WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
Browse
11 results
Search Results
Article Citation - WoS: 4Citation - Scopus: 4On Schrödinger Operators Modified by Δ Interactions(Academic Press, 2023) Akbaş, Kaya Güven; Erman, Fatih; Turgut, O. TeomanWe study the spectral properties of a Schrödinger operator H0 modified by δ interactions and show explicitly how the poles of the new Green's function are rearranged relative to the poles of original Green's function of H0. We prove that the new bound state energies are interlaced between the old ones, and the ground state energy is always lowered if the δ interaction is attractive. We also derive an alternative perturbative method of finding the bound state energies and wave functions under the assumption of a small coupling constant in a somewhat heuristic manner. We further show that these results can be extended to cases in which a renormalization process is required. We consider the possible extensions of our results to the multi center case, to δ interaction supported on curves, and to the case, where the particle is moving in a compact two-dimensional manifold under the influence of δ interaction. Finally, the semi-relativistic extension of the last problem has been studied explicitly. © 2023 Elsevier Inc.Review Citation - WoS: 25Citation - Scopus: 27Bacillus Cereus: a Review of “fried Rice Syndrome” Causative Agents(Academic Press, 2023) Leong, Sui Sien; King, Jie Hung; Korel, Figen“Fried rice syndrome” originated from the first exposure to a fried rice dish contaminated with Bacillus cereus. This review compiles available data on the prevalence of B. cereus outbreak cases that occurred between 1984 and 2019. The outcome of B. cereus illness varies dramatically depending on the pathogenic strain encounter and the host's immune system. B. cereus causes a self-limiting, diarrheal illness caused by heat-resistant enterotoxin proteins, and an emetic illness caused by the deadly toxin named cereulide. The toxins together with their extrinsic factors are discussed. The possibility of more contamination of B. cereus in protein-rich food has also been shown. Therefore, the aim of this review is to summarize the available data, focusing mainly on B. cereus physiology as the causative agent for “fried rice syndrome.” This review emphasizes the prevalence of B. cereus in starchy food contamination and outbreak cases reported, the virulence of both enterotoxins and emetic toxins produced, and the possibility of contaminated in protein-rich food. The impact of emetic or enterotoxin-producing B. cereus on public health cannot be neglected. Thus, it is essential to constantly monitor for B. cereus contamination during food handling and hygiene practices for food product preparation. © 2023 Elsevier LtdReview Citation - WoS: 6Citation - Scopus: 8Molecular Trojan Horses for Treating Lysosomal Storage Diseases(Academic Press, 2023) Leal, Andres Felipe; Rintz, Estera; Çelik, Betül; Ago, Yasuhiko; León, Daniel; İnci, Orhan Kerim; Seyrantepe, VolkanLysosomal storage diseases (LSDs) are caused by monogenic mutations in genes encoding for proteins related to the lysosomal function. Lysosome plays critical roles in molecule degradation and cell signaling through interplay with many other cell organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes. Even though several strategies (i.e., protein replacement and gene therapy) have been attempted for LSDs with promising results, there are still some challenges when hard-to-treat tissues such as bone (i.e., cartilages, ligaments, meniscus, etc.), the central nervous system (mostly neurons), and the eye (i.e., cornea, retina) are affected. Consistently, searching for novel strategies to reach those tissues remains a priority. Molecular Trojan Horses have been well-recognized as a potential alternative in several pathological scenarios for drug delivery, including LSDs. Even though molecular Trojan Horses refer to genetically engineered proteins to overcome the blood-brain barrier, such strategy can be extended to strategies able to transport and deliver drugs to specific tissues or cells using cell-penetrating peptides, monoclonal