Biomedical subjects

F Korkusuz

Publications and source records attributed to F Korkusuz.

At least 19 recordsLinked to original sources

PubMed2001

In vivo application of biodegradable controlled antibiotic release systems for the treatment of implant-related osteomyelitis.

In this study the construction and in vivo testing of antibiotic-loaded polyhydroxyalkanoate rods were planned for use in the treatment of implant-related osteomyelitis. The rods were constructed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate), carrying 50% (w/w) Sulperazone or Duocid. They were implanted in rabbit tibia in which implant-related osteomyelitis (IRO) had been induced with Staphylococcus aureus. The effectiveness of the antibiotics in the treatment of IRO was determined. The establishment of IRO with bacterial inoculation was complete after 3 weeks with 100% infection rate in all groups. There was no contamination or super-infection. Both antibiotics were found to be highly effective against the bacteria. Following the application of Sulperazone-P(3-HB-co-4-HB) rods, no infective agents could be isolated from the infection site within the 6-week test period, indicating complete treatment of the infection. Macroscopical evaluation at follow-up revealed no drainage, minimal swelling and increase in local warmth, most probably due to the surgery rather than to a reaction towards the implant. The overall scores for radiological findings by the end of 6 weeks were 0.8/5 for the antibiotic-loaded rod implanted in the right limb, and 1.1/5 for the antibiotic-free rod implanted in the left limb. There was no statistical difference between the antibiotic-loaded and antibiotic-free polymeric rods. In vivo drug release was almost complete within the first week. One interesting observation, however, was that the therapy was still very effective even when the release rate was very high. In the SEM of in vitro tested rods, the polymeric component was unchanged in 2 weeks while the drug leached out, leaving voids behind. In vivo, however, the morphology of the implant was significantly modified within 6 weeks post-implantation. Since a substantial degree of the in vivo drug release was complete within 1 week, we believe that dissolution of the drug must be the predominant mechanism through which the drug release is controlled.

Absorbable Implants↗

PubMed2001

Surgical repair of cartilage defects of the patella.

The structure and biomechanical forces on the patellar joint challenges researchers to define an ideal method for resurfacing the patellar cartilage. The articular surface of the patella presents variability between individuals, and has various minor articulations that bear partial or total compressive, shear, and combined forces during movement. Surgical techniques for the repair of patellar cartilage defects have evolved from cumulative advances in basic science and technology. Such surgeries include the techniques that promote either fibrocartilage formation or hyalinelike cartilage formation. Techniques promoting the formation of fibrocartilage yield short-term solutions because fibrocartilage lacks the durability and the mechanical properties of articular hyaline cartilage. Currently, there is no ideal method for the repair of patellar cartilage defects; all methods are considered experimental. Additional controlled and randomized clinical studies with large series of patients and long-term followup are required.

Cartilage Diseases↗

PubMed2001

In vivo response to biodegradable controlled antibiotic release systems.

In this study, the major goal was to evaluate in vitro and in vivo findings by macroscopy, radiology, and histology to determine the effectiveness of therapy of experimental implant-related osteomyelitis with antibiotic carrier rods constructed of microbial polyesters. The polymers used were poly(3-hydroxybutyrate-co-4-hydroxyvalerate) [P(3-HB-co-4-HB)] and poly(3-hydroxybutyrate-co-3-hydroxy- valerate) [P(3-HB-co-3-HV)]. Both the Sulperazone and the Duocid-P(3-HB-co-4-HB) rods with a drug to polymer ratio of 1:1 (w/w) were effective in treating the bone infection that was experimentally initiated by inoculation of a hemolytic strain of Staphylococcus aureus (coagulase positive; phage type 52/52b) together with metal implants into the medullary area of rabbit tibia. Macroscopical data revealed that the effectiveness of therapy was apparent at week 6 for all categories tested. Radiological findings with Duocid- and Sulperazone-loaded P(3-HB-co-4-HB) rods improved significantly when judged by changes in periosteal elevation, widening of bone shaft, new bone formation, and soft-tissue deformation after 6 weeks of implantation. Histologically the signs of infection were found to subside by weeks 3 and 6. Inflammatory cells were replaced with bone-forming cells upon treatment with Sulperazone-P(3-HB-co-4-HB) and Duocid-P(3-HB-co-4-HB). Osteoblastic activity was prominent. Intramedullary inflammation, although still present, started to be replaced by fibrous or bony tissue. Histological findings presented the subsidence of infection. In summary, the antibiotic-loaded biopolymeric rods appeared to have potential as a new controlled-release system for the treatment of implant related osteomyelitis and chronic osteomyelitis.

