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Biomedical subjects

M Tuna

Publications and source records attributed to M Tuna.

At least 19 recordsLinked to original sources
PubMed2003

Choroid plexus papilloma of bilateral lateral ventricle.

BACKGROUND: Choroid plexus papillomas are rare, accounting for less than 1% of all intracranial tumours in adults. However, they are relatively more common in childhood and constitute 1.5 to 4% of intracranial tumours. They are most often located in the lateral ventricle, followed by the fourth and third ventricles and, rarely, in the cerebellopontine angle. Bilateral lateral ventricle choroid plexus papilloma is very rare and only a few cases has been reported. CLINICAL PRESENTATION: A 3-year-old boy was admitted to our hospital with a history of irritability and vomiting. Neurological examination on admission was normal. A head computed tomographic scan and magnetic resonance imaging showed tumours in both lateral ventricles, hydrocephalus and a left temporal arachnoid cyst. The bilateral intraventricular mass enhanced densely and homogeneously. A presumptive diagnosis of choroid plexus papillomas was made. INTERPRETATION: The initial surgery was performed for removal of the lesion in the right lateral ventricle, and 20 days later removal of the left lateral ventricle tumour was carried out. Bilateral temporoparietal craniotomy and total removal of tumours was performed. Hydrocephalus was controlled by total tumour resection from both sides. The histology of these tumours was the same and revealed choroid plexus papilloma. Interpretation: Bilateral choroid plexus papilloma is extremely rare and distinct from diffuse villous hypertrophy and their surgical approaches are different from each other. Differential diagnosis should be made by MRI preoperatively. If bilateral choroid plexus papilloma is detected, total surgical resection should be performed. Total surgical removal of the neoplasm not only cures the tumour but also may lead to complete resolution of the hydrocephalus.

Child, Preschool↗
PubMed2002

The evaluation and comparison of cerebellar mutism in children and adults after posterior fossa surgery: report of two adult cases and review of the literature.

BACKGROUND: Although there are some cases of cerebellar mutism in adults after posterior fossa surgery for cerebellar tumour it generally occurs in children. Reversible pathophsiology and the anatomical substrate of this syndrome still remain unclear. The predominance of cerebellar mutism in children is suggested to be related to the higher incidence of posterior fossa tumours in children. However, the question regarding the reason for the obvious difference in the incidence of this syndrome between the paediatric and adult population still remaining unanswered. The aim of this study was to evaluate and compare children and adult groups separately to understand the incidence and the clinical characteristics better and to elucidate the pathophysiological basis and predictive factors for this syndrome. METHOD: We reviewed, analysed, and compared the cases of cerebellar mutism individually in children and in adults reported in the English literature. We found 106 reported cases in children and 11 cases in adults which were suitable for analysis. We added two adult cases to these. FINDINGS: The ages of the patients ranged from 2 to 16 (mean, 6.4 year) in children and from 17 to 74 (mean, 38.7 year) in adults. Although vermis was the main location in both groups, the incidence of vermis lesions was considered higher in the paediatric population (%91.5 versus %69.2). The rate of brain stem invasion was prominent in children (%31.1) when compared with adults (%7.6). The latency for the development of mutism and the duration of the mutism were similar in children and adults (mean, 1.4 d versus 2 d and mean, 5.07 wk versus 4.2 wk respectively). Mutism was transient in all the cases of both groups. INTERPRETATION: Recent concepts of cerebellar physiology disclose the importance of the cerebellum in learning, language, and mental and social functions. Pontine nuclei, the thalamus, motor and sensory areas and supplementary motor areas have been proven necessary for the initiation of speech. It can be hypothesized that uncompleted maturation of the reciprocal links in childhood connecting the cerebellum to these structure makes the children more vulnerable to have postoperative cerebellar mutism in comparison to the adult population.

Adolescent↗
PubMed2001

Postoperative radicular neuroma. Case report.

