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Biomedical subjects

A Colak

Publications and source records attributed to A Colak.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effect of CO2 laser on spinal epidural fibrosis.

In this study the effect of CO2 laser on spinal epidural fibrosis was examined in 24 guinea pigs which were divided into two groups. The first group was the control group, the second one the CO2 laser group. All animals had laminectomies at 3 levels. Re-exploration was performed three months after the laminectomy. In the second group the same procedure was performed but at the end of the re-exploration, CO2 laser irradiation of the epidural fibrotic tissue was done. The wounds in both groups were closed again. Four months later all animals were sacrificed. For verification and quantification of scar formation (postoperative fibrosis) light microscopic examinations and determination of hydroxyproline were done, using Bergman's spectrophotometric method. The differences which were observed between the two groups were statistically significant (U : 134, P < 0.05). This study demonstrates the reducing effect of CO2 laser irradiation on epidural scar formation. The findings encourage its use as an alternative method of prevention of epidural fibrosis after spinal surgery.

Animals↗
PubMed1995

Adenovirus-mediated gene therapy for experimental spinal cord tumors: tumoricidal efficacy and functional outcome.

We evaluated the efficacy of adenoviral-mediated gene therapy of experimental spinal cord tumors and the functional outcome after this treatment. Spinal cord tumors were generated in the thoracic region of the spinal cord in Fischer 344 rats by stereotaxic intramedullary injection of 1 x 10(4) 9L gliosarcoma cells. Seven days after tumor cell injection, a replication-defective adenoviral vector carrying the herpes simplex virus thymidine kinase gene (ADV-tk) or a control adenoviral vector carrying the beta-galactosidase gene (ADV-beta gal) was injected into the tumors. Beginning 12 h later the animals were treated with the antiviral drug ganciclovir (GCV; 50 mg/kg) or saline twice a day for 6 days. The neurological performance of the animals was assessed during and following treatment. Eighteen days after tumor cell injection, all of the control animals had paraplegia and large tumors. In contrast, no tumors were detected in animals treated with ADV-tk and GCV. In long-term studies, two of the 5 animals treated with ADV-tk and GCV remained tumor-free and remained neurologically intact at 6 months whereas all animals in the control groups became paraplegic within 18 days.

Animals↗
PubMed1995

Efficacy of high dose amino acid solution on spinal cord injury induced by focal Nd:YAG laser irradiation.

In this experimental study, a neodymium:yttrium-aluminium-garnet (Nd:YAG) laser was used to induce highly reproducible focal spinal cord lesions in anaesthetized guinea pigs. The efficacy of high dose amino acid solution (HDAAS) on this injury is investigated. Experiments were performed on 36 animals divided into three groups; sham operated controls, laser irradiated surgical controls, and amino acid groups. Acute responses to injury were evaluated with somatosensory (SSEP) and motor evoked potentials (MEP) and functional recovery was assessed for 8 weeks using the inclined plane technique. In the laser irradiated surgical control group, MEP disappeared one hour after the laser injury, but SSEP revealed changes of amplitude and latency. In this group, the average value of the inclined plane at 24 hours after the laser application was 45.3 +/- 1.4 degrees. In the amino acid group, at the sixth hour of injury, MEP and SSEP changes improved with infusion of HDAAS for 4 hours. This improvement was statistically significant (for latency of SSEP U = 140 p < 0.05). Inclined plane value at 24 hours after the laser application was 65.5 +/- 1.2 degrees in this group. This study showed that application of Nd:YAG laser irradiation on the spinal cord induced spinal cord injury which presented as paraparesis, HDAAS may provide significant therapeutic protection in secondary damage following this injury and may have a potential role in the treatment of acute spinal cord injury.

Amino Acids↗
PubMed1995

Adenovirus-mediated gene therapy in an experimental model of breast cancer metastatic to the brain.

