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Biomedical subjects

A Celik

Publications and source records attributed to A Celik.

At least 19 recordsLinked to original sources
PubMed2003

The role of surgery in intraabdominal Burkitt's lymphoma in children.

The role of surgery in intraabdominal Burkitt's lymphoma remains controversial and different opinions are present in the literature. In our institution, forty patients (30 boys and 10 girls) with intraabdominal Burkitt's lymphoma with ages ranging from 3 to 12 years have been treated and followed from 1989 through 2000. In ten cases, the patients underwent surgery because of their acute abdominal diseases (intestinal obstruction in 5, intussusception in 3, intestinal perforation in one, and acute appendicitis in one). The remaining thirty patients were referred to our clinic because of their abdominal masses, pain, anorexia and fatigue. Twelve children had localized tumors and total resection could be performed. There was one death in this group due to central nervous system involvement during chemotherapy. In the remaining 28 children, extensive intraabdominal diseases were detected. In four of them, debulking procedures were performed, while in 24 children only biopsies could be made; 8 of them underwent a second-look operation. In the debulking procedures group, two children were lost (50 %) due to tumorlysis and acute renal failure. In the biopsy group, there were six deaths (25 %). All patients received chemotherapy after operative recovery. In conclusion, our results suggest that when the tumor is localized, total resection results in a good outcome. However, in the presence of extensive intraabdominal diseases instead of resection, the operation should be limited to biopsy only.

Abdominal Neoplasms↗
PubMed2002

Solid and cystic tumor of the pancreas: a case report.

A case of a solid and cystic tumor of the pancreas occurring in a 15 year-old girl is reported. This patient was admitted with epigastric and left upper quadrant pain and vomiting. A mass was detected in the pancreas on CT scan and the patient was referred for surgery. A distal pancreatectomy was performed. A pathological diagnosis of solid and cystic tumor of the pancreas was made and the patient was discharged uneventfully.

Adolescent↗
PubMed2001

Quantitative measurements of cerebral blood flow in patients with unilateral carotid artery occlusion: a PET and MR study.

Although it has been demonstrated that quantitative measures of cerebral blood flow (CBF) can be obtained with the singular value decomposition (SVD) algorithm, the extent to which quantitative CBF measurements can be utilized under pathophysiological conditions has not been systematically studied. A total of five healthy volunteers and five patients with unilateral carotid artery occlusion were studied. Only magnetic resonance (MR) images were acquired for the volunteer group while both MR and positron emission tomography (PET) images were acquired for the patient group. Assessments of CBF from normal volunteers compared favorably with values reported in the literature. However, while a linear relationship was observed for each patient when MR measured CBF was compared to that obtained from PET, this linear relationship diminished when all patients were analyzed as a group (r = 0.41). A correction factor (CF) was proposed that was equal to the ratio of the area of the venous output function (VOF) in each patient to the mean VOF obtained from the volunteer group. After globally scaling the CBF of each patient based on the experimentally derived CF, a substantial improvement was observed (a slope of 1.02 and r = 0.8 for the linear regression line) in the relationship between MR estimated CBF and those obtained from PET.

Analysis of Variance↗
PubMed2001

Engineering the active site of ascorbate peroxidase.

Understanding the catalytic versatility of haem enzymes, and in particular the relationships that exist between different classes of haem-containing proteins and the mechanisms by which the apo-protein structure controls chemical reactivity, presents a major experimental and theoretical challenge. These issues are discussed in the general context of peroxidase and cytochrome P450 chemistry, and specific issues relating to the catalytic chemistry of ascorbate peroxidase are highlighted.

Ascorbate Peroxidases↗
PubMed2001

Engineering the active site of ascorbate peroxidase.

The oxidation of a number of thioethers, namely methyl phenyl sulphide (1), ethyl phenyl sulphide (2), isopropyl phenyl sulphide (3), n-propyl phenyl sulphide (4), p-chlorophenyl methyl sulphide (5), p-nitrophenyl methyl sulphide (6) and methyl naphthalene sulphide (7), by recombinant pea cytosolic ascorbate peroxidase (rAPX) and a site-directed variant of rAPX in which the distal tryptophan 41 residue has been replaced with an alanine (W41A) has been examined. The electronic spectrum (pH 7.0, mu = 0.10 M, 25.0 degrees C) for the ferric derivative of W41A (lambda(max)/nm = 411, 534, 560, 632) is indicative of an increased quantity of 6-coordinate, high-spin and/or 6-coordinate, low-spin haem compared to rAPX. Steady state oxidation of sulphides 1-4 and 7, gave values for kcat that are approximately 10-fold and 100-fold, respectively, higher for W41A than for rAPX. For rAPX, essentially racemic mixtures of R- and S-sulphoxides were obtained for all sulphides. With the exception of sulphide 7, the W41A variant shows substantial enhancements in enantioselectivity, with R : S ratios varying between R : S = 63 : 37 (sulphides 1 and 4) and R : S = 85 : 15 (sulphide 6). Incubation of sulphide 2 with rAPX or W41A and [(18)O] H(2)O(2) shows 95% (rAPX) and 96% (W41A) transfer of labelled oxygen to the substrate. Structure-based modelling techniques have provided a fully quantitative rationalization of all the experimentally determined R : S ratios and have indicated that reorientation of the sidechain of Arg38, such that access to the haem is much less restricted, is influential in controlling the stereoselectivity for both rAPX and W41A.

