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Biomedical subjects

N Ceviker

Publications and source records attributed to N Ceviker.

At least 19 recordsLinked to original sources
PubMed1999

Does thromboxane A2 synthase inhibitor UK-38485 prevent the vasoconstrictor effects of endothelin-1 on rabbit basilar artery?

Prevention of the production of thromboxane A2--a potent vasoconstrictor and aggregating metabolite of arachidonic acid--or infusion of the stable analogues of prostacyclin--which is another cyclo-oxygenase metabolite of arachidonic acid--has been shown to be beneficial in cerebral vasoconstriction. Endothelin-1, a peptide derived from endothelial cells, has been shown to induce a long-lasting cerebral vasoconstriction both in vivo and in vitro. The purpose of this study was to investigate the role of a novel thromboxane A2-synthase inhibitor UK 38485 on the acute vascular and morphological effects of Endothelin-1 applied intra-arterially on rabbit basilar arteries. The inguinal region of twenty four anaesthetized albino rabbits of both sexes were dissected and a catheter was inserted into the aorta via the femoral artery, for control angiography of the basilar artery and intra-arterial injection of ET-1 (0.25 ng total dose) and UK 38485 at a dose of 0.05 microgram kg-1 min-1 for 20 min or saline. Angiographic vasoconstriction quantification and morphological investigations of both vessels and brain stem either by light microscopy or transmission electron microscopy were the techniques applied for the study. We found out that, although the systemic administration of UK 38485 resulted in a potent antagonism of the acute vasoconstriction as visualized in angiographic studies, it did not affect the morphological changes induced by Endothelin-1 on the vessel wall. The results indicated that there might have been an interaction between Endothelin-1 and the prostaglandin synthesis mechanism in acute cerebral vasoconstriction.

Animals↗
PubMed1998

Clinical significance of acute traumatic intracranial pneumocephalus.

Among 1142 patients with head injuries hospitalized in the Neurosurgery Department of Gazi University Medical School during the period between 1979 and 1992, 583 had initial CT scans. A retrospective analysis of these initial CT images revealed intracranial air on admission in only 21 cases. These were classified as acute traumatic intracranial pneumocephalus: a potentially serious complication of head injury. CT scans were re-evaluated so as to reveal whether air was situated in the epidural, subdural, or subarachnoid spaces or intracerebrally; whether associated space-occupying lesions were present and whether the air bubbles were single or multiple. Clinical data such as the presence of persistent rhinorrhea and/or otorrhea, tension pneumocephalus, severity and type of trauma, and outcome were were also assessed to determine the significance of this rare finding.

Adolescent↗
PubMed1998

A new coated bipolar coagulator: technical note.

BACKGROUND: Sometimes charring or popping occurs and the bipolar blades get stuck to the vessel. METHODS: The tips of one of the many commercially available bipolar forceps were coated in a striped manner with Teflon--50 micro in thickness. RESULTS: The new bipolar coagulator coated with Teflon reduced the incidence of tissue sticking. CONCLUSIONS: Experience with this instrument was still quite limited, but preliminary results were promising.

Electrocoagulation↗
PubMed1998

Antiischemic effect of ZK-118.182 in rabbits: a comparative study with iloprost.

The effects of ZK-118.182, a stable analogue of PGD2, were evaluated in an endothelin-1-induced cerebral ischemia rabbit model. Ischemia was induced by endothelin-1 injection (0.25 ng bolus) into subcavian artery and ischemic changes were assessed histologically by the number of ischemic neurons in the brain stem. ZK-118.182 (2 micrograms/kg, bolus into subclavian artery) reduced the number of ischemic neurons when injected 20 min after endothelin-1 injection, Iloprost, a stable analogue of PGI2, was also effective in reducing the number of ischemic neurons in a dose of 0.5 microgram/kg (bolus into subclavian artery). The results suggested that ZK-118.182 has a potent antiischemic effect which is comparable to that of iloprost in rabbits.

Animals↗
PubMed1997

Pharmacological and pathophysiological effects of periadventitial stripping on immediate and subacute postoperative vasoconstriction in guinea pigs.

