Biomedical subjects

Y Türköz

Publications and source records attributed to Y Türköz.

16 recordsLinked to original sources

PubMed2003

Vascular endothelial growth factor levels are increased and associated with disease activity in patients with Behçet's syndrome.

BACKGROUND/AIMS: Vascular endothelial growth factor (VEGF) is a cytokine participating in inflammation with potent endothelial cell effects. It is produced by macrophages, neutrophils and vascular endothelial cells and can alter vessel permeability. Behçet's syndrome is a systemic inflammatory disorder with unknown etiology. Vascular endothelial dysfunction is one of the prominent features of the disease. We previously demonstrated the possible involvement of proinflammatory cytokines [tumor necrosis factor (TNF)-alpha, soluble interleukin-2 receptor (sIL-2R), interleukin (IL)-6 and IL-8], nitric oxide (NO) and adrenomedullin in the etiopathogenesis of Behçet's syndrome. Since VEGF expression is induced by these cytokines and VEGF itself is a potent stimulator of NO production with endothelial cell effects, this study aimed to investigate whether VEGF was affected during the course of Behçet's syndrome. We also assessed the possible involvement of VEGF in ocular Behçet's syndrome or in disease activity. METHODS: This multicenter case-control study included a total of 39 patients with active (n = 22) or inactive (n = 17) Behçet's syndrome (mean age, 38.1 +/- 10.4 years; 21 men and 18 women) satisfying International Study Group criteria, and 15 healthy hospital-based control volunteers (mean age, 39.2 +/- 9.3 years; eight men and seven women) matched for age and gender from a similar ethnic background. Patients were examined by a dermatologist and an ophthalmologist with an interest in Behçet's syndrome. Plasma VEGF concentrations were measured using a newly established enzyme-linked immunosorbent assay. Clinical findings and acute-phase reactant parameters such as erythrocyte sedimentation rate, alpha1-antitrypsin, alpha2-macroglobulin, and neutrophil count were used to classify the disease in Behçet's patients as active or inactive. The Wilcoxon test or the Mann-Whitney U-test was used for statistical analysis as indicated and the results were expressed as mean +/- SD, with range. RESULTS: The mean plasma VEGF level in patients with Behçet's syndrome (291.9 +/- 97.1 pg/mL; range 121-532 pg/mL) was higher than that in control subjects (103.0 +/- 43.6 pg/mL; range 25-187 pg/mL) and the difference was significant (P < 0.001). Patients with active disease had significantly (P < 0.001) higher VEGF levels than patients with inactive disease (347.6 +/- 87.1 vs. 219.9 +/- 51.6 pg/mL). In addition, ocular Behçet's patients (n = 23) had higher VEGF levels (315.7 +/- 92.1 pg/mL) than nonocular patients (n = 16, 257.8 +/- 96.6 pg/mL) and the difference was of borderline significance (P = 0.041). The levels of all acute-phase reactant parameters were significantly higher in the active stage than in the inactive stage (for each, P < 0.01) or in control subjects (for each, P < 0.001). CONCLUSIONS: VEGF may participate in the course of Behçet's syndrome, especially in the active stage, and elevated levels of VEGF may be an additional risk factor for the development of ocular disease, contributing to poor visual outcome.

Adult↗

PubMed2002

Comparison of serum NO, TNF-alpha, IL-1beta, sIL-2R, IL-6 and IL-8 levels with grades of retinopathy in patients with diabetes mellitus.