Animals↗

PubMed2001

Effects of step aerobics and aerobic dancing on serum lipids and lipoproteins.

BACKGROUND: To examine the effect of 8 weeks of step aerobics and aerobic dancing on blood lipids and lipoproteins. METHODS EXPERIMENTAL DESIGN: Comparative training. SETTING: Two months of physical fitness program. PARTICIPANTS: Forty-five sedentary female college student volunteers randomly assigned to one of the three groups as step aerobics (n=15), aerobic dancing (n=15) and the control group (n=15). The step aerobics and aerobic dancing groups participated in sessions of 45 min per day, 3 days per week for 8 weeks with 60-70 percent of their heart rate reserve. MEASURES: Total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol levels (HDL-C), the ratio of total cholesterol to high-density lipoprotein cholesterol (TC:HDL-C). RESULTS: At the end of the 8 week period, a significant difference has been found between the step aerobics group and the control group and between the aerobic dancing group and the control group in TC levels (F[2,44]=8.38; p<0.01). A significant difference in HDL-C levels (F[2,44]=3.65; p<0.05) and TC:HDL-C ratio (F[2,44]=11.56; p<0.01) has been found only between the step aerobics group and the control group. CONCLUSIONS: These results indicate that step aerobics training is an effective training mode for modifying lipid and lipoprotein profiles of female college-aged students.

Adolescent↗

PubMed2000

Assessment of mineral density and atomic content of fracture callus by quantitative computerized tomography.

The mineral density and atomic numbers of elements in the periosteal callus and the cortex area of a healing fracture were measured by quantitative computerized tomography (QCT) to obtain accurate information on the mineralization process in rabbit tibia. The mineral density of the periosteal callus was highest on day 15 and decreased gradually throughout the experiment. This was initially detected by QCT, but not with conventional radiography. An apparent decrease in cortical bone density on days 28 and 42 after fracture was observed. Atomic numbers of elements in the cortex remained stable, indicating a possible homeostatic mechanism of mineral preservation at the fracture callus and involved cortical area. QCT may predict density alterations in the fracture callus more accurately than conventional X-ray. Further studies are essential to predict a relationship between mineral density, atomic numbers, and mechanical stability.

Animals↗

PubMed1999

Sulbactam-cefoperazone polyhydroxybutyrate-co-hydroxyvalerate (PHBV) local antibiotic delivery system: in vivo effectiveness and biocompatibility in the treatment of implant-related experimental osteomyelitis.

In this study, a novel antibiotic carrier system for use in the treatment of implant-related and chronic osteomyelitis was developed. Sulbactam-cefoperazone was introduced to rods of polyhydroxybutyrate-co-hydroxyvalerate (22 mol % HV, w/w), a member of a family of microbial-origin polymer that is biodegradable, biocompatible, and osteoconductive due to its piezoelectric property. The antibiotic-loaded carrier was implanted into the infection site that was induced by Staphylococcus aureus inoculation into the rabbit tibia. The effectiveness of this was assessed macroscopically, radiographically, bacteriologically, and histopathologically. Findings of infection subsided on day 15 and almost complete remission was observed on day 30. The control side that contained antibiotic-free rods, however, worsened. These findings prompted us to conclude that the novel biodegradable antibiotic carrier developed in the present study seems to be a promising candidate for use in the treatment of severe bone infection.

Animals↗

PubMed1999

Development of a calcium phosphate-gelatin composite as a bone substitute and its use in drug release.