We investigated the therapeutic efficacy of adenovirus-mediated gene therapy to treat malignant mammary tumors in vitro and in vivo in the brain. A mammary adenocarcinoma cell line derived from Fischer rats (13762 MAT B III; MAT-B) was used. In vitro studies demonstrated that the MAT-B cells could be efficiently transduced with a replication-defective adenovirus (ADV) vector that carried the herpes simplex virus gene for thymidine kinase (ADV-tk), and that ADV-tk transduction rendered the MAT-B cells sensitive to killing, in a dose-dependent manner, with ganciclovir (GCV). An animal model of a mammary tumor metastatic to the brain was produced by injecting MAT-B cells into the caudate nucleus of Fischer rats. Seven days after MAT-B cell injection, when the tumors were approximately 5 mm2 in cross-sectional size, the tumors were injected with ADV-tk or a control adenovirus vector containing the beta-galactosidase (beta-Gal) gene (ADV-beta gal). After vector injection the animals were treated with GCV or with saline for 6 days. Sixteen days after tumor cell injection, the brains were examined histologically. The rats that were injected with ADV-beta gal and treated with GCV or saline, and those that were injected with ADV-tk and treated with saline had large tumors, whereas the rats that were injected with ADV-tk and treated with GCV had no visible tumor tissue at the site of tumor cell injection. In survival studies animals treated with ADV-tk+GCV survived a significantly longer time than animals treated with ADV-beta gal+GCV. Our results demonstrate that the recombinant adenoviral vector containing the tk gene confers GCV cytotoxic sensitivity to mammary tumor cells in vitro and in the brain, and suggest that this treatment strategy may be useful in treating somatic tumors that metastasize to the brain.

Adenocarcinoma↗
PubMed1994

Brainstem auditory evoked potentials and blink reflexes in patients with pontocerebellar angle tumors.

Brainstem auditory evoked potentials (BAEP) and blink reflexes (BR) were obtained from 13 patients with pontocerebellar angle (PCA) tumors whose pathological diagnosis was as follows: 7 acoustic neurinoma, 3 meningioma, 1 neurinoma, 1 brain stem epidermoid tumor, 1 arteriovenous malformation. The most prominent abnormality was noted in BAEP generated by stimulating the ear ipsilateral to the lesion and ipsilateral R1 reflexes obtained from ipsilateral stimulation of the supraorbital nerve.

Acoustic Stimulation↗
PubMed1994

A new experimental model: for further investigation of the secondary changes following spinal cord injury.

To investigate the pathophysiology of spinal trauma, several experimental models have been used. In this study, the authors present a new experimental model for further investigation of secondary damage following spinal injury. Nd:YAG laser irradiation was applied to the spinal cord of guinea pigs to produce an injury. A 30 Watt (20 Joule) laser produced paraparesis. The injury was evaluated with evoked potentials, lipid peroxidation values, and histopathological examination.

Animals↗
PubMed1993

Reaction of rabbit lateral periventricular tissue to non-infected and infected (Staphylococcus epidermidis) shunt tubing implants. A light and transmission electron microscope study.

The reactions of periventricular tissue of the lateral ventricle to non-infected and infected (Staphylococcus Epidermidis) silicone shunt tubing were examined by light and transmission electron microscopy. It was shown that reactive changes occurred in periventricular tissue in response to the implant of sterile shunt tubing. On the other hand in infected implanted silicone shunt tubing, proliferation of inflammatory cells within the ventricle and periventricular tissue, loss of integrity of the ependyma, glial cell proliferation, and excessive extracellular oedema were demonstrated. Proliferation of ependymal cells combined with inflammatory responses may be a factor in the pathogenesis of infected shunt obstruction.

Animals↗
PubMed1993

Adult medulloblastoma presenting as a large neck tumor. Case report.

Extension of neuroepithelial tumors outside the neuroaxis is uncommon and usually follows surgical intervention. We report a patient with medulloblastoma of the right cerebellar hemisphere with extracranial extension presenting as a large neck tumor and discuss the clinical and pathological features of this case.

Adult↗
PubMed1993

Efficacy of ampicillin/sulbactam combination in experimental shunt infections caused by Staphylococcus epidermidis. A light and scanning electron microscope study.

