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Biomedical subjects

M Korkmaz

Publications and source records attributed to M Korkmaz.

30 records · Page 2Linked to original sources
PubMed1997

The effects of mitomycin-C and temperature on dynamical properties of human erythrocyte membrane.

Alterations produced by mitomycin-C (hereafter MC) and temperature changes in human erythrocyte membrane molecular dynamics were studied, in vitro, by spin-labeling ESR technique. Erythrocyte cells were spin-labeled with 5- and 16-doxyl-stearic acids, 5- and 16-DSA, respectively, and membrane fluidity was quantified by measuring the changes in the order parameter (S), correlation time (tau), phase transition temperature and activation energies. Erythrocyte cells were first labeled with 5-DSA and 16-DSA at 37 degrees C for 10 min, then they were treated with MC of three different concentrations (2.5; 5 and 10 microM) for various time (0-300 min) at the same temperature. Experimental results indicate that treatment time and applied MC concentrations do not produce any significant reproducible changes in the spectral parameters. However, change in temperature was observed to alter significantly S and tau parameters that show biphasic character in the temperature range of 5-50 degrees C. Activation energy values of hydrocarbon chains above and below transition temperatures for untreated and MC-treated erythrocyte cells were also determined, and the effect of MC on these energy values were discussed.

Cell Membrane↗
PubMed1996

Evaluation of preoperative chemotherapy using PET with fluorine-18-fluorodeoxyglucose in breast cancer.

UNLABELLED: We retrospectively investigated the value of PET with fluorine-18 fluorodeoxyglucose (FDG) for preoperative chemotherapy response in patients with locally advanced breast cancer. METHODS: FDG-PET studies were performed on 16 consecutive patients. All patients had PET studies before chemotherapy, 13 patients between the end of the first cycle and at the midpoint of chemotherapy, and 14 patients before surgery. Visual diagnoses and the standardized uptake values (SUV) of PET scans were compared with pathology findings at surgery and with the results of mammography, ultrasonography (US) or both, which were performed before chemotherapy and before local surgery for residual disease. Each patient's clinical course was monitored for up to 3 yr. RESULTS: Sensitivity for detection of pathologically proven primary lesions was 100%, 62.5% and 87.5% with FDG-PET, mammography and US, respectively; and sensitivity for detection of initial nodal involvement was 77%, 70% and 87.5%, respectively. Sensitivity for detection of residual primary tumor was 75%, 71.4% and 87.5%, respectively; and sensitivity for detection of residual nodal involvement was 41.6%, 71.4% and 66.6%, respectively. The mean SUV value of primary lesions was 9.4 (range 2.0-20.7, n = 16), with only two lesions showing an SUV below 3. Clinical improvement of primary lesions was seen in all patients; improvement with smaller size and less FDG uptake was visible as early as the second study in 11 patients (69%). Mean SUV values obtained at the second and third studies decreased significantly from those obtained in the first study. In four patients, the disease recurred after breast surgery with high SUV values. The mammograms and sonograms obtained before surgery showed a decrease in the diameter of 6 and 12 primary lesions of the 13 and 14 patients examined, respectively. CONCLUSION: FDG-PET is valuable for monitoring the effects of preoperative chemotherapy in patients with locally advanced breast cancer with better sensitivity for primary tumor and better specificity for nodal metastasis in comparison with ultrasonography.

Adult↗
PubMed1996

Assessment of latex indirect agglutination test (Toxolatex Fumouze) for the detection of Toxoplasma specific antibodies in human sera in Turkey.

Sera from 50 patients were examined with conventional ELISA, IFA and Toxolatex Fumouze. Out of 50 specimens only 3 false positive cases were detected with Toxolatex Fumouze as compared with the results of ELISA & IFA tests. Toxolatex Fumouze represents a rapid, highly sensitive and specific technique for screening of specific antibodies against toxoplasmosis, but due to false negative results, sera from patients at risk of severe toxoplasmosis (fetus, HIV+, transplant, immunosupressed) should be tested with other serological methods such as the dye test, DS-ELISA and ISAGA.

