327 research outputs found
Computational Design of New Peptide Inhibitors for Amyloid Beta (A beta) Aggregation in Alzheimer's Disease: Application of a Novel Methodology
No full textAlzheimer's disease is the most common form of dementia. It is a neurodegenerative and incurable disease that is associated with the tight packing of amyloid fibrils. This packing is facilitated by the compatibility of the ridges and grooves on the amyloid surface. The GxMxG motif is the major factor creating the compatibility between two amyloid surfaces, making it an important target for the design of amyloid aggregation inhibitors. In this study, a peptide, experimentally proven to bind A beta 40 fibrils at the GxMxG motif, was mutated by a novel methodology that systematically replaces amino acids with residues that share similar chemical characteristics and subsequently assesses the energetic favorability of these mutations by docking. Successive mutations are combined and reassessed via docking to a desired level of refinement. This methodology is both fast and efficient in providing potential inhibitors. Its efficiency lies in the fact that it does not perform all possible combinations of mutations, therefore decreasing the computational time drastically. The binding free energies of the experimentally studied reference peptide and its three top scoring derivatives were evaluated as a final assessment/valuation. The potential of mean forces (PMFs) were calculated by applying the Jarzynski's equality to results of steered molecular dynamics simulations. For all of the top scoring derivatives, the PMFs showed higher binding free energies than the reference peptide substantiating the usage of the introduced methodology to drug design
Efficacy Levels of Organic Acids are Used for Controlling Varroa (Varroa jacobsoni Qudemans) and Their Effects on Colony Development of Honey Bees (Apis mellifera L.)
No full textThis study was carried out to determine the effects of using formic and oxalic acids against Varroa jacobsoni Q. which is the most hazardous parasite of honey bees (Apis mellifera L.) alternately in different seasons on the efficiency in Varroa treatment and colony development of honey bees. About 35 honey bee colonies in same of queen ages (1 year old) from Buckfast race were used in the research. Colonies were equalized for natural varroa levels and adult-brood bee population, prior to the research. Colonies were selected randomly as 2 treatment groups with 14 colonies and one control group with 7 colonies in the autumn and then the treatment goups were divided into 2 for using organic acids alternately so, 5 research groups (O/F, O/O, F/F, F/O and control) were used for the following spring. Varroa levels, treatment effectiveness, adult bee and brood population growth of groups were determined in autumn and spring, before and after the research. In autumn and spring experiments, Varroa infestation levels of the treatment groups were significantly reduced after the oxalic and formic acid applications (p0.05)
Forty years of research trends in long-acting injectable antipsychotics: a bibliometric analysis
No full textMert, Alper/0000-0001-5944-9089Background Using long-acting injectable (LAI) antipsychotics is crucial for treating psychiatric illnesses, particularly those within the schizophrenia spectrum. Through bibliometric analysis, our study aimed to provide an understanding of the changes in research trends related to LAIs over the past 40 years.Methods We collected the publications from 1983 to 2023 related to research studies on LAIs included in the Web of Science database. Two thousand four hundred and twelve publications were selected based on specific criteria and analyzed using the VOSviewer software and the Biblioshiny app. We obtained and presented data on institutional analysis, country analysis, author and co-authorship analysis, journal analysis, funding agencies, and keyword citation numbers.Results From the period 1983-1992 to 2014-2023, the number of total publications showed a significant growth of 4.91. The majority (approximately 90%) of publications were produced in high-income countries. The private sector may play a significant role in research. The most crucial keywords were schizophrenia and risperidone.Conclusions The trend in LAI research is currently dynamic and ongoing. There seems to be an increasing connection between studies and LAIs that contain second-generation antipsychotics. The number of studies relating to the private sector is noteworthy
Efficacy Levels of Organic Acids are Used for Controlling Varroa (Varroa jacobsoni Qudemans) and Their Effects on Colony Development of Honey Bees (Apis mellifera L.)
