Actin, the most abundant intracellular protein, exists in a monomeric globular form (G-actin) or as polymerized filamentous actin (F-actin), and is essential for cell morphology, motility, and intracellular transport. Colchicine is a well-established anti-inflammatory drug primarily known for binding tubulin and inhibiting microtubule polymerization, yet its full mechanism of action remains unclear. Here, we investigated whether colchicine directly modulates actin cytoskeleton dynamics. Using human monocytic and murine B-lymphoma cell lines, combined with in vitro biochemical and biophysical assays, we found that colchicine binds directly to G-actin with submicromolar affinity, enhances actin polymerization, and stabilizes F-actin. Colchicine treatment in cells shifted the F-/G-actin ratio toward the filamentous form, increased cortical actin organization, and altered cell mechanical properties. Thermal shift assays confirmed increased actin stability, while molecular docking identified two potential colchicine-binding sites-one at the ATP-binding cleft in G-actin and another at the intermonomeric interface in F-actin. These findings reveal a previously unrecognized actin-modulatory role of colchicine, providing mechanistic insight into its anti-inflammatory effects and suggesting potential applications in diseases involving actin cytoskeletal dysregulation.

Understanding the electrophysiological properties of antidepressant medications is important to resolve the response heterogeneity of these drugs in clinical practice. Administration of paroxetine, a selective serotonin reuptake inhibitor, has been shown to increase serotonin levels that affect cortical activities in healthy subjects. However, the extent to which cortical oscillations can be altered by ongoing administration of paroxetine is not known. Here, we develop EEG biomarkers showing long-term effects of paroxetine. EEG changes were analyzed using Neuroscan in healthy wakeful rats administered paroxetine (4 mg/kg/day) for six weeks. Subsequent EEG recordings taken at 3 and 6 weeks after treatment showed differences in cortical oscillations obtained from both hemispheres and frontal-central-parietal regions. Chronic paroxetine administration resulted in an increase in gamma band activity. Comparison of EEG frequency bands of paroxetine and saline groups showed an enhancement in higher frequency activities at third weeks after the treatment. Higher activity of alpha oscillations in the temporal cortex was persistent at sixth week of the administration. Overall, our results suggest that chronic paroxetine administration affects cortical oscillations across an expansive network.

Objective: Antimuscarinic treatment in fasted mice and rats causes clonic convulsion soon after food intake. This study was designed to evaluate the electrophysiological markers of these convulsions and fasting in electrocorticograms in rats. Methods: Male Wistar albino rats were stereotaxically implanted with 10 cortical electrodes, and baseline electroencephalogram recordings were taken for 10 minutes. After weighing, rats were deprived of food for 52 hours. At the 24th and 52nd hours of deprivation, continuous electroencephalogram recordings were repeated. After the deprivation period, animals were treated with saline or scopolamine (3 mg/kg). Twenty minutes after injections, animals were given food pellets. After eating food, electroencephalogram recordings were taken for 60 minutes and all animals were observed simultaneously to determine the incidence and onset of convulsions. Results: These results show that food deprivation for 52 hours decreased the amplitude of the gamma band when compared to basal (P <.05) and 24 hours (P <.008) food deprivation. And the amplitude of the beta band in the 52nd hour decreased when compared to the 24th hour of food deprivation (P <.05). The treatment with scopolamine changes the effects of food deprivation on the electroencephalogram. As a typical epileptiform manifestation, refeeding after scopolamine treatment caused a series of high-voltage polyspikes and synchronized spikes with a predominant frequency in the 1-3 Hz range. Conclusions: It was revealed that the behavioral patterns of rats and the electroencephalogram properties in these convulsions are in accordance with each other.

Nanotüp tünelleme hücreler arası iletişimde rol almaktadır. Ökaryotik hücrelerin yenilenmek, hayatta kalmak ya da strese direnmek üzere nanotüp tüneller oluşturduğu düşünülmektedir. Homotipik ya da heterotipik hücreler arasında köprüler oluşturan nanotüp tünellerin kalsiyum iyon akışı gibi sinyal moleküllerini ilettiği, organel, patojen ya da onkojenik molekülleri aktardığı gösterilmiştir. Nanotüp tünellerin temel yapısı mikrofilamentlerdir. Stres oluşturan çevresel etkenler altında aktin iskeletinin nanotüp tünellerin oluşmasını tetiklediği ve birbirinden uzak iki hücre arasında köprü oluşturduğu belirlenmiştir. Uzun-süreli hücre kültürü ortamı endotel hücrelerinde strese neden olmakta ve hücresel yaşlanma oluşmaktadır. Bu çalışmada standart hücre kültürü ortamında tekrarlayan pasajlar (P) ile çoğaltılan insan göbek kordonu damar endotel hücreleri (HUVEC) arasında nanotüp tünellemenin görüntülenmesi amaçlandı. Floresan mikroskop incelemesi için aktin iskeleti ve endozomlar sırası ile falloidin ve anti-EEA1 antikoru ile işaretlendi. Kontrol grubu (P3-4) ve deney grubu (P8-10) HUVEC’ler ile hazırlanan preparatlarda nanotüp tünel uzunlukları ölçüldü. P8-10 için ortalama uzunluk 30 μm olarak belirlendi. Endozomların nanotüp tünel yapısındaki aktin iskeleti ile birlikte konumlandığı gösterildi. Bu bulgular, hücre içinde kargo taşıyan endozomların, nanotüp tünelleme ile HUVEC’ler arasında da madde aktarımı yapabileceğini göstermektedir. Sonuçta tekrarlayan pasajlar ile çoğaltılan HUVEC’ler arasındaki nanotüp tünellerin mikrofilamentlerin dinamiğine bağlı olarak işlevsel olduğu belirlenmiştir. Hücreler arasında yeni bir iletişim yolu olarak kabul gören nanotüp tünelleme, stres cevabının irdelendiği çalışmalarda morfolojik bir parametre olarak değerlendirilebilir.