This study was carried out to develop a calcium phosphate-gelatin composite implant that would mimic the structure and function of bone for use in filling voids or gaps and to release bioactive compounds like drugs, growth hormones into the implant site to assist healing. XDS analysis of the synthesized calcium phosphate revealed a calcium to phosphorus molar ratio of ca. 2.30, implying a less erodible material than hydroxyapatite (1.67). Release of the antibiotic gentamicin from the implant was with a burst, whether in situ or in vivo, followed by an almost constant release for about three months. It was found that the release rate could be decreased by increasing the density of the gelatin membrane. Upon implantation into rabbit tibia the release duration was substantially shortened (to about 4 weeks) with respect to the in situ tests basically due to the degradation of gelatin. In vivo studies with rabbits confirmed this degradation. The composite was perfectly biocompatible as shown by the histological studies. It, thus, has a great potential as a bone substitute material.

Animals↗

PubMed1999

A novel osteochondral implant.

A novel implant for the use as an osteochondral graft was designed. This implant was prepared by stepwise formation of calcium phosphate crystals within the matrix of a lyophilised collagen sponge. Chondrocytes were then grown on this material to create the osteochondral implant. The implant was characterized with light microscopy, scanning electron microscopy (SEM), electron diffraction crystallography (EDX), and IR. It was observed with IR that the implant had a peak, that was not found so distinctly in its components, at 1400 cm(-1), implying a strong interaction of the two main ingredients of the implant, calcium phosphate and collagen. This strong interaction was also shown in the graft degradation test while the untreated collagen sponge degraded rapidly (in one day) the mineral loaded implant was able to maintain its integrity for two weeks. In the chondrocyte culture medium degradation of the implant was shown by a decrease of the calcium content and calcium to phosphorous ratio. Also, EDX revealed the presence of sulfur one and two weeks after incubation, an element not found among the components of the implant, possibly due to the development of an extracellular matrix. SEM showed that the form of the crystals of calcium phosphate differed depending on whether they were prepared on the template, collagen, or in the absence of a template. The chondrocytes appeared to be growing in number on the implant and their shapes were morphologically normal. The chondrocyte loaded collagen-calcium phosphate composite could thus be considered a potential tissue engineered osteochondral implant.

Biocompatible Materials↗

PubMed1999

Non-specific inflammation and bone marrow depletion due to intramedullary porous hydroxyapatite application.

Calcium hydroxyapatite (HA) ceramics are widely used in orthopaedic surgery and are known to be biocompatible, biodegradable, and osteoinductive. Recent studies of HA have identified early stage inflammatory reactions and third-body wear following hip replacement surgery. The aim of this study was to investigate the early stage inflammatory response toward HA by means of conventional radiography, histopathology, and scanning electron microscopy (SEM). HA was implanted into the medullary area of the tibiae of rabbits and followed from one week to six months. Radiography revealed local osteoporosis on Week 6 and Month 6 in some, but not, all rabbits. SEM presented favorable bonding between the implant and the cortical bone. Eosinophilic deposition, non-specific local inflammation, and bone marrow depletion were the histopathological findings. Multinuclear cells were identified in the inflammation area. Although bone ingrowth into the pores of the HA was demonstrated, there is no doubt that HA may cause an early inflammatory reaction in the bone marrow. This inflammatory reaction is followed by bone marrow depletion and may be the early sign and the cause of HA-coated implant failure.

Animals↗

PubMed1999

The effect of extracorporeal shock wave treatment (ESWT) on bone defects. An experimental study.

The aim of this study was to investigate the effects of extracorporeal shock wave therapy (ESWT) on the formation of callus in bone defects created in rabbit radii. this study searches for an answer to whether ESWT may have a therapeutic effect on bone defects. A bone defect with a radius of 1 cm was created in both forelimbs of 20 rabbits. At the 7th, 14th, and 21st days ESWT treatment was applied to the forming callus in the right radius under fluoroscopic control. At the 6th and 12th weeks, the animals were sacrificed and callus analysis was performed by computerized scan, dual energy x-ray absorptiometer. Histological analyses were also performed. The results revealed that the average callus area in the right (ESWT applied) radial defect was greater in both groups and statistically significant at the 12th week (p < 0.05). There was no difference in bone density between defects. Histologically the callus area was greater on the right side (ESWT applied side) in both groups. However in the first group trabeculae were occupying less space on the right side. Granulation tissue areas and chondroid areas were greater on the right side. We conclude that ESWT has a disorganizing and dispersing rather than a direct osteoinductive effect on forming callus. This effect may play a therapeutic role in bone defects and in situations like callus lengthening where a greater amount of callus is necessary.