Lumbar discectomy is the most common surgical procedure performed in neurosurgery clinics. Such a large number of procedures underscore not only the prevalence of conditions such as intervertebral disc herniation, but also the strong belief of surgeons that the operation does provide benefits to patients suffering from sciatica. In spite of this belief, sciatic pain may continue after the surgery. The recurrence of sciatic and/or back pain after primary discectomy is called the "failed back surgery syndrome." The rate of the complications involved in standard lumbar discectomy ranges from 5.4 to 14%. One of the complications of the lumbar disc surgery is nerve root injury. The complication rate of this injury ranges from 0.7 to 2.2%. Postoperative radicular neuroma must be considered in differential diagnosis for the patient who has failed back surgery syndrome. In this study the authors evaluate a patient who had undergone surgery for lumbar disc herniation and suffered intractable pain. A traumatic radicular neuroma is demonstrated and the pertinent literature is presented.

Adult↗
PubMed2001

Intracranial intraosseous hydatid cyst. Case report and review of literature.

Cerebral hydatidosis accounts for approximately 1 to 3% of all cases of hydatid disease. Generally, cerebral hydatid cysts are single lesions located in the watershed of the middle cerebral artery. Primary intracranial extracerebral hydatid cysts are extremely rare. Only 2% of hydatid cysts are localized in the skeleton, and of these 3 to 4% are found in the skull. The authors describe the case of a 10-year-old boy who was admitted to their clinic with headache and unilateral focal epileptic seizures. Computerized tomography scanning revealed a right parietal intraosseous hydatid cyst. A case of cranial intraosseous hydatid disease is presented, and the differential diagnosis and treatment are discussed in the light of literature.

Brain Diseases↗
PubMed2001

Intracerebral ganglioglioma: clinical and radiological study of eleven surgically treated cases with follow-up.

BACKGROUND: Gangliogliomas are rare benign tumors of the CNS consisting of differentiated neural elements and low-grade glial cells. METHODS: We reviewed our experience of 11 patients with histologically proven ganglioglioma who were surgically treated since 1986 at Cukurova University Medical Center. These patients presented at 18 to 45 years of age. Five were women and six were men. The most common initial symptom was seizures (in nine of 11 patients), which had sometimes persisted over long periods of time. At the time of diagnosis, four patients had focal neurological deficits and three had signs or symptoms of increased intracranial pressure. The cystic and well-circumscribed characteristics of these lesions were detected on computed tomography (CT). Despite their appearance on CT, all but one of the lesions were found to be mostly solid at operation. Magnetic resonance imaging (MRI) in six patients revealed abnormally high signal intensity on T2-imaging. The temporal lobe was the main tumor location (seven patients). All cases were diagnosed according to the Russel and Rubinstein histological criteria for ganglioglioma. RESULTS: Ten patients had radical total resection and one had subtotal resection. No patient underwent postoperative radiation or chemotherapy. Except for one, all are still alive and free of progressive disease 1 to 11 years (mean 6.2) after operation. Six are seizure-free and three have improved seizure control under anticonvulsant therapy. CONCLUSIONS: We conclude that ganglioglioma is a distinct histological phenomenon with mildly predictable clinical symptoms (seizures), mildly characteristic radiological features, and long-term survival after surgical resection without the need of adjuvant treatment such as radiotherapy.

Adolescent↗
PubMed2001

Effects of trapidil on ATPase, lipid peroxidation, and correlation with ultrastructure in experimental spinal cord injury.

The present study was performed to investigate the effect of trapidil on ischemic damage of cells after spinal cord injury. The injury was produced by extradural clip compression of the exposed spinal cord in rats according to Rivlin and Tator. The ten rats in group 1 were used to determine normal findings without any surgery or medication. On the 15 rats in group 2, only six-level laminectomy was performed to determine the influence of the total laminectomy on the biochemical factors measured and the, light and ultrastructural findings. The 15 rats each in groups 3 and 4 were used as trauma and trapidil (40 mg/kg) treatment groups, respectively. The injury actually produced a significant decrease in Na+-K+/Mg+2 ATPase activity of the injured segments as early as 10 min after trauma. Trapidil attenuated Na+-K+/Mg+2 ATPase inactivation in the traumatized rats for 120 min after treatment (P<0.05) and significantly reduced the malone dialdehyde content below that in the traumatized group at all determined times (P<0.05). Light and electron microscopic findings supported the biochemical results.