Objectives: Cardiac damage in patient with diphtheritic myocarditis is reported as the leading cause of mortality. Diphtheria toxin (DTx) is a well-known bacterial toxin inducing various cytotoxic effects. Mainly, catalytic fragment inhibits protein synthesis, induces cytotoxicity, and depolymerizes actin filaments. In this study, we aimed to demonstrate the extent of myofibrillar damage under DTx treatment to porcine cardiac tissue samples. Methods: Tissue samples were incubated with DTx for 1-3 h in culture conditions. To analyze whole toxin (both fragments) distribution, conjugation of DTx with FITC was performed. Measurements were carried out with fluorescence spectrophotometer before and after dialysis. Immunofluorescence microscopy was used to show localization of DTx-FITC (15 nM) on cardiac tissue incubated for 2 h. Ultrastructural characterization of cardiac tissue samples treated with DTx (15 or 150 nM) was performed with transmission electron microscopy. Results: DTx exerts myofibrillar disorganization. Myofilament degeneration, mitochondrial damage, vacuolization, and abundant lipid droplets were determined with 150 nM of DTx treatment. Conclusions: This finding is an addition to depolymerization of actin filaments as a result of the DTx-actin interactions in in vitro conditions, indicating that myofilament damage can occur with DTx directly besides protein synthesis inhibition. Ultrastructural results support the importance of filamentous actin degeneration at diphtheritic myocarditis.

Amaç: Ökaryotik hücrelerde mikrofilament yapısının ana bileşeni olan aktin, sinyal yolaklarını aktin bağlayan proteinlerle etkileşerek düzenler. Daha önceki çalışmalarımızda difteri toksini ve mutant difteri toksini (CRM-197) ile enfekte olan endotel hücrelerinde toksinin A fragmenti ile etkileşen filamentöz aktinin depolimerleştiği saptanmıştır

CRM197, cross-reacting material 197, is a mutant of diphtheria toxin (DTx). CRM197 is used in pharmacology as a carrier protein. It has been recently shown that CRM197 causes breakdown in actin filaments. In order to show intracellular localization of CRM197 and visualize cell structure via actin cytoskeleton, endothelial cells were cultured and subjected to CRM197 in vitro. To address the interaction between CRM197 and actin both experimental and theoretical studies were carried out. Colocalization of CRM197 with actin filaments was determined by immunofluorescence microscopy. Following 24-hour incubation, the loss of cell-cell contact between cells was prominent. CRM197 was shown to bind to G-actin by gel filtration chromatography, and this binding was confirmed by Western blot analysis of eluted samples obtained following chromatography. Based on crystal structure, docked model of CRM197-actin complex was generated. Molecular dynamics simulation revealed that Lys42, Cys218, Cys233 of CRM197 interacts with Gly197, Arg62 and Ser60 of G-actin, respectively. CRM197 binding to G-actin, colocalization of CRM197 with actin filament, and actin cytoskeleton rearrangement resulting in the loss of cell-cell contact show that actin comes into sight as target molecule for CRM197.

