Biomedical subjects

Feza Korkusuz

Publications and source records attributed to Feza Korkusuz.

14 recordsLinked to original sources

PubMed2006

Burden of osteoporosis.

UNLABELLED: The number of the people with osteoporosis increases as the population ages. Increasing numbers of patients with osteoporotic fractures may have a serious economic impact on society and on the quality of life of the patient. We review some literature and provide expert opinion on the burden of osteoporosis. Awareness among clinicians and health care professionals on osteoporosis should be increased to overcome the burden of the disease. Although most of the osteoporotic fractures are treated by orthopaedic surgeons, many patients with these problems are not diagnosed appropriately and treated for probable osteoporosis. Appropriate diagnosis of the disease is essential to prevent osteoporotic fractures and related mortality and morbidity. Indirect costs and sociologic and psychological impact of fractures should be evaluated together with the direct costs of the disease. LEVEL OF EVIDENCE: Economic and decision analysis, level V (expert opinion). See the Guidelines for Authors for a complete description of the levels of evidence.

Absorptiometry, Photon↗

PubMed2006

Vibration analysis of the human radius of elderly men.

UNLABELLED: Vibration analysis seldom has been used in detecting structural and mechanical changes in physiologic and pathologic bone conditions. We sought to correlate natural frequency of the radius measured by vibration analyses with bone mineral density measured by dual-energy xray absorptiometry and quantitative computed tomography (including cortical thickness). Sixty sedentary men between 50 and 70 years old were deemed osteopenic or healthy. A higher natural frequency of the dominant and nondominant radius was seen in the healthy men compared with the osteopenic men. Natural frequency was consistent with bone mineral density in dominant and nondominant radius in both groups. Moreover, there was a correlation between bone mineral density measured by dual-energy xray absorptiometry and natural frequency in the dominant and nondominant radius. Cortical thickness of the dominant and nondominant radius also correlated with natural frequency. We concluded natural frequency measured by vibration analysis is a precise method for the assessment of structural properties of bone and correlates with the bone mineral density of the radius. LEVEL OF EVIDENCE: Diagnostic study, Level II (Testing of previously developed diagnostic criteria on consecutive patients [with universally applied reference "gold" standard]). See the Guidelines for Authors for a complete description of the levels of evidence.

Absorptiometry, Photon↗

PubMed2005

Collagen-chondroitin sulfate-based PLLA-SAIB-coated rhBMP-2 delivery system for bone repair.

Bone morphogenetic proteins (BMPs) are osteoinductive proteins used intensively in clinical investigations involving various bone-related treatments. Owing to their high potential in new bone formation they require local application at the treatment site. For this purpose various controlled delivery systems with BMPs as the excipients have been prepared in recent years. Focusing on this clinical need a disc-shaped BMP carrier was designed as a local delivery system using soluble collagen and chondroitin sulfate. In situ release studies carried out with a model protein (FITC-labeled Protein A) presented a very high rate of release; with most of the protein content being released within 24 h. This rate could be decreased by providing a poly(L-lactide) (PLLA) and sucrose acetate isobutyrate-based (SAIB-based) coat around the release system, applied after BMP loading. In this way, it was possible to extend the release period from 24 h to about 12 days. In situ release of BMP from the same carriers, as quantitated using an ELISA kit, was even slower, with 50% of the protein being released in 15 days. In order to be able to secure the BMP delivery system at the bone defect site and to provide support a mesh knitted using Vicryl sutures and bonded with poly(L-lactide-co-glycolide) (PLGA) was tested in in vivo. Two time periods, 1 and 3 weeks, were used to evaluate the healing process. Osteoinduction by the BMP carrier system was assessed by histology-based bone scoring and X-ray examinations. PLLA-SAIB-coated collagen discs containing BMP presented good biocompatibility and optimum osteogenic stimulation. Structural changes in histological micrographs at week 1 indicated dose-dependent periosteal ossification. At the end of week 3 histological findings with both BMP (1 and 2 microg) doses were almost the same.

Animals↗

PubMed2005

Tissue engineered cartilage on collagen and PHBV matrices.

