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  • 1
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim: To investigate the effect of Bio-Oss® with and without the local application of recombinant human platelet-derived growth factor (rhPDGF-BB) on bone formation under Teflon capsules.Materials and Methods: Eight male, 6-month-old, Wistar strain rats were used in the study. In each animal, the lateral aspect of the mandibular ramus was exposed and small perforations were produced in the bone. A rigid, non-porous hemispherical teflon capsule (diameter 7 mm) was placed on the ramus in both sides of the animals. The capsule placed on the one side of the jaw was filled with Bio-Oss® granules soaked in a solution of PDGF-BB (20 μg/capsule) and autogenous blood prior to placement. The capsules placed on the other side of the jaw were filled with Bio-Oss® granules soaked in autogenous blood only (controls). Four rats were sacrificed after 3 months and the remaining four after 5 months. Undecalcified sections containing the capsule and surrounding tissues were prepared and analysed in the microscope.Results: Histologic analysis revealed limited amounts of bone formation. Most of the space underneath the capsules was occupied by Bio-Oss® particles surrounded by fibrovascular connective tissue. Given the small sample size statistical analysis was not possible, however, the mean amount of mineralized new bone in the control group (20.8%) appeared to be larger than that in the test group (6.7%). After 5 months the amount of newly formed bone appeared similar in the two groups (23.0% test, 26.0% controls). The Bio-Oss® particles occupied between 31.4% and 41.1% of the capsule area at 3 months and between 34.0% and 34.7% at 5 months. Only particles adjacent to the mandibular ramus were incorporated in newly formed bone.Conclusion: Limited bone formation was present in the capsules grafted with Bio-Oss® with or without the growth factor.
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  • 2
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim: To evaluate whether bone formation under Teflon capsules may be enhanced by concomitant implantation of recombinant human platelet-derived growth factor-BB/insulin-like growth factor-I (rhPDGF-BB/IGF-I) incorporated into a methyl cellulose gel.Materials and Methods: Fifty-five male 6-month-old albino rats of the Wistar strain were used in the study. The lateral aspect of the mandibular ramus was exposed on both sides of the jaw. In 70 sites, the periosteum was removed from the ramus, leaving the bone denuded, while in 35 sites, it was preserved. On 10 non-periosteal (P−) sites and five periosteal (P+) sites, an empty rigid teflon capsule (d=7 mm), serving as control, was placed on the ramus. In the 40 test animals, the capsule placed on the one side of the jaw was filled at random with one of three different concentrations (1200, 600, 150 μg/ml) of rhPDGF-BB/IGF-I gel. The capsules placed on the contralateral side of the jaw contained a placebo methyl cellulose gel. Each growth factor group, defined according to the gel concentration, and the placebo group contained 10 capsules placed on the P− side and five capsules placed on the P+ side. Two months after surgery, all animals were sacrificed.Results: Histologic analysis revealed that in the non-filled control capsules, the amount of new bone including the bone marrow was 29.9% and 39.7% of the capsule area on the P− and P+ sides, respectively. In the test capsules with the growth factor gel and placed on the P−sides, the amounts of new bone ranged from 5.6% to 6.3%, which were similar (p〉0.05) to that formed in the capsules filled with the methyl cellulose gel (5.5%). New bone formation was larger in the capsules on the P+ sides than in those on the P− sides but was similar in the capsules with different growth factor concentrations (range 17.9–19.6%) and in those with placebo gel (21.0%). In all groups, the carrier gel was poorly absorbed and occupied most of the capsules.Conclusion: Local application of a methyl cellulose gel obstructed bone formation under Teflon capsules placed adjacent to uninjured cortical bone in the mandibular ramus of rats. These data suggest that another material should be utilized to deliver growth factors under Teflon membranes for guided bone regeneration.
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  • 3
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Platelet-derived growth factor (PDGF) and insulin-like growth factor I (IGF-I) in combination have previously been shown to enhance periodontal regeneration. The objective of this study was to further characterize the biological effects of this combination of growth factors in non-human primates and compare the effects to those of each growth factor individually. Ligature-induced periodontitis was initiated in 10 cynomolgus monkeys. After periodontal lesions were established, surgery was performed, and either a methylcellulose gel vehicle or vehicle containing 10 μg each of either PDGF-BB, IGF-I or both PDGF-BB and IGF-I was applied to exposed root surfaces. Biopsies were taken 4 and 12 wk after treatment and the extent of periodontal regeneration was assessed by histomorphometry. At both 4 and 12 wk vehicle-treated lesions generally revealed minimal osseous defect fill (ODF) (8.5±2.1% and 14.5±5.7%, respectively) and new attachment (NA) (34.1±5.2% and 26.6±10.5%, respectively). IGF-I treatment did not significantly alter healing compared to vehicle in any parameter at both 4 and 12 wk. PDGFBB-treated sites exhibited significant (p〈0.05) regeneration of NA (69.6±12.0%) at 12 wk; trends for PDGF-BB treatment effect were also observed in other parameters at 4 and 12 wk. although these increases were not statistically significant. Treatment with PDGF-BB/IGF-I resulted in 21.6±5.1 % and 42.5±8.3% ODF at 4 and 12 wk, respectively, and 64.1±7.7% and 74.6±7.4% NA at 4 and 12 wk, respectively (all significantly greater than vehicle, p〈0.05). The results from this study demonstrated that: 1) IGF-1 alone at the dose tested did not significantly alter periodontal wound healing; 2) PDGF-BB alone significantly stimulated NA, with trends of effect on other parameters; and 3) the PDGF-BB/IGF-I combination resulted in significant increases in NA and ODF above vehicle at both 4 and 12 wk.
