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Biomedical subjects

A Ozkan

Publications and source records attributed to A Ozkan.

At least 19 recordsLinked to original sources
PubMed2006

Tumor lysis syndrome as a contributory factor to the development of reversible posterior leukoencephalopathy.

INTRODUCTION: Reversible posterior leukoencephalopathy syndrome (RPLS) is a recently described clinical and radiological entity comprising headache, seizures, altered level of consciousness and visual disturbances in association with transient posterior cerebral white-matter abnormalities. METHOD: We report a young woman with Burkitt's lymphoma who developed RPLS after combined chemotherapy administered during the tumor lysis syndrome. RESULTS: The symptoms in this patient fitted well with those of RPLS; they included abrupt alterations in mental status, seizures, headache, visual changes and characteristic neuroradiological findings. She was given further combination chemotherapy without any neurological complications, at which time she had already recovered from both RPLS and tumor lysis syndrome. CONCLUSION: Although many etiological factors have been reported in the development of RPLS, the underlying mechanism is not yet well understood. With prompt and appropriate management, RPLS is usually reversible, and chemotherapy can be continued after complete recovery from RPLS. We suggest that tumor lysis syndrome should be considered as a contributory factor to the development of RPLS in patients for whom treatment with combined chemotherapy for hematological malignancies is planned.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Placental tissue cyclo-oxygenase 1 and 2 in pre-eclamptic and normal pregnancy.

OBJECTIVE: To investigate the activities of the 2 isoforms of prostaglandin synthetic enzyme cyclo-oxygenase (COX), COX-1 and COX-2, in the placental tissue of women with pre-eclampsia and healthy pregnant women. The relationship between placental lipid peroxidation and the activities of COX-1 and COX-2 was also investigated. METHODS: Tissue specimens were obtained from pre-eclamptic women (20 had severe pre-eclampsia and 38 had mild pre-eclampsia) and 27 healthy pregnant women who underwent cesarean section before the onset of labor. Malondialdehyde (MDA) levels and COX-1 and COX-2 activities were measured in placental tissue homogenates. RESULTS: Mean activities for COX-1 and COX-2 were significantly lower in women with severe pre-eclampsia than in healthy controls (P<0.05 and P<0.01, respectively). COX-1 and COX-2 activities were also lower in women with mild pre-eclampsia than in healthy controls, but the difference was of borderline significance (P=0.049 and P=0.059, respectively). The mean placental MDA level was significantly higher in pregnant women with severe and mild pre-eclampsia than in healthy pregnant women (P<0.01 for both). The correlation analysis showed significant negative correlations between MDA and COX-1 (r=-0.44, P<0.001) and MDA and COX-2 (r=-0.45, P<0.001) in the placental tissue of women with pre-eclampsia. CONCLUSION: These results suggest that COX-1 and COX-2 activities are decreased in the placental tissue of women with pre-eclampsia, probably by oxidative stress.

Adolescent↗
PubMed2006

Bacillus spp. among hospitalized patients with haematological malignancies: clinical features, epidemics and outcomes.

Between April 2000 and May 2005, 350 bacteraemic episodes occurred among patients treated in our haematology unit. Two hundred and twenty-eight of these episodes were caused by Gram-positive pathogens, most commonly coagulase-negative staphylococci and Staphylococcus aureus. One hundred and twenty-two episodes were due to Gram-negative pathogens, with a predominance of Escherichia coli, Acinetobacter baumannii and Pseudomonas aeruginosa. Bacillus bacteraemias constituted 12 of these episodes occurring in 12 patients, and accounted for 3.4% of all bacteraemic episodes. Of the 12 strains evaluated, seven were Bacillus licheniformis, three were Bacillus cereus and two were Bacillus pumilus. Seven episodes presented with bloodstream infection, three with pneumonia, one with severe abdominal pain and deterioration of liver function, and one with a catheter-related bloodstream infection. B. licheniformis was isolated from five patients who had been hospitalized at the same time. This outbreak was related to non-sterile cotton wool used during skin disinfection. B. cereus and B. licheniformis isolates were susceptible to cefepime, carbapenems, aminoglycosides and vancomycin, but B. pumilus isolates were resistant to all antibiotics except for quinolones and vancomycin. Two deaths were observed. In conclusion, Bacillus spp. may cause serious infections, diagnostic and therapeutic dilemmas, and high morbidity and mortality in patients with haematological malignancies. Both B. cereus and B. licheniformis may be among the 'new' Gram-positive pathogens to cause serious infection in patients with neutropenia.