antibodies, vesicles, extracellular vesicles, and patient-derived cells. Only some of those platforms have been attempted in LSDs. In this paper, we review the most recent efforts to develop molecular Trojan Horses and discuss how this strategy could be implemented to enhance the current efficacy of strategies such as protein replacement and gene therapy in the context of LSDs. © 2023Article Citation - WoS: 19Citation - Scopus: 21Telomerase Activators From 20(27)-Octanor Via Biotransformation by the Fungal Endophytes(Academic Press, 2021) Duman, Seda; Ekiz, Güner; Yılmaz, Sinem; Yusufoğlu, Hasan; Ballar Kırmızıbayrak, Petek; Bedir, ErdalCycloastragenol [20(R),24(S)-epoxy-3 beta,6 alpha,16 beta,25-tetrahydroxycycloartane] (CA), the principle sapogenol of many cycloartane-type glycosides found in Astragalus genus, is currently the only natural product in the anti-aging market as telomerase activator. Here, we report biotransformation of 20(27)-octanor-cycloastragenol (1), a thermal degradation product of CA, using Astragalus species originated endophytic fungi, viz. Penicillium roseopurpureum, Alternaria eureka, Neosartorya hiratsukae and Camarosporium laburnicola. Fifteen new biotransformation products (2-16) were isolated, and their structures were established by NMR and HRESIMS. Endophytic fungi were found to be capable of performing hydroxylation, oxidation, ring cleavage-methyl migration, dehydrogenation and Baeyer-Villiger type oxidation reactions on the starting compound (1), which would be difficult to achieve by conventional synthetic methods. In addition, the ability of the metabolites to increase telomerase activation in Hekn cells was evaluated, which showed from 1.08 to 12.4-fold activation compared to the control cells treated with DMSO. Among the compounds tested, 10, 11 and 12 were found to be the most potent in terms of telomerase activation with 12.40-, 7.89- and 5.43-fold increase, respectively (at 0.1, 2 and 10 nM concentrations, respectively).Article Citation - WoS: 2Citation - Scopus: 2Novel 2 '-alkoxymethyl Substituted Klavuzon Derivatives as Inhibitors of Topo I and Crm1(Academic Press, 2020) Çetinkaya, Hakkı; Yıldız, Mehmet Salih; Kutluer, Meltem; Alkan, Aylin; Otaş, Hasan Ozan; Çağır, AliIn this work, 2'-alkoxymethyl substituted klavuzon derivatives were prepared starting from 2-methyl-1-naphthoic acid in eight steps. Anticancer potencies of the synthesized compounds were evaluated by performing MTT cell viability test over cancerous and healthy pancreatic cell lines, along with CRM1 inhibitory properties in HeLa cells by immunostaining and Topo I inhibition properties by supercoiled DNA relaxation assay. Their cytotoxic activities were also presented in hepatocellular carcinoma cells (HuH-7) derived 3D spheroids. Among the tested klavuzon derivatives, isobutoxymethyl substituted klavuzon showed the highest selectivity of cytotoxic activity against pancreatic cancer cell line. They showed potent Topo I inhibition while their CRM1 inhibitory properties somehow diminished compared to 4'-alkylsubstituted klavuzons. The most cytotoxic 2'-methoxymethyl derivative inhibited the growth of the spheroids derived from HuH-7 cell lines and PI staining exhibited time and concentration dependent cell death in 3D spheroids.Article Citation - WoS: 8Citation - Scopus: 91,2-Diborolanes With Strong Donor Substituents: Synthesis and High Antimicrobial Activity(Academic Press, 2021) Şahin, Yüksel; Poyrazoğlu Çoban, Esin; Sevinçek, Resul; Bıyık, Halil H.; Özgener, Hüseyin; Aygün, Muhittin1,2-diborolanes with strong and without strong donor substituents have been described, and are also referred to as 1,2-diboracyclopentane. The 1,2-diaryl/alkyl-amino-1,2-diboracyclopentanes 2, 3, and 4 were obtained in good yield after the reaction of 1,2-dichloro-1,2-diboracyclopentane 1 with ArNHLi and Me3Si-NR2. The structures of these new derivatives were characterized by nuclear magnetic resonance spectroscopy. The molecular structures of 2b, 2c, 2e, 4, and 5f were also determined by single-crystal X-ray diffraction. The newly synthesized 1,2-borolanes are stable in air and showed particularly high activity against some Gram-positive bacteria. © 2020 Elsevier