Ismail Peker

Effects of exercise on visual evoked potentials.

The aim of this study was to investigate the effects of acute or habitual exercise on visual evoked potentials (VEP). The study group consisted of 9 female and 7 male volleyball players and the control group contained 9 female and 7 male students who were not involved in any sportive activity. The N75, P100, and N145 latency and amplitudes were measured before and after exercise. Intragroup comparison was made to evaluate the acute effects and intergroup comparison for the chronic effects of exercise. Significant differences were noted between athletes and the sedentary subjects in terms of pre-exercise left-N145 latencies and amplitudes and left -P100 amplitudes. Right-eye N145 latencies of inactive female subjects obtained before and after exercise were also statistically different. The results suggest that acute and habitual exercise affects the VEP responses independent from the body temperature and other physiological parameters. Small sized pre-exercise P100 amplitudes in the athletes can be attributed to the effect of rapid visual-activity-demanding sports on the central nervous system. Visual evoked potentials maybe used as neurophysiological criteria in defining the performance of an athlete.

Controlled release of 5-aminosalicylicacid from chitosan based pH and temperature sensitive hydrogels.

A series of temperature and pH responsive hydrogels based on chitosan and poly(N-isopropyl acrylamide) (PNIPA) was prepared by redox polymerization. Effect of the composition on swelling behavior of the hydrogels and the release of 5-aminosaylcilic acid (5-ASA) at different temperatures and pHs have been investigated. Ammonium persulphate and TEMED were used as a redox pair at room temperature. As a cross linker, methacrylated chitosan was synthesized through the reaction of chitosan with glycidyl methacrylate (GMA). Introduction of the cross-linker provided the hydrogels with pH and temperature sensitivities. The phase transition temperatures of the hydrogels were determined by derivative differential scanning calorimeter (DDSC). Their phase transition temperatures were increased by chitosan content. Swelling behaviors and the release of 5-ASA varied significantly with pH, temperature and the gel composition. The release of 5-ASA from the hydrogels was followed by UV-Vis and fluorescence spectroscopy.

Angiotensin-converting enzyme gene polymorphism, left ventricular remodeling, and exercise capacity in strength-trained athletes

The mechanisms that regulate the development of human physiological cardiac hypertrophy remain poorly understood. The renin-angiotensin system, which is modulated by genetic polymorphism, plays an important role in the regulation of vascular tone and myocardial hypertrophy. Although a few studies have analyzed the association of angiotensin-converting enzyme (ACE) polymorphism and left ventricular (LV) hypertrophy in isotonic exercise-trained subjects who developed eccentric cardiac hypertrophy, there has been no research done in power athletes who developed concentric cardiac hypertrophy. We have hypothesized that ACE genotypic modulation characteristics may affect LV mass in power athletes. This study included 29 elite Caucasian wrestlers (mean age, 22.6 years) and 51 age-matched sedentary subjects. According to the absence or presence of the insertion segment in the polymerase chain reaction (PCR) product, the subjects were classified as homozygous deletion-deletion (DD), insertion-insertion (II), or heterozygous insertion-deletion (ID). The association of LV hypertrophy with ACE gene insertion/deletion (I/D) polymorphism was analyzed. Left ventricular mass and index were determined by echocardiography. Angiotensin-converting enzyme genotyping was performed on peripheral leukocytes using the polymerase chain reaction technique. The study and control group subjects were similar in height and weight. Left ventricular hypertrophy in the athletes was more apparent than in the controls. Angiotensin-converting enzyme genotype II frequency was 17.2% (5) in the athletes, 17.6% (9) in the controls; ID frequency was 51.7% (15) in the athletes, 56.8% (29) in the controls; and the DD frequency was 31% (9) in the athletes and 25.4% (13) in the controls. Left ventricular mass and mass index were found to be higher in genotype DD (126.2 ± 2.9 g/m2) than genotype II (85.5 ± 4.0 g/m2) or genotype ID (110.1 ± 2.3 g/m2) in the athletes (P < 0.001). Furthermore, maximal oxygen consumption in genotype DD was found to be higher than in II and ID. An association was found between ACE gene I/D polymorphism and LV hypertrophy in strength-trained athletes.

The Influence of Sintering Temperature on Mechanical and Microstructural Properties of Bovine Hydroxyapatite

The influence of sintering temperature on densification, microstructure and the mechanical properties of bovine hydroxyapatite (BHA), produced by a calcination method, was investigated. Densification and mechanical properties increased over increasing sintering temperature in the range between 1000°C and 1300°C, and there are evidences of optimum sintering temperature at 1200°C. The measured mechanical properties indicate sintered BHA-bodies as interesting biomaterials for further investigation in biomedical applications.

Exercise-Induced Increase in Lipid Peroxidation in Patients with Chronic Heart Failure: Relation to Exercise Intolerance

Background: Little is known about the relationship between exercise intolerance and lipid peroxidation in chronic heart failure (CHF) patients. This study was designed to investigate the relationship between exercise-induced plasma malondialdehyde (MDA) changes in CHF patients and to determine whether there is any association between plasma MDA levels and exercise capacity assessed by cardiopulmonary exercise testing. Methods: Cardiopulmonary exercise testing was applied to 31 CHF patients (16 ischemic, 15 idiopathic) and controls. Rest and peak exercise blood samples were analyzed for MDA. Results: Patients with CHF had elevation of plasma MDA levels during exercise compared with controls (p < 0.001 vs. p = 0.588). MDA change remained significant both in ischemic and idiopathic cardiomyopathy groups (p < 0.05 and p < 0.01, respectively). ΔMDA (peak exercise MDA – rest MDA) showed significant inverse correlation with peak oxygen consumption in patients with CHF. Conclusion: Lipid peroxidation is increased in patients with CHF during exercise regardless of etiology, and this increase is inversely related to oxygen consumption.

