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Dive into the research topics where Olgun Kontas is active.

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Featured researches published by Olgun Kontas.


Journal of Pediatric Surgery | 1995

Hypoxia-induced necrotizing enterocolitis in the immature rat: The role of lipid peroxidation and management by vitamin E

Hamit Okur; Mustafa Küçükaydin; Kader Köse; Olgun Kontas; Pakize Doǧan; Ahmet Kazez

The authors developed an experimental model of necrotizing enterocolitis (NEC) by hypoxia-reoxygenation, and determined the content of malondialdehyde levels as an index of lipid peroxidation, related with a free-radical reaction in the gastrointestinal tract of newborn rats. They also investigated the role of vitamin E, an antioxidant, in this free-radical injury. The study was performed on 1-day-old rats. The 30 rat pups were divided into three groups. Hypoxia was induced by placing the pups in a 100% carbon dioxide chamber for 5 minutes. The pups were reoxygenated with 100% oxygen for 5 minutes. Group 1 (n = 10) was subjected to hypoxia-reoxygenation and killed 3 days after hypoxia. Group 2 (n = 10) was subjected to hypoxia-reoxygenation and treated with vitamin E (30 IU/kg/d intraperitoneally) for the next 3 days, and killed. Group 3 (n = 10) rats served as controls. The histopathology of the intestinal lesions in group 1 animals was characteristic of ischemic injury and ranged from superficial epithelial damage with villous shortening to transmural necrosis. In the vitamin E-treated animals these lesions were milder. The malondialdehyde levels of group 1 were significantly higher than those of the other two groups (P < .001). This study shows that oxidant-mediated lipid peroxidation injury plays a central role in mediating hypoxia-induced intestinal necrosis and suggests that vitamin E may play a therapeutic role in NEC.


Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery | 2004

Previous injuries or scars as risk factors for the development of basal cell carcinoma.

İrfan Özyazgan; Olgun Kontas

Basal cell carcinoma (BCC) is the most common malignant tumour in humans and most occur in elderly people. The pathogenesis of BCC is directly related to exposure to ultraviolet radiation in sunlight, but trauma is also mentioned occasionally. As well as one published series, several single cases have been reported. Our aim in the present study was to assess any possible relation between the development of BCC and trauma in a series of 92 patients, 12 of whom (13%) gave a history of previous injury. These lesions either developed directly after a sharp or blunt injury or in the scar tissue that had resulted from previous surgical incisions, burns, or dog bites. The male:female ratio was higher in the injured group (10:2) than in the uninjured group (44:36), but not significantly so (p = 0.11). Morphoea‐like basal cell carcinomas were more common in the injured group (n = 91) (p = 0.06). We conclude that trauma might be considered as another aetiological agent for BCC.


Neurosurgical Review | 2006

Torticollis secondary to posterior fossa and cervical spinal cord tumors: report of five cases and literature review

Hüseyin Per; Hakan Gumus; Bülent Tucer; Ali Yikilmaz; Olgun Kontas; Abdulhakim Coskun; Ali Kurtsoy

Torticollis is either congenital or acquired in childhood. Acquired torticollis is not a diagnosis but rather a sign of an underlying disorder. The causes of acquired torticollis include ligamentous, muscular, osseous, ocular, psychiatric, and neurologic disorders and may be a symptom of significant abnormalities of the spinal cord and brain, such as spinal syrinx or central nervous system neoplasia. Torticollis is rarely considered to be an initial clinical presentation of posterior fossa and cervical spinal cord tumors. We report five cases of pediatric tumors with torticollis at the onset: an astrocytoma originating from the medulla oblongata, another presumptive astrocytoma of the spinal cord located between C1 and C6 cervical vertebrae (not operated), an ependymoma located throughout the whole cervical spinal cord extending into the bulbomedullary junction, an astrocytoma originating from the bulbus and extending into the posterior fossa, and another case of a eosinophilic granuloma located extradurally through the anterior and posterior portions of the vertebral bodies from C3 to C7 producing the collapse of the sixth cervical vertebra. All five cases were seen in children, aged between 3 and 12 years. All these cases reflect the misinterpretation of this neurological sign and the lack of association with the possibility of spinal or posterior fossa tumor. This delay in the diagnosis of these diseases led to progressive neurological deterioration and to the increase in the tumor size, which made surgical intervention difficult and the prognosis unfavorable. Although torticollis secondary to tumors is rarely seen, it is necessary to be kept in mind in the differential diagnosis.


Pediatric Pathology & Laboratory Medicine | 1995

Ectopic adrenal tissue in the inguinal region in children.

Hamit Okur; Mustafa Küçükaydin; Ahmet Kazez; Olgun Kontas

Adrenal rests are common in children and are most often found as bright yellow, retroperitoneal nodules from the diaphragm to the pelvis. They are usually incidental findings during surgery. In a 12-month period, 268 children, 18 days to 15 years (mean 3.2 years) of age, underwent 304 operations for common inguinoscrotal disorders at the Department of Pediatric Surgery, Erciyes University Medical School. There were 252 males and 16 females, (M/F 15.7:1). Ectopic adrenal tissue was found in nine males (3%). This report concerns the incidence and structure of aberrant adrenal tissue found in children during inguinoscrotal operations, including its embryology, histology, and clinical implications.


