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Biomedical subjects

H Yavuz

Publications and source records attributed to H Yavuz.

At least 19 recordsLinked to original sources
PubMed2006

Molecular recognition based iron removal from human plasma with imprinted membranes.

The aim of this study is to prepare ion-imprinted poly(2-hydroxyethyl methacrylate) (HEMA) based membranes which can be used for the selective removal of Fe3+ ions from Fe3+-overdosed human plasma. N-methacryloyl-(L)-glutamic acid (MAGA) was chosen as the ion-complexing monomer. In the first step, Fe3+ was complexed with MAGA and then, the Fe3+-imprinted poly(HEMA-MAGA) membranes were prepared by UV-initiated photo-polymerization of HEMA and MAGA-Fe3+ complex in the presence of an initiator (benzoyl peroxide). After that, the template (i.e., Fe3+ ions) was removed by using 0.1 M EDTA solution at room temperature. The specific surface area of the Fe3+-imprinted poly(HEMA-MAGA) membranes was found to be 49.2 m2/g and the swelling ratio was 92%. According to the elemental analysis results, the polymeric membranes contained 145.7 micromol MAGA/g polymer. The maximum adsorption capacity was 164.2 micromol Fe3+/g membrane. The relative selectivity coefficients of ion-imprinted membranes for Fe3+/Zn2+ and Fe3+/Cr3+ were 12.6 and 62.5 times greater than the non-imprinted matrix, respectively. The Fe3+-imprinted poly(HEMA-MAGA) membranes could be used many times without decreasing their Fe3+ adsorption capacities significantly.

Glutamic Acid↗
PubMed2004

Influence of magnetic field on the kinetics of activated sludge.

This investigation was performed as a background study for magnetically stabilized fluidized bed biofilm reactors for wastewater treatment. The aim of this study is to show the influence of magnetic field application on microbial growth and to use a simplified method in batch wise study to determine this influence on the biological kinetic parameters. The kinetic parameters of mu(max), K(s), Y(x/s) and m of the activated sludge on glucose removal as a model substrate for wastewater treatment were determined in a simple way by using the data of only one batch experiment at a definite condition. At the same condition, instead of the difficult, expensive and time consuming several continuous steady state studies with different influent substrate concentrations the results of only one batch experiment of two identical reactors, one with and the other without magnetic field application, could be enough for the evaluation. It was found that kinetic parameters were changing with magnetic field strengths of 8.9, 17.8, 24.4, 36.6 and 46.6 mT and 17.8 mT is the optimum strength for biological glucose removal under the studied conditions. While mu(max) and m are increasing with the application of optimum magnetic field strength of 17.8 mT, K(s) and Y(x/s) are decreasing implying that average affinity of microorganisms present in activated sludge to the substrate and their growth rates are increasing but a smaller amount of sludge corresponding to the amount of substrate removal was produced with the application of magnetic field. This result shows an improvement in the treatment efficiency by the application of magnetic field.

Biofilms↗
PubMed2003

A novel biodegradable PCL film for tendon reconstruction: Achilles tendon defect model in rats.

This study aims to investigate applicability of poly(epsilon-caprolactone) (PCL) biodegradable films for repair of gaps in Achilles tendons in a rat model, also comparing surgical repair versus no repair approaches. PCL was synthesized with tailor-made properties, then, PCL films were prepared by solvent casting. Seventy-five outbred Sprague-Dawley rats were randomly allocated into five groups: (i) sham operated (skin incision only); (ii) no repair (complete division of the Achilles tendon and plantaris tendon without repair); (iii) Achilles repair (with a modified Kessler type suture); and (iv) plasty of Achilles tendon defects with the biodegradable PCL films, and (v) animals subjected to 1 cm mid-substance defect with no repair. Functional performance was determined from the measurements of hindpaw prints utilizing the Achilles functional index. The animals were killed 8 weeks after surgery and histological and biomechanical evaluations were made. All groups subjected to Achilles tendon division had a significant functional impairment that gradually improved so that by day 28 there were no functional impairments in any group whereas animals with a defect remained impaired. The magnitude of the biomechanical and morphological changes at postoperative 8 weeks were similar for no repair group (conservative), Achilles repair group and tendonplasty group (biodegradable PCL film group). The initial rate of functional recovery was significantly different for primary suture, Achilles repair group and PCL film group (p>0.01). But, at the 28th day, functional recovery was quite similar to the other groups. In summary, our results suggest that the PCL film can be an alternative biomaterial for tendon replacement.

Absorbable Implants↗
PubMed2001

Transverse myelopathy: an initial presentation of acute leukemia.

An 8-year-old female with a history of back pain and loss of the ability to walk is presented. Transverse myelopathy was considered clinically after assessing magnetic resonance imaging results of the thoracic spine. Acute lymphoblastic leukemia was diagnosed approximately 5 months after the beginning of symptoms. Reviewing the related literature suggests that transverse myelopathy is not uncommon in neoplastic diseases. Children with a disorder of the spinal cord, especially if accompanied with fatigue and anemia, might have transverse myelopathy-associated malignant disease. Transverse myelopathy can be the initial presentation of acute lymphoblastic leukemia.