Sintering Effect on Mechanical Properties of Composites of Bovine Hydroxyapatite (BHA) and Li2O

In this study, hydroxyapatite (HA) material, obtained from calcinated bovine bone (BHA), was mixed with 0.25, 0.50, 1.00, and 2.00 wt% Li2CO3. The pressed pellets were sintered at various sintering temperatures between 900°C and 1300°C. Measurements of compression strength, microhardness, and density, along with SEM observation and X-ray diffraction analysis were performed. The experimental results showed that the samples with 0.25 and 0.50% Li2CO3 reached a maximum of densification and the highest values of compression strength and microhardness were achieved after sintering at 1300°C. The wetting effect of a Li2O-associated glassy phase was observed even from 900°C.

Effects of Acute Aerobic and Anaerobic Exercise on Humoral Immune Factors in Elite Athletes

ABSTRACT The aim of this study was to investigate the effects of acute aerobic and anaerobic exercise on humoral immune system parameters (IgA, IgG, IgM, C3, C4) in elite sportsman. Forty elite volleyball players and twenty healthy age-matched sedentary subjects were enrolled in this study. Subjects in the exercise group were randomly divided into two groups. Twenty athletes forming Group 1 (G1) performed 30-minutes of aerobic exercise on treadmill after determination of workload using the Karvonen protocol. Twenty athletes forming Group 2 (G2) performed anaerobic exercise for 30 seconds according to the Wingate test protocol. The sedentary subjects were enrolled as the control group. Blood samples were obtained from the control group once and five times from the exercise groups (prior to exercise, immediately post exercise, 4 hours post exercise, and two and five days after the exercise protocol). Immunoglobulin A (IgA) Immunoglobulin G (IgG), Immunoglobulin M (IgM), complement C3 and C4 levels were determined from each sample. Statistical analysis was performed using SPSS for Windows; and comparisons were made using Kruskal Wallis Variance Analysis and Wilcoxon Signed Rank Tests. P<0.05 was considered to be statistically significant. Initial heart rate and blood pressure values were significantly higher in the sedentary group where as IgA and IgG levels of the athletes were higher than the sedentary subjects (p<0.05). C3 and C4 values of the athletes were found to be suppressed immediately after both of the exercise protocols as compared to the pre-exercise values (p<0.05). Four hours post either exercise protocols, none of the values were significant as compared to the pre exercise values. After two and five days of aerobic exercise the IgA, IgG and IgM levels of athletes were significantly increased as compared to pre-exercise levels (p<0.05). In G2 there were no significant changes in IgA, IgG or IgM values. In conclusion, this study suggests that regularly performed moderate exercise affects hormone release and enhances some of the humoral immune system parameters (IgA, IgG or IgM) while maximal exercise stressing the organism suppresses these parameters. But, there still remains a need for further studies to fully explain the mechanism responsible for the influence of exercise on the immune system.

Sintering Effects on Mechanical Properties of Hydroxyapatite-Titanium Dioxide (HA-TiO2) Composites

Composites of bovine bone derived HA with 5 wt% and 10 wt% of TiO2 were sintered at different temperatures. Their characterization comprised measurements of density, microhardness, and compression strength together with SEM observations and X-ray diffraction analysis. Better densification behaviour was achieved at higher sintering temperatures. The highest microhardness value was measured in the samples sintered at 1300°C. The best compressive strengths of the samples containing 5% and 10% TiO2 were obtained after sintering at 1300°C and 1200°C, respectively.

A Complementary Biocompatibility Evaluation of Plasma Sprayed Dentine (DHA) and Enamel Derived Hydroxyapatite (EHA) Using Fibroblasts

Hydroxyapatite (HA) material, collected from human tooth, was calcined and then separated very easily to enamel HA (EHA) and dentine HA (DHA). The EHA and DHA were plasma sprayed on pre-prepared titanium implants. HeLa (a lineage malignant fibroblast cell) and primary fibroblast cells cell lines were used in this study. The results using fibroblasts from primary culture are interesting since the cells did not die or became apoptotic. However, this does not mean that the present method reveals the complete biocompatibility of the tested HA material. This study aimed to investigate if fibroblasts with fluorescent tests could be used as a secondary evaluation method for biocompatibity fibroblasts cell culture studies prior to osteoblasts cell culture.

An Economic Method for Chitosan Production

Chitosan is a deacetylated derivative of chitin, which is a naturally abundant mucopolysaccharide, supporting the matter of crustaceans, insects, and fungi. Because of its unique properties, such as non-toxicity, biodegradability, and biocompatibility, chitosan has a wide range of applications in various fields. Increasing interest on chitosan’s usage has resulted in high consumption. Therefore, production of chitosan from essential sources with desired characteristics has become an important issue. Several methods, with different chemicals and reaction conditions, have been reported in the literature. This study aimed to shed light in several features of a very promising chitin isolation method described by Tolaimate et al. and its effect on the produced chitosan’s phisico-chemical characteristics.