Mechanically induced vasospasm observed in the immediate post-operative period was investigated, and the effect of factors such as temporary clip applications and post-operative intervals were studied. Guinea pig "cervical internal carotid arteries" were used and temporary clips, chosen according to the diameter of the artery and systolic pressure, were applied for a standard period. The same procedure was applied on arteries in which periadventitial tissue had been removed using appropriate microsurgical techniques. On postoperative days 1, 5, and 10, arterial rings were removed while the animals were still alive and Endothelium Dependent Relaxations were measured using a bioassay system. Morphological investigations were also performed using light microscopy on the same arterial preparations. We observed no difference between perioperative and first day postoperative results. The relaxations were minimum. The most striking pathological changes were observed on postoperative day 5, and the relaxation responses began to rise on day 10 together with morphological improvement. It was also found that periadventitial tissue stripping could be used to prevent subacute post-operative vasoconstriction, since its effect was marked on postoperative day 5 and began to resolve on day 10.

Animals↗
PubMed1997

Early phase alterations in endothelium dependent vasorelaxation responses due to aneurysm clip application and related manipulations.

Mechanically induced vasoconstriction observed throughout surgery and in the immediate postoperative period was investigated to assess the effects of various microsurgical manipulations. Factors such as the type of aneurysm clip, duration of temporary clipping and peri-adventitial tissue stripping were the variables in this study. Microsurgical clips were applied on guinea pig "cervical carotid arteries" in which peri-adventitia had been removed microsurgically. Arterial rings were removed immediately after surgery. Endothelium dependent relaxations were measured and morphological investigations were performed using light microscopy. It was observed that as the clip application period increased, relaxation responses decreased. Peri-adventitial tissue stripping caused a marked decrease in the relaxation responses in all types of the clips. Microvascular clips, in spite of their lower closing forces, had the greatest deleterious effect on relaxation responses of the vessel, in both normal and peri-adventitial tissue stripped. When the peri-adventitial tissue of the vessel had been stripped, convolutions of the lamina elastica interna were found to be lost in parallel with the decreased tonus of the artery. In the vessels subjected to clipping endothelial denudation and cracking took place. As a conclusion it can be stated that both peri-adventitial tissue stripping and microvascular clip application have deleterious effects in the early postoperative period. While choosing clips from minimal occlusion force tables, care must be taken to choose clips with less width; and while performing microvascular anastomosis, temporary clips with a lesser width must be used in place of microvascular clips. Adventitial stripping must not be unnecessarily generous during microvascular anastomosis.

Animals↗
PubMed1995

Assessment of mortality associated with mild head injury in the pediatric age group.

Reducing mortality among accident and trauma patients requires careful attention to monitoring those regarded as being at low risk. We hospitalized almost 1600 head-injured patients in the period between 1979 and 1992 at the Neurosurgery Department of Gazi University Medical School, Ankara, Turkey. These patients were selected from among the numerous patients admitted to our emergency unit and treated with the same protocol in the same department. Among the hospitalized children, there were three patients defined as having a mild head injury on the basis of Glasgow Coma Scale scores of 15 who later had unfavorable outcomes. Clinical signs that might identify potentially endangered patients with mild injury were gathered; these included the presence of post-traumatic amnesia, somnolence, irritability, anisocoria, local evidence of trauma to the head, associated injuries, history of altered consciousness, and skull fracture. The study was designed to identify features by which patients who are in real danger can be distinguished among the many with trivial trauma that we face every day. We did not find any identifying clinical features and concluded that computed tomographic scanning is the only reliable answer. This will reduce avoidable mortality and morbidity by identifying the patients who are at higher risk than is at first evident.

Adolescent↗
PubMed1995

Immediate ultrastructural effects of endothelin-1 on rabbit basilar artery. A comparison between immersion and perfusion fixation techniques.

In this study intra-arterial Endothelin-1 was applied to rabbit basilar arteries and morphological findings were compared between two groups who were either perfusion fixed or immersion fixed. We planned to establish the quantitative dimension of the drug-induced morphological alterations, independent of the fixation technique's effect. There was an abundance of collagenous fibres deposited among the smooth muscle cells which was not observed in control arteries and after immersion fixation. These degenerative changes are similar to the finding following subarachnoid haemorrhage. The only fixation-related difference was the fact that lamina elastica interna was not corrugated in the perfusion fixation group. It is concluded that, the observed changes in the connective tissue of the arterial wall alter the passive elastic properties and so affect the degree of the response to the vasoactive messengers.

Animals↗
PubMed1995

Moderate head injuries in children as compared to other age groups, including the cases who had talked and deteriorated.

