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Biomedical subjects

M Polat

Publications and source records attributed to M Polat.

At least 19 recordsLinked to original sources
PubMed2006

Effect of pH and hydration on the normal and lateral interaction forces between alumina surfaces.

Interaction forces between alumina surfaces were measured using an AFM-colloid probe method at different pHs. For an alpha-alumina-sapphire system at acidic pH, the force curve exhibited a well-defined repulsive barrier and an attractive minimum. At basic pH, the interactive force was repulsive at all separations with no primary minimum. Lateral force measurements under the same conditions showed that frictional forces were nearly an order of magnitude smaller at basic pH than those observed at acidic pH. This behavior was attributed to the hydration of the alumina surface. Normal and lateral force measurements with the strongly hydrated rho-alumina surfaces supported these findings.

Journal Article↗
PubMed2006

Effect of various treatment and glazing (coating) techniques on the roughness and wettability of ceramic dental restorative surfaces.

Surface treatment procedures such as grinding and polishing are needed to provide the ceramic dental restorative materials with proper fitting and occlusion. The treated surfaces are customarily glazed to improve the strength and smoothness. Though smoothness and wetting of the dental surfaces are important to minimize bacterial plaque retention, influence of the surface treatment and glazing procedures on the final surface roughness and its correlation to wettability are overlooked. In this work, effect of various treatment (diamond fraising, stoning, sanding and aluminum oxide and rubber polishing) and glazing (auto and overglazing) techniques on the final roughness and the resulting wettability of dental ceramic surfaces were investigated using scanning electron microscopy (SEM) observations and atomic force microscopy (AFM) scans, 75 scans per sample. The surfaces were characterized and assigned an average roughness measure, R(a). The wettability of the same surfaces was evaluated using micro-contact angle measurements (25 micro-bubbles placed on a grid on each surface) to correlate the final surface roughness and wettability. The results show that overglazing prevails over surface irregularities from different treatment procedures and provides homegeneously smooth surfaces with mean R(a)<10 nm. It also produces uniformly wetted surfaces with low contact angles around 20 degrees . The autoglazed surfaces are less smooth (mean R(a) around 50 nm) and displays sporadic topographic irregularities. They display larger and less uniform contact angles ranging between 35 degrees and 50 degrees . The results suggest that overglazing should be preferred after surface treatment to obtain a smooth and well-wetted dental ceramic surface.

Aluminum Silicates↗
PubMed2006

Role of free radicals on mechanism of radiation nephropathy.

PURPOSE: In our study, after applying a single dose of 612 cGy irradiation, we aimed to observe the role of free radicals on tissue damage in the kidney caused by radiation by measuring NO level, Na/K-ATPase activity and TBARS amount which is an indicator of free radical damage. On the other hand we investigated whether the tissue damage can be prevented by vitamin A or not. MATERIALS AND METHODS: This study was performed on three groups: 1. Control group 2. The group to which irradiation was administrated 3. The group which was given radiation + vitamin A. The irradiation group of animals were given a single dose of gamma irradiation at a sublethal dose. In the group which was administrated both irradiation + vitamin A, vitamin A was given for two days prior to irradiation. The amount of NO was measured by ESR spectroscopy, Na/K-ATPase and TBARS were measured by spectrophotometry. RESULTS AND CONCLUSIONS: As a result of radiation mediated tissue damage in the kidney, we observed a NO loss, a decrease in Na/K-ATPase activity and an increase in TBARS amount. Although the administration of vitamin A before radiation, did not have any effect on NO loss and decrease in Na/K-ATPase.

Animals↗
PubMed2006

Neutralization of an extremely acidic sludge and stabilization of heavy metals in flyash aggregates.