Cartilage engineering is a very novel approach to tissue repair through use of implants. Matrices of collagen containing calcium phosphate (CaP-Gelfix), and matrices of poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) were produced to create a cartilage via tissue engineering. The matrices were characterized by scanning electron microscopy (SEM) and electron diffraction spectroscopy (EDS). Porosity and void volume analysis were carried out to characterize the matrices. Chondrocytes were isolated from the proximal humerus of 22 week-old male, adult, local albino rabbits. For cell type characterization, Type II collagen was measured by Western Blot analysis. The foams were seeded with 1x10(6) chondrocytes and histological examinations were carried out to assess cell-matrix interaction. Macroscopic examination showed that PHBV (with or without chondrocytes) maintained its integrity for 21 days, while CaP-Gelfix was deformed and degraded within 15 days. Cell-containing and cell-free matrices were implanted into full thickness cartilage defects (4.5 mm in diameter and 4 mm in depth) at the patellar groove on the right and left knees of eight rabbits, respectively. In vivo results at 8 and 20 weeks with chondrocyte seeded PHBV matrices presented early cartilage formation resembling normal articular cartilage and revealed minimal foreign body reaction. In CaP-Gelfix matrices, fibrocartilage formation and bone invasion was noted in 20 weeks. Cells maintained their phenotype in both matrices. PHBV had better healing response than CaP-Gelfix. Both matrices were effective in cartilage regeneration. These matrices have great potential for use in the repair of joint cartilage defects.

Absorbable Implants↗

PubMed2005

In vivo human brain biochemistry after aerobic exercise: preliminary report on functional magnetic resonance spectroscopy.

BACKGROUND: Our aim was to disclose whether the positive psychological changes observed after a single bout of aerobic exercise have a biochemical correlate that can be visualized by proton magnetic resonance spectroscopy (MRS) of the human brain. METHODS: Right-handed male volunteers underwent psychological testing and MRS of the frontal lobe of the left hemisphere, both before and after 20 minutes of jogging at about 70% of their maximal aerobic capacity. RESULTS: Although there was a significant decrease on the postexercise anxiety test scores (z = -2.201, P < .05), there was no significant difference between the preexercise and postexercise scores of positive and negative affect. Considering both "amplitude" and "area under the curve" values calculated for the peaks of metabolites N-acetylaspartate (NAA), creatine, and choline, none were found to be significantly changed (P > .05) after the exercise. CONCLUSION: This is, to our knowledge, the first study to report on a functional application of MRS to mood states. Because it offers the ability to directly measure metabolic changes in the brain during neuronal activation, "functional MRS" may be a potential new tool that may be used as an adjunct to functional magnetic resonance imaging.

Adolescent↗

PubMed2005

Hydroxyapatite reinforced poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) based degradable composite bone plate.

Poly(3-hydroxybutyrate) (P3HB), its co-polymers with 3-hydroxyvalerate (HV) (PHBV8 and PHBV22), and their hydroxyapatite (HAp) containing composites (5 and 15%, w/w) were prepared by injection molding. PHBV bone plates with low valerate contents and 15% (w/w) HAp appear to have better mechanical properties than the others. Flexural strengths of 15% (w/w) HAp-loaded P3HB, PHBV8 and PHBV22 were 78.28, 63.45 and 39.38 MPa, respectively. Tensile strengths of 15% (w/w) HAp-loaded P3HB, PHBV8 and PHBV22 were 18.99, 15.44 and 11.02 MPa, respectively. For the ageing test, bone plates were incubated in phosphate-buffered saline PBS (0.1 M, pH 7.4) at 37 degrees C and at pre-determined time points they were removed and subjected to a three-point bending test. Incubation in PBS caused a sharp decrease in the mechanical properties within the first 24 h, followed either by a gradual decrease or no change for a period of about 1 month. SEM results showed that there was no significant material erosion in the 4-week incubation period. P3HB loaded with 15% HAp appeared to yield the most suitable bone plate, insofar as mechanical properties are concerned with potential for further testing in vivo.

Biocompatible Materials↗

PubMed2005

Reliability and validity of the modified Conconi test on concept II rowing ergometers.

The purpose of this study was to assess the reliability and validity of the modified Conconi test on Concept II rowing ergometers. Twenty-eight oarsmen conducted 3 performance tests on separate days. Reliability was assessed using the break point in heart rate (HR) linearity called the Conconi test (CT) and Conconi retest (CRT) for the noninvasive measurement of anaerobic threshold (AT). Blood lactate measurement was considered the gold standard for the assessment of the AT, and the validity of the CT was assessed by blood samples taken during an incremental load test (ILT) on ergometers. According to the results, the mean power output (PO) scores for the CT, CRT, and ILT were 234.2 +/- 40.3 W, 232.5 +/- 39.7 W, and 229.7 +/- 39.6 W, respectively. The mean HR values at the AT for the CT, CRT, and ILT were 165.4 +/- 11.2 b.min, 160.4 +/- 10.8 b.min, and 158.3 +/- 8.8 b.min, respectively. Interclass correlation coefficient (ICC) analysis indicated a significant correlation between the 3 tests with one another. Also, Bland and Altman plots showed that there was an association between noninvasive tests and the ILT PO scores and HRs (95% confidence interval [CI]). In conclusion, this study showed that the modified CT is a reliable and valid method for determining the AT of elite men rowers.