Neurosurgical Review | 1996

Cranioplasty with bone flaps preserved under the scalp

Aydin Paşaoğlu; Ali Kurtsoy; R. Kemal Koç; Olgun Kontas; Hidayet Akdemir; I. Suat Öktem; Ahmet Selcuklu; I. Argun Kavuncu

Cranial bone defects in 27 patients were repaired with bone flaps preserved under the scalp. Head trauma (thirteen patients), cerebrovascular disorder (five patients), postoperative brain swelling (seven patients), and cerebral infective disease (two patients) accounted for the cranial defects. The bone flaps are reimplanted after 14–98 days. The follow-up period was 6 to 26 months. We have encountered no complications releated to this technique in 27 consecutive cases.


International Journal of Pediatric Otorhinolaryngology | 2001

Inflammatory myofibroblastic tumor of the nasal cavity : a case report and review of the literature

V Soysal; Orhan Gazi Yigitbasi; Olgun Kontas; H.A Kahya; Ercihan Güney

Our aim is to describe clinicopathological, histochemical, and immunohistochemical findings of one case of inflammatory myofibroblastic tumor of the nasal cavity. A 10-year-old female presented with a short history of nasal obstruction, epistaxis, nasal discharge and headache. Computerized tomography (CT) scans showed a space-occupying lesion in the right nasal cavity. Histological examination of initial biopsy showed fascicles of spindle cells in a mixed inflammatory background with a predominance of plasma cells, typical of inflammatory pseudotumor. The spindle cells were positive for vimentin and actin. The mass was completely excised without any difficulty under generalized anesthesia. Inflammatory myofibroblastic tumor of the nasal cavity is a localized and completely benign lesion. Simple complete excision is curative.


Leukemia & Lymphoma | 2005

Familial nodular lymphocyte predominant Hodgkin lymphoma: Successful treatment with CHOP plus rituximab

Ali Unal; Ibrahim Sari; Kemal Deniz; M. Ozkan; Olgun Kontas; Bulent Eser; Mustafa Cetin

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare tumor type distinct from classical Hodgkin lymphoma and its familial form is unusual. The two cases (mother at age 48 and son at age 30 years) of NLPHL in advanced clinical stage are described. The patients were successfully treated with an immunochemotherapy schedule consisting CHOP plus rituximab (CHOP-R). This chemotherapy was well tolerated and the patients reached complete remission. These remissions were for 34 and 40 months for mother and son, respectively. In patients with NLPHL, CHOP-R regimen should be used as an alternative treatment regimen to obtain a good long-lasting response without any adverse events.


Journal of Pediatric Surgery | 1997

A model of hypoxia-induced necrotizing enterocolitis: The role of distension

Ahmet Kazez; Nursel Küçükaydin; Mustafa Küçükaydin; Olgun Kontas; Hamit Okur; Pakize Dogan

BACKGROUND/PURPOSE This study was performed to investigate additional effects of intestinal distension in the damage to the gut caused by hypoxia-reperfusion. METHODS Five groups each consisting of ten 1-day-old Wistar albino rat pups were studied; Group 1, hypoxia-reoxygenation; Group 2, hypoxia-reoxygenation and distension; Group 3, distension and hypoxia-reoxygenation; Group 4, distension; and Group 5, control. Hypoxia was induced by placing the rat pups in a 100% carbon dioxide chamber for 5 minutes. After the hypoxia, the pups were exposed to 100% oxygen for reoxygenation for 5 minutes. The intestinal distension was carried out with a fine 21-gauge SILASTIC cannula via rectal route. The rats were killed on the third day, and all the intestine were harvested from duodenum to sigmoid colon. Malondialdehyde (MDA) levels were determined as an index of lipid peroxidation related to free radical reaction in the intestine. The histopathologic investigation was carried out by light microscopy in a blinded fashion. RESULTS The MDA levels of Group 3 animals were significantly higher than those in Group 1, 4, and the control group (P < .05). The MDA level of Group 2 did not differ significantly from that of the Group 3 (P > .05). All MDA levels of the study groups also were significantly higher than the control group (P < .05). CONCLUSION The results demonstrated that intestinal distension increased the damaging effects of hypoxia-reoxygenation in the gut.


Ophthalmic and Physiological Optics | 2003

Effect of gestational nicotine treatment on newborn rat retina: a histopathological and morphometric analysis

Cem Evereklioglu; Abdullah Ozkiris; Belgin Alasehirli; Ibrahim Sari; Emin Güldür; Beyhan Cengiz; Olgun Kontas

Background:  Smoking is a significant risk factor in several debilitating and fatal diseases. It has been implicated in bilateral tobacco‐toxic and Lebers hereditary optic neuropathies. Although it has been demonstrated that smoking has a cumulative effect on retinal and optic nerve functions and causes diffuse and localised retinal sensitivity decrease in healthy chronic heavy smokers, the affected retinal layer has not been identified and there is no experimental study investigating the effect of nicotine exposure during gestation on the newborn rat retina.


Burns | 1999

Burn scar sarcoma

İrfan Özyazgan; Olgun Kontas

Malignancies developing in burn scars have been known for a long time and are generally epidermoid carcinomas although a few sarcoma cases have been reported. A case of fibrosarcoma developing in the burn scar was presented in this report and the literature reviewed.

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