Brain lipid profiling of triply mouse model with the deficiencies of sialidase neu1, neu4 and β-hexosaminidase a enzymes

Thesis (Master)--Izmir Institute of Technology, Molecular Biology and Genetics, Izmir, 2011Includes bibliographical references (leaves: 41-61)Text in English; Abstract: Turkish and Englishxi, 61 leavesTay-Sachs disease is a severe lysosomal storage disorder caused by mutations in the HEXA gene coding for α subunit of lysosomal β-hexosaminidase A enzyme, which converts GM2 to GM3 ganglioside. HexA-/- mice, depleted of β-hexosaminidase A enzyme, remain asymptomatic to 1 year of age, so it was thought there is a difference between human and mice lipid degradation. Previously identified a novel ganglioside metabolizing sialidase, Neu4, is abundantly expressed in mouse brain neurons. It was demonstrated that mice with targeted disruption of both HexA and Neu4 genes (HexA-/- Neu4-/-) show accumulating GM2 ganglioside and epileptic seizures with 40% penetrance. Since all mice didn't show symptoms, it was suggested that Neu4 is not the only sialidase contributing to the metabolic bypass in HexA-/- mice (Seyrantepe et al. 2010). Therefore, we studied the role of another sialidase Neu 1 in glycolipid degradation. We profiled brain glycolipid content of triple deficient mouse model with the deficiency of β-hexosaminidase A (0% activity), sialidase Neu4 (0% activity) and sialidase Neu 1 (10% activity) (NeoIn) by thin layer chromatography. Analysis of both double (HexA-/-NeoIn-/-) and triple (HexA-/-Neu4-/-NeoIn-/-) mice models showed that sialidase Neu 1 deficency causes not significant difference in brain lipid profile and though also other sialidase/sialidases might have role in glycolipid degradation pathway in mice

An analysis of the changes in food consumption frequencies before and during the COVID-19 pandemic: Turkey

Caused by the SARS-CoV-2, the COVID-19 outbreak that has turned into a global pandemic has proved that many events that would have been deemed as elements of pure fiction can indeed become reality. Millions of people in many countries isolated/are isolating themselves within the scope of self-quarantine to control the outbreak. This might affect one's dietary habits either positively or negatively. One of the first in its field, the present study statistically examines the changes in food consumption frequencies of 3017 individuals living in one of the seven regions of Turkey before and during the COVID-19 pandemic using a scale formulated with this specific purpose. As far as food consumption frequencies are concerned, while no statistically significant differences were spotted in the general total of the scale, 9 out of 10 sub-groups, the exception being the bread group, manifested statistically significant variations (p<0.001). Specifically, while the consumption of dietary supplements like propolis or vitamins C and D surged, the consumption of flour, sugar, salt, and various beverages (instant coffee, soft drinks) fell significantly. The post-COVID-19 era is considered to bring about an increase in the demand for products boosting the immune system

The impact of the covıd-19 pandemic on the frequency of food consumption

This study aimed to statistically analyze the change in the frequency of food consumption in the pre-and during the COVID-19 pandemic period in terms of the demographic characteristics of individuals. In this context, a food list consisting of 47 items and a 5-point Likert-type scale was prepared to determine the frequency of food consumption. The data were collected with an electronic questionnaire. The construct validity and reliability of the scale were examined with Confirmatory Factor Analysis, and the Cronbach Alpha (α) reliability coefficient, respectively. The data were analyzed by the Independent Sample T-Test and One-Way Analysis of Variance (ANOVA). Tukey test was used to determine the difference between groups. 3017 people with different demographic characteristics participated in the study. Compared to the pre-pandemic period, an increase was found in the frequency of dairy and breakfast products, vegetables, fruits, and nutritional supplements consumption during the pandemic. On the other hand, it was seen that there was a decrease in the frequency of bread group, meat products, and beverage consumption. There are many statistically significant findings between the frequency of food consumption according to demographic characteristics. It is estimated that lockdown, social isolation, the desire to have a strong immune system, and economic problems, which are included in our lives due to the pandemic, have led to a change in the frequency of food consumption. Besides, individuals have tended to have a healthy diet during this period. This research is one of the most comprehensive studies examining the frequency of food consumption during the COVID-19 pandemic

