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Biomedical subjects

M Bavbek

Publications and source records attributed to M Bavbek.

At least 19 recordsLinked to original sources
PubMed2001

Lumbar myxopapillary ependymoma mimicking neurofibroma.

OBJECTIVE: To report a case of lumbar myxopapillary ependymoma in whom neuroradiological and surgical findings strongly suggested neurofibroma. CLINICAL PRESENTATION: The patient presented with a 2 year history of progressive monoparesthesia and monoparesia of his right leg. He reported having minimal fecal and urinary incontinence. INTERVENTION: Total resection of the tumor was achieved by total L1-L2 laminectomies. There was no attachment to the spinal cord and dura. CONCLUSION: In spite of contemporary sophisticated neuroradiological facilities, we may still have diagnostic difficulties in some spinal tumors.

Ependymoma↗
PubMed2000

Systemic administration of mexiletine for attenuation of cerebral vasospasm following experimental subarachnoid haemorrhage.

Mexiletine is a class Ib drug that is widely used to treat ventricular arrhythmias. This compound is mainly known as a sodium channel blocker, but studies have demonstrated that it can also activate ATP-sensitive K+ channels and block Ca2+ channels. Recent in vitro data from experiments on liposomes indicate that mexiletine is also a potent antioxidant. The unique activity profile of this drug raised the possibility that it might be of benefit in limiting cerebral vasospasm. Our first series of experiments assessed the effects of mexiletine on transclivally exposed rabbit basilar arteries. The arteries were treated with 50-mM KCl, 20-nM endothelin-1 (ET-1), or 100-microM lysophosphatidic acid (LPA) in the presence or absence of 400-mM mexiletine. Vasoconstriction caused by KCl, ET-1, and LPA was inhibited by mexiletine. In a second series of experiments, subarachnoid haemorrhage (SAH) was induced in rabbits by injecting 3-ml of autologous arterial blood into the cisterna magna. Forty-eight hours after SAH induction, transclivally exposed basilar arteries exhibited a spastic constriction that was partially reversed by topical application of 400-microM mexiletine. In a third set of experiments, mexiletine was administered orally at dosages of 80-, 20, and 5-mg/kg/day t.i.d., beginning 3 hours before SAH to study the prevention of vasospasm. In a separate group of animals, 80- and 20-mg/kg/day t.i.d. of mexiletine was administered 21 hours post-SAH induction, to study the reversal of vasoconstriction. Microscopic analysis of vessels from controls (no SAH), SAH-only, and SAH + mexiletine groups indicated there was 71.43% vascular constriction in the SAH-only group compared with controls. Considerable vasorelaxation was seen in the prevention study, in which average arterial cross-sectional areas were reduced by only 17.86% and 39.29% in the mexiletine 80- and 20-mg/kg/day groups, respectively, compared with controls (p < 0.001). Compared with controls, average arterial cross-sectional areas were reduced by 53.58% and 64.29% in the mexiletine 80- and 20-mg/kg/day reversal groups, respectively. Our findings indicate that mexiletine induces potent relaxation in cerebrovascular arteries contracted with various agents, and that it prevents and partially reverses SAH-induced vasoconstriction.

Administration, Topical↗
PubMed2000

Ogilvie's syndrome as a rare complication of lumbar disc surgery.

BACKGROUND: In this study we report a rare complication after lumbar surgery, Ogilvie's syndrome, that presents as acute colonic dilatation in the absence of mechanical obstruction. CASE: A 43-year-old obese woman underwent lumbar surgery for L4-L5 lumbar disc herniation. The patient complained of persistent abdominal distention and lack of bowel sounds. Plain radiography and ultrasonography revealed massive dilatation of the colon. Nasogastric aspiration was initiated and all analgesic drugs were withdrawn. Abdominal distention gradually disappeared within three days. CONCLUSIONS: Only three cases of Ogilvie's syndrome following lumbar spinal surgery have been reported in the literature. In our case obesity, chronic constipation, and narcotic drugs were the most likely precipitating causes. Ogilvie's syndrome may resolve with conservative treatment, but if the cecal diameter continues to increase, colonoscopy or laparotomy may be needed to prevent perforation of colon.

Adult↗
PubMed2000

Central nervous system hydatidosis in Turkey: a cooperative study and literature survey analysis of 458 cases.

