Biomedical subjects

S Bek

Publications and source records attributed to S Bek.

5 recordsLinked to original sources

PubMed2006

Diffuse villous hyperplasia of choroid plexus.

Diffuse villous hyperplasia of choroid plexus (DVHCP) is a rare condition which is characterized by the presence of diffuse enlargement of the entire choroid plexus throughout the length of the choroidal fissure and overproduction of CSF. The diagnosis of diffuse villous hyperplasia of choroid plexus can be established by the MR demonstration of diffusely large, contrast enhanced choroid plexus in the cases of overproduction hydrocephalus. Although some authors recommend choroid plexus excision or coagulation, ventriculo-atrial shunt insertion is a simple and effective treatment modality in cases of diffuse villous hyperplasia of the choroid plexus. In this report we present a case of diffuse villous hyperplasia of the choroid plexus and a short review of the literature. To our knowledge, in the CT and MRI era only 5 cases of DVHCP cases have been reported.

Cerebrospinal Fluid↗

PubMed2006

Non-traumatic intradiploic arachnoid cyst.

In this report, we present a case of non-traumatic intradiploic arachnoid cyst in a 65 year-old woman with a slow growing swelling in the right frontotemporal region without a history of head trauma, which was diagnosed intra-operatively. Extradural intracranial location of non-traumatic arachnoid cyst is a rare clinical entity with a few reported cases in the literature. Characteristic features of non-traumatic intradiploic arachnoid cysts are also described in this mini-review article.

Aged↗

PubMed2004

Aspergillus pituitary abscess.

BACKGROUND: Pituitary abscess is rare and most of the cases are of bacterial origin. True fungal pituitary abscess is extremely rare only five cases have been reported. In this report, we present a case of aspergillus pituitary abscess. Mortality rate in intracranial aspergillosis is close to 100% especially in immunsuppressed patients when undiagnosed and untreated. In focal CNS aspergillosis total cure can be achieved in approximately 30% of the cases by surgical drainage and intensive antifungal therapy. Although this is the first reported case with magnetic resonance imaging examination the definitive diagnosis was established only by histopathological examination. CLINICAL PRESENTATION: A 42 year-old man was referred to our hospital with the diagnosis of sellar suprasellar mass accompanied by frontal headache and decreased visual acuity. His medical history was insignificant. Physical examination was normal and the patient was afebrile. The neurological examination revealed bilateral papilledema and bitemporal hemianopsia but no stiff neck and motor or sensory deficit. In the light of MRI examination, the preoperative diagnosis was pituitary abscess secondary to paranasal sinus infection or hemorrhagic pituitary adenoma. INTERVENTION: The patient was successfully treated by transsphenoidal surgery. Histopathological examination of sphenoid sinus mucosa revealed normal mucosal appearance with inflammation and histopathological examination of the intrasellar mass resulted in the diagnosis of aspergillosis. All cultures obtained from sphenoid sinus were reported as having no growth. However in the second week after the operation fungal culture of the intrasellar mass grew aspergillus. After 8 weeks of amphothericine-B treatment, the patient was discharged. At the last follow up examination two years after the operation, the patient was symptom free with normal pituitary function. CONCLUSION: Aspergillus pituitary abscess should be considered in the differential diagnosis of a pituitary mass. The correct diagnosis of pituitary aspergillosis can only be achieved by histopathological examination because clinical and radiological findings including MRI are not specific and culture results are obtained later. Immediately after the diagnosis, intensive antifungal therapy should be started for a successful treatment.

Abscess↗

PubMed2004

Phenytoin penetration into chronic subdural haematomas.

The pathophysiology of chronic subdural haematomas (CSH) is still unclear. In the light of recent ultrastructural examination, exudation from the macrocapillaries in the outer membrane of CSH may play an important role in the enlargement of CSH. In this study, exudation from the macrocapillaries was assessed by the measurement of phenytoin, a protein-bound antiepileptic agent used in cases of CSH. In 22 patients, 1 h after the administration of 250 mg of phenytoin intravenously, blood and subdural haematoma samples were taken and phenytoin levels were measured. The ratio of subdural haematoma level to the blood phenytoin level was determined and defined as the phenytoin penetration ratio (PPR). The correlation between the phenytoin penetration ratio and clinical neurological grades (Markwalder and Glasgow Coma Scale), age of the patients and the CT appearance of CSH were investigated. The mean phenytoin penetration ratio was 19.5%. As the neurological grades of patients increased, average PPR also increased. The average PPR values were 17.64 and 20.84% in the patients younger than 60 years (nine patients) and older patients (13 patients), respectively. Mean PPRs in the groups according to the CT appearance were as follows: low density 11.21% (seven patients), isodensity in 15.88% (10 patients), high density in 38.5% (five patients). A subdural reaccumulation was detected in nine patients with a mean PPR of 27.72%, while mean PPR was 14.56% in the others. Exudation from macrocapillaries in the outer membrane of chronic subdural haematomas probably plays an important role in the enlargement of chronic subdural haematoma, and measuring phenytoin levels in the chronic subdural haematoma is a simple method for the quantitative estimation of the exudation in CSH.

Adult↗

PubMed1994

Brownian dynamics study of a multiply-occupied cation channel: application to understanding permeation in potassium channels.

The behavior of a multiply-occupied cation-selective channel has been computed by Brownian dynamics. The length, cross-section, ion-ion repulsion force, and ionic mobility within the channel are all estimated from data and physical reasoning. The only free parameter is a partition energy at the mouth of the channel, defining the free energy of an ion in the channel compared to the bath. It is presumed that this partition energy is associated with the energetics of exchanging a bulk hydration environment for a channel hydration environment. Varying the partition energy alone, keeping all other parameters fixed, gives approximately the full range of magnitudes of single channel conductances seen experimentally for K channels. Setting the partition energy at -11 kT makes the computed channel look similar to a squid axon K channel with respect to magnitude of conductance, shape of the I-V curve, non-unity of Ussing flux ratio exponents, decrease of current and increase of conductance with extracellular ion accumulation, and saturation at high ion concentration in the bathing solution. The model includes no preferred binding sites (local free energy minima) for ions in the channel. Therefore it follows that none of the above-mentioned properties of K channels are strong evidence for the existence of such sites. The model does not show supersaturation of current at very high bathing concentrations nor any pronounced voltage-dependence of the Ussing flux ratio exponent, suggesting that these features would require additional details not included in the model presented herein.

Animals↗