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  • 4
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract The objective of this study was to correlate the levels of 2 putative markers of bone metabolism, namely osteocalcin and pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP). to the progression of experimental alveolar bone loss in the beagle dog, 36 control sites and 36 experimental sites in 2 beagle dogs were assessed longitudinally at 2-week intervals for gingival crevicular fluid (GCF) osteocalcin and ICTP levels during a 6-month observation period. Analysis of osteocalcin and ICTP in GCF was performed by RIA. During the study, bone-seeking radiopharmaceutical uptake (BSRU) of 99mTc-MDP was assessed monthly; standardized radiographs were taken al 2-week intervals. The results showed osteocalcin and ICTP levels in GCF increased significantly (p〈0.05) by 2 weeks following initiation of disease. This increase preceded significant increases in BSRU by 2 weeks and radiographic evidence of bone loss by 4 weeks, BSRU was significantly elevated (p〈0.05) at experimental sites as compared to controls at 4 and 8 weeks post-disease initiation. Osteocalcin in GCF peaked 8 and 10 weeks after ligature placement in experimental sites at levels nearly 10-fold greater than contralateral paired control sites. ICTP levels in GCF remained elevated throughout the entire disease progression phase. Following the removal of ligatures, both GCF ostocalcin and ICTP levels dropped precipitously approaching control values. Osteocalcin revealed overall a positive predictive value (PPV) and negative predictive value (NPV) for future bone loss during disease progression of 0.87 and 0.34. respectively, while ICTP showed both high PPV and NPV of 0.87 and 0.91 respectively. Results from this study in the dog model indicate that osteocalcin and especially ICTP relate to indices of active periodontal bony destruction and suggest that these molecules may serve as predictive markers for future alveolar bone loss.
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  • 5
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Platelet-derived growth factor and insulin-like growth factor-I have been shown to interact synergistically to enhance repair of skin wounds in normal healing swine. Platelet-derived growth factor alone has shown promise in treating human chronic ulcers. The objective of this study was to compare the wound healing effects of platelet-derived growth factor-BB alone with those of a combination of platelet-derived growth factor-BB and insulin-like growth factor-I in an improved model with the use of “older” animals with diabetes. Older diabetic (db/db) mice (〉15 weeks of age) have less elevated insulin levels compared with young db/db mice. The serum insulin levels in the older animals is 1.0 to 2.5 times that of the nondiabetic animals, a similar increase to that which occurs in human patients with type II diabetes. Healing was evaluated in two studies involving a total of 104 animals. Treatment groups included the following: 4.0 µg/cm2 of platelet-derived growth factor-BB, 40.0 µg/cm2 of platelet-derived growth factor-BB, 4.0 µg/cm2 of both platelet-derived growth factor-BB and insulin-like growth factor-I or vehicle. All growth factors were applied topically in a methylcellulose vehicle to full-thickness wounds every other day for 24 days. Efficacy end points were median and mean time to complete healing and rate of wound closure. The median time to complete healing for animals receiving the platelet-derived growth factor-BB/insulin-like growth factor-I combination was 38% and 33% faster (p 〈 0.001) than animals receiving 4.0 µg/cm2 and 40.0 µg/cm2 of platelet-derived growth factor-BB, respectively. The mean time to complete healing for platelet-derived growth factor/insulin-like growth factor-I treated animals was 31% and 29% faster (p 〈 0.001) than 4.0 µg/cm2 and 40.0 µg/cm2 platelet-derived growth factor-BB treated animals, respectively. Wounds treated with 4.0 µg/cm2 platelet-derived growth factor-BB/insulin-like growth factor-I healed, on average, in 22 days compared with 31 days for 40.0 µg/cm2 platelet-derived growth factor-BB alone and 38 days for vehicle. Also, platelet-derived growth factor-BB/insulin-like growth factor-I significantly improved the rate of wound closure throughout the duration of the studies compared with either dose of platelet-derived growth factor-BB alone (p 〈 0.005) or vehicle (p 〈 0.001). In conclusion, the data show that the combination of platelet-derived growth factor-BB and insulin-like growth factor-I is more effective than platelet-derived growth factor-BB alone at the doses tested or vehicle treatment in stimulating cutaneous wound healing in older, diabetic mice.
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  • 6
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The combination of insulin-like growth factor-I and platelet-derived growth factor-BB has previously been shown to stimulate healing of soft tissue wounds and the formation of bone and ligament around teeth. The purpose of the present study was to evaluate the effects of platelet-derived growth factor-BB and insulin-like growth factor-I individually and in combination on the healing of osseous wounds. Four standardized cortical wounds were created in each tibia of 11 adult Yucatan miniature pigs. The wounds in one tibia per animal were treated with either purified recombinant human insulin-like growth factor-I, platelet-derived growth factor-BB, or both in a methylcellulose gel. The wounds in each contralateral tibia received placebo gel alone. Coded serial sections of each wound were evaluated by computer-aided histomorphometry 21 days after surgery. The area and perimeter of the newly formed mineralized callus, the thickness of the total callus, and the percentage of mineralized tissue within the callus were significantly increased compared with the values of matched controls only in wounds treated with a combination of insulin-like growth factor-I and platelet-derived growth factor-BB. No significant differences in the measured parameters of callus formation were found in wounds treated with either insulin-like growth factor-I or platelet-derived growth factor-BB alone. Cartilage was present only in sites treated with insulin-like growth factor-I alone. These results suggest that the combination of platelet-derived growth factor-BB and insulin-like growth factor-I stimulates bone formation in wounds in long bones of adult animals and that these growth factors act via different pathways during the repair process.
    Type of Medium: Electronic Resource
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