Biomedical subjects

Y Ozkan

Publications and source records attributed to Y Ozkan.

At least 19 recordsLinked to original sources

PubMed2006

A comparison between the effects of low (1 microg) and standard dose (250 microg) ACTH stimulation tests on adrenal cortex functions with Behçet's disease.

INTRODUCTION: Behçet's disease is a rare, chronic disorder. The cause of Behçet's disease is unknown. It is believed to be caused by an autoimmune reaction. As in other chronic autoimmune diseases, Behçet's disease may show a subclinical adrenal failure and some changes in cortisol levels. We aimed to evaluate adrenal gland function in Behçet's disease patients. MATERIAL AND METHOD: This study included 18 Behçet's disease patients and 15 healthy controls. Patient and control groups were administered i.v. 1 microg low dose test (LDT) and 250 microg standard dose test (SDT) adrenocorticotropic hormone (ACTH) stimulation test after 12 h of night fasting with an interval of 3-days and cortisol responses in the 0th, 30th and 60th minutes were evaluated. RESULTS: There was no statistically significant difference between basal cortisol values of Behçet's disease and control groups. Cortisol values in the 60th minute in LDT were significantly lower in Behçet's disease group than in the control group. In the peak cortisol responses to LDT, a significant decrease was found in Behçet's disease group. CONCLUSION: These findings suggest that hypothalamo-pituitary adrenal axis is partially suppressed in Behçet's disease.

Adrenal Cortex↗

PubMed2005

A study to assess the colour stability of acetal resins subjected to thermocycling.

The purpose of this study was to compare colour stability of pink and white acetal resin with one conventional poly (methylmethacrylate) resin. Five specimen disks 50 +/- 0.1 mm in diameter and approximately 1.0 mm thick were prepared from each material. The discs were hydrated for a period of 30 days in distilled water and were then desiccated to a constant weight. Total of fifteen specimens were thermocycled for 100 and 300 hours (4000-12000 cycle) between water baths of 5-55 degrees C. Changes from baseline colour readings were recorded at each interval. Data were analysed with descriptive statistic, repeated measured analysis of variance and single factor analysis of variance. The colour changes for all materials at 100 hours were in the categories of slight, based upon the National Bureau of Standard System (NBS) for expressing colour difference. At 300 hours, the colour changes of materials were significantly different (p = 0.0001). All the materials tested showed clinically acceptable discolouration values.

Color↗

PubMed2004

Validated RP-hPLC method for the assay of zalcitabine in drug substance, formulated products and human serum.

A HPLC method for zalcitabine determination in bulk form, pharmaceutical dosage forms and human serum has been developed and validated. The proposed method was conducted using a reverse phase technique, and UV monitoring at 265 nm. The mobile phase consisted of methanol: 0.01 M NaH2PO4 (85:15; v/v) adjusted to pH 4.62 with 1 M NaOH. The detector response was linear in the range of 0.015-50 microg mL(-1). The limit of detection and the limit of quantification of the procedure were 0.0066 microg mL(-1) and 0.022 microg mL(-1), respectively. The retention time was 2.5 min for zalcitabine and 3.5 min for the internal standard. No interferences from tablet additives were observed and analysing tablets containing zalcitabine proved the applicability of the method. This method was also applied for the determination of zalcitabine in spiked human serum samples.

Calibration↗

PubMed2001

A rapid, sensitive high performance liquid chromatographic method for the determination of meropenem in pharmaceutical dosage form, human serum and urine.

A new, simple, precise and rapid high performance liquid chromatographic method was developed for the determination of meropenem in human serum, urine and pharmaceutical dosage forms. Chromatography was carried out on an LC(18) column using a mixture of 15 mM KH(2)PO(4):acetonitrile:methanol (84:12:4; v/v/v), adjusted to pH 2.8 with H(3)PO(4). The proposed method was conducted using a reversed-phase technique, UV monitoring at 307.6 nm and cefepime as an internal standard. The retention times were 5.98 and 7.47 min for cefepime and meropenem, respectively. The detector response was linear over the concentration range of 50-10,000 ng/mL. The detection limit of the procedure was found to be 22 ng/mL. The detection limit for meropenem in human plasma was 108.4 ng/mL and the corresponding value in human urine was 179.3 ng/mL. No interference from endogenous substances in human serum, urine and pharmaceutical preparation was observed. The proposed method is sufficiently sensitive for determination of the concentrations of meropenem and may have clinical application for its monitoring in patients receiving the drug.

Carbapenems↗

PubMed2001

Dental caries prevalence, tooth brushing and periodontal status in 150 young people in Istanbul: a pilot study.

