Electrochemical xanthine detection by enzymatic method based on Ag doped ZnO nanoparticles by using polypyrrole.

A sensitive electrochemical detection of xanthine (X), which is an early biomarker of fish meat spoilage, was achieved by a novel biosensor developed via three main steps. The first step is the electropolymerization of a conducting polymer (pyrrole) onto the pencil graphite electrode (PGE). The second step is the entrapment of silver-doped zinc oxide nanoparticles (nano Ag-ZnO) onto PGE, which has already been doped with polypyrrole (PPy). The third step is the immobilization of the enzyme (xanthine oxidase) onto the modified electrode (nano Ag-ZnO/PPy/PGE) surface. The biosensor was characterized by scanning electron microscopy (SEM). The addition of Ag-doped ZnO nanoparticles into the conducting polymer structure played an important role in the performance of the biosensor by increasing the porous structure of the conducting polymer surface. The electrochemical behaviour of the biosensor was studied by electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). This enzyme biosensor showed the maximum response at pH 7.40 when +0.7 V was applied to reach 95% of steady-state current at ~3.2 s. The designed biosensor showed high selectivity with a sensitivity of 0.03 µA/mM and a low detection limit of 0.07 µM.

Effect of SiC interlayer between Ti6Al4V alloy and hydroxyapatite films.

Bioactive coatings are frequently used to improve the osseointegration of the metallic implants used in dentistry or orthopaedics. Among different types of bioactive coatings, hydroxyapatite (Ca10(PO4)6(OH)2) is one of the most extensively used due to its chemical similarities to the components of bones and teeth. In this article, production and characterization of hydroxyapatite films deposited on Ti6Al4V alloy prepared by magnetron sputtering were reported. Besides, SiC was deposited on substrate surface to study the interlayer effect. Obtained coatings were annealed at 600 °C for 30 and 120 min in a mixed atmosphere of N2 + H2O vapours with the heating rate of 12 °C min(-1). The effects of SiC interlayer and heat treatment parameters on the structural, mechanical and corrosion properties were investigated. After heat treatment process, the crystalline hydroxyapatite was obtained. Additionally, cell viability tests were performed. The results show that the presence of the SiC interlayer contributes a decrease in surface roughness and improves the mechanical properties and corrosion performance of the hydroxyapatite coatings. Biological properties were not affected by the presence of the SiC interlayer.

Effects of pentoxifylline and alpha lipoic acid on methotrexate-induced damage in liver and kidney of rats.

The aim of the current study was to investigate the probable protective effects of Pentoxifylline (PTX) and Alpha Lipoic Acid (ALA), which display anti-oxidative efficacy against hepatotoxicity and nephrotoxicity, those being the major side effects of Methotrexate (MTX). Rats were divided into four groups: a control group; MTX (20mg/kg/day) group; MTX+PTX (20mg/kg/day+50mg/kg/day) group; and an MTX+ALA (20mg/kg/day+100mg/kg/day) group. At the end of the experiment, biochemical, histochemical and immunohistochemical analyses were performed on liver and kidney tissues of rats. We determined Glutathione Peroxidase (GSH-Px), Superoxide Dismutase (SOD), Catalase (CAT), Malondialdehyde (MDA), Nitric Oxide (NO) and Xanthine Oxidase (XO) levels in the liver and kidney. Moreover, Gamma Glutamyl Transferase (GGT), Direct Bilirubin (DBil), Blood Urea Nitrogen (BUN), and urea levels were measured in the serum. The histochemical evaluation revealed a significant decrease in MTX caused damage in the PTX- and ALA-treated groups (especially in ALA group). On the other hand, the immune staining of iNOS and TNF-α were observed most densely in the MTX group, while the density decreased in the PTX- and ALA-administered groups. We determined increased GGT, BUN, urea and levels of CAT, MDA, NO, and XO values in both groups, while GSH-Px (an increase in liver tissue) and DBil levels were decreased in the group that received MTX. However, we determined decreased SOD levels in liver tissue. In the PTX and ALA groups, the levels of GGT, BUN and urea as well as the levels of CAT, MDA, NO and XO decreased (SOD increased in the liver tissue), and the levels of GSH-Px and DBil increased. In conclusion, it can be stated that, although ALA is more effective in preventing the toxic effects of MTX on the liver and kidney, PTX also has a preventive effect. As a result, we can readily suggest that ALA and PTX can have protective effects by decreasing MDA, NO, BUN and urea values as antioxidants against MTX-induced damage in liver and kidney of rats.

Increased plasma monocyte chemoattractant protein-1 levels in patients with isolated low high-density lipoprotein cholesterol.