Adenosine Triphosphatases↗
PubMed2001

The effects of the pre-treatment of intravenous nimodipine on Na(+)-K+/Mg+2 ATPase, Ca+2/Mg+2 ATPase, lipid peroxidation and early ultrastructural findings following middle cerebral artery occlusion in the rat.

Excessive calcium influx has been implicated in the pathophysiology of ischemic cerebral damage. The effects of nimodipine, a calcium antagonist, on the Na(+)-K+/MG+2 ATPase activity, Ca+2/Mg+2 ATPase, lipid peroxidation, and early ultrastructural findings were examined at the acute stage of ischemia in the rat brain. Ischemia was produced by permanent unilateral occlusion of the middle cerebral artery. In Group I, the rats which had no ischemia and not received medication were used for determining Na(+)-K+/Mg+2 ATPase, Ca+2/Mg+2 ATPase, the extent of lipid peroxidation by measuring the malondialdehyde content and normal ultrastructural findings. In Group II, the rats which had only subtemporal craniectomy without occlusion and received saline solution were used for determining the effect of the surgical procedure on the biochemical indices and ultrastructural findings. In Group III, the rats received saline solution following the occlusion in the same amount of nimodipine and in the same duration as used in Group IV. In Group IV, nimodipine pre-treatment 15 min before occlusion (microgram kg-1 min-1 over a 10 min period) was applied i.v. Na(+)-K+/Mg+2 ATPase and Ca+2/Mg+2 ATPase activities decreased significantly and promptly as early as 10 min and remained at a lower level than the contralateral hemisphere in the same group and at the normal level in Group I. Nimodipine pre-treatment immediately attenuated the inactivation of Na(+)-K+/Mg+2 ATPase (p < 0.05) but there was no change on Ca+2/Mg+2 ATPase activity (p < 0.05). Malondialdehyde content increased significantly in Group III following ischemia as early as 30 min. Nimodipine pre-treatment decreased the malondialdehyde level in Group IV (p < 0.05). This study supports the possibility that nimodipine pre-treatment effects the membrane stabilizing properties via inhibiting the lipid peroxidation and subsequently restoring some membrane bound and lipid dependent enzymes' activity such as Na(+)-K+/Mg+2 ATPase and the ultrastructural findings.

Animals↗
PubMed2001

Effect of anti-rat interleukin-6 antibody after spinal cord injury in the rat: inducible nitric oxide synthase expression, sodium- and potassium-activated, magnesium-dependent adenosine-5'-triphosphatase and superoxide dismutase activation, and ultrastructural changes.

OBJECT: The inflammatory cells that accumulate at the damaged site after spinal cord injury (SCI) may secrete interleukin-6 (IL-6), a mediator known to induce the expression of inducible nitric oxide synthase (iNOS). Any increased production of NO by iNOS activity would aggravate the primary neurological damage in SCI. If this mechanism does occur, the direct or indirect effects of IL-6 antagonists on iNOS activity should modulate this secondary injury. In this study, the authors produced spinal cord damage in rats and applied anti-rat IL-6 antibody to neutralize IL-6 bioactivity and to reduce iNOS. They determined the spinal cord tissue activities of Na+-K+/Mg++ adenosine-5'-triphosphatase (ATPase) and superoxide dismutase, evaluated iNOS immunoreactivity, and examined ultrastructural findings to assess the results of this treatment. METHODS: Seventy rats were randomly allocated to four groups. Group I (10 rats) were killed to provide normal spinal cord tissue for testing. In Group II 20 rats underwent six-level laminectomy for the effects of total laminectomy alone to be determined. In Group III 20 rats underwent six-level T2-7 laminectomy and SCI was produced by extradural compression of the exposed cord. The same procedures were performed in the 20 Group IV rats, but these rats also received one (2 microg) intraperitoneal injection of anti-rat IL-6 antibody immediately after the injury and a second dose 24 hours posttrauma. Half of the rats from each of Groups II through IV were killed at 2 hours and the other half at 48 hours posttrauma. The exposed cord segments were immediately removed and processed for analysis. CONCLUSIONS: The results showed that neutralizing IL-6 bioactivity with anti-rat IL-6 antibody significantly attenuates iNOS activity and reduces secondary structural changes in damaged rat spinal cord tissue.