OBJECTIVE: Diphtheria toxin (DTx) is a well-characterized bacterial toxin. However, the endocytic pathway of the mutant of DTx, CRM197, which is used as an immunological adjuvant, has not yet been fully explained. The aim of this study was to investigate the intracellular trafficking of CRM197-loaded endosomes. METHODS: Human umbilical vein endothelial cells (HUVECs) were used in a cell culture. The effective incubation time was determined by transmission electron microscopy in toxin-treated cells. Density gradient centrifugation and ADP-ribosylation assay were used to isolate and detect toxin-loaded endosomal fractions. Endosomal fractions from CRM197-treated cells were elicited after 15 minutes of incubation and the presence of fragment A was demonstrated using Western blot. Immunofluorescence microscopy was used to identify endosomes in CRM197-treated endothelial cells. RESULTS: DTx-loaded endosomes were detected as enlarged vesicles in the perinuclear area with 15 minutes of toxin treatment. DTx-loaded endosomal fractions were determined by ADP-ribosyltransferase activity test and Western blot analysis. Enzymatic activity of the toxin-loaded endosomal fraction increased by 20% in actin cytoskeletal-damaged cells treated with cytochalasin D. The steps for the toxin treatment of HUVECs with DTx and obtaining endosomal fractions were repeated for CRM197. In the CRM197-loaded endosomal fraction, actin and Hsp90 were identified in addition to fragment A. Fluorescent images revealed that CRM197-loaded endosomes were co-localized with actin filaments and that Rab11, which signals the return to the plasma membrane, was more prominent than Rab7, the lysosomal pathway indicator. CONCLUSION: These results suggest that CRM197-loaded endosomes participate in the recycling pathway.

Eukaryotic elongation factor 2 (eEF2) plays an important role in eukaryotic polypeptide chain elongation. Adenosine diphosphate (ADP)-ribosylation is a post-translational modification reaction that catalyzes the transfer of ADP-ribose group to eEF2 and this causes the inhibition of protein synthesis. Indeed, in the absence of diptheria toxin, endogenous ADP-ribosylation can occur. eEF2 is phosphorylated by eEF2 kinase which prevents binding to ribosomes thus inhibiting its activity. Increase in endogenous ADP-ribosylation level approximately 70–75 % was observed in IL-1β treated HUVECs. Moreover, a 70 % rise of phosphorylation of eEF2 was measured. Alteration of endogenous ADP-ribosylation of eEF2 activity was related with cellular mono-ADP-ribosyltransferases (ADPrT). Increment of endogenous ADP-ribosylation on eEF2 did not seem to occur as a direct effect of IL-1β; it arises from the activation of ADPrT. This 2.5 fold increase was abolished by ADPrT inhibitors. Due to these post-translational modifications, global protein synthesis is inhibited. After dephosphorylation of phospho-eEF2, around 20 % increase in protein synthesis was observed. In conclusion, systemic IL-1β has an important role in the regulation of global protein synthesis.

The aim of this study was to present the 31 year scientific research of Istanbul Faculty of Medicine (IFM) and to evaluate its national and international scientific contribution. The IFM addressed original research articles published in the 31-year period (January 1980-December 2010) were determined by using search engines PubMed, ISI Web of Sciences and Google Scholar were evaluated. A total of 4,728 IFM addressed original articles were identified [yearly mean: 151.5 +/- 145.9 (range:14-479)]. The IFM articles were 3.5% of all medical articles originated from Turkey between 1981 and 2007. One hundred and fourteen IFM articles published between 2005 and 2009 were originated from thesis (6.3% of total IFM articles between the same periods). The number of original IFM articles in 1980 was 23 and increased to 443 in 2010. The highest numbers of articles were published in the field of Internal Medicine, followed by Surgery and Basic Sciences during the 31 year period. In the last 12 years, the highest number of articles per faculty was found in the Department of Medical Genetics (2.6/faculty/year) in the field of Internal Medicine, Department of Heart and Vascular Surgery (1.87/faculty/year) in the field of Surgery and Department of Medical Biology (1.05/faculty/year) in the field of Basic Science. The number of articles increased from 0.2 to 1 per faculty between the same periods. Until the end of 2011 the total citations were 28,750, with an impact of 6.08.The number of articles with higher than 50 citations were 412. Istanbul Faculty of Medicine with its 4,728 original articles between 1980 and 2010 contributed crucially to scientific reproduction of our country. With a scientific acceleration in the last decade, Istanbul Faculty of Medicine contributed notably for Istanbul University to become the 383rd in general and 156th in the field of medicine among the leading universities of the world.

The purpose of this study is to investigate the effect of decorin, a naturally occurring proteoglycan with anti-transforming growth factor beta (TGF-β) activity, on the rat model of Peyronie's disease (PD). Twenty-five adult male Sprague-Dawley rats were divided in three groups: I) TGF-β (0.5 μg) injected (n: 8); II) TGF-β injected and decorin treated (n: 8); and III) controls (n: 9). Decorin (0.5 μg per day) was given with intracavernous injection on the second, third, fourth and fifth day following TGF-β injection. All rats underwent electrical stimulation of the cavernous nerve after 6 weeks. Intracavernosal and arterial blood pressures were measured during this procedure. Cross-sections of the rat penises were examined using Mason trichrome and H&E stains. Statistical analyses were carried out using one-way anova. Histopathological examinations confirmed the Peyronie's-like condition in TGF-β-injected rats, which exhibited a thickening of the tunica albuginea (TA), when compared to controls. Disorganisation of collagen on the TA was also prominent in TGF-β-injected rats, but not in decorin-treated and control rats. Decorin-treated rats showed significantly higher maximal intracavernosal pressure (MIP) responses to cavernous nerve stimulation, when compared to group 1 (P < 0.05). Our results indicate that decorin antagonises the effects of TGF-β in the rat model of PD and prevents diminished erectile response to cavernous nerve stimulation.