OBJECT: Hydatidosis is both a medical and an economic problem in Turkey. The aim of this study was to analyze central nervous system (CNS) involvement in this disease, the related problems the disease causes, and its diagnostic and therapeutic aspects. METHODS: The authors conducted an extensive literature survey of the subject, in which papers published by Turkish authors in international and domestic journals were carefully analyzed. In addition, the authors conducted a cooperative study in which data were gathered from 47 neurosurgery departments across the country. The purpose was to determine the current status of the disease in Turkey; thus, each unit was questioned about their experience over the past 5 years. Contrary to common belief, the incidence of hydatidosis has not decreased significantly in Turkey. However, computerized tomography and magnetic resonance imaging have tremendously increased diagnostic specificity. Incidences of morbidity and mortality have improved over time, according to the results of the cooperative study, although these changes are not statistically significant. This may be attributed to experience that has been gained and to more frequent use of chemotherapy, as reflected by the cooperative study data. The two statistically significant findings of that study were expanded use of chemotherapy in the management of hydatidosis, and a higher rate of extraneural involvement in the disease. The cooperative study revealed that chemotherapy was being used more often and that there was a wider range of indications for this treatment than previously reported. The higher rate of extraneural involvement was predictable because lesions in the CNS are typically secondary in this disease. With regard to the studies' findings on cases of spinal hydatid cysts, the authors found that administration of chemotherapeutic drugs was the only statistically significant parameter (t = 3.78, p < 0.05), with the rate of chemotherapy higher in the cooperative study. CONCLUSIONS: Morbidity, mortality, and recurrence rates of hydatidosis uncovered by the cooperative study and the literature survey were not statistically significant.

Adolescent↗
PubMed1999

Giant posterior fossa teratoma.

In this study we report a rare case of a giant midline posterior fossa teratoma; its clinical presentation, radiological appearance, treatment and outcome, with an extensive review of the literature.

Brain Neoplasms↗
PubMed1999

Antioxidant action of the antiarrhythmic drug mexiletine in brain membranes.

Mexiletine is a class Ib antiarrhythmic drug used in the treatment of ventricular arrhythmias. The Na+ channel blocker mexiletine inhibits calcium influx in cells via decreasing reverse operation of the Na+-Ca2+ exchanger. Thus this drug is shown to protect the CNS white matter against anoxic/ischemic injury. The aim of our study was to investigate if this drug could act as an antioxidant drug as well. The antioxidant action of this drug was studied under different oxidant conditions in vitro, and thiobarbituric acid-reactive substances were measured to follow lipid peroxidation. Mexiletine inhibited iron-ascorbate-H2O2-induced lipid peroxidation in brain membranes, liver microsomes and phospholipid liposomes, being most effective in brain membranes. The inhibition was dose- and time-dependent. Mexiletine also inhibited copper-ascorbate-H2O2-induced lipid peroxidation but to a lesser extent. It is concluded that mexiletine has a dual effect toward oxidative injury in brain, both by inhibiting Na+-Ca2+ exchanger-dependent Ca2+ influx and by acting as an inhibitor of lipid peroxidation. However, as this drug is effective at millimolar concentrations, it should be considered less active than natural antioxidants that are effective at micromolar concentrations.

Animals↗
PubMed1998

Intracranial meningiomas. Analysis of 344 surgically treated cases.

The authors present 344 (230 females, 114 males) surgical cases of intracranial meningioma. A total of 370 interventions (344 primary procedures, 10 reexplorations for neurologic deterioration, 16 operations for recurrence) were made. Mean follow-up was 38 months. The overall evaluation revealed that 306 (88.95%) patients were completely normal or in a better condition than before operation. 18 (5.23%) were in a worse condition after operation and 20 (5.81%) died. Results suggested that complications and mortality were mostly related to localization and large volume; we also still have problems with aggressive and malignant meningiomas.

Adult↗
PubMed1998

Attenuation of experimental subarachnoid hemorrhage-induced cerebral vasospasm by CGS 26303, an endothelin-converting enzyme inhibitor.

The effect of CGS 26303, an endothelin-converting enzyme inhibitor, on the prevention and reversal of cerebral vasospasm was investigated in a rabbit model of subarachnoid hemorrhage (SAH). In the prevention study, rabbits were injected with 3 ml of autologous blood in the cisterna magna and treatment with CGS 26303 i.v. was initiated 1 h later. The compound was subsequently administered at 12, 24, and 36 h post SAH and animals were sacrificed at 48 h post SAH. Treatment with CGS 26303 at 3, 10, and 30 mg/kg resulted in dose-dependent increases in the concentrations of the compound in cerebrospinal fluid samples, and the arterial narrowing after SAH was significantly attenuated in all three groups. Morphologically, corrugation of the internal elastic lamina of vessels was often observed in the vehicle-treated group, but it was not prominent in the CGS 26303-treated groups and the healthy controls. In the reversal study, treatment with CGS 26303 was initiated 24 h post SAH and a second injection was given 12 h later. Arterial narrowing was significantly attenuated in rabbits treated with CGS 26303 at 30 mg/kg. These results demonstrate that CGS 26303 may be an effective agent in prevention and reversal of cerebral vasospasm after aneurysmal SAH.