OBJECTIVE: To evaluate periodontal conditions, prevalence and determination of dental caries and oral health behaviours in a group of young people in Istanbul. DESIGN: Subjects were orally examined and questioned. SETTING: A high school in Istanbul. SUBJECTS: One hundred of fifty students. RESULTS: This study showed that 28 per cent of teenagers had adequate oral hygiene. These findings suggest that 72 per cent of the subjects needed oral hygiene education and required restorative dental care. CONCLUSIONS: The present study showed that dental treatment need is very high in the sample group. Strong co-operation should be set up between families, schools, communities, regulators and legislators in order to develop and implement comprehensive oral health promotion programmes.

Adolescent↗

PubMed2001

Simultaneous determination of paracetamol and methocarbamol in tablets by ratio spectra derivative spectrophotometry and LC.

The application of the ratio spectra derivative spectrophotometry and high-performance liquid chromatography (HPLC) to the simultaneous determination of paracetamol (PAR) and methocarbamol (MET) in combined pharmaceutical tablets is presented. The spectrophotometric procedure is based on the use of the first derivative of the ratio spectra obtained by dividing the absorbtion spectrum of the binary mixtures by a standard spectrum of one of the compounds. The first derivative amplitudes were measured at 243.0 and 230.3 nm for the assay of PAR and MET, respectively. Calibration graphs were established for 2-30 microg ml for PAR and 2-36 microg/ml for MET in binary mixture. The detection limits for PAR and MET were found 0.097 and 0.079 microg/ml, respectively; while the quantification limits were 0.573 microg/ml for PAR and 1.717 microg/ml for MET. For the HPLC procedure, a reversed-phase column with a mobile phase of methanol-water (60:40, v/v), was used to separate both compounds with a detection of 274.0 nm. Linearity was obtained in the concentration range of 2 300 and 1.5-375 microg/ml for PAR and MET, respectively. The detection and quantification limits were found to be 0.42 and 1.4 microg/ml for PAR and 0.36 and 1.2 microg/ml for MET, respectively. The relative standard deviations were found to be less than 0.52%, indicating reasonable repeatibility of both methods. The proposed methods were successfully applied to the determination of these drugs in commercial tablets.

Acetaminophen↗

PubMed2001

Plasma malondialdehyde (MDA) levels in breast and lung cancer patients.

OBJECTIVE: To measure the levels of malondialdehyde (MDA), a marker of lipid peroxidation, in patients with breast and lung cancer. METHOD: Analysis of plasma MDA, and serum uric acid, albumin, cholesterol and triglycerides in 26 breast and 12 lung cancer patients and 41 healthy controls. The effects of age, body mass index (BMI), and menopausal status on plasma MDA were evaluated in the 26 patients with breast cancer. RESULTS: Plasma MDA levels in cancer patients were significantly higher than those in controls (P < 0.001). Average MDA levels were 6.33 micromol/L in breast cancer patients and 5.87 micromol/L in lung cancer patients. There was no correlation between MDA and triglyceride levels in either controls or cases. There was no correlation between MDA and cholesterol levels in patients with breast cancer, but there was a correlation in patients with lung cancer. Albumin levels did not differ significantly between controls and cases (P > 0.05), but uric acid levels in breast cancer patients were significantly higher than those of controls (P < 0.01). CONCLUSION: The results of this study provide further evidence of the relationship between lipid peroxidation and cancer and should contribute to the interpretation of epidemiological studies in this area and the planning of future research.

Adult↗

PubMed2001

Color stability of different denture teeth materials: an in vitro study.

The aim of this in vitro study was to compare the color stability of commercially available porcelain, reinforced acrylic, and conventional acrylic denture teeth materials used in removable prostheses. Two brands of porcelain (Unilux-Enta Lactona-Holland and Vivoperl-Ivoclar-Liechtenstein), 2 brands of reinforced acrylic (Optodent-Bayer-Germany and Ivolek-Ivoclar-Liechtenstein), and 2 brands of conventional acrylic (Isodent-Güney Diş Deposu-Turkey and Samed-Turkey), were made, for a total of 6 different denture teeth groups. Denture teeth were subjected to 3 staining solutions (filtered coffee, tea, and cola) and distilled water. From each group of denture teeth, 4 sets of maxillary anterior denture teeth were immersed in each of the 4 solutions. The color values of denture teeth were measured colorimetrically with the Gardner XL 20 Tristimulus Colorimeter (Gardner Lab. Inc., Bethesda, Maryland, USA). Color changes were characterized in the CIEL*a*b* color space. Color change values were determined after 1 day, 1 week, 2 weeks, and 4 weeks. The color difference values were calculated and then evaluated by two-way ANOVA statistically. The filtered coffee solution was found to be more chromogenic than the other 2 staining solutions, while porcelain denture teeth materials were more color stable. Assuming the color change of deltaE* < 1.0 as a discernible limit and deltaE* = 3.3 as an acceptable value, the filtered coffee, tea, and cola had slight staining effects on all 6 groups of denture teeth.