A guide for more accurate and precise estimations in simulative unidimensional IRT models

There is a great deal of research about item response theory (IRT) conducted by simulations. Item and ability parameters are estimated with varying numbers of replications under different test conditions. However, it is not clear what the appropriate number of replications should be. The aim of the current study is to develop guidelines for the adequate number of replications in conducting Monte Carlo simulation studies involving unidimensional IRT models. For this aim, 192 simulation conditions which included four sample sizes, two test lengths, eight replication numbers, and unidimensional IRT models were generated. Accuracy and precision of item and ability parameter estimations and model fit values were evaluated by considering the number of replications. In this context, for the item and ability parameters; mean error, root mean square error, standard error of estimates, and for model fit; M-2, RMSEA(2), and Type I error rates were considered. The number of replications did not seem to influence the model fit, it was decisive in Type I error inflation and error prediction accuracy for all IRT models. It was concluded that to get more accurate results, the number of replications should be at least 625 in terms of accuracy of the Type I error rate estimation for all IRT models. Also, 156 replications and above can be recommended. Item parameter biases were examined, and the largest bias values were obtained from the 3PL model. It can be concluded that the increase in the number of parameters estimated by the model resulted in more biased estimates

Influence of the C/O ratio on titanium and vanadium oxides in protoplanetary disks

Context. The observation of carbon-rich disks have motivated several studies questioning the influence of the C/O ratio on their gas phase composition in order to establish the connection between the metallicity of hot-Jupiters and that of their parent stars. Aims. We to propose a method that allows the characterization of the adopted C/O ratio in protoplanetary disks independently from the determination of the host star composition. Titanium and vanadium chemistries are investigated because they are strong optical absorbers and also because their oxides are known to be sensitive to the C/O ratio in some exoplanet atmospheres. Methods. We use a commercial package based on the Gibbs energy minimization technique to compute the titanium and vanadium equilibrium chemistries in protoplanetary disks for C/O ratios ranging from 0.05 to 10. Our calculations are performed for pressures ranging from 1e-6 to 1e-2 bar, and for temperatures ranging from 50 to 2000 K. Results. We find that the vanadium nitride/vanadium oxide and titanium hydride/titanium oxide gas phase ratios strongly depend on the C/O ratio in the hot parts of disks (T > 1000 K). Our calculations suggest that, in these regions, these ratios can be used as tracers of the C/O value in protoplanetary disks.Comment: Accepted for publication in A&

Green tea extract exerts anabolic effects on extracellular matrix of the skin

An in vitro trial was carried out to reveal the effects of an extract of Camellia sinensis (green tea extract) on the major extracellular matrix components of human skin. After preparing the green tea extract its phytochemical contents were analysed and its effects on gene expression of hyaluronan synthase 2, matrix metalloproteinase-9 and elastase in a human dermal fibroblast cell line were determined. Cell proliferation assay was performed using XTT reagent. Ribonucleic acid isolations were realized by using TRI reagent. Expressions of the relevant enzymes and a control enzyme glyceraldehyde-3-phosphate dehydrogenase were determined using RT-qPCR analysis. Green tea extract caused statistically significant upregulation of hyaluronan synthase-2 gene expression compared to untreated control cells. Also, as a positive outcome, the treatment resulted in significant downregulations of matrix metalloproteinase-9 and elastase gene expressions. Green tea extract was found to have substantial anabolic effects on hyaluronic acid, collagen and elastin. The results obtained in this study might partially explain the molecular basis of the health benefits and antiaging effects of Camellia sinensis on skin

Modeling the officer recruitment and manpower planning process in Turkish land forces

Cataloged from PDF version of article.The objective of this study is to improve the Turkish Land Forces officer accessions and manpower planning process. A model for planning officer accessions to Turkish Land Forces from sources that have different characteristics is presented. This model takes into account factors such as attritions, involuntary retirements, promotions and transitions to determine the impact of existing policies over the long term and to determine adjustments that might be required to reach authorized strength goals. The annual supply of accessions necessary to meet the strength goal with minimum deviations is determined. This manpower planning model is created using the modeling software GAMS.Pekmezci, ArzM.S