Animals↗
PubMed1998

Monoclonal antibodies against ICAM-1 and CD18 attenuate cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits.

BACKGROUND AND PURPOSE: Inflammatory responses have been implicated in the elaboration of several forms of central nervous system injury, including cerebral vasospasm after subarachnoid hemorrhage (SAH). A critical event participating in such responses is the recruitment of circulating leukocytes into the inflammatory site. Two of the key adhesion molecules responsible for the attachment of leukocytes to endothelial cells are intercellular adhesion molecule-1 (ICAM-1) and the common beta chain of the integrin superfamily (CD18). This study examined the effects of monoclonal antibodies on ICAM-1 and the effects of CD18 on cerebral vasospasm after SAH. METHODS: A rabbit model of SAH was utilized to test the influence of intracisternally administered antibodies to ICAM-1 and CD18 on cerebral vasospasm. Antibodies were administered alone or in combination, and the cross-sectional area of basilar arteries was assessed histologically on day 2 post-SAH. RESULTS: Treatment with antibodies to ICAM-1 or CD18 inhibited vasospasm by 22% and 27%, respectively. When administered together, the attenuation of vasospasm increased to 56%. All of these effects achieved statistical significance. CONCLUSIONS: These findings provide the first evidence that the severity of cerebral vasospasm can be attenuated using monoclonal antibodies against ICAM-1 and CD18. The results reinforce the concept that cell-mediated inflammation plays an important role in cerebral vasospasm after SAH and suggest that therapeutic targeting of cellular adhesion molecules can be of benefit in treating cerebral vasospasm.

Animals↗
PubMed1998

Enhanced endogenous antioxidant activity and inhibition of cerebral vasospasm in rabbits by pretreatment with a nontoxic endotoxin analog, monophosphoryl lipid A.

OBJECT: Monophosphoryl lipid A (MPL) and diphosphoryl lipid (DPL) are derivatives of the lipopolysaccharide (endotoxin) of Salmonella minnesota strain R595. Monophosphoryl lipid A is relatively nontoxic and can stimulate the natural defense or immune system. Diphosphoryl lipid is relatively toxic; however, at higher concentrations, it can also stimulate an immune response. The purpose of the present study was to determine the effects of these endotoxin analogs on cerebral vasospasm after the onset of subarachnoid hemorrhage (SAH) in rabbits. METHODS: Intrathecal administration of MPL or DPL (5 microg/kg) was performed immediately before and 24 hours after induction of SAH in New Zealand White rabbits. Forty-eight hours after induction of SAH, the animals were killed by perfusion fixation for morphometric analyses of vessels or perfused with saline and assayed for superoxide dismutase (SOD) activity. Additional rabbits were administered MPL or DPL and killed 24 hours later for assessment of SOD activity; no SAH was induced in these animals. Experimental SAH elicited spasm of the basilar arteries in each group. Vasospasm was markedly attenuated in animals treated with MPL (p < 0.01 compared with vehicle-treated animals), but not in animals treated with DPL. A substantial reduction in SOD activity in the basilar artery accompanied the vasospasm; this loss of activity was significantly blocked by treatment with MPL, but not DPL. In animals that were not subjected to experimental SAH, MPL elicited a significant increase in SOD activity over basal levels, whereas DPL was ineffective. CONCLUSIONS: These data provide evidence of a marked protective effect of the endotoxin analog MPL against vasospasm. Although the mechanism(s) responsible for the protective effect of MPL remains to be verified, an enhancement of basal antioxidant activity and an inhibition of SAH-induced loss of this activity are attractive candidates. An MPL-based therapy could represent a useful addition to current therapies for SAH-induced cerebral injury.

Adjuvants, Immunologic↗
PubMed1998

Detection of soluble E-selectin, ICAM-1, VCAM-1, and L-selectin in the cerebrospinal fluid of patients after subarachnoid hemorrhage.