AIDS-Related Opportunistic Infections↗
PubMed1996

Comparison of fluorine-18-fluorodeoxyglucose and carbon-11-methionine PET in detection of malignant tumors.

UNLABELLED: Two commonly used tumor-seeking agents for PET are 2-deoxy-2-18F-fluoro-D-glucose (FDG) and L-methyl-11C-methionine (Met). This study compared FDG and Met in detecting residual or recurrent malignant tumors in the same patients. METHODS: Thirty-four lesions in 24 patients with clinically suspected recurrent or residual tumors were studied with PET using Met as well as FDG. FDG scans were conducted 1 hr after the completion of PET with Met. The color-coded superimposed images of standardized uptake values (SUVs) and transmission data were produced, and the peak SUVs in the lesions were then evaluated. Lesions above 2.5 SUV were interpreted as positive results for active tumor. RESULTS: The sensitivity of FDG-PET and Met-PET were 64.5% (20/31 lesions) and 61.3% (19/31 lesions), respectively. The mean SUV of FDG in residual or recurrent malignant tumors (n = 31) was significantly higher than that of Met but there was a significant correlation (r = 0.788, p < 0.01) between FDG and Met SUVs in all lesions (n = 34). CONCLUSION: PET using FDG and Met appear equally effective in detecting residual or recurrent malignant tumors although FDG uptakes were slightly higher than Met uptakes. Both showed a limited diagnostic sensitivity for small (< 1.5 cm) tumors.

Adult↗
PubMed1996

Comparison of fluorine-18-FDG PET and technetium-99m-MIBI SPECT in evaluation of musculoskeletal sarcomas.

UNLABELLED: We compared the diagnostic accuracy of [18F]FDG PET and 99mTc-MIBI SPECT in musculoskeletal sarcomas. METHODS: Forty-eight patients with clinically suspected recurrent or residual musculoskeletal sarcomas were examined with both FDG-PET and MIBI-SPECT within 2 wk of each study (one follow-up study in nine patients and we follow-up studies in one patient). Imaging findings were visually inspected with grading scales in conjunction with CT and/or MRI, and count-density ratios of lesion-to-contralateral area and standard uptake values (SUVs) of FDG and MIBI in lesions were also generated. The results were correlated with histologic findings (in 51 studies) and/or long-term follow-up evaluations. RESULTS: The diagnostic sensitivities and specificities were 98% and 90% using FDG, and 81.6% and 80% using MIBI, respectively, with statistical significance in the sensitivity. The tumors were demonstrated better in FDG studies, which produced higher visual grades (2.1 versus 1.6), and the tumors showed increasing SUVs with time (from 6.3 to 7.3). Four of nine patients with positive FDG but negative MIBI scans failed to respond to multidrug therapy. CONCLUSION: FDG-PET and MIBI-SPECT are useful in differentiating active sarcomas from post-treatment changes and in evaluating therapeutic response. MIBI-SPECT and FDG-PET findings should be interpreted in con junction with CT and/or MRI. FDG-PET shows statistically significant higher sensitivity than MIBI-SPECT. A positive FDG but negative MIBI scan might suggest a multidrug resistance.

Adult↗
PubMed1995

In-111 DTPA Ommayagrams in leptomeningeal carcinomatosis.

Radionuclide Ommayagrams in 25 patients with leptomeningeal carcinomatosis were performed after injection of 0.5 mCl of In-111 DTPA into Ommaya shunt reservoirs to evaluate cerebrospinal fluid-shunt communication, detect the blockage of the cerebrospinal fluid pathway, evaluate the cerebrospinal fluid flow pattern, and predict the distribution of the chemotherapeutics. All results were correlated with MRI evaluations of the brain and spine, as well as clinical findings. Radionuclide Ommayagrams were found to be 73% sensitive and 100% specific in the evaluation of cerebrospinal fluid space disease. MRI of the spine and head was found to be 100% sensitive, but 86% specific for obstructive cerebrospinal fluid space disease.

Adolescent↗
PubMedDate not supplied

Colonoscopy is a useful diagnostic tool for transplant recipients with lower abdominal symptoms.