An extremely acidic, heavy metal-rich sludge (pH=-1.2) was scrubbed with a Class-F fly ash in order to simultaneously neutralize the acidity and stabilize the heavy metals contained in both wastes. This paper outlines the leaching behavior of the aggregate material generated by scrubbing. For proper fly ash/sludge ratios, the fly ash acted as an outstanding neutralizer for the acidic waste. Leaching of heavy metals from the aggregate samples was below the environmental limits within a pH range between 3 and 9. Subsequent washing of the leached aggregate with acidic CALWET solutions did not result in an additional release of heavy metals. It is proposed that coordinative bonding of the metal cations onto neutral surface sites and electrostatic adsorption led to stabilization of the heavy metals within the aggregate structure below hydrolysis pHs.

Adsorption↗
PubMed2006

Identification of axonal involvement in Hallervorden-Spatz disease with magnetic resonance spectroscopy.

Hallervorden-Spatz disease is a neurodegenerative disorder associated with cysteine-iron complex accumulation typically seen as bilateral symmetrical hypointense signal changes in the medial globus pallidus on magnetic resonance imaging. We used magnetic resonance spectroscopy to identify and quantify neuronal damage in two siblings with Hallervorden-Spatz disease. The first patient presenting with a rapidly progressive extrapyramidal syndrome had markedly decreased N-acetylaspartate (NAA) to creatinine (Cr) ratios in the globus pallidi and the periatrial white matter. He also had increased myoinositol (mI) to creatinine (Cr) ratios implying glial proliferation in the affected regions. However the second patient who had the initial presentation of disease had normal NAA/Cr and mI/Cr ratios. These findings indicate that the quantification of NAA:Cr and mI:Cr ratios might be used to predict the extent of neuronal axonal loss and glial proliferation in patients with Hallervorden-Spatz disease respectively.

Aspartic Acid↗
PubMed2006

Relationship between impaired elastic properties of aorta with left ventricle geometric patterns and left ventricle diastolic functions in patients with newly diagnosed essential hypertension.

The aim of this study was to investigate the association between elastic properties of aorta with left ventricle (LV) geometric patterns and LV diastolic functions in patients with newly diagnosed hypertension (HT). We studied 149 patients with newly diagnosed HT and 29 healthy control subjects. Echocardiographic examination was performed to all subjects. Ascending aorta (Ao) diameters (mm/m2) and Ao elastic indexes - namely, Ao strain [AS] (%), Ao distensibility [AD] (cm2 dyn(-1) x 10(-6)) were calculated. Four different geometric patterns were identified in hypertensive patients according to LV mass index (LVMI) and relative wall thickness (RWT). Tissue Doppler-derived Ea/Aa was determined from the all subjects. Patients vs. control subjects had lower mean AS and AD (p < 0.001 for both). Mean AS and AD of all geometric patterns significantly decreased compared with control group (p < 0.05 for all). Both AS and aortic AD of concentric remodelling (CR; p = 0.017 for both) and concentric hypertophic groups (p < 0.001 for both) were decreased compared with normal LV group. AS and AD of concentric hypertrophic pattern was lower than that of the CR group (p = 0.011 and 0.020 respectively) and the eccentric hypertrophic group (p < 0.001 and p = 0.002, respectively). Both AS and AD of the CR group were similar to that of the eccentric hypertrophic group (p > 0.05 for both). Both AS and AD were significantly correlated with age (beta = -0.178, p = 0.025, beta = -0.158, p = 0.029 respectively), LVMI (beta = -0.223, p = 0.022, beta = -263, p = 0.003 respectively), RWT (beta = -0.196, p = 0.019, beta = -0.189, p = 0.013 respectively) and Ea/Aa (beta = 0.174, p = 0.045, beta = 0.247, p = 0.002 respectively) in multiple linear regression analysis. Elastic properties of aorta were impaired in newly diagnosed HT. The degree of this impairment is different among various LV geometric patterns. In addition, impaired elastic properties of aorta were associated with RWT, LVMI and diastolic disfunctions, besides age, but not with LV geometry.

Adult↗
PubMed2003

ESR detection and dosimetric properties of irradiated naproxen sodium.