Acrylic Resins↗

PubMed2000

Clarithromycin targeting to lung: characterization, size distribution and in vivo evaluation of the human serum albumin microspheres.

Microspheres of clarithromycin have been prepared from human serum albumin using the emulsion polymerization technique. Albumin microspheres containing the active substance were injected into the tail vein of mice. Mice were sacrificed at intervals and microspheres collected from lungs and livers. The clarithromycin amount in microspheres was determined by reversed phase high performance liquid chromatographic (HPLC) method from the mice organs. Morphological and histopathological observations were also reported. The microsphere accumulation began at 10 min, and increased gradually until 6 h, then a decrease was observed. The microspheres were still present after 24 h. In the liver sample, no microsphere accumulation was observed at any time.

Albumins↗

PubMed2000

High-performance liquid chromatographic analysis of verapamil and its application to determination in tablet dosage forms and to drug dissolution studies.

A high-performance liquid chromatographic procedure with two detectors is presented for the determination of verapamil in pharmaceutical dosage forms. The procedure is based on the use of reversed-phase high-performance liquid chromatography with UV and fluorimetric detectors. Each analysis required no longer than 6 min for both detection procedures. Quantification was achieved by measurement of the ratio of the peak area of the drug to the internal standard (fluoxetine) and the detection limit was 10 ng/ml for the UV detector and 750 pg/ml for the fluorimetric detector. There was no significant difference between inter- and intra-day studies for verapamil determined for two different concentrations (0.05 and 1.00 microgram/ml). This process could be used to determine verapamil concentrations in the range 0.025-50 and 0.0008-20 micrograms/ml for UV and fluorimetric detection, respectively. These methods were applied, without any interference from the excipients, for the determination of the drug in tablets and in drug dissolution studies. It is suggested that the proposed HPLC procedures could be used for routine quality control and dosage form assay of verapamil hydrochloride.

Calcium Channel Blockers↗

PubMed2000

Improvement of water solubility and in vitro dissolution rate of gliclazide by complexation with beta-cyclodextrin.

Inclusion complexes of gliclazide with beta-cyclodextrin were prepared using different two methods: neutralization and recrysstalization. Host-guest interactions were studied in the solid state by X-ray diffractometry and infrared spectroscopy. The stability constant between gliclazide and beta-cyclodextrin was calculated from the phase solubility diagram. It was found that the neutralization technique and a solid complex of gliclazide with beta-cyclodextrin in a molar ratio of 1.5:1 could be used to prepare the amorphous state of drug inclusion complexes. The dissolution rates of gliclazide from the inclusion complex made by neutralization was much faster than the pure drug, physical mixture of drug and cyclodextrin, recyristalization system and also comparable to the data reported in literature. Results of this report indicate that beta-cyclodextrin could be useful for the solid gliclazide formulations as it may results in a more rapid and uniform release of the drug.

Cyclodextrins↗

PubMed2000

Voltammetric investigation of oxidation of zuclopenthixol and application to its determination in dosage forms and in drug dissolution studies.

The oxidative voltammetric behaviour of zuclopenthixol (ZPT) at a glassy carbon has been studied using cyclic, linear sweep and differential pulse voltammetry. Oxidation of the drug produced three pH dependent anodic steps (representing an irreversible oxidation). Using differential pulse voltammetry, the drug yielded a well-defined voltammetric response in phosphate buffer, pH 5.2 at + 0.82 V (vs. Ag/AgCl). This process could be used to determine ZPT concentrations in the range 8 x 10(-7)-2 x 10(-4) M. The method was applied, without any interferences from the excipients, to the determination of the drug in tablets and oral drops, and in drug dissolution studies.

Antipsychotic Agents↗

PubMed2000

Studies of floating dosage forms of furosemide: in vitro and in vivo evaluations of bilayer tablet formulations.

