Biomedical subjects

O Dogru

Publications and source records attributed to O Dogru.

12 recordsLinked to original sources

PubMed2005

Percolation transition in the heterogeneous vortex state of NbSe2.

A percolation transition in the vortex state of a superconducting 2H-NbSe2 crystal is observed in the regime where vortices form a heterogeneous phase consisting of ordered and disordered domains. The transition is signaled by a sharp increase in critical current that occurs when the volume fraction of disordered domains reaches the value P(c) = 0.26 +/- 0.04. Measurements on different vortex states show that, while the temperature of the transition depends on history and measurement speed, the value of P(c) and the critical exponent characterizing the approach to it, r = 1.97 +/- 0.66, are universal.

Journal Article↗

PubMed2004

Observation of the vortex lattice spinodal in NbSe2.

Metastable superheated and supercooled vortex states in NbSe2 crystals were probed with fast transport measurements over a wide range of field and temperature. The limit of metastability of the superheated vortex lattice defines a line in the phase diagram that lies below the superconducting transition and is clearly separated from it. This line is identified as the vortex lattice spinodal, and is in good agreement with recent theoretical predictions by Li and Rosenstein [Phys. Rev. B 65, 220504 (2002)]; cond-mat/0305258]. By contrast, no limit of metastability is observed for the supercooled disordered state.

Journal Article↗

PubMed2004

SV40 in human thyroid nodules.

BACKGROUND: Simian virus 40 (SV40) has been a model experimental system for the study of cell transformation and tumorigenesis for many years. The study of SV40 in humans has aroused interest in the related BK virus (BKV) and JC virus (JCV) and their role in human disease. OBJECTIVES: SV40 has been found in a variety of human samples, both malignant and normal. Many independent studies have suggested that SV40 plays a role for some cancers. However, in most cases the role of SV40 remains unclear. STUDY DESIGN: The subject of this study consisted of 99 patients with thyroid nodules. Both thyroid nodule and normal thyroid tissue were taken from each patient to test whether they contained SV40 sequences. RESULTS: We detected SV40 sequences by polymerase chain reaction (PCR) in four of 99 thyroid nodules. Two of them were papillary thyroid carcinomas and the others were benign thyroid nodules. No SV40 was detected in 99 of normal thyroid tissues of the same patients. DNA sequence analysis, performed in four positive samples, confirmed that PCR products belong to the SV40 T antigen (Tag) region. CONCLUSION: The possible role of SV40 in the development of thyroid nodules and the spread of SV40 by horizontal infection in the human population are discussed.

Adolescent↗

PubMed2004

[Clinical, angiographical, and procedural causes of acute vessel closure during transluminal coronary intervention].

AIM: To elucidate factors related to acute vessel closure (AVC) after transluminal coronary intervention. METHODS: From population of 10439 patients subjected to transluminal coronary intervention 2 groups were formed: with (n=885) and without (n=885) acute vessel closure (AVC). Twenty five clinical, angiographical and procedural characteristics of patients of these 2 groups were included into mono and multifactorial logistic regression analysis. RESULTS AND CONCLUSION: The following factors were univariate predictors of acute vessel closure: smoking [odds ratio (OR) 1.42], unstable angina (OR=2.130, acute myocardial infarction within previous 24 hours (OR 2.76), cardiogenic shock (OR 4.31), urgent procedure (OR 1.94), eccentric stenosis (OR 1.67), calcified lesion (OR 2.21), preexisting thrombosis (OR 3.79), lacerated complicated stenosis (OR 2.02), tortuous lesion (OR 1.35), low operator experience (OR 3.37), balloon angioplasty as sole procedure (OR 1.66), concomitant rheolytic thrombectomy (OR 1.95), urgent stenting (OR 1.45). Elective stenting significantly lowered risk of acute vessel thrombosis. Multifactorial step-up analysis selected the following independent predictors of AVC: smoking, acute myocardial infarction within previous 24 hours, cardiogenic shock, preexisting thrombosis, lacerated complicated stenosis, and concomitant rheolytic thrombus extraction. Thus only elective stenting significantly reduced risk of AVC.