Transplant recipients are at higher risk for infection and malignancy due to therapies aimed at preventing rejection. Early detection and successful treatment of such complications is of pivotal importance for both patient and graft survival. In this study, we evaluated findings of 91 colonoscopies and colonic histopathologic findings in recipients who presented with lower gastrointestinal system complaints between January 1996 and January 2003. The study group included 79 renal and liver transplant patients. The indications for colonoscopy were diarrhea (n = 58), abdominal pain (n = 5), hematochezia (n = 19), unexplained anemia (n = 5), thickening of a colonic segment detected on computerized tomography (n = 2), screening for lymphoma (n = 1), and Kaposi's sarcoma (n = 1). During the procedures, all suspicious lesions were biopsied and specimens of normal-appearing mucosa collected when deemed necessary in relation to the clinical complaints. The endoscopic findings were classified as follows: 0 = "normal," with clear visualization of the vascular network and normal-appearing mucosa; 1 = "erythema", with tissues showing erythema, edema, hyperemia, and loss of normal vascular network; 2 = "ulcerative," with tissues exhibiting ulceration and fragility; and 3 = "coincidental findings," such as polyp or angiodysplasia. Colonoscopic and/or histopathologic abnormalities were detected in 44.5% of the 91 colonoscopy procedures. The results indicate that colonoscopy is a valuable diagnostic tool for evaluation of transplant recipients with lower gastrointestinal complaints. After an initial workup colonoscopy is important to establish an accurate diagnosis.

Adolescent↗
PubMedDate not supplied

Investigation of possible clinical and laboratory predictors of liver fibrosis in hemodialysis patients infected with hepatitis C virus.

Hepatitis C virus (HCV) infection is common in patients with end-stage renal disease. The severity of liver damage, including fibrosis, in these cases varies widely. Although many investigators have searched for noninvasive alternatives to liver biopsy for evaluating the extent of liver fibrosis, no useful noninvasive predictors have been found. Currently, liver biopsy is essential to assess the degree of fibrosis. The aim of this retrospective study was to investigate a range of clinical and laboratory parameters in HCV-infected hemodialysis (HD) patients and identify possible predictors of fibrosis. Ninety-five consecutive HD patients with HCV infection underwent liver biopsy. Each specimen was evaluated for fibrosis stage. Correlations were sought between the degree of fibrosis and the age, HD duration, time since first possible HCV exposure, body mass index, HCV RNA titer, serum ferritin level, and serum alanine aminotransferase (ALT) level. The analysis revealed no significant correlations between fibrosis stage and the parameters investigated (mean age: r =.017, P =.89; mean HD duration: r =.066, P =.576; body mass index r =.231, P =.152; HCV RNA titer: r =.015, P =.091; serum ferritin: r =.134, P =.32; serum ALT r =.108, P =.927). Links with serum ALT were reevaluated with upper normal levels arbitrarily set at 30 IU/L and 20 IU/L, but these analyses also revealed no correlations between fibrosis stage and ALT level (P =.98 and P =.449, respectively). Therefore liver biopsy is still essential for accurate assessment of liver pathology in HD patients with HCV.

Biopsy↗
PubMedDate not supplied

In vitro effects of colchicine on human erythrocyte membranes: an ESR study.

Colchicine (CC) is an antimitotic and antitubular agent which is currently used in medicine as a drug to treat various diseases. In spite of its widespread use the interaction of this drug with membranes is not yet known clearly. To characterize alterations in membrane molecular dynamics produced by CC, human erythrocytes were spin-labeled with 5-doxylstearic acid (5-DSA) and 16-doxylstearic acid (16-DSA), and membrane fluidity was quantified by measuring the changes in the order parameter (S) which reflects the anisotropy due to restricted motional averaging, correlation time (tau c) representing the spin label tumbling rate in the sample and phase transitions derived from ESR measurements. CC induced significant changes in both order parameter and correlation time at the surface of 5-DSA labeled membrane, but this was not the case at the core of 16-DSA labeled membrane. Order parameter, S and rotational correlation time, tau c, showed a biphasic character in the temperature range of 5-50 degrees C. This fact was used to calculate phase transition temperatures and activation energies of untreated (control) and treated erythrocyte cells with CC.

Colchicine↗