In the present work, the electron spin resonance (ESR) dosimetric properties of naproxen sodium (NS) was investigated in the dose range of (2.5-25 kGy). Irradiated NS exhibited a very simple ESR spectrum consisting of a broadened antisymmetric single resonance line not saturating up to 2 mW microwave power at room temperature. The sum of two exponential increasing functions associated with two different radicals of different spectroscopic features and relative weights were found best describing experimental dose-response curve. Radiation induced radicals were observed to be very stable at room temperature but the increase in storage temperature increased very appreciably the decay of the contributing radicals. The results of the simulation calculation based on a model of two radicals showed that two carbon dioxide ionic free radicals (*CO(2))(-) of different orientational and environmental features produced by preferential rupture of carboxyl group from the rest of NS molecules in the crystalline matrix, were, likely at the origin of the experimentally observed ESR spectrum. Features such as good time stability of the signal intensity and relatively high radiation yield (G=0.13) were considered providing NS with potential use as dosimetric material in measuring radiation dose in the range of 2.5-25 kGy by ESR technique.

Dose-Response Relationship, Radiation↗
PubMed2003

An investigation of the presence of methane and other gases at the Uzundere-Izmir solid waste disposal site, Izmir, Turkey.

Izmir is a large metropolitan city with a population of 3,114,860. The city consists of 27 townships, each township has a population of not less than 10,000 inhabitants. The two major solid waste disposal sites are in the townships of Uzundere and Harmandali. The amount of solid waste that is disposed at each of these sites is about 800 and 1800 t/day, respectively. In Uzundere, compost is produced from the organic fraction of urban solid wastes while the residual material is deposited at a disposal site with a remaining capacity of 700,000 m(3) as of 2001. Gas monitoring and measurements were carried out at the disposal site in Uzundere. For this purpose, nine sampling wells were drilled on selected locations. Each well was furnished with perforated metal pipes suitable for gas monitoring and measurements. The following gases were monitored: O(2), CH(4), CO, CO(2), and H(2)S. The most important finding was that the concentrations of CH(4) in the wells ranged from 7 to 57%. Dilution of the CH(4) by O(2) down to the LEL levels (5-15%) is always possible and poses a continuing risk at the site. Furthermore, the levels of O(2) require that access to the site be limited to only authorized personnel.

Cities↗
PubMed2002

Kinetics of the radicals induced in gamma-irradiated naproxen sodium and apranax. Applicability of ESR technique to monitor radiosterilization of naproxen sodium-containing drugs.

In the present work the spectroscopic and kinetic features of the radicals induced in gamma-irradiated naproxen sodium (NS) and apranax (AP) tablet are investigated at room and different temperatures in the dose range of 2.5-25 kGy by electron spin resonance technique (ESR). Radiation produces two different radicals (I, II) in NS quite stable at room temperature but relatively unstable above room temperature, giving rise to a broad singlet centered at g = 2.0057. Dose-response and decay curves associated with the broad singlet were found to follow bi-exponentials. Information concerning the saturation decay rates and activation energies were obtained through the characteristics of these exponentials. Similar calculations were also performed for AP, which contains 550 mg NS as active ingredient, and the applicability of ESR technique for monitoring radiosterilization of AP was discussed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Electrodermal activities and autonomic nervous system in Behçet's patients.

Behçet's disease is often a progressive disorder. In some cases, there is a possibility of subclinical involvement without neurologic signs and symptoms. The autonomic nervous system is affected in Behçt's disease. The aim of the present study was to investigate autonomic nervous system functions in Behçt's patients by analyzing electrodermal activities. A total of 16 patients and 16 healthy volunteers were accepted for the study. Skin potential recordings were taken at room temperature in a quiet place within a Faraday's cage. The mean values of basal skin potentials and skin potential responses in the patients' group were reduced when compared with those of the control group ( p=0.0001). There was no difference between the groups regarding the mean values of latency ( p=0.09). The findings suggest that electrodermal activities may reflect autonomic nervous system dysfunction in Behçet's patients, and the measurement of electrodermal activities may be useful for the assessment of autonomic nervous system involvement in Behçet's disease.