BACKGROUND: Vitreal interleukin (IL)-1beta (IL-1beta), IL-6, IL-8, tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) levels have previously been determined in patients with proliferative diabetic retinopathy (PDR). However, at present there is no cohort study linking serum levels of NO and many inflammatory cytokines such as TNF-alpha, IL-1beta, soluble IL-2 receptor (sIL-2R), IL-6 and IL-8 to the grade of the microvascular complications. PURPOSE: To determine the relation between the stages of DR and the levels of serum NO, TNF-alpha, IL-1beta, sIL-2R, IL-6 and chemokine IL-8 in patients with diabetes compared with healthy controls. METHODS: Fifty-three consecutive patients with diabetes (25 men, 28 women) with or without DR and 15 non-diabetic healthy subjects (seven men, eight women) as controls were included in this prospective study. As an indicator for NO, serum total nitrite (NO2- + NO3-) levels (end-product of NO) were measured by the Griess reaction. Serum TNF-alpha, IL-1beta, sIL-2R, IL-6 and IL-8 levels were determined by a spectrophotometric technique using an Immulite chemiluminescent immunometric assay. The patients with diabetes were classified into three groups according to the stage of DR: no DR (NDR; n = 16), non-proliferative DR (NPDR; n = 18) and PDR (n = 19). The data were analysed using a Mann-Whitney U-test and the results were expressed as mean +/- SE (range). RESULTS: The levels of IL-1beta and IL-6 were below the detection limits of the assay (for each, <5.0 pg/ml) in all patients with diabetes and controls. Soluble IL-2R levels ranged from 260 to 958 U/ml, with the highest values observed in the patients with PDR. In 47 of the 53 samples (89%) tested for diabetic patients, IL-8 levels were above the detection limits of the assay (5.0 pg/ml). IL-8 levels ranged from <5.0 to 25.0 pg/ml, with the highest mean values observed in PDR patients. TNF-alpha was detectable in 46 of 53 patients with diabetes (87%), ranging from <4.0 to 26.4 pg/ml, with again the highest values obtained in the patients with PDR. Serum NO levels ranged from 80 to 188 micromol/l, with the highest values obtained in patients with PDR. Taken together, the mean serum NO, sIL-2R, IL-8 and TNF-alpha levels increased with the stage of DR and the highest levels were found in patients with PDR. The PDR patients had significantly (for each, P < 0.001) higher serum NO (166.8 +/- 3.2 micromol/l), sIL-2R (807.9 +/- 33.3 U/ml), IL-8 (17.9 +/- 0.4 pg/ml) and TNF-alpha (15.0 +/- 0.8 pg/ml) levels compared with NPDR patients (149.5 +/- 2.1, 659.4 +/- 23.4, 12.9 +/- 1.1, 11.5 +/- 0.6, respectively), NDR patients (115.9 +/- 5.8, 373.8 +/- 15.0, 8.3 +/- 1.0, 6.6 +/- 0.9, respectively) and controls (116.6 +/- 2.3, 392.4 +/- 16.6, 7.2 +/- 0.3, 7.3 +/- 0.5, respectively). Serum levels of these parameters for NPDR patients were also significantly (for each, P < 0.01) higher compared with those of NDR patients and controls. On the other hand, serum NO, sIL-2R, IL-8 and TNF-alpha levels of patients with NDR were comparable with those of controls (for each, P > 0.05). CONCLUSION: The results of the present study suggest that NO, sIL-2R, IL-8 and TNF-alpha may play important roles in the pathophysiology and progression of DR. We think that these potentially inflammatory cytokines and NO with their endothelial implications may act together during the course and progression of DR. These molecules may serve as therapeutic targets for the treatment and/or prevention of diabetes with its systemic and ocular microvascular complications.

Adult↗

PubMed2002

Serum homocysteine level is increased and correlated with endothelin-1 and nitric oxide in Behçet's disease.

BACKGROUND/AIMS: Behçet's disease (BD) is a systemic inflammatory vasculitis of young adults with unknown aetiology, characterised by endothelial dysfunction and occlusion in both deep venous and retinal circulation. Ocular involvement occurs in 70% of cases and is characterised by periphlebitis, periarteritis, vascular occlusion, and thrombosis leading to blindness despite vigorous treatment. Endothelin-1 (ET-1) is a vasoconstricting peptide while nitric oxide (NO) is a relaxing molecule and both are released by endothelium for blood flow regulation. Homocysteinaemia is a newly defined term connected to the increased risk of atherothrombotic and atherosclerotic systemic and retinal vascular occlusive diseases, and its role in the course of BD has not been previously described. The authors aimed to detect serum total homocysteine (tHcy), ET-1, and NO in BD and to assess if tHcy, ET-1, and NO are associated with ocular BD or disease activity. METHODS: 43 consecutive patients with ocular (n = 27) or non-ocular (n = 16) BD (36.95 (SD 9.80) years, 22 male, 21 female) satisfying international criteria, and 25 age and sex matched healthy control subjects (37.88 (8.73) years, 13 male, 12 female) without a history of systemic or retinal venous thrombosis were included in this study. Patients were examined by two ophthalmologists with an interest in BD. Serum tHcy, ET-1, and NO concentrations were measured in both groups. Hyperhomocysteinaemia was defined as a tHcy level above the 95th percentile in the control group. Patients were divided into active and inactive period by acute phase reactants including alpha(1) antitrypsin, alpha(2) macroglobulin, erythrocyte sedimentation rate, and neutrophil count. RESULTS: The overall mean serum tHcy, ET-1, and NO levels were significantly higher in patients with BD than in control subjects (tHcy = 15.83 (4.44) v 7.96 (2.66) ng/ml, p <0.001; ET-1 = 17.47 (4.33) v 5.74 (2.34) micromol/ml, p <0.001; NO = 37.60 (10.31) v 27.08 (7.76) micromol/l, p <0.001). Serum tHcy, ET-1, and NO levels were significantly higher in active patients than in inactive patients and control subjects. In addition, among patients with ocular BD, the mean tHcy levels were significantly increased and correlated with ET-1 and NO levels when compared with non-ocular disease and control subjects. All acute phase reactant levels were significantly higher in active period than in inactive stage and controls. CONCLUSIONS: Elevated tHcy may be responsible for the endothelial damage in BD and may be an additional risk factor for the development of retinal vascular occlusive disease, contributing to the poor visual outcome in these patients. Assessment of tHcy may be important in the investigation and management of patients with BD, especially with ocular disease.