In this study, the efficacy of ampicillin/sulbactam combination in reactions of periventricular tissue of the lateral ventricle induced by the presence of infected (Staphylococcus epidermidis) silicone rubber shunt tubing was examined by using light and scanning electron microscopy. It was demonstrated that reactive changes to implants had occurred in periventricular tissue in the control group. In infected shunt tubing without given prophylactic antibiotic group, generalized meningitis and ventriculitis, loss of integrity of ependymal cells, numerous inflammatory cells, bacterial colonies, exuda and even pus were seen. It was also shown that rarely inflammatory reactions, minimal disintegration of ependymal cells, no bacterial colonies, and phagocytes were present in the group which was given prophylactic ampicillin/sulbactam combination per and postoperatively. We think that ampicillin/sulbactam combination is very effective in prevention and treatment of shunt infections.

Ampicillin↗
PubMed1992

Meningiomas of the lateral ventricle. Report on six cases.

In this study 6 patients who had meningioma of the lateral ventricle are reviewed. The incidence is 1.8% of cases of meningiomas in our series. Microsurgical techniques were employed in all patients. There was no death and the follow-up period was between 5 months and 10 years. No recurrence was seen. Although the origin of these tumors is still not known, DUNN and KERNOHAN note that the choroid plexus has the potential for the production of meningothelial, fibrous, or mixed patterns. Our pathological results confirmed this suggestion.

Adult↗
PubMed1992

Congenital lumbosacral lipomas presenting as a form of occult spinal dysraphism. A report of 9 surgically treated cases.

Nine cases of congenital lumbosacral lipoma have been diagnosed and treated surgically at the Hacettepe University School of Medicine, Department of Neurosurgery during the last 16 years. Five patients were male and four female with ages ranging from 18 months to 30 years. The most frequent complaints were mass in the back (in five cases), motor weakness in the lower extremities (in five), urinary incontinence (in five), and lumbosacral hypertrichosis (in five). On neurological examination, four patients had deep tendon reflex changes, five had motor changes and four were normal. There was significant improvement in seven cases. Two had no improvement. In this report, we review nine patients retrospectively, and discuss the surgical intervention and the results achieved.

Adolescent↗
PubMed1991

Occipital depression fractures in childhood. A report of 14 cases.

In this paper, we present 14 cases with depression fracture of the occipital bone in pediatric age. There were 7 males and 7 females. Their ages ranged from 1 year to 15 years with a median of 5.8 years. The most common causes were: falling (8 cases); traffic accidents (2); assault (2 cases). Five of our 14 cases had compound fractures and the remaining 9 had closed fractures. Epidural and subdural hematomas were observed in 5 and 1 cases, respectively. There was significant improvement in 11 cases; two patients died.

Adolescent↗
PubMed1991

Primary multiple cerebral hydatid cysts.

Primary multiple cerebral hydatid cysts are extremely rare: In this paper, an 8-year-old male patient who has one primary cerebral hydatid cyst in each cerebral hemisphere is presented. CT findings and operation are discussed. The literature is reviewed and the incidence of multiple cerebral hydatid cyst is compared with the published reports.

Brain Diseases↗
PubMed1991

CNS involvement in Ewing's sarcoma. A report of 12 cases.

Ewing's sarcoma is one of the malignant bone tumours, which occurs in various bones of the body. When the spinal column or skull bones are involved, it may cause spinal cord compression or brain invasion. In this study, 12 cases of Ewing's sarcoma with central nervous system (CNS) involvement are presented. Seven of them were male and five female. In seven of the cases tumoural mass was located in the spinal column, whereas in the others it was found in the cranium. The major complaints were motor weakness in the lower extremities in seven cases, and a mass on the cranial vault in four cases. On neurological examination, eight of the patients had impairment of movements of the extremities (67%), and seven had sensory loss (58%). All except one patient underwent surgery. In seven cases, decompressive laminectomy plus subtotal tumour excision was performed, in three, craniectomy with grossly total tumour excision, and in one, biopsy. In this report, age and sex distribution, complaints, clinical and laboratory findings, neurological examination, and histopathology of our cases are reviewed and surgical results are compared with others reported in the literature.

Adolescent↗