Adult↗
PubMed2001

Lower arrythmogenic risk of low dose albuterol plus ipratropium.

OBJECTIVE: Wheezy infants are in need of urgent bronchodilatation owing to their intermittent bronchoconstriction. beta 2 agonists are frequently used in emergencies and have previously shown to increase the QT dispersion (QTd), which may be associate with high risk of cardiac arrhythmia, in asthmatics. However, effect of low dose beta 2 agonist therapy in combination with the anticholinergic agents on QTd in wheezy infants is not known. This study aimed to assess the effect of standard dose of nebulized albuterol (NAB) and low doses of NAB combined with ipratropium-bromide (NIB) on QTd in wheezy infants. METHODS: Twenty-nine children, under 2 years old, with the diagnosis of wheezy infant with acute exacerbation were enrolled in the study. Thirteen were treated by standard dose of NA therapy (0.15 mg/kg) and low doses of NAB (0.075 mg/kg) plus NIB (250 micrograms/dose) therapy was given to the remaining subjects. Respiratory distress score, O2 saturation and side effects were studied and QTd were measured from the standard electrocardiograms at baseline and after treatment. Significant improvement was achieved in clinical score and oxygenation of both groups. RESULT: The evaluation of the corrected QTd (QTcd) showed that there was no significant difference between pretreatment values of both groups (p > 0.05). However, while there was no statistically significant difference in the pre and post-treatment values of QTcd of infants treated with combination therapy, QTcd was found to be significantly increased in NAB group after treatment (p < 0.05). CONCLUSION: Our results suggest that, while clinical improvement is same, the increase of the QT dispersion is more prominent with the use of standard dose of NAB compared to low dose NAB plus NIB therapy. So, low dose of beta 2 agonist in combination with anticholinergic agents may much safer than the use of standard dose of beta 2 agonists alone in regard to preventing the possibility of arrythmogenic effects in wheezy infants with acute exacerbation.

Albuterol↗
PubMed2001

Triterpenoid saponins from Isertia pittieri.

Two new 27-nor-triterpenoid saponins, pyrocincholic acid 3 beta-O-beta-D-quinovopyranosyl-28-[beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl] ester (1) and pyrocincholic acid 3 beta-O-beta-D-quinovopyranosyl(1-->6)-beta-D-glucopyranosyl-28-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl] ester (2) were isolated from the stem bark of Isertia pittieri, together with two known bidesmosidic quinovic acid glycosides. The structures of 1 and 2 were determined on the basis of spectroscopic studies.

Chromatography, High Pressure Liquid↗
PubMed2001

Proximal isovelocity surface area (PISA) as a noninvasive method for the estimation of the shunt quantification in perimembranous ventricular septal defects.