Algılanan COVİD-19 tehdidi ve ölüm anksiyetesinin akademisyenlerde satın alma davranışına etkisi: Türkiye-Kuzey Avrupa ülkeleri karşılaştırması

Academics, one of the occupational groups exposed to isolation in the COVID-19 epidemic, tried to adapt to the remote working regulations by not being able to maintain the social environment they were accustomed to in universities. This study aimed to examine the impact of perceived COVID-19 threat and death anxiety on revenge buying behavior by comparing academics who work in Türkiye and Northern Europe (the United Kingdom, the Netherlands, and Norway). “Revenge buying” is a term popularized in the marketing field during the global COVID-19 quarantines. It refers to the surge in shopping desire observed after the lifting of pandemic-related lockdown measures. Data was collected online by using three scales: the “Perceived COVID-19 Threat Scale”, “Templer’s Death Anxiety Scale” and “Revenge Buying Behavior Scale”. The sample consisted of total 327 academics: 163 from Türkiye (TR) and 164 from Northern Europe (NE). Structural Equation Modelling (SEM) was adopted for the analyses. The results showed that academics in NE were more prone to revenge buying behavior than TR. As the perceived threat of COVID-19 and death anxiety increased, it was determined that academics working in both TR and NE have tendencies for revenge buying. However, there was insufficient evidence to support the mediating role of death anxiety in the relationship between perceived COVID-19 threat and revenge buying behavior. In this interdisciplinary study, statistically significant differences identified based on the demographic characteristics of academics working in TR and NE have also been indicated.COVİD-19 salgınında izolasyona maruz kalan meslek gruplarından biri olan akademisyenler, üniversitelerde alıştıkları sosyal ortamlarını sürdüremeyerek, uzaktan çalışma düzenlemelerine uyum sağlamaya gayret etmişlerdir. Bu çalışmanın amacı, Türkiye ile Kuzey Avrupa’da (Birleşik Krallık, Hollanda ve Norveç) görev yapmakta olan akademisyenlerin, ölüm anksiyetesi ve algılanan COVİD-19 tehdidi algısının intikam satın alma davranışı üzerindeki etkisini incelemektir. “İntikam alışverişi”, küresel COVID-19 karantinaları sırasında pazarlama alanında popüler hale gelmiş olan bir terimdir. Pandemiye bağlı kısıtlamaların kaldırılmasının ardından, alışveriş isteğinde gözlenen artışı ifade etmektedir. Araştırma verileri çevrimiçi ortamda üç ölçek kullanılarak toplanmıştır: “Algılanan COVİD-19 Tehdit Ölçeği”, “Templer Ölüm Kaygısı Ölçeği” ve “İntikam Satın Alma Davranışı Ölçeği”. Çalışmanın örneklemini Türkiye’den 163 ve Kuzey Avrupa’dan 164 olmak üzere toplam 327 akademisyen oluşturmuştur. Analizler için Yapısal Eşitlik Modellemesi (YEM) benimsenmiştir. Sonuçlar, Kuzey Avrupa’da çalışan akademisyenlerin intikam alışverişi eğiliminin Türkiye’dekilere kıyasla daha yüksek olduğunu göstermiştir. Hem Türkiye’de hem de Kuzey Avrupa’da çalışan akademisyenlerin, algılanan COVİD-19 tehdidi ve ölüm anksiyetesi arttıkça, intikam alışverişine yönelme eğiliminde artış tespit edilmiştir. Ancak algılanan COVİD-19 tehdidi ile intikam satın alma davranışı arasındaki ilişkide ölüm anksiyetesinin aracılık rolünü destekleyecek yeterli kanıt bulunamamıştır. Disiplinlerarası olan bu çalışmada, Türkiye’de ve Kuzey Avrupa’da çalışan akademisyenlerin demografik özelliklerine göre tespit edilen istatistiksel anlamlı farklılıklar da belirtilmiştir