Absorptiometry, Photon↗

PubMed1998

Effect of 25-OH-vitamin D on fracture healing in elderly rats.

To investigate the effect of 25-OH-vitamin D supplements (calcidiol) on fracture healing in the elderly, an experimental model with 15 18-month-old female Wistar rats was designed. An experimental fracture in the middle third of both femora of each rat was made. Then the rats were randomly assigned to two groups: one group was subcutaneously treated with 25-OH-vitamin D during all healing processes, and the other group (the control group) was not. After 5 weeks of healing, the animals were killed and both femora were extracted. Blood samples were collected before fracture and at death to determine the levels of 25-OH-vitamin D. All bones that were extracted were subjected to a torsion test to assess healing; a significantly greater maximum shear force before failure was supported in the treated group (p < 0.01). Moreover, a positive correlation (p < 0.01; r=0.55) was found between blood levels of 25-OH-vitamin D at death and the mechanical strength of the callus. Thus, the administration of 25-OH-vitamin D after the experimental fracture significantly improved the mechanical strength of the fractured bone. If similar results are found in the human, then treatment with 25-OH-vitamin D after the occurrence of a fracture would be a good way to improve fracture healing in the elderly.

Aging↗

PubMed1998

Relation between mechanical stiffness and vibration transmission of fracture callus: an experimental study on rabbit tibia.

It has been suggested that the vibration transmission across a fracture is affected by the stages of healing of the fracture callus. This study aims to correlate the change in vibration transmission with mechanical stiffness of the callus measured by three-point bending. The right tibiae of male, three-month old local albino rabbits were osteotomized and stabilized by intramedullary fixation following open reduction. The intramedullary rods were removed on the 15th, 28th, 42nd and 90th days postoperatively and the tibiae were excised for vibration, three-point bending and bone mineral density analysis by quantitative computerized tomography (QCT). Optimum time for clinical weight bearing was determined by checking the convergence of the vibration parameters of the fractured tibia to those of the unfractured contralateral. The conclusions obtained from curvature analysis, based on vibration experiments, were in considerable correlation (Spearman's rank correlation coefficient r = 0.93, p = 0.003) with the conclusions obtained from the three-point bending test data which reflected the mechanical condition of the bone by direct means. However, no correlation between bone mineral density change and vibration transmission was noted.

Animals↗

PubMed1997

Biomechanical analysis of the effects of single high-dose vitamin D3 on fracture healing in a healthy rabbit model.

In a previous ultrastructural study, the benefit of a single high dose of vitamin D3 on fracture healing in a healthy animal model was demonstrated. This study examined the biomechanical consequences of applying a single high dose of vitamin D3 in a healthy rabbit model subsequent to femoral fracture. The fracture load, the values of energy absorbed until fracture and the flexural rigidity values of the vitamin D group were significantly higher than the corresponding ones of the control group in the case of fracture. On the other hand, for intact bones, those values did not differ significantly between the two groups. It was concluded that single high-dose vitamin D3 application had positive effects on fracture healing in a healthy animal model, as far as the parameters related to mechanical strength are concerned.

Animals↗

PubMed1997

Prevention of postoperative late kyphosis in Pott's disease by anterior decompression and intervertebral grafting.

A total of 185 patients with Pott's disease were operated on between 1973 and 1992. Anterior decompression by preserving the pleura (extrapleural approach) was the preferred method in the thoracic spine. In the lumbar spine the approach was retroperitoneal, and interbody fusion was performed in both for the thoracic and the lumbar regions. Anterior decompression and intervertebral grafting comprised the treatment. In five patients, internal fixation accompanied anterior decompression and intervertebral grafting. The aim of instrumentation was to enhance anterior spinal stability, and Alici spinal instrumentation was the preferred device. Graft destruction and a late increase in kyphosis was prevented by this means. The mean follow-up period was 7.5 years. Thirty-two of the cases were admitted to the clinic because of Pott's paraplegia: 19 of the cases recovered completely following anterior decompression; partial recovery was observed in 5 cases; but 3 cases did not recover. Various complications, including seven deaths, were observed in 42 of the cases.

Adolescent↗

PubMed1997

Biomechanics of the Gazi type pelvis external skeletal fixator.