OBJECT: The goal of this study was to explore whether the levels of soluble adhesion molecules were elevated in cerebrospinal fluid (CSF) after subarachnoid hemorrhage (SAH). This association was suggested by the known inflammatory response in vasospasm and the role of vascular adhesion molecules in regulating leukocytic adhesion to, and migration across, vascular endothelium. METHODS: A prospective analysis was performed on CSF samples obtained in 17 patients who had suffered a recent aneurysmal SAH and in 16 control patients by using quantitative enzyme-linked immunosorbent assays for E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), and L-selectin. Levels of soluble forms of E-selectin (p=0.0013), ICAM-1 (p=0.0001), and VCAM-1 (p=0.048) were found to be elevated in the CSF of patients after SAH compared with levels in the CSF of norminal controls, patients with unruptured aneurysms, and patients tested months after SAH occurred. In addition, individual patients tested at the time of their initial ictus demonstrated a fall in adhesion molecule levels over time. Levels of E-selectin (p=0.044) were highest in patients who later developed moderate or severe vasospasm. CONCLUSIONS: Adhesion molecules are known to be involved in white cell adherence to the endothelium and subsequent diapedesis and migration in which a role in initiation of tissue damage is postulated. The authors have demonstrated the elevation of three adhesion molecules, with severely elevated levels of E-selectin seen in patients who later develop vasospasm. A correlation with a role of vascular adhesion molecules in the pathogenesis of cerebral vasospasm is suggested.

Adult↗
PubMed1998

Anterior pontine hydatid cyst: case report.

We report a rare case of anterior pontine hydatid cyst. Diagnosis was established on magnetic resonance imaging (MRI) findings preoperatively and was confirmed during surgery and by laboratory findings of cyst fluid, and section of cyst wall. A classical suboccipital craniectomy was performed, followed by an approach through the floor of the fourth ventricle. After a failed attempt at the Dowling technique, we punctured the cyst, aspirated the contents, then extirpated the cyst membrane. The patient survived suffering only minor morbidity. The surgical technique and pontine myelotomy are discussed.

Brain Diseases↗
PubMed1998

Interesting radiologic findings in suprasellar mass lesions. Report of three cases.

The authors report three quite rare lesions of the sellar/parasellar region. They are namely; pituitary abscess, cystic macroadenoma and osteochondroma. In none of the cases, the preoperative diagnostic priority was not same as the final histopathologic diagnosis. The radiologic findings of these pathologies are discussed with emphasis on differential diagnosis.

Abscess↗
PubMed1997

Prevention and reversal of cerebral vasospasm by an endothelin-converting enzyme inhibitor, CGS 26303, in an experimental model of subarachnoid hemorrhage.

Delayed cerebral ischemia due to cerebral vasospasm is a major cause of morbidity and mortality in patients with aneurysmal subarachnoid hemorrhage (SAH). Increasing evidence implicates the potent vasoconstrictor peptide endothelin (ET) in the pathophysiology of cerebral vasospasm. In the present study the authors examined the therapeutic value of blocking the production of ET-1 by inhibiting the conversion of its relatively inactive precursor, Big ET-1, to a physiologically active form. An inhibitor of ET-converting enzyme (ECE), CGS 26303, was injected intravenously after inducing SAH in New Zealand white rabbits. Injections of CGS 26303 were initiated either 1 hour after SAH (prevention protocol) or 24 hours after SAH (reversal protocol). One of three concentrations (3, 10, or 30 mg/kg) of CGS 26303 was injected twice daily, and all animals were killed by perfusion fixation 48 hours after SAH occurred. Basilar arteries were removed and sectioned, and their cross-sectional areas were measured in a blind manner by using computer-assisted videomicroscopy. Treatment with CGS 26303 attenuated arterial narrowing after SAH in both the prevention and reversal protocols. The protective effect of CGS 26303 achieved statistical significance at all dosages in the prevention protocol and at 30 mg/kg in the reversal protocol. These findings demonstrate that inhibiting the conversion of Big ET-1 to ET-1 via intravenous administration of an ECE inhibitor can be an effective strategy for limiting angiographic vasospasm after SAH. Moreover, the results demonstrate that treatment with the ECE inhibitor is capable of reducing vasospasm even when initiated after the process of arterial narrowing has begun. Finally, the results provide further support for the role of ET in the establishment of cerebral vasospasm. The ECE inhibitor CGS 26303 thus represents a promising therapeutic agent for the treatment of cerebral vasospasm following aneurysmal SAH.

Animals↗
PubMed1997

An unusual dumbbell form of cavernous hemangioma of the cervical spine.

Cavernous hemangiomas are vascular malformations of the central nervous system that may rarely affect the epidural space of the spine. We report a case of an epidural cavernous hemangioma which was originating from the left C8 nerve root and extending anteriorly to the apex of the left lung.

Adult↗