Animals↗
PubMed1999

Core-directed protein design. I. An experimental method for selecting stable proteins from combinatorial libraries.

The design of proteins represents a significant challenge to modern-day structural biology. A major obstacle here is the specification of well-packed hydrophobic cores to drive the folding and stabilization of the target. Computational approaches have been used to alleviate this by testing alternate sequences prior to the production and characterization of a few proteins. Here we present the experimental counterpart of this approach. We selected stable variants from a library of ubiquitin hydrophobic-core mutants as follows. Hexahistidine-tagged proteins were displayed on the surface of phage. These protein-phage were immobilized onto Ni-coated surfaces. The bound fusion-phage were treated with protease to remove unstable or poorly folded proteins. Stable phage fusions were eluted and infected into Escherichia coli, which allowed amplification for further selection, sequencing, or protein expression. Two Ni-derivatized supports were tested: Ni-NTA chips for surface plasmon resonance (SPR) and Ni-NTA agarose beads. SPR had an advantage in that the selection process could be monitored directly. This allowed individual clones and experimental conditions to be tested rapidly prior to preparative panning of the library, which was carried out using Ni-NTA agarose beads. We demonstrate the method by selecting stable core mutants of ubiquitin, the characterization of which is described in the following paper [Finucane, M. D., and Woolfson, D. N. (1999) Biochemistry 38, XXXXX-XXXXX]. As our method selects only on the basis of structure and stability, it will be of use in improving the stabilities and structural specificities of proteins of de novo design, and in establishing rules that link sequence and structure.

Amino Acid Sequence↗
PubMed1999

Multiple anterolateral cervical meningoceles associated with neurofibromatosis.

In neurosurgical practice, the term 'spinal meningocele' is generally used to describe a congenital spinal malformation including protrusion of the spinal meninx from the congenitally dysraphic vertebrae. Although non-dysraphic meningocele is very rare, it is usually associated with neurofibromatosis or Marfan's syndrome in the literature. Thoracic and/or lumbar spinal levels are the most common localization. Anterolateral localization of meningocele is very rare in the cervical region. Operative treatment is indicated if the lesion is symptomatic. Detailed radiological assessment of the meningocele is necessary since it may be associated with neuroma in the sac. If the neuroma is found in the meningocele, an anterior surgical approach should be considered for the treatment of both of the lesions.

Adult↗
PubMed1999

Huge meningiomas: a review of 93 cases.

Between 1972 and 1996, 450 consecutive patients with intracranial meningiomas were operated on at Cukurova University School of Medicine. By size, intracranial meningiomas were classified as huge (>6 cm minimum diameter when extrapolated to anatomic size) or not huge (<6 cm). The present study involves 93 patients who underwent 109 craniotomies for the removal of huge meningiomas. All patients are adult, with 31 men and 62 women or a 1:2 male to female ratio, with a mean age of 48.7 +/- 2.3 years at the time of diagnosis. The average duration of observed survival in 85 patients followed in the computed tomography (CT) era was 4.8 years and that of 8 patients in the pre-CT era was 8.8 years. Eleven patients died by the last follow-up assessment. Seventy-nine patients were still alive at the last follow-up assessment. The overall postoperative mortality rate was 3.2%. The overall recurrence rate was 19%. In descending order of frequency, the first five anatomic locations of the huge meningiomas were the parasagittal region in 18 patients (19.3%), the cerebral convexity in 15 (16.1%), the olfactory groove in 15 (16.1%), the falx in 12 (12.9%), and the tuberculum sellae in 11 (11.8%). The overall results of surgical treatment in 93 patients were total removal in 59 (63.4%), radical subtotal in 18 (18.3%), and subtotal in 16 (17.2%), with good outcome in 69 (74.1%), fair in 16 (17.2%), and poor in 5 (5.3%). In conclusion, the huge size of meningiomas affects the extent of removal, recurrence rate, postoperative outcome, operative morbidity and mortality rates, and survival time negatively.

