Researcher:
Ruacan, Ahmet Şevket

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Faculty Member

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Ahmet Şevket

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Ruacan

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Ruacan, Ahmet Şevket

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2013 - 20193

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Researcher Of Publications: search.filters.isAuthorOfPublication.9421485f-3d1c-4112-b96f-b2e27dd05fc6

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    Loss-of-function mutations in ELMO2 cause intraosseous vascular malformation by impeding RAC1 signaling
    (CELL PRESS, 2016) Çetinkaya, Arda; Xiong, Jingwei Rachel; Vargel, İbrahim; Kösemehmetoğlu, Kemal; Canter, Halil İbrahim; Gerdan, Ömer Faruk; Longo, Nicola; Alzahrani, Ahmad; Camps, Mireia Perez; Taşkıran, Ekim Zihni; Laupheimer, Simone; Botto, Lorenzo D.; Paramalingam, Eeswari; Görmez, Zeliha; Uz, Elif; Yüksel, Bayram; Sağıroğlu, Mahmut Şamil; Takahashi, Tokiharu; Reversade, Bruno; Akarsu, Nurten Ayşe; N/A; Ruacan, Ahmet Şevket; Faculty Member; School of Medicine; N/A
    Vascular malformations are non-neoplastic expansions of blood vessels that arise due to errors during angiogenesis. They are a heterogeneous group of sporadic or inherited vascular disorders characterized by localized lesions of arteriovenous, capillary, or lymphatic origin. Vascular malformations that occur inside bone tissue are rare. Herein, we report loss-of-function mutations in ELMO2 (which translates extracellular signals into cellular movements) that are causative for autosomal-recessive intraosseous vascular malformation (VMOS) in five different families. Individuals with VMOS suffer from life-threatening progressive expansion of the jaw, craniofacial, and other intramembranous bones caused by malformed blood vessels that lack a mature vascular smooth muscle layer. Analysis of primary fibroblasts from an affected individual showed that absence of ELMO2 correlated with a significant downregulation of binding partner DOCK1, resulting in deficient RAC1-dependent cell migration. Unexpectedly, elmo2-knockout zebrafish appeared phenotypically normal, suggesting that there might be human-specific ELMO2 requirements in bone vasculature homeostasis or genetic compensation by related genes. Comparative phylogenetic analysis indicated that elmo2 originated upon the appearance of intramembranous bones and the jaw in ancestral vertebrates, implying that elmo2 might have been involved in the evolution of these novel traits. The present findings highlight the necessity of ELMO2 for maintaining vascular integrity, specifically in intramembranous bones.
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    A short-term in vivo evaluation of the Istanbul heart left ventricular assist device in a pig model
    (Middle East Society for Organ Transplantation, 2019) Küçükaksu, Deniz Süha; Bakuy, Vedat; Arat, Nurcan; Erkasap, Pelin Çelikbilek; Aksoy, Emin; Department of Mechanical Engineering; N/A; N/A; N/A; N/A; N/A; Lazoğlu, İsmail; Öztürk, Çağlar; Aka, İbrahim Başar; Yalçın, Özlem; Uğurel, Elif; Ruacan, Ahmet Şevket; Faculty Member; PhD Student; PhD Student; Faculty Member; Researcher; Faculty Member; Department of Mechanical Engineering; Manufacturing and Automation Research Center (MARC); College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; School of Medicine; School of Medicine; School of Medicine; 179391; N/A; N/A; 218440; N/A; N/A
    Objectives: a continuous-flow centrifugal blood pump system has been recently developed as an implantable left ventricular assist device for patients with endstage heart failure. The objective of this study was to evaluate the initial in vivo performance of a newly developed left ventricular assist device (iHeart or Istanbul heart; Manufacturing and Automation Research Center, Koc University, Istanbul, Turkey) in an acute setting using a pig model. Materials and Methods: three pigs (77, 83, 92 kg) received implants via a median sternotomy, with animals supported for up to 6 hours. An outflow cannula was anastomosed to the ascending aorta. Anticoagulation was applied by intravenous heparin administration. During the support period, pump performance was evaluated under several flow and operating conditions. All pigs were humanely sacrificied after the experiments, and organs were examined macroscopically and histopathologically. Results: flow rate ranged between 1.5 and 3.6 L/min with pump speeds of 1500 to 2800 revolutions/min and motor current of 0.6 to 1.3 A. Initial findings confirmed thatthe iHeart ventricular assist device had sufficient hydraulic performance to support the circulation. During the experimental period, plasma free hemoglobin levels were found to be within normalranges. Thrombus formation was not observed inside the pump in all experiments. Conclusions: the iHeart ventricular assist device demonstrated encouraging hemodynamic performance and good biocompatibility in the pig model for use as an implantable left ventricular assist device. Further acute in vivo studies will evaluate the short-term pump performance prior to chronic studies for long-term evaluation.
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    Epitheloid hemangioendothelioma of the palpebral lobe of the lacrimal gland
    (Taylor & Francis Inc, 2013) Kıratlı, Hayyam; Tarlan, Berçin; N/A; Ruacan, Ahmet Şevket; Faculty Member; School of Medicine; Koç University Hospital; N/A
    Purpose: To describe a case of an epitheloid hemangioendothelioma which is a tumor of endothelial origin with borderline malignancy between hemangioma and angiosarcoma and which is very rare in the orbit. Methods: Clinical features, results of imaging and histopathological studies and postoperative clinical course of a 22-year-old female patient who presented with a gradual swelling of the left upper eyelid were reviewed. Results: Magnetic resonance imaging studies suggested a solid lesion with moderate contrast enhancement in the palpebral lobe of the lacrimal gland. A short course of systemic corticosteroid therapy failed to resolve the lesion. Excisional biopsy of the tumor yielded the diagnosis of epitheloid hemangioendothelioma of the lacrimal gland. The tumor was composed of nests of epitheloid cells, some forming CD31 positive intracytoplasmic vascular channels containing erythrocytes. CD34 and EMA were also positive and desmin, SMA, p63, S100, Factor VIII and HHV-8 were negative on immunohistochemical studies. During 44 months of follow-up, there has been no recurrence or systemic metastasis. Conclusion: Epitheloid hemangioendothelioma can occur in the palpebral lobe of the lacrimal gland as a hard, painless, immobile mass. Simple excisional biopsy of the tumor, assumed to have an intermediate malignancy grade, without further local or systemic therapy provided a disease-free 3-year survival.