Acute-Phase Proteins↗

PubMed2000

Adrenomedullin and nitrite levels in children with minimal change nephrotic syndrome.

Nitric oxide (NO) serves many functions within the kidney, and recent evidence suggests that NO contributes to glomerular injury. Adrenomedullin (AM) is a novel hypotensive peptide originally isolated from human pheochromocytoma. Recent studies showed that plasma AM concentrations correlated with the extent of proteinuria. We have examined the possible role of these two agents by studying plasma and urinary total nitrite (NO-2 + NO-3) and AM levels in children with minimal change nephrotic syndrome (MCNS). In comparison with healthy controls, children with MCNS had increased urinary nitrite excretion (micromol/mg urinary creatinine), irrespective of whether the disease was in relapse or remission (3.2+/-0.2 in relapse, n=13; 1.9+/-0.3 in remission, n=12; 1.0+/-0.2 in controls, n=10, P<0.05). Plasma nitrite levels (micromol/l) were high in relapse compared with controls (53.2+/-8.7 vs. 32+/-4.0, P<0.05). Plasma AM levels (pmol/ml) were decreased in relapse (27.6+/-1.4 in relapse, 43.3+/-1.2 in remission, 41.5+/-1.6 in controls, P<0.05). Urinary AM levels (pmol/mg urinary creatinine) were significantly higher in relapse than in remission and in controls (156+/-43 in relapse, 56+/-18 in remission, 36+/-16 in controls, P<0.05). Our data indicate that NO may play a role in mediating the clinical manifestations of MCNS in children. However, changes in AM levels may be the result of heavy proteinuria.

Adrenomedullin↗

PubMed2000

Adrenomedullin and nitrite levels in children with Bartter syndrome.

Children with Bartter syndrome have lower than normal vascular reactivity with normotension in spite of biochemical and hormonal abnormalities which are typical of hypertension. Nitric oxide (NO) is a potent endogenous vasodilator, and plays an important role in the control of vascular tone. Adrenomedullin (AM) is a novel hypotensive peptide originally isolated from human pheochromocytoma. The possible role of NO and AM in maintaining this reduced vascular reactivity was examined by studying plasma and urinary nitrite, a stable metabolite of NO, and AM levels in ten children with Bartter syndrome, ten healthy controls, and five children with hypokalemia of causes other than Bartter syndrome (pseudo-Bartter). Urinary excretion of nitrite (mumol/mg urinary creatinine) was 8.9 +/- 1.2 in children with Bartter syndrome, 4.7 +/- 0.9 in healthy controls, and 2.9 +/- 0.8 in pseudo-Bartter (P < 0.05). Plasma nitrite levels (mumol/l) were 101.9 +/- 23.4, 59.9 +/- 14.7, and 65.0 +/- 29.7, respectively (P < 0.05), in the three groups. Urinary excretion of AM (pmol/mg urinary creatinine) was 187 +/- 40, 65 +/- 10, and 160 +/- 50, respectively (P < 0.05), in the three groups. Plasma AM levels were 47.4 +/- 1.8, 39.9 +/- 5.9, and 42.4 +/- 3.9, respectively (P > 0.05), in the three groups. The same parameters were repeated in the two groups of controls and in the Bartter patients in the 6th month of therapy. Urinary nitrite and AM levels were still higher in the Bartter patients than in the other groups. We conclude that in Bartter syndrome the increased NO production may be responsible for the reduced vascular response of the disease. Initially, increased levels of AM in Bartter syndrome and pseudo-Bartter may be a compensatory response to acute hypokalemia; however, continuation of a high level of urinary excretion of AM in children with Bartter syndrome may suggest also the possible role of AM in the reduced vascular response of the disease.

Adolescent↗

PubMed2000

Use of pleural fluid C-reactive protein in diagnosis of pleural effusions.