Amino Acid Substitution↗
PubMed2001

Primary pulmonary rhabdomyosarcoma arising within cystic adenomatoid malformation: a case report and review of the literature.

The current report describes a 13-month-old boy with primary pulmonary rhabdomyosarcoma (RMS) that originated within a congenital cystic adenomatoid malformation (CCAM). To the best of our knowledge, he is the youngest patient of all primary pulmonary RMS cases reported in the English-language literature. The tumor, localized in left upper lobe, was removed completely, and histologic examination showed embryonal subtype. Postoperative systemic chemotherapy was carried out. Recent evaluation 15 months after resection has not identified any residual or recurrent disease. Primary pulmonary RMS, although very rare in the pediatric age group, should be considered in young patients with solitary pulmonary masses and associated cystic lesions.

Cystic Adenomatoid Malformation of Lung, Congenita↗
PubMed2001

Laparoscopic management of a giant adrenal cyst: case report.

A 22-cm left adrenal cyst in a 30-year-old woman was laparoscopically drained and then excised. The main symptom was dull left-upper-quadrant pain. Operative time was 95 minutes, and the hospital stay was 1 day. The patient returned to normal activity 7 days after surgery. Histology revealed a benign adrenal cyst. At the 3-month follow-up, ultrasonography showed the absence of any cystic recurrence, and adrenal endocrine function was normal. The advantages and disadvantages of this modality for the management of adrenal gland cysts are discussed.

Adrenal Gland Diseases↗
PubMed2001

Acute renal failure following latrodectism.

Latrodectism is considered dangerous for human beings. Acute renal failure after envenomation is not common and usually results from prerenal failure. We report a 59-y-o man with acute oliguric renal failure due to a combination of prerenal and renal causes after being bitten by a black Latrodectus spider. He had the characteristic anxiety, severe hypertension, tremor, facial edema, and generalized diaphoresis. The patient recovered within a week without sequelae. Clinicians should not overlook the possibility of acute renal failure in latrodectism.

Acute Kidney Injury↗
PubMed2000

Catalytic oxidation of p-cresol by ascorbate peroxidase.

Transient and steady state kinetics, together with a range of chromatographic and spectroscopic techniques, have been used to establish the mechanism and the products of the H(2)O(2)-dependent oxidation of p-cresol by ascorbate peroxidase (APX). HPLC, GC-MS, and NMR analyses are consistent with the formation of 2, 2'-dihydroxy-5,5'-dimethylbiphenyl (II) and 4alpha,9beta-dihydro-8, 9beta-dimethyl-3(4H)-dibenzofuranone (Pummerer's ketone, III) as the major products of the reaction. In the presence of cumene hydroperoxide, two additional products were observed which, from GC and MS analyses, were shown to be 1,1-dimethylbenzylalcohol (IV) and bis-(1-methyl-1-phenyl-ethyl)-peroxide (V). The product ratio II:III was dependent on enzyme concentration: at low concentrations Pummerer's ketone (III) predominates and at high concentrations formation of the biphenyl compound (II) is favored. Steady-state data showed a sigmoidal dependence on [p-cresol] that was consistent with the presence of 2.01 +/- 0.15 binding sites for the substrate (25.0 degrees C, sodium phosphate, pH 7.0, mu = 2.2 mM) and independent of ionic strength in the range 2.2-500 mM. Single turnover kinetic experiments (pH 7.0, 5.0 degrees C, mu = 0.10 M) yielded second-order rate constants for Compound I reduction by p-cresol, k(2), of 5.42 +/- 0.10 x 10(5) M(-1) s(-1), respectively. Rate-limiting reduction of Compound II by p-cresol, k(3), showed saturation kinetics, giving values for K(d) = 1.54 +/- 0.12 x 10(-3) M and k(3) = 18.5 +/- 0.7 s(-1). The results are discussed in the more general context of APX-catalyzed aromatic oxidations.

Ascorbate Peroxidases↗
PubMed2000

Serum immunoglobulins and immunoglobulin G subclasses with recurrent wheezing.