Journal Article↗
PubMed1999

Correlation of the relationships of brain-tumor interfaces, magnetic resonance imaging, and angiographic findings to predict cleavage of meningiomas.

OBJECT: The authors examined the relationships of brain-tumor interfaces, specific magnetic resonance (MR) imaging features, and angiographic findings in meningiomas to predict tumor cleavage and difficulty of resection. METHODS: Magnetic resonance imaging studies, angiographic data, operative reports, clinical data, and histopathological findings were examined retrospectively in this series, which included 126 patients with intracranial meningiomas who underwent operations in which microsurgical techniques were used. The authors have identified three kinds of brain-tumor interfaces characterized by various difficulties in microsurgical dissection: smooth type, intermediate type, and invasive type. The signal intensity on T1-weighted MR images was very similar regardless of the type of brain-tumor interface (p > 0.1). However, on T2-weighted images the different interfaces seemed to correlate very precisely with the signal intensity and the amount of peritumoral edema (p < 0.01), allowing the prediction of microsurgical effort required during surgery. On angiographic studies, the pial-cortical arterial supply was seen to participate almost equally with the meningeal-dural arterial supply in vascularizing the tumor in 57.9% of patients. Meningiomas demonstrating hypervascularization on angiography, particularly those fed by the pial-cortical arteries, exhibited significantly more severe edema compared with those supplied only from meningeal arteries (p < 0.01). Indeed, a positive correlation was found between the vascular supply from pial-cortical arteries and the type of cleavage (p < 0.05). CONCLUSIONS: In this analysis the authors proved that there is a strong correlation between the amount of peritumoral edema, hyperintensity of the tumor on T2-weighted images, cortical penetration, vascular supply from pial-cortical arteries, and cleavage of the meningioma. Therefore, the consequent difficulty of microsurgical dissection can be predicted preoperatively by analyzing MR imaging and angiographic studies.

Adult↗
PubMed1998

A giant dissecting aneurysm mimicking serpentine aneurysm angiographically. Case report and review of the literature.

Intracranial dissecting and giant serpentine aneurysms are rare vascular anomalies. Their precise cause has not yet been completely clarified, and the radiological appearance of such lesions can be different in each case according to the effect of hemodynamic stress on a pathologic vessel wall. For berry aneurysms, available evidence overwhelmingly favors their causation by hemodynamically induced degenerative vascular disease and there is an obvious need to determine the hemodynamic parameters most likely to induce the precursor atrophic lesions. In this study, a case of a giant dissecting aneurysm angiographically mimicking serpentine aneurysm of the right ophthalmic artery is reported and the relevant literature is reviewed to investigate the pathological characteristics and pathogenesis of this lesion. In the present case, radiological investigation of the lesion suggested a serpentine aneurysm, but the diagnosis was corrected to dissecting aneurysm subsequent to the pathological examination of the resected aneurysm. A giant dissecting aneurysm angiographically mimicking serpentine aneurysm and developing as the result of a circumferential dissection located between the internal elastic lamina and media is of particular interest when the etiology of these aneurysms is considered. To our knowledge this is the first report on intracranial dissecting aneurysm mimicking serpentine aneurysm angiographically. Our case illustrates the importance of careful serial section studies for a better understanding of the vascular pathology underlying the processes involved in intracranial serpentine aneurysms. We conclude that serpentine, dissecting and berry aneurysms may all arise by way of similar pathophysiological mechanisms.