Acinetobacter baumannii↗
PubMed2006

Spectrum and clinical implications of syntaxin 11 gene mutations in familial haemophagocytic lymphohistiocytosis: association with disease-free remissions and haematopoietic malignancies.

OBJECTIVE: To determine the frequency and spectrum of mutations in the gene encoding syntaxin 11 (STX11) in familial haemophagocytic lymphohistiocytosis (FHL), a rare autosomal recessive disorder of immune dysregulation characterised by a defect in natural killer cell function. METHODS: Mutational analysis of STX11 by direct sequencing was done in 28 FHL families that did not harbour perforin mutations, previously identified in some FHL patients. A detailed investigation of clinical features of these patients was also undertaken. RESULTS: Two different STX11 mutations were identified, one nonsense mutation and one deletion, affecting six of 34 children in four of 28 unrelated PRF1 negative families. Both mutations have been reported before. Three patients experienced long periods (> or = 1 year) in remission without specific treatment, which is very uncommon in this disease. Despite the milder phenotype, some children with STX11 mutations developed severe psychomotor retardation. Two of the six patients harbouring STX11 gene defects developed myelodysplastic syndrome (MDS) or acute myelogenous leukaemia (AML). CONCLUSIONS: STX11 gene mutations were found in 14% of the PRF1 negative FHL families included in the present cohort. These results suggest that STX11 gene mutations may be associated with secondary malignancies (MDS/AML), and that there is segregation of specific clinical features in FHL patients with an underlying genotype.

Acute Disease↗
PubMed2006

Protective effect of antioxidant enzymes against drug cytotoxicity in MCF-7 cells.

AIM: To evaluate protective effect of antioxidant enzymes against epirubicin-HCI (EPI) cytotoxicity in vitro. MATERIALS AND METHODS: Viability of MCF-7 cells treated with EPI was measured using the MTT test. Glutathione (GSH), protein content and enzymatic activity were measured spectrophotometrically. NADPH - dependent cytochrome P-450 reductase (NADPH-CYP-450) and glutathione S-transferase pi (GST-pi) expression in MCF-7 cells were determined by Western blot analysis. RESULTS: The IC50 values of EPI in MCF-7 cells were 1.0, 0.7 and 0.5 ng/ml respectively for 24, 48 and 72 h applications. Simultaneously enzymatic activity of glutathione S-transferase, glutathione peroxidase, GSH and expression of GST-pi, NADPH-CYP-450 reductase were increased in EPI (1 ng/ml) - treated cells at the end of the 24 h incubation. Addition of superoxide dismutase, catalase and GSH decreased cytotoxicity of EPI. CONCLUSION: We hypothesized that the production of reactive oxygen species and hydrogen peroxide as result of EPI treatment can cause cytotoxicity in MCF-7 cells and antioxidant enzymes protect the cells against this process.

Antineoplastic Agents↗
PubMed2005

Comparison of the serum erythropoietin levels in chemotherapy-naive and cisplatin-treated cancer patients.

There are conflicting data about the effects of cisplatin on erythropoietin (EPO) response to anemia. Aim of our study was to investigate whether endogenous EPO response to anemia in cisplatin treated patients was insufficient in comparison to the anemic chemotherapy-naive cancer patients and non cancer patients with iron deficiency anemia. Patients who had hemoglobin (Hb) levels of less than 110 g/l were included in the study. Fifteen chemotherapy- naive cancer patients were enrolled in Group A. Group B consisted of 15 patients who had been treated with three cycles of cisplatin chemotherapy and then became anemic and in Group C were included 15 patients who had iron deficiency anemia, without any malignancy. The mean Hb values were not different between all groups (102.8+/-39.8 g/l, 103.1+/-2.5 g/l and 99.3+/-3.6 g/l in Group A, Group B and Group C, respectively). However, EPO levels were found to be significantly lower in Group A and Group B than Group C (29.63+/-9.09 mU/ml, 20.87+/-2.43 mU/ml and 85.38+/-25.72 mU/ml, respectively; p=0.017 Group A vs. Group C, p=0.005 Group B vs. Group C). No significant difference was found between Group A and B (p=0.917). Opposite the iron deficiency anemia, cancer anemia is associated with an inadequate EPO response to anemia and administration of cisplatin does not lead to it further deterioration.

Anemia↗
PubMed2004

Determination of the critical surface tension of wetting of minerals treated with surfactants by shear flocculation approach.