Angina, Unstable↗

PubMed2004

[Prognosis of unstable angina resulting from restenosis after percutaneous angioplasty of saphenous vein grafts].

AIM: To assess frequency of unstable angina due to restenosis after percutaneous angioplasty of venous grafts and to elucidate risk factors of its development. MATERIAL AND METHODS: Percutaneous interventions were successfully performed in 100 out of 106 patients with venous graft stenoses. These patients were followed up for 17+/-11 (maximum 36) months. RESULTS: Unstable angina due to venous graft restenosis developed in 24% of patients. Patients with unstable angina compared with those without were characterized by higher frequency of hyperlipidemia (83 vs. 51%, respectively, p=0.032), lower rate of stenting (46 and 72%, respectively, p=0.032), greater residual stenosis (15+/-13 and 9+/-8%, respectively, p=0.008). At multifactorial regression analysis the following factors were significant predictors of unstable angina: hyperlipidemia (odds ratio [OR] 3.55, 95% confidence interval [CI] 1.64-8.39), and residual stenosis after intervention (OR 1.04, 95% CI 1.01-1.07, p=0.04). In a subgroup of patients with hyperlipidemia there was a tendency to greater rate of unstable angina among patients not taking statins compared with users of statin (50 and 29%, respectively, p=0.083). CONCLUSION: Unstable angina developed in (1/4) of patients after balloon dilatation of venous grafts and hyperlipidemia was its most powerful predictor.

Angina, Unstable↗

PubMed2003

Hemobilia.

BACKGROUND: Laparoscopic procedures are safe and effective treatment methods in experienced hands. However, complications have been reported for laparoscopic procedures. One of the complications of laparoscopic cholecystectomy is vascular injuries. Hepatic and cystic artery injuries may occur alone or in association with bile duct injury. Bleeding from arterial injury may be seen during operation or in the late postoperative period. One of the most significant pathologies leading to this rare phenomenon is hemobilia. METHODS: We present a case of a 62-year-old woman who underwent routine laparoscopic cholecystectomy for cholelithiasis at another hospital. She presented 6 months later with the clinical feature of upper gastrointestinal bleeding. RESULTS: There was a 42 x 40 x 11 mm anechoic lesion and an echoic pattern compatible with a metallic object was found in the subhepatic region using abdominal ultrasonography. In the endoscopic examination, fresh blood was found in the stomach. The source of hemorrhage could not be identified. Bulbus duodeni was normal but a fresh clot on the papilla of Vateri was seen on gastroduodenoscopic examination. Laparotomy was performed and the provisional diagnosis of hemobilia was reached. The injured hepatic artery and pseudoaneurysmatic structure were repaired. CONCLUSION: Hemobilia is a late complication of laparoscopic cholecystectomy. We believe that it is important to take into consideration that bile duct injuries may be accompanied by arterial pathology.

Aneurysm↗

PubMed2003

[Effectiveness of excimer laser coronary angioplasty in treatment of patients with in-stent restenosis].

In-stent restenosis (ISR), when treated with balloon angioplasty (PTCA) alone, has an angiographic recurrence rate of 30-85%. Ablating the hypertrophic neointimal tissue prior to PTCA is an attractive alternative, however late outcomes of such treatment have not been fully determined. This multicenter case control study assessed angiographic and clinical outcomes of 137 consecutive procedures in 125 patients treated for ISR with either PTCA alone (n = 58) or excimer laser assisted coronary angioplasty (ELCA, n = 67). Demographics were similar. Lesions selected for ELCA compared with those selected for \PTCA were longer (17.1+/-9.9 mm vs. 13.6+/-9.1 mm; p=0,034), more complex (ACC/AHA type C: 36,5% vs. 14,3%; p=0,006), and with reduced antegrade flow (TIMI flow < 3: 18,9% vs. 4,8%; p = 0,025). ELCA- and PTCA treated patients had similar rates of procedural success (98,5 and 98,3%, respectively, p=1,0), major clinical complications (3,0% and 8,6%; respectively, NS), major cardiac events at 1 year (37,3 and 46,6%. respectively, NS), and target lesion revascularization (32,8 and. 34,5%; respectively, NS). These data suggest that ELCA in patients with complex in-stent restenosis is as safe and effective as PTCA. Despite higher lesion complexity in ELCA-treated patients, no increase in event rates was observed.