Biopsy, Needle↗
PubMed2000

Human serum albumin chromatography by Cibacron Blue F3GA-derived microporous polyamide hollow-fiber affinity membranes.

An affinity dye ligand, Cibacron Blue F3GA was covalently attached onto commercially available microporous polyamide hollow-fibre membranes for human serum albumin (HSA) adsorption from both aqueous solutions and human plasma. Different amounts of Cibacron Blue F3GA were incorporated on the polyamide hollow-fibres by changing the dye attachment conditions, i.e. initial dye concentration, addition of sodium carbonate and sodium chloride. The maximum amount of Cibacron Blue F3GA attachment was obtained at 42.5 micromol g(-1) when the hollow-fibres were treated with 3 M HCI for 30 min before performing the dye attachment. HSA adsorption onto unmodified and Cibacron Blue F3GA-derived polyamide hollow-fibre membranes was investigated batchwise. The non-specific adsorption of HSA was very low (6.0 mg g(-1) hollow-fibre). Cibacron Blue F3GA attachment onto the hollow-fibres significantly increased the HSA adsorption (147 mg g(-1) hollow-fibre). The maximum HSA adsorption was observed at pH 5.0. Higher HSA adsorption was observed from human plasma (230 mg HSA g(-1) hollow-fibre). Desorption of HSA from Cibacron Blue F3GA derived hollow-fibres was obtained using 0. 1 M Tris-HCl buffer containing 0.5 M NaSCN or 1.0 M NaCl. High desorption ratios (up to 98% of the adsorbed HSA) were observed. It was possible to reuse Cibacron Blue F3GA derived polyamide hollow-fibre without significant decreases in the adsorption capacities.

Adsorption↗
PubMed1999

Autologous skin graft, human dura mater and polypropylene mesh for the repair of ventral abdominal hernias: an experimental study.

OBJECTIVE: To compare primary repair and grafting with one of two materials (one biological human dura mater, and one synthetic polypropylene mesh) or autologous skin, with primary repair alone in abdominal wall hernias in rats. DESIGN: Randomised experiment. SETTING: Teaching hospital, Turkey. ANIMALS: 72 male Wistar albino rats randomised into 4 groups of 18 rats each. These were further randomly divided into subgroups of 6 each that were killed on days 15, 30,and 45 postoperatively. INTERVENTIONS: Each test material was sutured to the abdominal wall by an onlay technique. MAIN OUTCOME MEASURES: Macroscopic and microscopic appearance, and strength of the abdominal wall. RESULTS: Macroscopically, dura mater grafts lost their original shape, but polypropylene and skin did not. When completely incorporated the skin grafts had developed a new fascia. Dura mater and polypropylene induced a pronounced inflammatory reaction at all three times postoperatively, and there were significantly more fibroblasts in the dura mater group on days 15 and 30, and in the skin graft group on day 45, than in the other groups (p < 0.05). Mechanical resistance and mean breaking strength were significantly greater in the skin graft group than in the other groups at all times tested (p < 0.05). CONCLUSION: Full thickness autologous skin grafts were stronger than both human dura mater and polypropylene mesh when used to reinforce primary repairs of abdominal wall hernias in rats.

Animals↗
PubMed1996

Quantitative computed tomography for measuring bone mineral density in athletes.

We studied the effect of different training patterns on vertebral trabecular and cortical bone mineral density (BMD) in male athletes using quantitative computed tomography. Vertebral trabecular (t) and cortical (c) BMDs of the first three lumbar vertebrae were measured using single energy quantitative computed tomography in 51 athletes including 10 weight lifters (mean age 20 years), 13 soccer players (mean age 27 years), 28 wrestlers (mean age 17 years), and 45 age-matched volunteers (mean age 21 years). Measured BMDs were correlated with age, body height and weight, training hours per week, sports years, and type of physical activity. Vertebral tBMDs were found to be 44%, 23%, and 24% higher in the weight lifters, soccer players, and wrestlers, respectively, compared with the volunteers. The corresponding cBMDs were 18%, 6%, and 11% higher than that of volunteers. There was significant correlation between the trabecular and cBMD, and height of the athletes, sports years, training hours per week, and physical activity. The most significant correlation with BMD was the type of physical activity. Both the height of the subjects and physical activity variables showed variations of 47% and 32% in trabecular and cBMD, respectively. According to the multiple analysis of variance (MANOVA) only the physical activity factor was effective, with a significance level of P < 0.01; the other factors and interactions were not effective (P > 0.05) on trabecular and cBMD. Different training patterns have a different anabolic effect on both trabecular and cBMDs of the vertebrae, and this effect is more pronounced on the trabecular compartment. Weight lifting showed the highest anabolic effect on both trabecular and cBMDs compared with soccer playing and wrestling. Of the independent variables, physical activity showed the highest anabolic effect on the vertebrae. These results may have implications for devising exercise strategies to reduce the possibility of fracture in old age.

Adult↗