Adult↗
PubMed1998

The effect of collagen, interleukin-1 alpha and glicosaminoglycan on the neovascularization of central nervous system.

Neovascularization, the development of a new microvasculature, has an important role in physiological and pathological processes. The vascular changes in the brain can be easily detected because the proliferation of endothelial cells in its vascular structure is quite small, and so constitutes a good model for neovascularization studies. In the present investigation, to induce intracerebral neovascularization, we implanted collagen, Interleukin-1 alpha (IL-1 alpha) and glicosaminoglycan into the brain of pigs, in order to test the hypothesis that IL-1 alpha, collagen and glicosaminoglycan play a pivotal role in the process of neovascularization. Both pure collagen and collagen combined with IL-1 alpha induced neovascularization according to light-electron microscopic findings and values of enzymes' activities. In particular, collagen combined with IL-1 alpha synergically affected the increase of neovascularization. However, glicosaminoglycan did not affect it significantly. Although the results of this study provided us with some interesting data indicating the beneficial effects of collagen combined with IL-1 alpha on neovascularization, further studies should be done to study the short term effect of these biochemical substances.

Adenosine Triphosphatases↗
PubMed1998

The effect of trapidil on the reactive astrocytic proliferation following spinal cord trauma in rats: light and electron microscopic findings.

Platelet-derived growth factor (PDGF) released from platelets is one of the mitogens in serum, which plays a major role upon the cell biology, namely enhancing cell division and controlling of the maturation, especially upon the glial cell growth and its differentiation. Trapidil, which is an anti-PDGF agent, inhibits the effect of PDGF, especially the proliferative effects on the glial and tumoral cells in vitro. Previous studies suggested that the astrocytic proliferation stimulated by PDGF was inhibited by trapidil via the selective antagonism. Trapidil was not found to have a considerable effect on the prevention of nonpermissive astrocytes in this study. It should be theorized that trapidil, administered immediately even after the trauma, could not reach the injury site in effective measure because of secondary events such as edema and impairment of blood circulation. This suggestion should be another subject for studies concerning trapidil which is administered prior to the trauma.

Animals↗
PubMed1997

Variability in the pattern of random amplified polymorphic DNA.

The random amplified polymorphic DNA (RAPD) technique is a simple method to detect DNA polymorphism. It is sensitive to reaction conditions. Small changes in the reactants' concentration cause variations in amplification products. Using DNA from Asparagus officinalis, Dactylis glomerata, Mercurialis annua and Escherichia coli, we examined variability in the amplification pattern associated with reaction constituents. An increase in the ratio of Taq DNA polymerase to DNA in the reaction increased the number of amplified fragments. Increasing the concentration of primer resulted in the amplification of low molecular weight DNA fragments, while lowering the concentration resulted in high molecular weight fragments. Subsets of amplified fragments required different concentrations of magnesium for their highest intensity. Mechanical shearing of DNA obtained by sonication led to reduction in amplification of a subset of products. Enzymatic fragmentation of DNA by restriction enzymes led to loss or gain of specific fragments, depending on the DNA, primer, and restriction enzyme. RAPD markers of pooled DNA of anonymous pedigree should be critically evaluated for frequent 'false positive' markers.

Base Composition↗
PubMed1997

Percutaneous radiofrequency rhizotomy of lumbar spinal facets: the results of 46 cases.

The results of percutaneous radiofrequency rhizotomy of lumbar spinal facets in 46 patients followed at least three months (mean 15 months) are reported and compared with those reported previously. Satisfactory pain relief three months after the procedure was achieved in 36.4 percent of patients without operations and in 41.7 percent of patients, with operations other than fusion. No patient had previously undergone fusion. Treatment of low-back pain by using radio-frequency thermocoagulation of spinal facets is a simple, safe, and well-tolerated procedure. It can be used to relief of pain in spite of decreasing rates of success within the follow-up period.

Adult↗