External skeletal fixation is an alternative method of treatment to conventional therapy and open surgical procedures in pelvis fractures. The appropriate type of frame and the configuration of the connecting bars of these fixators are under investigation. In the Gazi type pelvis external fixator (GPEF) which has been developed, a 70 degree angulation is applied to the connecting bars of the anterior quadrangular frame. This configuration, which is expected to improve the stability of the posterior column of the pelvis, was evaluated biomechanically on a phantom with various types of pelvic fractures and separations. The results suggest that the GPEF effectively controls anterior column pelvis fractures such as unilateral pubic ramus fractures, unilateral ischium pubis rami fractures and symphysis pubis separations under vertical loads. The fixator is partially capable of stabilizing the posterior column; however, loads above 700 N cause separation at the fracture site. Further studies and clinical trials are essential to determine the GPEF's effectiveness in reducing blood loss and in providing stability at the posterior column.

Adult↗

PubMed1995

Do porous calcium hydroxyapatite ceramics cause porosis in bone? A bone densitometry and biomechanical study on cortical bones of rabbits.

Porous calcium hydroxyapatite (CHA) ceramics are biocompatible and present osteoconductive properties. These ceramics are widely used in orthopaedic surgery; however, it is not yet known whether they have some adverse effects on bone and bone marrow healing. Our previous radiological study revealed possible local porosis at the adjacent sites of the CHA ceramic. Histological findings of the same study revealed bone marrow swelling and depletion at the implantation site. Osteoclasts removed particles of the implant that may be the cause of local porosis. In the present study, possible local osteoporosis was evaluated by bone densitometry analyses, and compression and three-point bending tests. CHA particles were implanted into the left limbs and a sham operation was utilized on the right limbs of 75 white rabbits. The animals were followed up for 23 weeks for bone mineral density and for 6 months for biomechanical analyses. The CHA implanted area and its distal or proximal adjacent areas were evaluated with a Hologic QDR-2000 bone densitometer. Three-point bending and compression tests were performed with an M-30 K material testing device. The results revealed a time-dependent bone density increase at the CHA implantation site and no significant porosis at adjacent areas of the implant. The stiffness of CHA-implanted bones in three-point bending is larger than that of the control group. CHA-implanted rabbit bones presented a different fracture pattern from the control group. The stiffness of the control and CHA-implanted bones generally increased with time indicating no adverse effects of porous CHA ceramics in bone and bone marrow healing. The clinical relevance of this work is that porous CHA ceramics do not cause local porosis at adjacent areas when implanted into osseous sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Experimental implant-related osteomyelitis treated by antibiotic-calcium hydroxyapatite ceramic composites.

The efficacy of locally implanted antibiotic-calcium hydroxyapatite ceramic composites was investigated for the treatment of experimentally produced, implant-related osteomyelitis in rats. High concentrations of antibiotics were detected at the site of infection and bacteria were eradicated without removal of the metal implants. Parenteral antibiotics and surgical debridement, alone or in combination with antibiotic-impregnated acrylic bone cement, all failed to eradicate the infections.

Animals↗

PubMed1992

Calcium hydroxyapatite ceramic used as a delivery system for antibiotics.

Porous blocks of calcium hydroxyapatite ceramic were evaluated as delivery systems for the sustained release of antibiotics. We tested gentamicin sulphate, cefoperazone sodium, and flomoxef sodium in powder form placed in a cylindrical cavity in calcium hydroxyapatite blocks, using in vitro studies of elution and in vivo studies in rats. Gentamicin sulphate gave a maximum concentration within the first week, which gradually decreased but was still effective at 12 weeks, when 70% of the antibiotic had been released. Even at this stage the antibiotic concentration from a 75 mg dose was five times the minimum inhibitory concentration for staphylococci. In the in vivo studies the release of gentamicin sulphate into the normal bone of rats was at similar rates and levels. The bacteriocidal activity of the drugs was not affected by packing into calcium hydroxyapatite ceramic and the blocks were completely biocompatible on histology. This new system overcomes the disadvantages of other drug delivery systems, avoiding thermal damage to the antibiotics and a second operation for the removal of the carrier. Some mechanical strength is provided by the ceramic and healing may be accelerated by bone ingrowth into its micropores.

Animals↗