Aged↗

PubMed2003

[Rheolytic thrombectomy with AngioJet catheter during transluminal coronary revascularization in patients with acute myocardial infarction].

BACKGROUND: Although balloon angioplasty and stenting are effective in the treatment of acute myocardial infarction (M1), reduced coronary flow and distal embolization frequently complicate interventions when thrombus is present. Adjunctive treatment with mechanical thrombectomy devices was suggested to reduce these complications. METHODS: We evaluated immediate angiographic, in-hospital and 30-day follow-up clinical outcomes of 185 patients with acute MI and angiographically evident thrombus who were treated with AngioJet rheolytic thrombectomy followed by immediate definitive treatment. RESULTS: Procedural success (residual diameter stenosis <50% and thrombolysis in myocardial infarction [TIMI] flow >2 after final treatment) was 97%. Rheolytic thrombectomy success was achieved in 7% of patients. Subsequent definitive treatment included stenting in 67% and balloon angioplasty alone in 26% of patients. Final TIMI 3 flow was achieved in 89%. AngioJet treatment resulted in mean thrombus area reduction from 69.6 mm(2) at baseline to 17.3 mm(2) post-thrombectomy (p<0.001). Procedural complications included distal embolization (7.6%) and perforation (1.1%). Clinical success (procedure success without major in-hospital cardiac events) rate was 88%, in-hospital mortality - 7.0%. There were no further major adverse events during 30-day follow-up. CONCLUSION: Rheolytic thrombectomy can be performed safely and effectively in patients with acute MI, allowing for immediate definitive treatment of thrombus-containing lesions.

Angioplasty, Balloon, Coronary↗

PubMed2003

The effects of melatonin and prostaglandin E1 analogue on experimental hepatic ischaemia reperfusion damage.

The effects of antioxidant melatonin and a prostaglandin E1 analogue (PGE1) on hepatic ischaemia reperfusion damage were investigated. Fifty rats were divided into five equal groups: sham, control, melatonin, PGE1 and combined treatment. No procedures were applied to the sham group. In the control and treatment groups, the hepatic hilus was clamped at the level of the hepatic artery and portal vein for 60 min and reperfusion was provided for two hours. In the treatment and combined treatment groups, melatonin was administered intramuscularly at a dose of 20 mg/kg 15 mins before reperfusion, and PGE1 was administered intravenously at a dose of 25 mg/kg 1 min before reperfusion. Blood samples for SGOT, SGPT, GSH-Px, SOD and MDA measurements and hepatic tissue samples were taken. The decrease in the plasma MDA levels was statistically significant in the melatonin and combined treatment groups, but not in the PGE1 group (p > 0.025). A significant decrease was found in the tissue MDA levels of the treatment groups (p < 0.025). The decrease in SGOT and SGPT levels in the PGE1 group was significant (p < 0.025), but the decreases in the melatonin and combined treatment groups were not significant (p>0.025). Melatonin and PGE1 were found to be effective in reducing the hepatic ischaemia reperfusion damage in rats. However, the damage could not be reversed. Combined treatment was found not to be superior to melatonin or PGE1 alone.

Alanine Transaminase↗

PubMed2001

Interferon-alpha therapy in idiopathic thrombocytopenic purpura.