No full textTensor-Based Graph-Cut in Riemannian Metric Space and Its Application to Renal Artery Segmentation
No full textRenal artery segmentation remained a big challenging due to its low contrast. In this paper,we present a novel graph-cut method using tensor-based distance metric for blood vessel segmentation in scalevalued images. Conventional graph-cut methods only use intensity information,which may result in failing in segmentation of small blood vessels. To overcome this drawback,this paper introduces local geometric structure information represented as tensors to find a better solution than conventional graph-cut. A Riemannian metric is utilized to calculate tensors statistics. These statistics are used in a Gaussian Mixture Model to estimate the probability distribution of the foreground and background regions. The experimental results showed that the proposed graph-cut method can segment about 80% of renal arteries with 1mm precision in diameter.</p
Meslek yüksekokulu öğrencilerinin kariyer planlarının motivasyon düzeylerine etkilerinin araştırılması
No full textAkdemir, Ali (Arel Author), Mert Karagöz, Aslı (Arel Author), Salihoğlu, Gülay (Arel Author), Adalı, Pınar (Arel Author), Koçyiğit, Erol (Arel Author), Zaimoğlu, Özlem (Arel Author).Bu araştırma Meslek Yüksekokulları ön lisans öğrencilerinin kariyer planlarının motivasyon düzeylerine etkisini cinsiyet, vakıf veya devlet üniversitesi olma, üniversiteye giriş şekli ve okunulan bölüm boyutlarıyla araştırmaktadır. Araştırmanın örneklem grubunu 2013-2014 eğitim öğretim dönemindeki İstanbul Arel Üniversitesi ve Kocaeli Üniversitesi Meslek Yüksekokulu öğrencileri oluşturmaktadır. Basit tesadüfî örnekleme yöntemi ile belirlenen 1514 öğrenciye anket uygulanmıştır. İstatistiksel analizlerde t testi, tek yönlü varyans analizi(one-way Anova), Kariyer Planları ve Motivasyon Düzeyleri arasındaki ilişkiyi ölçmek amacıyla Korelasyon analizi yapılmıştır. Kariyer ve motivasyon için yapılan geçerlilik ve güvenirlilik analizlerine göre kariyeri oluşturan soruların Cronbach Alfa katsayısı 0,798 ve Cronbach Alfa değeri 0,742 olarak bulunmuştur. Öğrencilerin eğitim gördükleri Üniversite, eğitim alanı ile kariyer planları ve motivasyon düzeyleri arasında anlamlı farklılıklar bulunmuştur. Kariyer ile motivasyon düzeyi arasında pozitif yönde bir ilişki vardır
Reconstruction of Coronary Artery Centrelines from X-Ray Angiography Using a Mixture of Student’s t-Distributions
No full textThree-dimensional reconstructions of coronary arteries can overcome some of the limitations of 2D X-ray angiography,namely artery overlap/foreshortening and lack of depth information. Model-based arterial reconstruction algorithms usually rely on 2D coronary artery segmentations and require good robustness to outliers. In this paper,we propose a novel probabilistic method to reconstruct coronary artery centrelines from retrospectively gated X-ray images based on a probabilistic mixture model. Specifically,3D coronary artery centrelines are described by a mixture of Student’s t-distributions,and the reconstruction is formulated as maximum-likelihood estimation of the mixture model parameters,given the 2D segmentations of arteries from 2D X-ray images. Our method provides robustness against the erroneously segmented parts in the 2D segmentations by taking advantage of the inherent robustness of t-distributions. We validate our reconstruction results using synthetic phantom and clinical X-ray angiography data. The results show that the proposed method can cope with imperfect and noisy segmentation data.</p
Direct estimation of wall shear stress from aneurysmal morphology: a statistical approach
No full textComputational fluid dynamics (CFD) is a valuable tool for studying vascular diseases, but requires long computational time. To alleviate this issue, we propose a statistical framework to predict the aneurysmal wall shear stress patterns directly from the aneurysm shape. A database of 38 complex intracranial aneurysm shapes is used to generate aneurysm morphologies and CFD simulations. The shapes and wall shear stresses are then converted to clouds of hybrid points containing both types of information. These are subsequently used to train a joint statistical model implementing a mixture of principal component analyzers. Given a new aneurysmal shape, the trained joint model is firstly collapsed to a shape only model and used to initialize the missing shear stress values. The estimated hybrid point set is further refined by projection to the joint model space. We demonstrate that our predicted patterns can achieve significant similarities to the CFD-based results
A Multi-Resolution t-Mixture Model Approach to Robust Group-wise Alignment of Shapes
No full textA novel probabilistic, group-wise rigid registration framework
is proposed in this study, to robustly align and establish correspondence
across anatomical shapes represented as unstructured point sets.
Student’s t-mixture model (TMM) is employed to exploit their inherent
robustness to outliers. The primary application for such a framework is
the automatic construction of statistical shape models (SSMs) of anatomical
structures, from medical images. Tools used for automatic segmentation
and landmarking of medical images often result in segmentations
with varying proportions of outliers. The proposed approach is able to
robustly align shapes and establish valid correspondences in the presence
of considerable outliers and large variations in shape. A multi-resolution
registration (mrTMM) framework is also formulated, to further improve
the performance of the proposed TMM-based registration method. Comparisons
with a state-of-the art approach using clinical data show that
the mrTMM method in particular, achieves higher alignment accuracy
and yields SSMs that generalise better to unseen shapes
Improved Diagnosis of Systemic Sclerosis Using Nailfold Capillary Flow
No full textNailfold capillaroscopy (NC) allows non-invasive imaging of systemic sclerosis (SSc) related microvascular disease. We have developed a state-of-the-art NC system that enables fast, panoramic imaging of the whole nailfold at high-magnification, and incorporates novel software to make fully automated estimates of capillary structure and blood flow velocity. We present the first results of a study in which 50 patients with SSc, 12 with primary Raynauds phenomenon (PRP) and 50 healthy controls (HC) were imaged using the new system, and show that a combined model of capillary measurements strongly separates SSc from HC/PRP (ROC AzAz=0.93). Including capillary flow improves model performance, suggesting flow provides complementary information to capillary structure for diagnosing SSc
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