This paper contributes the shear flocculation method as a new approach to determine the critical surface tension of wetting of minerals treated with surfactants. This newly developed approach is based on the decrease of the shear flocculation of the mineral suspension, with decreasing of the surface tension of the liquids used. The solution surface tension value at which shear flocculation does not occur can be defined as the critical surface tension of wetting (gamma c) of the mineral. By using the shear flocculation method, the critical surface tensions of wetting (gamma c) for calcite and barite minerals, treated with surfactants, were obtained as 30.9 and 35.0 mN/m, respectively. These values are in good agreement with data reported previously on the same minerals obtained by the contact angle measurement and flotation methods. The chemical agents used for the treatment of calcite and barite particles were sodium oleate and sodium dodecyl sulfate, respectively.

Flocculation↗
PubMed2004

Shear flocculation of celestite with sodium oleate and tallow amine acetate: effects of cations.

Sodium oleate and tallow amine acetate (TAA) were used as surfactants for the shear flocculation of celestite. The shear-flocculation power values obtained with sodium oleate were higher than those obtained with TAA in terms of the concentrations used in the shear-flocculation experiments. In addition, sodium oleate and TAA were more effective on the celestite suspension in the pH ranges of 7-11 and 6-10, respectively. For the shear-flocculation experiments with sodium oleate at pH 11, with preaddition of calcium or magnesium ions at 5 x 10(-5) M and lower concentrations into the suspension, the shear flocculation of the celestite suspension was promoted by the coagulation process due to the calcium and magnesium cations added. However, the shear-flocculation power values decreased due to the interaction between surfactant and cations at concentration values higher than 5 x 10(-5) M for magnesium ions and 10(-3) M for calcium ion. Particularly, magnesium ions significantly reduced the shear-flocculation power values by slime coating of Mg(OH)2 precipitates.

Journal Article↗
PubMed2004

Combined effect of epirubicin and lymphokine-activated killer cells on the resistant human breast cancer cells.

Accumulating evidence suggests the concept that epirubicin and lymphokine-activated killer (LAK) cells cytotoxicity may be mediated by free radicals generation and P-glycoprotein-positive (Pg-p+) cancer cells are more sensitive for LAK cells than their drug-sensitive parental lines. We tested this hypothesis further by exposing drug-sensitive (WT) and epirubicin-resistant MCF-7 human breast tumor cells to epirubicin and LAK cells. Subsequently, we monitored cell proliferation as a measure of cytotoxicity. The cytotoxicity of epirubicin, LAK, and LAK + epirubicin (1/10 of IC50) was evaluated in 400-fold epirubicin resistant MCF-7 EPI(R) (P-glycoprotein overexpressing) and drug-sensitive MCF-7 WT cells. IC50 values were measured using the MTT cytotoxicity test. The MCF-7 EPI(R) cells exhibited an increased susceptibility to LAK cells than did the MCF-7 WT cells. P-gp+ MCF-7 EPI(R) cells were lysed by human LAK cells to a greater extend than were their drug-sensitive counterparts. LAK + epirubicin combined treatment increased susceptibility of MCF-7 WT and MCF-7 EPI(R) cells to LAK cells cytotoxicity. For both cell lines, cytotoxicity was dependent upon the concentration of the epirubicin and effector cell/target cell (E/T) ratio. The resistance of MCF-7 EPI(R) cells to epirubicin appears to be associated with a developed tolerance to superoxide, most likely because of a tree-fold increase in superoxide dismutase (SOD) activity and 13-fold augmented selenium dependent glutathione peroxidase (GSH-Px) activity. Acting in concert, these two enzymes would decrease the formation of hydroxyl radical from reduced molecular oxygen intermediates. The addition of SOD decreased cytotoxicity of epirubicin and LAK cells. Taken together, these observations support the role of oxygen radicals in the cytotoxicity mechanism of epirubicin and suggest further that the development of resistance to this drug by the MCF-7 EPI(R) tumor cells may have a component linked to oxygen free radicals. It is proposed that production of reactive oxygen species by the treatment of epirubicin and LAK cells can cause cytotoxicity of MCF-7 WT and MCF-7 EPI(R) cells. SOD, catalase, GSH-Px, GST (glutathione S-transferase), and GSH (reduced glutathione) must be considered as part of the intracellular antioxidant defense mechanism of MCF-7 WT and MCF-7 EPI(R) cells against reactive oxygen species.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Blue rubber bleb nevus syndrome associated with consumption coagulopathy: treatment with interferon.

The blue rubber bleb nevus syndrome (BRBNS) is a rare vascular malformation syndrome with cutaneous and visceral lesions frequently associated with serious, even fatal bleeding. No systemic therapy is currently available. We report here a case with disseminated skin and gastrointestinal venous malformations and findings of disseminated intravascular coagulation that was treated with interferon beta. The disseminated intravascular coagulation manifestations were cleared with the treatment. The regression of the coagulopathy in our patient led us to think that the use of interferon beta in BRBNS might be beneficial.