BACKGROUND: High-density lipoprotein cholesterol (HDL-C) inhibits inflammation associated with the development of atherosclerotic plaques. Monocyte chemoattractant protein-1 (MCP-1) contributes to the pathogenesis of atherosclerosis. The aim of this study was to evaluate the relationship between plasma MCP-1 levels and low HDL-C levels in patients without cardiovascular disease (CVD). METHODS: This study included 55 patients with low HDL-C (≤ 35 mg/dL) and 33 age- and sex-matched control subjects with normal HDL-C (˃ 35 mg/dL). In addition to MCP-1 levels, laboratory parameters associated with inflammation such as neutrophil-lymphocyte ratio (NLR), uric acid and high sensitivity C-reactive protein (hs-CRP) were also evaluated. RESULTS: HDL-C levels was significantly lower in study group compared to that of the control group (p < 0.001). MCP-1 were prominently higher in the low HDL-C group compared with those of the control group (p < 0.01). NLR, uric acid and hs-CRP levels were also higher in patients with low HDL-C than controls. CONCLUSION: These findings suggest that elevated plasma MCP-1 levels and inflammation status might be associated with the increased cardiovascular risk in patients with low HDL-C.

An ultra sensitive fluorescent nanosensor for detection of ionic copper.

A stable and ultra sensitive nano-scale fluorescent chemo-sensor for trace amounts of Cu(2+) was proposed. The Cu(2+) selective fluoroionophore 2-{[(2-aminophenyl)imino]methyl}-4,6-di-tert-butylphenol (DMK-7) was encapsulated in polymeric ethyl cellulose. The sensing membranes were fabricated in form of nanofibers and thin films. When embedded in polymers, the exploited DMK-7 dye exhibited enhanced photophysical characteristics in absorbance, Stoke's shift, fluorescence quantum yield, and short and long-term photostability with respect to the solution phase. Sensing abilities of the nanofibers and thin films were tested by steady state and time resolved fluorescence spectroscopy. To our knowledge, this is the first attempt using the DMK-7-doped electrospun nanofibrous materials for copper sensing. The offered sensor displayed a sensitive response with a detection limit of 3.3×10(-13) M for Cu(2+) ions over a wide concentration range of 5.0×10(-12)-5.0×10(-5). Additionally, exhibited high selectivity over convenient cations; Na(+), K(+), Ca(2+), Mg(2+), NH4(+) and Ag(+), Al(3+), Ba(2+), Co(2+), Cr(3+), Fe(3+), Fe(2+), Hg(2+), Li(+), Mn(2+), Ni(2+), Pb(2+), Sn(2+) and Zn(2+).

Effect of melatonin on kidney cold ischemic preservation injury.

Melatonin is a potent free radical scavenger of reactive oxygen species, nitric oxide synthase inhibitor and a well-known antioxidant secreted from pineal gland. This hormone has been reported to protect tissue from oxidative damage. In this study, we aim to investigate the effect of melatonin on kidney cold ischemia time when added to preservation solution. Thirty male Wistar albino rats were divided equally into three groups; Ringer Lactate (RL) solution, University of Wisconsin (UW) solution with and without melatonin. The serum Lactate Dehydrogenase (LDH) activities of the preservation solutions at 2(nd), 24(th), 36(th), and 48(th) hours were determined. Tissue malondialdehyde (MDA) levels were also measured and a histological examination was performed at 48(th) hour. Melatonin that added to preservation solution prevented enzyme elevation and decreased lipid peroxidation in preservation solution when compared to the control group (p<0.05). The histological examination revealed that UW solution containing melatonin significantly prevented the kidney from pathological injury (p<0.05). Melatonin added to preservation solutions such as UW solution seemed to protect the tissue preserved effectively from cold ischemic injury for up to 48 hour.

Determining the pain-affecting factors of university students with nonspecific low back pain.

[Purpose] This study was conducted on university students with nonspecific low back pain in order to determine the independent variables that affect their pain. [Methods] A total of 514 students were included in this study. Pain was evaluated using a Visual Analogue Scale (VAS). A special form was prepared in order to evaluate the following independent variables: gender, weight, height, Body Mass Index (BMI), working periods sitting straight (television, computer, seminar, etc.), working periods bending at a table (reading, writing, etc.), using lumbar support while sitting, the mean duration of pain within the last one year, type of pain, time of the pain, faculty, class, physical activity habits and smoking. The collected data were evaluated using the CHAID (Chi-squared Automatic Interaction Detection) analysis method. [Results] The working hours bending at a table, physical activity, height, weight, BMI and educational departments were found not to affect the severity of the pain. The pain severity was affected by the duration of pain complaints within the last one year, the duration of working staying upright, smoking, classes, usage of lumbar support and age variables. [Conclusions] The results of this study show that nonspecific low back pain of university students is affected by many factors such as smoking, class, age, using a computer and lumbar support.

Assessment of antimicrobial activity of nanosized Ag doped TiO(2) colloids.

