Researcher:
Çakmak, Yusuf Özgür

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Yusuf Özgür

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Çakmak

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Çakmak, Yusuf Özgür

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2014 - 20186

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    Afferent projections of the subthalamic nucleus in the rat: mphasis on bilateral and interhemispheric connections
    (Nencki Inst Experimental Biology, 2018) Çavdar, Safiye; Özgür, Merve; Çakmak, Yusuf Özgür; Kuvvet, Yasemin; Kunt, Kezban Sıla; Sağlam, Gökay; Faculty Member; PhD Student; Faculty Member; PhD Student; Undergraduate Student; Undergraduate Student; School of Medicine; Graduate School of Health Sciences; School of Medicine; Graduate School of Health Sciences; School of Medicine; School of Medicine; Koç University Hospital; 1995; 197462; N/A; N/A; N/A; N/A
    The subthalamic nucleus (STN) is important for normal movement as well as in movement disorders. The STN is a target nuclei in patients with advanced Parkinson's disease (PD). Deep brain stimulation (DBS) is a standard surgical treatment for PD. Although DBS results in a significant reduction in motor disability, several negative side effects have been reported. Thus, to understand the side effects of DBS the connection of the STN should be well known. Therefore, the present study aims to re-examine the STN with an emphasis on poorly- or un-documented connections. Furthermore, the bilateral and interhemispheric connections of the STN are evaluated. Fifteen male albino rats received injections of Fluoro-Gold retrograde and biotinylated dextran amine anterograde tracers into the STN. Following a 7-10 day survival period, the animals were processed according to the relevant protocol for each tracer. The present study demonstrates ipsilateral connections of the STN with cortical regions (i.e., infralimbic, cingulate, frontal, piriform, primary motor, primary sensory, insular and retrosplenial cortices), the endopiriform nucleus, basal ganglia related structures (i.e., caudate putamen, globus pallidus, ventral pallidum, nucleus accumbens, claustrum and substantia innominata) and the deep cerebellar nuclei (i.e., lateral, anterior interposed). Bilateral connections of the STN were observed with limbic (amygdala, bed nucleus of stria terminalis), hypothalamic (ventromedial, posterior, anterior, lateral and mammillary) thalamic (thalamic reticular nucleus), epithalamic (habenular nucleus), and brainstem structures (superior colliculus, substantia nigra, spinal nucleus of the trigeminal nerve, red nucleus, dorsal raphe nucleus, pedunculopontine tegmental nuclei). Interhemispheric connections between left and right STN were also observed. The present study fills important gaps in connectivity of the STN. In particular, we report STN connectivity with cortical areas (i.e., piriform, endopiriform and insular), claustrum, hypothalamic, thalamic reticular, cerebellar, habenular, trigeminal, red, cuneate and gracile nuclei and substantia innominate. These connections, which have not been previously described or poorly described, provide new routes that can alter the conceptual architecture of the basal ganglia circuitry and may modify our view of the functional identity of the STN.
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    Early onset of atherosclerosis of the carotid bifurcation in newborn cadavers
    (Premchand Shantidevi Research Foundation, 2016) Uslu, Bahar; Sehirli, Umit; Keskinoz, Elif Nedret; Cosgun, Erdal; Arbak, Serap; Yalin, Aymelek; Çakmak, Yusuf Özgür; Faculty Member; School of Medicine; N/A
    Introduction: The anatomy of arterial bifurcations affects blood flow and has a significant role in the development of vascular disease. Therefore, it is important to know the structural characteristics of the Common Carotid Artery (CCA) and its branches for early onset of atherosclerosis in newborns. Aim: The present study was conducted to evaluate the characteristics of CCA in newborn cadavers. Materials and Methods: Eight carotid arteries obtained from newborn cadavers were used. The outflow to inflow area ratios was calculated to evaluate vessel diameters. Additionally, scanning electron and light microscopic investigations were conducted with tissue samples. The brachial artery of each cadaver was used as controls. Correlation between area ratios and atherosclerotic endothelial damage was determined. Results: Light microscopic investigations demonstrated that control group sections showed no positivity for Oil red O staining, while carotid bifurcation regions depicted widespread occurrence of intimal lipid accumulations. Scanning electron microscopic examination of control group sections presented regular endothelial topography, while carotid bifurcation region topography exhibited numerous blood cells and separated endothelial cells. Fibrin accumulation on endothelial surface in low area ratios was another important finding in the examination of its endothelial surface degeneration. The above-mentioned morphological findings seemed to be quite parallel to outflow to inflow area ratio data favouring low area and degeneration. Conclusion: The correlation between area ratios and the histological characteristic of cerebral vessels of newborn cadavers indicate that early stages of atherosclerosis began in early embryologic life.