Child, Preschool↗
PubMed2003

A new microcolumn flotation cell for determining the wettability and floatability of minerals.

Flotation is one of the most important physicochemical processes for mineral separations and other recovery operations. Flotation machines have been developed since the beginning of the 19th century and are still under intensive research and development. The cell we devised is a combination of the Canadian column flotation cell and the Partridge-Smith cell. The materials used for the construction of the new cell are cheap and use available laboratory accessories and aquarium materials. The cell functions well in terms of its scale, control, and sample requirement. It can be used both in the laboratory for research and in classrooms for demonstrations of experiments. Some of the data obtained by the flotation method using this cell are in good agreement with data measured independently on the same minerals by the contact angles method. The critical values of surface tension of wetting (gamma(c)) for talc, sulfur, and chemically treated surfaces of calcite and barite obtained by the contact angle measurements were 31, 26, 30.5, and 31.2 mN/m, respectively. On the other hand, the gamma(c) values of those minerals, obtained using our new designed flotation cell, were 30, 28, 31.4, and 34.5 mN/m, respectively. The measurements obtained in our experiment are also comparable to those previously published for the same minerals.

Journal Article↗
PubMed2003

Psychiatric symptoms in Turkish infertile women.

The aims of this study were to determine the psychiatric symptoms which may develop because of infertility in Turkish women and to find out the precipitating factors. Fifty women with primary infertility and 50 health controls were evaluated using the Beck Depression Inventory, Spielberger Stait-Trait Anxiety Inventory, Rosenberg self-esteem scale and Symptom Checklist scale. They were also asked to describe the reactions received from their husband, husbands' families and social group because of infertility. Psychiatric symptoms were not significantly different between the two groups. However, within the infertile group, depression and anxiety were more frequent in the women who received negative reactions from their husband, their husbands' families and social group. Depression, anxiety and self-esteem were improved in the infertile women as age and the duration of infertility increased. In conclusion, our findings indicate that the reactions the infertile women are faced with play an important role in the development of certain psychiatric symptoms.

Adult↗
PubMed2000

Multidisciplinary approach to Wilms' tumor: 18 years of experience.

BACKGROUND: The aim was to evaluate the characteristics of Wilms' tumor and the results of combined modality treatment obtained in our center in Turkey. METHODS: From January 1978 to December 1996, 106 patients with Wilms' tumor were diagnosed. Of these 106 patients, 61 were male and 45 were female (M/F = 1,35); the median age at diagnosis was 39 months. The distribution of the 106 patients according to clinical stage was stage I 10%, stage II 42%, stage III 35%, stage IV 9% and stage V 4%. Histologically, 102 of the cases could be evaluated: favorable histology was diagnosed in 88.2% and unfavorable histology in 11.8% of the patients. Ninety-eight patients were treated according to NWTS and eight patients according to SIOP protocols. RESULTS: The EFS and overall survival rates at 2 years were 74.2 and 79.5% respectively, and at 5 years 72.4 and 76.6% respectively. CONCLUSION: As a developing country we evaluated our survival rates and report an improvement in treatment in recent years.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Tropisetron (Navoban) in the control of nausea and vomiting induced by combined cancer chemotherapy in children.

BACKGROUND: We aimed to assess the potency and efficacy of tropisetron, a 5-HT3 receptor antagonist, in the prevention of nausea and emesis observed in the pediatric patient population taking various chemotherapy protocols. METHODS: Tropisetron (Navoban) was given to 100 children (62 boys and 38 girls aged 6 months to 15 years) with various malignancies. Patients received tropisetron during one or more courses of emetogenic chemotherapy for a total of 350 courses administered intravenously or intravenously and intrathecally. Tropisetron (0.2 mg/kg/day, maximum: 5 mg/day) was administered as a single intravenous dose slowly, before the start of chemotherapy on day 1 and intravenously or by mouth on subsequent days (median treatment duration: 5 days). RESULTS: The patients receiving cytotoxic chemotherapy had a 70% complete response rate and a 24% partial response rate during the first 24 h period of the first course. We observed headache (five courses), diarrhea (three courses) and loss of appetite (one course) as side-effects (2.5%). CONCLUSION: Tropisetron is safe, effective, easy to use, has no serious side-effects and can be recommended for pediatric patients. The efficacy of tropisetron may be enhanced by the addition of corticosteroids in patients receiving highly emetogenic cancer chemotherapy.

Adolescent↗