Inc.Article Citation - WoS: 5Citation - Scopus: 5Nanoscale Curved Dielectric Film Characterization Beyond Diffraction Limits Using Spatially Structured Illumination(Academic Press, 2020) Ataç, Enes; Dinleyici, Mehmet SalihOptical fiber based sensor systems often utilize thin dielectric films coated on non-planar surfaces are needed to be inspected for quality assurance. However, non-destructive optical characterization of these films is not a simple method especially on curved large surfaces. In this study, we propose a real time procedure to estimate the optical properties of sub-wavelength transparent dielectric films coated on optical fibers. The paper includes developing a mathematical model and its experimental verification. The near field phase diffraction method is combined with the structured light illumination that is spatial modes of optical fibers to estimate the thickness of the phase object beyond the classical diffraction limits. Numerical simulations and experimental results show that the film thickness can safely be characterized up to one tenth of wavelength of interest via selective spatial field distribution determined according to the morphology of the thin film. The outcomes have good agreements with destructive Scanning Electron Microscope (SEM) measurements. © 2020 Elsevier Inc.Conference Object Deletion of Sialidase Neu3 Causes Progressive Neurodegeneration in Tay-Sachs Mice(Academic Press, 2016) Seyrantepe, VolkanTay-Sachs disease is a severe lysosomal disorder caused by mutations in the HEXA gene coding for α subunit of lysosomal βhexosaminidase A which converts GM2 to GM3 ganglioside. HexA-/-mice, depleted of β-hexosaminidase A gene, remains asymptomatic to 1 year of age, owing to the ability of these mice to catabolise stored GM2 ganglioside via sialidase(s) removing sialic acid into glycolipid GA2 which further processed by β-Hexosaminidase B, thereby bypassing the HexA defect.Conference Object Abnormal Gm2 Accumulation Alters the Function of the Autophagic Pathway in Early-Onset Tay-Sachs Disease Mouse Model(Academic Press, 2018) Seyrantepe, Volkan; Ateş, Nurselin; Can, Melike; Şengül, Tuğçe; Akyıldız Demir, SeçilTay-Sachs disease (TSD) is an inborn error of metabolism, a prototypical lysosomal disease of the nervous system. In humans, the fatal infantile acute form is the most common, and with no current treatment, prevention and palliative care the only options. TSD mice did not mimic human infantile TSD, and although mice showed some early pathology and storage of GM2 ganglioside, clinical disease would take many months to develop. The extremely mild disease in the TSD mice was likely due to a biochemical bypass, a neuraminidase. We recently demostrated that at least one of the principal murine neuraminidase, Neu3, responsible for the biochemical bypass in the catabolism of the GM2 ganglioside.Conference Object Alteration in Redox Homeostasis in Early-Onset Tay-Sachs Disease Mouse Model(Academic Press, 2020) Seyrantepe, Volkan; Ateş, Nurselin; Başırlı, Hatice Hande; Demir, Seçil Akyıldız; Dağalp, Berkay; Nalbant, Ayten; Çalışkan, Tufan UtkuTay-Sachs disease is an autosomal recessively inherited lysosomal disorder. It is caused by mutations on the HEXA gene encoding α-subunit of β-Hexosaminidase A enzyme. The enzyme normally catalyzes GM2 to GM3 conversion but when it is absent or dysfunctional the GM2 degradation is interrupted. The undegraded GM2 ganglioside is progressively accumulated especially in neurons and causes neurodegenaration at the end. The Hexa−/− mice generated as Tay-Sachs model was nearly normal and a bypass mechanism mediated by a sialidase was suggested. Recently we determined that Neu3 sialidase involves in ganglioside degradation in the Tay-Sachs disease pathology and the Hexa−/-Neu3−/− mice mimic the neuropathologic and clinical phenotype of the disease. It was reported that oxidative stress is triggered in neurodegenerative diseases and several lysosomal disorders. It is caused by the imbalance between antioxidant defence mechanism and production of reactive oxygen species (ROS). ROS have high chemical reactivity which react and damage DNA, protein, carbohydrates and lipids.