This study was designed to assess the reliability of the proximal isovelocity surface area (PISA) method for the estimation of shunt quantification in perimembranous ventricular septal defects (PVSD). The study group was composed of 30 patients (age 11 +/- 7 years, 13 female) with PVSD. The shunt flow (Qp-Qs) and the ratio of the pulmonary flow to the systemic flow (Qp/Qs) were calculated by spectral Doppler and catheterization. The Qp-Qs, the defect area (DA), and the shunt volume (SV) were obtained by the PISA method. The PISA method estimated the DA (cm(2)/m(2)), the SV (cm(3)/m(2)), and the Qp-Qs (L/min/m(2)) to be equal to (2 x pi x R(2) x NL)/(V(max) x Body surface area), DA x TVI(shunt), and to SV x Heart rate, respectively (R is the distance of the maximal PISA from the first aliasing line to the left ventricular side of the defect, NL is the nyquist limit, and V(max) and TVI(shunt) are the peak velocity and time-velocity integral of transdefect Doppler tracing obtained by continuous-wave Doppler). The PISA method (3.4 +/- 1.5 L/min/m(2)) underestimated the Qp-Qs according to spectral Doppler (r = 0.96, P < 0.001; mean difference -0.74 +/- 0.61 L/min/m(2); SEE = 0.11 L/min/m(2), P < 0.001) and catheterization (r = 0.92, P < 0.001; mean difference -0.45 +/- 0.7 L/min/m(2); SEE = 0.13 L/min/m(2), P < 0.001). The correlations between the PISA findings (Qp-Qs, DA, SV) and the catheterization Qp/Qs (r = 0.86, 0.84, and 0.86; P < 0.001, respectively), or between these and the spectral Doppler Qp/Qs (r = 0.80, 0.80, and 0.79; P < 0.001, respectively) were significant. The accuracies of the PISA findings in identifying large defects were high (0.90, 0.93, and 0.90 for cut-off values of Qp-Qs = 3.67 L/min/m(2), DA = 0.44 cm(2)/m(2), and SV = 43 cm(3)/m(2), respectively). As a result, the PISA method can be a simple and reliable alternative to the spectral Doppler method in the identification of large shunts in PVSD.

Adolescent↗
PubMed1999

Sneddon's syndrome and antithrombin III.

Sneddon's syndrome, an uncommon disorder, is characterized by multiple cerebrovascular accidents along with ideopathic livedo reticularis. In this article, two cases who had increased amounts of antithrombin III and were diagnosed with Sneddon's syndrome are presented.

Adult↗
PubMed1997

Urinary enzyme changes in newborns with unconjugated hyperbilirubinemia.

Various changes in renal function caused by unconjugated hyperbilirubinemia in newborns have been suggested in previous reports. Disclosing an injury in renal tubulus epithelium is feasible by measurement of urinary enzymes. Thus, renal function tests and urinary enzymes in 25 terms newborns with unconjugated hyperbilirubinemia were evaluated before and after phototherapy. Ten healthy term newborns without hyperbilirubinemia formed the control group. Mean values of the variables obtained before and after phototherapy in the study group and in the controls were, respectively: urine osmolality (osm/kg H2O): 0.147 +/- 0.009, 0.174 +/- 0.011, and 0.153 +/- 0.018; endogenous creatinine clearance (mL/min per 1.73 m2): 45.7 +/- 2.15, 46.0 +/- 1.6 and 46.7 +/- 3.9; fractional excretion of sodium (%): 1.27 +/- 0.30, 0.79 +/- 0.19 and 1.24 +/- 0.07; tubular phosphorus reabsorption (%): 85.8 +/- 3.3, 87.8 +/- 2.8 and 86.6 +/- 1.7; urinary N-acetyl-beta-D glucosaminidase/creatinine (IU/mg): 0.617 +/- 0.226, 0.574 +/- 0.214 and 0.619 +/- 0.210; fractional excretion of alkaline phosphatase (%): 0.422 +/- 0.103, 1.001 +/- 0.374 and 0.596 +/- 0.201; fractional excretion of lactic dehydrogenase (LDH; %): 0.102 +/- 0.019, 0.121 +/- 0.023 and 0.119 +/- 0.041; fractional excretion of AST (%): 0.433 +/- 0.127, 0.530 +/- 0.113 and 0.502 +/- 0.074; fractional excretion of alanine aminotransferase (ALT; %) 0.856 +/- 0.413, 1.619 +/- 1.076 and 1.066 +/- 0.366. No significant difference was found between these values before and after phototherapy in the study group, or between the values before phototherapy in hyperbilirubinemic neonates and in the control group. In conclusion, unconjugated hyperbilirubinemia up to a serum level of 18.4 mg/dL in term neonates does not seem to result in injury of normal tubulus epithelium as shown by urinary enzyme levels.

Alanine Transaminase↗