Adult↗

PubMed2005

Correlation between mechanical vibration analysis and dual energy X-ray absorptiometry (DXA) in the measurement of in vivo human tibial bone strength.

It is assumed that bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DXA) has its limitation in identifying bone strength, and therefore other methods should be developed. Non-invasive strength measurement, which is needed to diagnose and monitor metabolic bone diseases such as osteoporosis, can become an alternative to current methods. In this study, mechanical vibration analysis was compared to BMD measured by DXA in human female tibia. Seven mother (Ms) and daughter (Ds) pairs' (total n = 14) left and right tibiae were evaluated by DXA and mechanical vibration analysis. Mechanical vibration analysis was consistent in the same bone and also in both sides. Correlation between BMD measured by DXA and vibration analysis was found in the Ds and Ms groups; the former being stronger than the latter. Natural frequencies of the Ms group were higher than that of the Ds group, and the response velocity of the Ds group was shorter than that of the Ms group. It is concluded that mechanical vibration analysis is consistent in bones and a correlation between BMD measured by DXA and vibration analysis can be established in young females that may be used in field studies to predict peak bone strength.

Absorptiometry, Photon↗

PubMed2004

Comparison of landing maneuvers between male and female college volleyball players.

OBJECTIVE: To compare differences in kinematic and kinetic parameters of knee, hip and ankle joints between male and female college volleyball players. DESIGN: Cross-sectional study. BACKGROUND: Landing injuries, which usually involve anterior cruciate ligament injuries, are common in volleyball with a higher incidence in females. Landing preferences of both male and female players may provide additional background about the mechanisms contributing to the anterior cruciate ligament injuries. METHODS: Eight female and eight male college volleyball players performed spike and block landings from 40 and 60 cm height platforms. Lower extremity joint kinetics and kinematics, and leg muscle strengths were recorded. RESULTS: Females demonstrated significantly lower knee and hip flexion angles compared to their male counterparts in knee flexion at 40 cm spike and hip flexion at 40 cm block landings. Group comparison also revealed that male players' peak knee extensor moment at 60 cm block landing was significantly different than female players. Additionally, female players applied significantly higher normalized ground reaction forces and males knee flexion angles and thigh muscle strength results positive and highly correlated but relation could not found in females. It is likely that females may not use their thigh muscles as effective as males in landing. CONCLUSION: Female volleyball players initiate different lower extremity mechanics during landings than that of males. RELEVANCE: Identifying the landing strategy differences between female and male college volleyball players may provide detailed perspective about the load distribution in lower extremity joints for determining major factors affecting the increased incidence of anterior cruciate ligament injuries in females.

Acceleration↗

PubMed2003

Soccer causes degenerative changes in the cervical spine.

BACKGROUND: Radiological changes and degeneration of the cervical spine have been previously described in soccer players. The onset of such changes was 10-20 years earlier than that of the normal population. The aim of this study was to assess these early degenerative changes in amateur active and veteran soccer players in a cross-sectional descriptive study using biomechanical, radiological, and magnetic resonance measures. METHODS: The subjects were active (<30 years; n=15) and veteran (>30 years; n=15) male amateur soccer players, and their age-matched controls ( n=13 and n=15). Biomechanical measurements were made on a cervical dynamometer. Dynamic radiological and magnetic resonance findings were also obtained and evaluated. RESULTS: The normalized mean extension moment was higher in the active soccer players, but the mean range of motion was lower. Degenerative changes were prominent in veteran players, and the sagittal diameter of their spinal canal at C2 to C6 was lower when compared to active players and controls. Magnetic resonance findings of degeneration were more prominent in soccer players when compared to their age-matched controls. CONCLUSION: A tendency towards early degenerative changes exists in soccer players most probably due to high- and/or low-impact recurrent trauma to the cervical spine caused by heading the ball.

Adult↗

PubMed2003

Poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) based tissue engineering matrices.

In this study, the aim was to produce tissue-engineered bone using osteoblasts and a novel matrix material, poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV). In order to prepare a porous PHBV matrix with uniform pore size, sucrose crystals were loaded in the foam and then leached leaving pores behind. The surface of the PHBV matrix was treated with rf-oxygen plasma to increase the surface hydrophilicity. SEM examination of the PHBV matrices was carried out. Stability of PHBV foams in aqueous media was studied. The pH decrease is an indication of the degradation extent. The weight and density were unchanged for a period of 120 days but then a significant decrease was observed for the rest of the study. Osteoblast cells were then isolated from rat bone marrow and seeded onto PHBV matrices. The metabolization and proliferation on the foams was determined with MTS assay which showed that osteoblasts proliferated on PHBV. It was also found that cells proliferated better on large pore size foams (300-500 microm) than on the small pore size foams (75-300 microm). Production of ALP was measured spectrophotometrically. The present study demonstrated that PHBV matrices are suitable substrates for osteoblast proliferation and differentiation.