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    Improving testicular blood flow with electroacupuncture-like percutaneous nerve stimulation in an experimental rat model of testicular torsion
    (Wiley, 2015) Acar, Ömer; Çolakoğlu, Bülent; Camlı, Mehmet Fatih; N/A; N/A; Esen, Tarık; Çakmak, Yusuf Özgür; Faculty Member; Faculty Member; School of Medicine; School of Medicine; Koç University Hospital; 50536; N/A
    Introduction The purpose of this study was to determine the blood-flow-enhancing effect of electroacupuncture (EA) in an experimental rat model of testicular torsion. MethodsAt the first stage, 3D color Doppler ultrasound (3D-CDUS) scans were made to detect baseline perfusion of each testicle in 12 male albino Wistar rats. Then, the left testicles of all rats were twisted 180 degrees clockwise, and 3D-CDUS recordings were repeated. In the next step, 10-Hz EA was applied for 5min over the T13 and L4 dermatome territories in the study group of six rats. In the control group of six rats, acupuncture needles were inserted in the same manner, but EA was not applied. Baseline, posttorsion, and postintervention (EA and manual needling) 3D-CDUS perfusion recordings were interpreted as volumetric data, and group comparisons were performed. ResultsAfter EA, we observed statistically significant perfusion improvements in both the ipsilateral torsed and contralateral nontorsed testicles. In the control group, testicular perfusion did not show a significant change after manual needling. ConclusionEA can improve testicular blood flow bilaterally in a rat model of unilateral testicular torsion at 180 degrees.
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    Provotella-derived hydrogen sulfide, constipation, and neuroprotection in Parkinson's disease
    (Wiley-Blackwell, 2015) Çakmak, Yusuf Özgür; Faculty Member; School of Medicine; N/A
    N/A
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    The short appendix vermiformis as a risk factor for colorectal cancer
    (Wiley, 2014) Ergelen, Rabia; Ekinci, Gazanfer; Kaspar, Elif Çiğdem; Çakmak, Yusuf Özgür; Faculty Member; School of Medicine; N/A
    The human appendix vermiformis is regarded as an evolutionarily vestigial organ, although it has presumptive immune system functions and appears to support beneficial bacterial gut flora, both of which could influence cancer progression. A review of the comparative anatomy of the mammalian appendix reveals a significantly longer appendix in herbivores than in carnivorous animals. The lengthier appendix vermiformis in herbivores has been associated with the presence of cellulose-digesting bacteria that colonize the structure. In light of recent studies that have reported the digestion of small amounts of cellulose in humans and the preventive effects of a vegetarian diet on colon cancer, we conducted a retrospective study of abdominal CT scans of 60 colon cancer patients and 60 healthy people to investigate a possible relationship between colon cancer and appendix vermiformis length. The mean length of the appendix in cancer patients [65.178 mm +/- 13.46 (SD)] was shorter than that in the healthy control group [101.99 mm +/- 16.58 (SD)] and the difference was statistically significant (P < 0.001). Statistical analysis demonstrated that the ages of the cancer patient group and the control group did not differ significantly (P = 0.534). The results of the present study indicate that the appendix is not merely a vestigial structure or regressed lymphoid tissue, but rather an organ that could be critical in the development of colon cancer, whether as a result of congenital or acquired appendicular factors. Clin. Anat. 27:498-502, 2014. (c) 2014 Wiley Periodicals, Inc.
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    An earplug technique to reduce the gag reflex during dental procedures
    (Karger, 2014) Ozdogmus, Omer; Gunay, Yumusan; Gurbuzer, Bahadir; Tezulas, Emre; Kaspar, Elif Cigdem; Hacioglu, Husniye; Çakmak, Yusuf Özgür; Faculty Member; School of Medicine; N/A
    Background: The gag reflex is a frequent problem occurring during dental treatment procedures, especially while making impressions of the maxillary teeth. The present study aims to evaluate the efficacy of a simple earplug as an external auditory canal stimulator to supress the profound gag reflex and as a second step, to map areas of the oropharynx suppressed by this technique. Methods: In the first step of the study, 90 patients who had a gag reflex during the impression procedure were allocated to a study group, a sham group, and a control group for evaluating the efficacy of the earplug technique. Second, 20 new patients with a gag reflex were included in order to map the oropharnygeal areas suppressed by this technique. Results: The severity of the gag reflex was reduced in the earplug group (but not in the sham or the control group). The affected area included the hard palate, uvula, and the tongue but not the posterior wall of oropharynx. Conclusion: An earplug technique can be a useful, practical, and effective tool to overcome the gag reflex during oral procedures, such as impression procedures of maxillary teeth.