In this study serum immunoglobulins (Ig) and IgG subclasses were measured in 42 patients (ranging 9 month-6 year) with recurrent wheezing and in 37 healthy children determined the relationship between serum Igs and recurrent wheezing. Patients were divided into two groups according to the age [9 month-2 year (n: 15), and 2-6 year (n: 27)]. In the patients placed in 9-24 month age group, serum IgG4 level was found to be lower than controls (p < 0.05). But there was not a significant difference in mean serum concentrations of total IgG, IgA, IgM, IgE, IgG1, IgG2 and IgG3 subclasses between the groups (P > 0.05). In the 25 month-6 year age group the mean IgE level was increased compared to the control while IgG3 and IgG4 levels were decreased (p < 0.05). On the other hand, in the 9-24 month age group there was no significant difference between the patients and controls for IgG subclasses deficiency (P > 0.05). However, significant difference in IgG subclasses deficiency was present between the patients and controls in the 25 month-6 year group (P < 0.001). In conclusion, our findings suggest that wheezing in childhood may be associated with low IgG3 and/or IgG4, and in older children high IgE level may be a part of pathogenetic mechanism in patients with recurrent wheezing.

Child↗
PubMed2000

Results of rhabdomyosarcoma treatment in a developing country.

Fifty-one children (median age: 4.5 years; 4 months-16 years) diagnosed with rhabdomyosarcoma were treated in our center between 1980-1999. The primary sites were head and neck in 31.4%, the genito-urinary system in 21.6%, and extremities in 9.8% of the patients. The histopathologic subtypes were embryonal in 80.4%, alveolar in 9.8%, and undifferentiated in 9.8%. The majority of the patients were considered group III (47%) and group IV (25.5%) according the criteria of the Intergroup Rhabdomyosarcoma Study (IRS). Primary total tumour resection was performed in only 27.5% of the patients. The patients were treated with assigned regimens of IRS II and IRS III protocols. Radiotherapy was applied to 92.1% of the patients. Thirty-four patients (66.7%) were lost to follow up, and of the remaining 17 patients, 7 patients (41.2%) died, relapse occurred in 9 patients (52.9%) and 10 patients (58.8%) are alive. The percentage of cases lost to follow up during the first 10 years and the following 9 years of the study were 77.4% and 50%, respectively. In compliance with cancer treatment remains a major problem in developing countries.

Adolescent↗
PubMed2000

[Gastritis localization and GERD incidence in patients with Cag A(+) and Cag A(-) Helicobacter pylori infection].

The relationship between Helicobacter pylori (HP) and gastroesophageal reflux disease (GERD) is very complex and still not well understood. However, many issues, even those as basic as whether HP induces or protects against GERD, are still controversial. The gastritis location could play also a role in the induction of GERD. Some investigators suggested that infection by the Cag A strain of HP seems to have a positive association with reflux esophagitis. Therefore, the aim of this study was to investigate the relationship between GERD, gastritis location, HP infection and Cag A positivity.

Adolescent↗
PubMed1999

Regional cerebral blood volume: a comparison of the dynamic imaging and the steady state methods.

Accurate assessment of regional cerebral blood volume (rCBV) is of critical importance in the study of cerebrovascular disease and other disorders of the central nervous system. Currently, magnetic resonance imaging (MRI) is able to measure rCBV non-invasively with two commonly used methods: the dynamic imaging (DI) and steady state (SS) approaches. In this study, two questions were investigated. First, how do partial volume effects between gray matter (GM) and white matter (WM) and between epicortical vessels and brain parenchyma affect the estimation of rCBV when using the SS approach? Second, how comparable are the ratios of rCBV in GM to rCBV in WM (rCBV GM/WM) obtained with the two methods? We used a paramagnetic contrast agent, OPTIMARK (Mallinckrodt, St. Louis, MO), at a dose of 0.2 mmol/kg in anesthetized pigs (n = 6) to obtain rCBV maps using both methods. When a 10% rCBV threshold was used to minimize effects from large epicortical vessels, and tissue segmentation was used to separate GM from WM, rCBV values of 4.8 +/- 0.3% and 3.3 +/- 0.5% were obtained for GM and WM, respectively, with the SS approach. Significantly higher rCBV values for both GM (P < 0.001) and WM (P < 0.01) were observed when the contribution from large epicortical vessels was not removed. When tissue segmentation and rCBV thresholding were used on SS data, an rCBV GM/WM ratio of 1.5 +/- 0.2 was obtained. This value did not differ significantly from the rCBV GM/WM ratio of 1.8 +/- 0.6 obtained using the DI approach.

Animals↗
PubMed1999

Primary torsion of the omentum in a 6-year-old boy: report of a case.

In the absence of any pathological condition in the pelvis of children who present with acute abdomen, the observation of serosanguineous intraabdominal fluid should prompt the surgeon to investigate the omentum. A 6-year-old boy who was admitted with a clinical picture of acute appendicitis, and was later diagnosed during a laparotomy to have primary torsion of the omentum, is reported. Obesity, exercise, and the presence of a bifid omentum were confirmed to be the predisposing factors.

Child↗