Journal Article↗

PubMed2003

Histological alterations after irradiation of cartilage using Ho:YAG laser.

OBJECTIVE: The authors carried out an experimental study to evaluate the histological alterations after irradiation of cartilage using Holmium:YAG (Ho:YAG) laser VersaPulse Select 60 watts and Infra Tome Delivery Systems 30 degrees Handpiece (spot size at fiber tip 0.4 mm; Coherent Medical, Palo Alto, CA). BACKGROUND DATA: Recently, some authors reported cases with articular cartilage damage following arthroscopic laser surgery in the knee joint for the treatment of articular cartilage or meniscal pathology. MATERIALS AND METHODS: The cartilage specimens immersed in saline were exposed to Ho:YAG laser irradiation. The laser wavelength was 2.1 microm, and pulse duration was 250 microsec. Power settings were 0.2-1 joules per pulse and 10-15 Hz. Total laser energy used in these procedures was 1.5 K joules. During the procedures, the handpiece was used at an angle of 30 degrees and at a distance of 1 mm. RESULTS: Electron microscopic evaluation demonstrated that the ultrastructure of the cartilage is preserved in both experiment and control groups. CONCLUSION: When Ho:YAG laser is used in optimal dosage (optimal joule and Hertz) with optimal technique (keeping the handpiece at an appropriate angle and distance) and avoiding overtreatment, it does not cause cartilage damage.

Arthroscopy↗

PubMed2003

Quantitative forearm muscle strength influences radial bone mineral density in osteoporotic and healthy males.

Fractures are not rare in male osteoporosis and bone mineral density (BMD) measurement is used in the diagnosis and monitoring, preventing and/or treating the disease. Muscle strength and BMD are highly related to each other. The distal radius is one of the most common sites of osteoporotic fractures. The relationship of quantitative muscle strength and BMD of the forearm has not yet been established. The objective of this study was to assess forearm muscle strength and grip strength in relation to BMD in 46 osteoporotic and randomly selected 45 healthy male participants. Forearm muscle strength and BMD were quantitatively measured using an isokinetic dynamometer and dual-energy-X-ray-absorptiometry (DEXA), respectively. Significant correlation was found among the muscle strength and dominant forearm BMD in 60 and 120 deg/s velocities. In the non-dominant arm, the 120 deg/s velocity was only significantly positively correlated to forearm BMD. Pearson's Product coefficient presented a moderate correlation between muscle strength and BMD at the dominant arms of both groups, whereas, the difference in the non-dominant forearm came from the difference of usage frequency. In conclusion, quantitative forearm muscle strength and BMD is moderately correlated and exercise can be advised to prevent distal radius fractures in male osteoporosis.

Absorptiometry, Photon↗

PubMedDate not supplied

In vivo tissue engineering of bone using poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) and collagen scaffolds.

Porous poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) and calcium phosphate-loaded collagen (CaP-Gelfix) foams were seeded with rat bone marrow stromal cells and implanted into defects created in rat femurs to study in vivo bone formation and to test their suitability for use in bone tissue engineering. At 3 and 6 weeks, new bone formation was evaluated by macroscopy, radiography, dual-energy X-ray absorptiometry (DEXA), and quantitative computerized tomography (QCT). Atomic contents of the implants were further assessed by QCT. Some initial inflammation that significantly decreased with time was observed in the CaP-Gelfix group. PHBV inflammation was minimal at all stages. Fibrous tissue formation in the CaP-Gelfix group was more than in the PHBV group. Both cell-loaded and cell-free PHBV matrices elicited minimal fibrous tissue formation during the 6-week implantation duration. Macroscopic and radiological studies demonstrated better healing with PHBV matrices than with CaP-Gelfix in 3 weeks. Histologically, fibrous connective tissue establishment and inflammation scores were significantly higher in the CaP-Gelfix group when compared with the PHBV group at both time intervals. At 6 weeks, however, the extent of healing was almost the same with both implants. DEXA and QCT results indicated that there was an increase in bone mineral density in both PHBV and CaP-Gelfix implants at the end of 6 weeks. This study suggests that even though PHBV and CaP-Gelfix have different bulk and surface chemistries they both are promising cell carriers that may be suitable for use in bone tissue engineering.

Animals↗