BACKGROUND: Acute idiopathic thrombocytopenic purpura (ITP) represents the most frequent hemorrhagic diathesis in childhood. Up to 30% of patients with ITP are regarded as refractory to standard therapy. The rare mortality from acute ITP in childhood is almost exclusively due to intracranial hemorrhage. This complication occurs in less than 1% of ITP patients. This study was designed to evaluate the effect of alpha-interferon (IFN-alpha) in eight patients whom did not respond to conventional therapy. METHOD: In spite of conventional therapies, the patient whose platelet count could not be increased to 50;10(9)/L were accepted as refractory ITP. Eight of these patients whose platelet count lower than 20;10(9)/L were included in the prospective cohort study. Interferon alpha 2b 5 MU/m(2) was administered subcutaneously three times a week, totalling 12 times in a month. According to the platelet count on the 28th day of therapy, we grouped the patients into three categories. After 60 days, the survey was re-evaluated according to the platelet count. RESULTS: The mean age of children was 3.5+/-2.5 (ranged between 3.5 and 9) years. Six of them were boys and two were girls. There was no response in one patient, partial response in one, and good response in six patients on the 28th day of therapy. The maximum rise in platelet count was observed from 7 to 14 days after the initiation of interferon. The median platelet count which was 15+/-5;10(9)/L before therapy, raised to 60+/-12;10(9)/L after therapy. However, on the 60th day of therapy, there were only two patients who had a platelet count over 100;10(9)/L. CONCLUSION: In our study, we did not observe the long-term benefit of IFN-alpha therapy in refractor ITP in childhood. However, in good responding patients, platelet levels were increased in a short time. Alpha-interferon may be alternative therapy for patients whom had a platelet count below 20;10(9)/L and not responding to standard therapy, or for patients whom immunosuppressive therapy is contraindicated.

Child↗

PubMed2001

Lamivudine and interferon-alpha combination treatment of childhood patients with chronic hepatitis B infection.

BACKGROUND: The aim of our study was to compare the efficacy of combined interferon-alpha and lamivudine in children with chronic hepatitis B infection and two durations of treatment (6 and 12 months). METHODS: Combination of interferon-alpha 2b (10 MU/m2 of body surface) and lamivudine 4 mg/kg (maximum, 100 mg) were given synchronously to 30 patients for 6 months (Group 1) and to 27 patients for 12 months (Group 2). Biochemical, virologic and serologic features were compared between two groups at the end of therapy and 6 months after therapy. RESULTS: Hepatitis B e antigen clearances were 33 and 59% at the end of treatment and 37 and 56% 6 months after therapy in Groups 1 and 2, respectively (P > 0.05). Hepatitis B virus DNA clearances were 97 and 100% at the end of treatment and 97 and 96% 6 months after therapy in Groups 1 and 2, respectively (P > 0.05). In both groups normalization of alanine aminotransferase was maintained at the end of therapy and 6 months after therapy (P < 0.05). Sustained complete responses were obtained in 20 and 37% of patients at the end of therapy and 6 months after therapy, respectively (P = 0.07). CONCLUSIONS: When the combination of large dosage interferon-alpha 2b and lamivudine therapy in children was compared at the end of therapy and 6 months after therapy, normalization of alanine aminotransferase and the clearances of hepatitis B e antigen and hepatitis B surface antigen in both groups were directly proportional to the duration of treatment. However, the higher complete response rate at 12 months of combination therapy was not statistically different from that at 6 months.

Adolescent↗

PubMedDate not supplied

Ghrelin immunohistochemistry of gastric adenocarcinoma and mucoepidermoid carcinoma of salivary gland.

Ghrelin (G-HH) synthesized in several tissues including salivary and stomach glands stimulates appetite in humans by modulating neuropeptide Y neurons in the hypothalamic arcuate nucleus. Loss of appetite is one of the most important symptoms of stomach cancer. We conducted a study using immunohistochemistry to determine whether salivary glands and stomach cancer tissues produce ghrelin. We determined that negative ghrelin immunohistochemistry discriminates tumors from normal tissues and may therefore further our understanding of the clinically important problem of reduced food intake and anorexia in cancer patients. Radioimmunoassay analyses confirmed that cancer cells do not produce a G-HH peptide, whereas normal cells yield this peptide.

Adenocarcinoma↗