases (butyl-sepharose, octyl-sepharose and phenyl-sepharose; Amersham Bioscience, Sweden) were studied by using hydrophobic interaction chromatography (HIC) method After butyl- and octyl-sepharose chromatography, it was determined that slime negative S aureus strains were separated into three fractions eluted with phosphate buffered saline (PBS), 40% and 96% ethanol, while slime positive strains were separated into two fractions eluted with 40% and 96% ethanol, respectively. By phenyl-sepharose chromatography analysis, both slime negative and positive strains were separated into two fractions eluted in 40% and 96% ethanol. Hydrophobicity tests were repeated at 4 C and pH 6-9 to evaluate the effect of changing conditions on hydrophobicity However, no changes were observed at these temperature and pH values. According to these analysis it was concluded that; (a) S aureus strains consist heterogeneous fractions with distinct hydrophobic binding strengths, (b) hydrophobic surface protein secretion may be different in heterogeneous groups, and (c) slime positive S aureus strains were more hydrophobic than non-slime producing strains Further research is required in order to characterise the eluted fractions and to evaluate their pathogenic capacities.Öğe Potential linkages between circadian rhythm and membrane lipids: timekeeper and bilayer(Taylor & Francis Ltd, 2023) Guldur, TayfunMembrane lipids play significant roles in cellular functions, including those controlled by circadian machinery (e.g., membrane transport). Membranes have been overlooked during the investigation of circadian mechanisms. The findings of previous studies suggest that membrane action potentials and phospholipid composition exhibit daily oscillations, which involve changes in fatty acid saturation and chain length, and are subjected to fatty chain remodeling. Thus, it is possible that membranes are affected by oscillatory output rhythms from cellular autonomous clocks. The regulation of lipid chain length and degree of unsaturation, along with resulting changes in membrane lipid polymorphic properties, may serve as the basis of an important mechanism that mediates the circadian regulation of various membrane-associated processes. However, direct evidence indicating that membrane lipid oscillations are part of the circadian machinery has yet to be reported. This review updates the current understanding of potential connections between the membrane bilayer and the circadian clock, with important implications for circadian rhythm disorders and related chronic diseases, such as obesity, diabetes, and cardiovascular disease.