In the ongoing effort to build micro- and nanoscale machines, one of the key approaches is the bio-hybrid approach, which focuses on the use of biological constructs and engineered cells. As a natural extension of this concept to nanoscale communication, molecular communication is an umbrella term encompassing various communication systems that are built based on biological intra-and intercellular communication methods, most of which use molecules and molecular concentration as the information carrier. Compared to other proposed molecular communication systems such as diffusion-based communication and microtubular networks, calcium signaling is expected to provide a faster and more controllable system that is suitable for information dissemination and group behavior in nanoscale sensor networks. In this article, we give a general overview of calcium signaling, a novel communication paradigm that uses intercellular calcium waves in biology as a baseline, explain its capabilities, limitations, and some possible deployment scenarios. We also describe various open issues of this novel communication system and elaborate on some research directions for calcium signaling.

Background: The role of neurotrophins in allergic rhinitis (AR) has been well studied, but it has not been evaluated in idiopathic rhinitis (IR).Objective: We aimed to evaluate the nasal beta-nerve growth factor (beta-NGF) expressions of mast cells in patients with AR and IR.Methods: Seventeen patients with house dust mites-induced persistent moderate/severe allergic rhinitis (mean age: 29.7 +/- 11.96), 14 patients with idiopathic rhinitis (mean age, 29.3 +/- 10.62), and 16 healthy controls (29.9 +/- 11.57) were included in the study. Nasal biopsy specimens were taken from the posterior part of the inferior turbinate from all of the study subjects. Nasal beta-nerve growth factor and its receptors, pan-neurotrophin receptor p75, and tyrosine kinase A (trkA) were assessed with an immunofluorescence assay. Mast cells were determined by both an immunofluorescence assay and immunohistochemistry as tryptase-positive cells.Results: The beta-NGF, trkA, and p75 receptor counts were significantly higher in AR and IR patients than in the control group (P < .001, for each), but they were not different between AR and IR patients. Similarly, the ratio of beta-NGF + mast cells/total mast cells and the ratio of beta-NGF + mast cells/total beta-NGF + cells in AR and IR patients was found to be elevated when compared with the control group (P < .001, P < .001, P < .001, and P = .046, respectively); furthermore, the 2 ratios were not statistically different between the 2 patient groups.Conclusion: The increase in beta-NGF-expressing mast cells does not differ between idiopathic and allergic rhinitis. Therefore, we propose that mast cells do play a role in the pathogenesis of IR as important as in that of AR. (C) 2012 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Diphtheria toxin has been well characterized in terms of its receptor binding and receptor mediated endocytosis. However, the precise mechanism of the cytosolic release of diphtheria toxin fragment A from early endosomes is still unclear. Various reports differ regarding the requirement for cytosolic factors in this process. Here, we present data indicating that the distribution of actin filaments due to cytochalasin D action enhances the retention of diphtheria toxin in early endosomes. Treating cells with cytochalasin D reduces the cytosolic fragment A activity and leads to changes in the intracellular distribution and size of early endosomes with toxin cargo. F-actin and eukaryotic elongation factor 2 can promote fragment A release from toxin-loaded early endosomes in an in vitro translocation system. Moreover, these proteins bind to toxin-loaded early endosomes in vitro and promote each other's binding. They are thus thought to be involved in the cytosolic release of fragment A. Finally, ADP-ribosylation of eukaryotic elongation factor 2 is shown to inhibit fragment A release and, via a feed-back mechanism, to account for the minute amounts of fragment A normally found in the cytosol.

Abstract Molecular communication is a new communication paradigm that uses molecules for information transmission between nanomachines. Similar to traditional communication systems, several factors constitute limits over the performance of this communication system. One of these factors is the energy budget of the transmitter. It limits the rate at which the transmitter can emit symbols, i.e., produce the messenger molecules. In this paper, an energy model for the communication via diffusion system is proposed. To evaluate the performance of this communication system, first a channel model is developed, and also the probability of correct decoding of the information is evaluated. Two optimization problems are set up for system analysis that focus on channel capacity and data rate. Evaluations are carried out using the human insulin hormone as the messenger molecule and a transmitter device whose capabilities are similar to a pancreatic β-cell. Results show that distance between the transmitter and receiver has a minor effect on the achievable data rate whereas the energy budget’s effect is significant. It is also shown that selecting appropriate threshold and symbol duration parameters are crucial to the performance of the system.