The aims of the study were to assess whether C-reactive protein (CRP) is a sensitive marker for discriminating between transudative and exudative and pleural effusions to evaluate whether it can be used to distinguish inflammatory pleural effusions from other types of effusion. Pleural fluid and serum CRP levels were obtained in 97 patients with pleural effusion, using an immunoturbidimetric method (Olympus AU-600 autoanalyser). We compared CRP levels between transudates and exudates, inflammatory effusions and other types of effusion. According to the criteria used, 16 patients were included in the transudate group and 81 patients in the exudate group. Pleural fluid CRP levels were significantly lower in the transudate group (P<0.04; 14.9 +/- 4.9 mg l(-1) and 35.5 +/- 4.9 mg l(-1) respectively). Also, the ratio of pleural fluid to serum was significantly lower in the transudate group (P<0.009; 0.8 +/- 0.5 mg l(-1) and 2.8 +/- 0.7 mg l(-1), respectively). In the exudate group, 35 patients had neoplastic effusions, 10 chronic non-specific pleurisy, 19 tuberculous pleurisy, 16 parapneumonic effusion and one Dressler Syndrome. When these sub-groups were compared, the parapneumonic effusion subgroup CRP levels (mean 89 +/- 16.3 mg l(-1)) were significantly higher than those in the other subgroups, other exudate of neoplastic effusion, tuberculous pleurisy and chronic non-specific effusion and the transudate group (P<0.0001; P<0.0001; P<0.0004 and P<0.0001, respectively). The ratio between pleural fluid and serum CRP was significantly higher in the parapneumonic effusion subgroup than in the neoplastic subgroup (P<0.0002; 6.6 +/- 2.7 mg l(-1) and 1 +/- 0.2 mg l(-1), respectively). Pleural fluid CRP levels > 30 mg l(-1) had a high sensitivity (93.7%) and specificity (76.5%) and a positive predictive value of 98.4%. In the differential diagnosis of pleural effusions, higher CRP levels may prove to be a rapid, practical and accurate method of differentiating parapneumonic effusions from other exudate types. Although the high level of CRP obtained in the exudate group may be due to the number of patients with parapneumonic effusion who were included, the pleural CRP level may also be helpful in discriminating between exudative and transudative pleural effusions.

Biomarkers↗

PubMed1996

Relationship between various functional impression techniques and different operators.

The purpose of the present investigation was to determine the relationship between the reproducibility of soft tissue contours by three different functional impression techniques and four dentists for mandibular distal-extension removable partial dentures. The selected functional impression methods were Lejoyeux, Rouot and McLean techniques. A mucostatic impression technique was used for the control group. To compare and measure the degree of tissue displacement, a three-dimensional coordinate measuring system was used. The differences in vertical displacement of soft tissue among the operators were statistically determined for each impression technique used. Lejoyeux technique produced the least variation in tissue displacement followed respectively by McLean, mucostatic and Rouot methods.

Computing Methodologies↗

PubMed1989

[Effects of various enzymes on Candida albicans activity on denture base materials].

In this study, the effects of various enzymes to remove C. Albicans, contamined on to the different kinds of specimens prepared from 5 different denture base materials were investigated. All kinds of enzymes investigated were found to be effective, but both protase and the pure lipase were observed to be more effective than the others by their zero colonies calculated. It was decided that pepsin, trypsin and pancreatic amylase have less effects on C. Albicans than the others.

Amylases↗

PubMed1989

[Influences of remelting on physical properties of denture base metal alloys].

This research was designed in order to evaluate the mechanical properties, such as tensile strength, compressive strength, surface hardness and the elongation and reduction percentages of the length, of the metal specimens prepared from first, second and third generation castings of a denture base metal. The results revealed only a proportional decrease on surface hardnesses of the specimens casted from first, second and third meltings. While the other properties of all specimens had showed no significant differences between themselves, it was concluded that the denture base metals could be melted and used again at least three times.

Dental Alloys↗

PubMed1989

[Effects of various prosthodontic strengtheners on fatigue behaviour of acrylic resins].

The fatigue behaviour of acrylic sheet specimens containing reinforcers were investigated. Three different kinds of reinforcers namely, stainless steel, aluminum reinforcer and three flex wire were used as strengtheners in acrylic resin sheets. The tests were carried out on alternating bending fatigue testing machine specially designed to test sheet specimens. By applying static and dynamic bending moments of any desired magnitude within the permissible capacity likits of the machine the fatigue lives of the specimens were determined. Experimental results showed that stainless steel strengtheners had a significant positive effect on the fatigue behaviour of acrylic resin.

Acrylic Resins↗

PubMed1988