For the purpose of enhancement the bioavailability of furosemide (FR), a floating dosage form with controlled release of FR was designed in this study. Because of the lower solubility of active material in the gastric medium, it was first enhanced by preparing an inclusion complex of FR with beta-cyclodextrin (beta-CD) in a 1:1 proportion using the kneading method. Following the design of dosage form, bilayer floating tablets were prepared. After dissolution rate studies were performed using the continuous flow-through cell method, the formulation that provided delivery of active material near the target profile was given to six healthy male volunteer subjects, and in vivo tests were performed. It was determined by radiographs that floating tablets prepared by adding BaSO4 stayed in the stomach for 6 hr. Further, values of the area under the plasma concentration-time curve (AUC) obtained with the floating dosage form were about 1.8 times those of the conventional FR tablet in blood analyses; maximum and minimum plasma concentrations were also found to be between the desired limits. In urine analyses, the peak diuretic effect seen in classical preparations was decreased and prolonged in floating dosage forms. Also, a considerably significant correlation was detected between in vivo results and in vitro data of the dissolution rate, and it was concluded that the modified continuous flow-through cell method is usable for in vitro dissolution rate tests of floating dosage forms.

Biological Availability↗

PubMed1999

A prospective, randomized, double-blind, placebo-controlled trial of glyceryl-trinitrate ointment in the treatment of children with anal fissure.

BACKGROUND: Anal fissure in children usually is treated by sitz baths, stool softeners, and analgesic ointments. However, some cases are intractable to the treatment. In recent years, it has been reported that nitric oxide donors such as local glyceryl-trinitrate (GTN) ointment causes a reversible chemical sphincterotomy. Although the GTN ointment can be an alternative therapy for adult cases, it has not yet been studied in the children who suffer from anal fissure. METHODS: Sixty-five children with anal fissure were divided randomly into 3 groups. Each group received double-blinded a topical ointment that contained either 0.2% GTN, 10% lidocaine, or placebo. These ointments were applied to the lowest part of the anal canal twice daily. Patients were periodically reviewed, and the study was ended after 8 weeks. RESULTS: Complete healing of the fissure occurred in 26 of 31 (83.9%) patients treated with GTN, 7 of 14 (50%) patients treated with lidocaine, and 6 of 17 (35.2%) treated with placebo. In 29 of 31 (93.5%) GTN-treated patients, a total relief of symptoms was observed, whereas this occurred in 7 of 14 (50%) treated with lidocaine and 6 of 11 (35.3%) in the placebo group. The differences between the study group and control groups were highly statistically significant (P < .001). CONCLUSION: The majority of children suffering from anal fissure will be cured and have relief of symptoms after topical application of GTN ointment to the anal canal.

Child↗

PubMed1998

Electroanalytical study of nifedipine using activated glassy carbon electrode.

The electrochemical properties of nifedipine have been investigated in aqueous solution by linear sweep and cyclic voltammetry. The method is based both on the reduction and on the oxidation of the drug at a glassy carbon electrode activated by applying a new pre-treatment. The voltammograms of nifedipine on pH, concentration and scan rate have been carefully examined. Both the electroreduction and electrooxidation of nifedipine allow its determination at pH 1.5 in the concentration range of 2 x 10(-5)-6 x 10(-4) M and 8 x 10(-5)-1 x 10(-3) M, respectively. The method has been applied to commercial samples (tablets and capsules).

Calcium Channel Blockers↗

PubMed1998

Electrochemical reduction of metronidazole at activated glassy carbon electrode and its determination in pharmaceutical dosage forms.

A voltammetric method has been developed for the determination of metronidazole in dosage forms. The method is based on the electrochemical reduction of the drug at a glassy carbon electrode activated by applying a new pretreatment. The influence of pH, concentration, scan rate and presence of organic solvent and surfactant has been studied. The current is proportional to the concentration and permits the drug to be determined in the concentration range 2 x 10(-6)-6 x 10(-4) M in Britton-Robinson buffer (pH 10). Furthermore, results obtained by the proposed method have been compared with USP XXIII procedure which involves a HPLC method.

Antitrichomonal Agents↗

PubMed1996

A study of the nutrient foramina in the shaft of the fibula.

In this study a total of 305 adult fibulae were examined to determine the number and location of the nutrient foramina in the shafts of bones. Of 305 fibulae, 281 had one foramen, 12 had two and the remaining 12 had no foramen. The foramina were seen primarily on the posterior surface (48.36%) and in the middle third (98.00%) of the bone. The mean foraminal index of the fibula was found to be 48.14 +/- 0.46.

Adult↗

PubMed1994

A study of the nutrient foramina of lower limb long bones.

In this study a total of 269 adult lower limb long bones were examined to determine the number and location of the nutrient foramina in the shafts of bones. The mean of foraminal index was 48.82 for femur, 33.17 for tibia, and 47.82 for fibula. The number of foramina noted were: two on the linea aspera in the middle third of the femur, one on the posterior surface of the upper third of the tibia, and one on the posterior surface of the middle third of the fibula.

Arteries↗