In the present research, the antimicrobial effects of nanosized silver (Ag) doped TiO(2) colloidal solutions prepared using a sol-gel technique were investigated. In order to determine the solution characteristics, the turbidity, viscosity and pH of the colloidal solutions were measured. Differential thermal analysis-thermogravimetry equipment was used to determine the chemical structures and reaction types of the films formed from these solutions. The morphology of Ag doped TiO(2) nanoparticles was evaluated by atomic force microscopy. The disc diffusion method was employed to explore antimicrobial activity, and the Broth Microdilution method was used to obtain MIC values of nanosized Ag doped TiO(2) colloidal solutions against the test microorganisms Escherichia coli, Staphylococcus aureus, Candida albicans, Bacillus subtilis, and Salmonella typhimurium. It was found that the silver doped TiO(2) nanoparticles inhibited the growth and multiplication of the test microorganisms, including the fungus C. albicans. Antimicrobial activity was observed against all tested microorganisms at a very low concentration of 1.125-2.81 µg/ml of nano silver in 1-25 % Ag-TiO(2) solutions.

Optical CO2 sensing with ionic liquid doped electrospun nanofibers.

The first use of electrospun nanofibrous materials as highly responsive fluorescence quenching-based optical CO(2) sensors is reported. Poly(methyl methacrylate) and ethyl cellulose were used as polymeric materials. Sensing slides were fabricated by electrospinning technique. A fiber-optic bundle was used for the gas detection. CO(2) sensors based on the change in the fluorescence signal intensity of ion pair form of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS). The sensor slides showed high sensitivities due to the high surface area-to-volume ratio of the nanofibrous membrane structures. The preliminary results of Stern-Volmer analysis show that the sensitivities of electrospun nanofibrous membranes to detect CO(2) are 24 to 120 fold higher than those of the thin film based sensors. The response times of the sensing reagents were short and the signal changes were fully reversible. The stability of ion pair form of HPTS in the employed matrix materials was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 7 months. Our stability tests are still in progress.

A new approach in biomimetic synthesis of calcium phosphate coatings using lactic acid-Na lactate buffered body fluid solution.

The main objective of this study was to investigate calcium phosphate (CaP) coatings on Ti6Al4V substrates by using the biomimetic technique. To this purpose, a new solution was developed to coat CaP on Ti6Al4V alloy substrates. The newly formulated body fluid (Lac-SBF) contained appropriate amounts of sodium lactate (NaL) and lactic acid (HL), as well as all the other ionic constituents of the human blood plasma. The inorganic ion concentrations of the Lac-SBF solutions were identical with those of human blood plasma. The new Lac-SBF solution of this study eliminated the need for using Tris/HCl or Hepes/NaOH buffers. Prior to coating, Ti6Al4V substrates were chemically treated in NaOH and/or NaOH+H(2)O(2) solutions as an alternative route and then heated at 600 degrees C for 1h in air. In the previous applications, the Cl(-) ion concentration was found to be higher than blood plasma 103mM, which exists in human blood plasma as a result of Tris/HCl which are used to prevent precipitation and to keep the pH level at certain values. In this study, instead of using Tris/HCl, HL/NaL which are generated by human body and do not show any toxic behavior, are used and Cl(-) concentration was kept at 103mM value for the first time. The prepared Lac-SBF was shown to have similar concentration to human blood plasma in terms of all inorganic ions for the first time. Solution properties were evaluated by using turbidimeter, pH meter and rheometer. The coatings were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and a scratch tester. The obtained results are presented and discussed.

DASH questionnaire for the analysis of musculoskeletal symptoms in industry workers: a validity and reliability study.

PURPOSE: The disabilities of the arm, shoulder and hand (DASH) questionnaire is a self-administered region-specific outcome instrument developed as a measure of self-rated upper-extremity disability and symptoms. The aim of this study was to evaluate the reliability and the construct validity of the DASH questionnaire by establishing its correlation to the Medical Outcomes Study Short Form-36 (SF-36) in industry workers. Also we aimed to investigate whether the DASH can be used as a standardized questionnaire to evaluate the work-related musculoskeletal disorders (WMSDs) in upper extremity in industrial settings and epidemiological studies. MATERIAL AND METHODS: The Turkish version's reliability and construct validity were evaluated in 240 industry workers with upper-extremity musculoskeletal complaints. Workers were asked to complete a packet that included the DASH and the SF-36. Test-retest reliability was assessed in all workers who filled in the DASH questionnaire 15 days later. Construct validity was evaluated by comparing the overall and work component DASH scores with SF-36 summary and subscales. RESULTS: The mean DASH score for the textile workers whose duties were confection, dyeing, sewing, quality control and packaging was calculated as 65, 55, 68, 54 and 67, respectively. As a result of this study, pain intensity in shoulder, wrist and hand was significantly associated with the DASH score (p<0.05). Internal consistency of the DASH was high (Cronbach alpha 0.91). Test-retest reliability was excellent for the overall DASH (intraclass correlation coefficient (ICC) 0.92). Moderate correlations (p<0.05) were found between the overall and work component DASH and the SF-36 summary scales. Pearson correlation coefficients of the overall and work component DASH to the SF-36 subscales ranged from -0.33 to -0.82. CONCLUSION: These results support that DASH is a reliable and valid instrument to measure functional disability and investigate the ergonomic risk factors in textile workers with upper-extremity musculoskeletal complaints.