Patients defined as having a moderate head injury on the basis of Glasgow Coma Scale scores within the ranges of 9 to 13 after acute nonsurgical procedures were selected. Almost 1600 cases were hospitalized in the Neurosurgery Department. The cases were admitted through the Emergency Unit of Gaz University Medical School, Ankara, Turkey during the period between 1979 and 1992. The group studied consisted of 231 selected patients assessed separately in paediatric, adult and elderly age groups. Possible risk factors such as: GCS score, anisocoria, unilateral or bilateral fixed pupils, impaired oculocephalic reflexes, presence of multiple systemic injuries, aetiology of head trauma, presence of linear or depressed skull fractures, space occupying mass on CT or operation was also assessed. Subarachnoid haemorrhage turned out to be the only independent significant risk factor in predicting mortality. The data about the patients who have "talked and deteriorated" were also reported so as to assisst physicians charged with the care of trauma victims.

Adolescent↗
PubMed1995

Sella turcica fractures in a trauma series and their clinical significance.

BACKGROUND: Fractures in the region of the sella turcica (ST) are usually associated with severe blunt head trauma and may produce many complications. The true incidence is difficult to assess since there have been only about 30 cases reported in the literature. METHODS: A total of 470 computed tomography (CT) sections--with optimum bone window images of skull bone--of 1600 head trauma patients who were admitted between 1979 and 1992, inclusive, to the Neurosurgery Department of Gazi University Medical School were analyzed retrospectively. RESULTS: There were a total of 17 patients with a fracture of the ST, constituting an incidence of 3.6%, and there was a preponderance of children. CONCLUSIONS: Computed tomography was very helpful in assessing the extent of ST fractures. In our cases, these fractures were not associated with a high complication or death rate, although a cerebrospinal fluid fistula was present in 53%.

Adolescent↗
PubMed1994

Alteration by Iloprost of the vasospastic effects of endothelin-1 in rabbit cerebral vessels.

The reversal of endothelin-1 induced cerebral vasospasm with Iloprost was studied in the rabbit. Vasospasm in the basilar artery was evaluated by angiography; cerebral ischaemia by 'red-neurone-count' on light microscopy and morphological changes by electron microscopy. A potent antagonistic effect of Iloprost against ET-1 was observed in each of the parameters measured.

Animals↗
PubMed1994

Head trauma and leucocytosis.

A prospective analysis of 153 cases of head trauma was conducted with respect to their white blood cell counts. A white blood cell count exceeding 20 x 10(6)/l is associated with a poor clinical grade on admission and with a 96% mortality as opposed to that of a 23% mortality for those with slightly lower or slightly above normal white blood cell count. The sensitivity for this level is a mortality of 96% while the specificity is 77%.

Adolescent↗
PubMed1994

Co-incidence of Guillain-Barré syndrome and spinal cord compression in non-Hodgkin lymphoma.

Extradural, radicular and spinal cord compressions are severe neurological complications of lymphomas. Less frequently, involvement of the peripheral nervous system, polymyositis, myasthenia gravis and Guillain-Barré syndrome (GBS) occur. We report a patient with GBS along with a lymphoma of the spinal extradural space where at the beginning the features of GBS outweighed the symptomatology of the extradural spinal mass.

Child, Preschool↗
PubMed1993

Computer assisted quantification of vasospasm on angiograms.

We describe a new computer-based, automated method for the assessment of in vivo cerebral vasospasm. Arterial diameter measurements were performed on post-processed digital substraction angiographic images, using "pixel" as the unit. Vasospasm which was difficult to detect by visual inspection could be measured by the "stenosis quantification" program. A computer-assisted method such as we describe might decrease the risk of subjective errors.

Angiography, Digital Subtraction↗
PubMed1993

Autogenous bone grafts in cervical vertebrectomy and fusion practice for injuries.

Among the patients with a cervical injury admitted to our clinic between 1980 and 1988, 18 cases underwent a ventral fusion operation (Cloward) and 8 of them needed additional vertebrectomy. The injury in all of these cases was due to falls and presented with major compression fractures. In each case the vertebral body was resected and replaced by a "T" shaped iliac bone graft. The graft was fixated by a screw or wire when necessary, than the patients were immobilized by a bed rest for 2 weeks duration. During the follow-up period, cervical alignment was found to be stable in all patients. The radiological characteristics of the lesions, intraoperative surgical modifications for specific aspects of the lesion, other technical availabilities and the results are discussed.

Adolescent↗