Biomedical subjects

Cameron M L Clokie

Publications and source records attributed to Cameron M L Clokie.

15 recordsLinked to original sources

PubMed2006

Comparison of remifentanil with fentanyl for deep sedation in oral surgery.

PURPOSE: The aim of this study was to compare recovery for oral surgery patients given a deep sedation regimen of midazolam, propofol, and remifentanil with a standard control of fentanyl in place of remifentanil. MATERIALS AND METHODS: This investigation was designed as a randomized, prospective, single-blinded controlled study. Group 1, the control, received midazolam 0.03 mg/kg, fentanyl 1 microg/kg, and propofol initially at 140 microg/kg/min. Group 2 received midazolam 0.03 mg/kg, remifentanil: propofol (1:500) given at an initial propofol infusion rate of 40 microg/kg/min. Outcome measures included time to response to verbal command, Aldrete score = 9, Postanesthesia Discharge Scoring System = 7, and assessment by the Digit Symbol Substitution Test. RESULTS: Forty-seven subjects were entered in the study. Baseline findings were homogenous between the 2 groups. Subjects in group 2 recovered earlier (P < .005) and required less propofol for both the induction (0.8 +/- 0.4 versus 1.2 +/- 0.6 mg/kg; mean +/- SD, P < .01) and maintenance of deep sedation (46 +/- 9 versus 131 +/- 17 microg/kg/min; P < .005). There were minor differences in vital signs. CONCLUSIONS: This study demonstrated that this remifentanil regimen provided significantly more rapid recovery and used significantly less propofol compared with the fentanyl regimen.

Adolescent↗

PubMed2006

Hyperbaric oxygen results in an increase in rabbit calvarial critical sized defects.

OBJECTIVE: This study was undertaken to evaluate whether the effects of hyperbaric oxygen (HBO) therapy could alter the critical size for spontaneous healing of a bone defect in the rabbit calvarial model. STUDY DESIGN: An animal trial of 12 weeks duration was conducted using 20 New Zealand white rabbits, which were randomly divided into 2 groups of 10 animals each. Calvarial defects were created in the parietal bones of each animal bilaterally. Defects were critical-sized, 15 mm on one side and supra-critical-sized, 18 mm on the contralateral side. Group 1 received a 90-min HBO treatment sessions at 2.4 absolute atmospheric pressure (ATA) per day for 20 consecutive days. Group 2 served as a control without any HBO treatment sessions. Five animals in each group were sacrificed at 6 and 12 weeks. Data analysis included qualitative assessment of the calvarial specimens, post-sacrifice radiographs, as well as histomorphometric analysis to compute the amount of regenerated bone within the defects. ANOVA and paired sample t test were used for statistical analysis. RESULTS: Both radiographic analysis and histomorphometric analysis demonstrated that HBO-treated animals had significantly more new bone within their defects compared with the control group (P < .001). There was no statistically significant difference between the percentage of new bone forming in the 15-mm and 18-mm HBO-treated defects. There was no difference between the 6-week and the 12-week HBO-treated groups. HBO is effective in enhancing the bony healing of full thickness critical sized as well as supra-critical-sized defects in the rabbit calvarial model. CONCLUSION: Bone regeneration was significantly greater in the HBO-treated animals regardless of the defect size. HBO may have increased the diameter of the rabbit critical-sized calvarial defect to more than 18 mm.

Analysis of Variance↗

PubMed2006

Closure of rabbit calvarial critical-sized defects using protective composite allogeneic and alloplastic bone substitutes.

This study evaluated the repair of critical-sized cranial vault defects in thirty New Zealand white rabbits using various allogeneic and alloplastic bone substitutes designed to provide mechanical protection to the brain as well as osteoinductivity. The strategies employed included demineralized bone matrix (DBM), a putty used in combination with a rigid resorbable plating system as a protective covering and calcium phosphate cement (CPC) combined with native partially purified bone morphogenetic protein (BMP). Bilateral critical-sized defects measuring 15 mm in diameter were created in the parietal bones of 30 adult male New Zealand white rabbits. They were divided into three groups with ten animals in each. Group 1 had one defect left unfilled as a control while autogenous bone was placed in the defect on the other side. In Group 2 a rigid resorbable copolymer membrane, Lactosorb (Lorenz Surgical, Jacksonville, Florida), was placed over both defects to cover them and protect the underlying tissues. The pericranial aspect of one defect was left unfilled while the other defect was filled with DBM putty. Group 3 had a CPC, Mimix (Lorenz Surgical, Jacksonville, Florida), placed into one of the defects while the defect on the other side was filled with the same CPC in combination with BMP in a concentration of 25 mg/mL. Bone healing was assessed clinically, radiographically, and histomorphometrically. All unfilled controlled defects, the defects covered with the resorbable Lactosorb membrane and those filled with calcium phosphate cement alone, healed with a fibrous scar. Defects reconstructed with DBM putty in combination with the resorbable Lactosorb membrane and calcium phosphate in combination with BMP healed with bone bridging the entire defect. This was obvious radiographically where the defects appeared completely filled with a dense radiopaque tissue. Histological analysis demonstrated that specimens where DBM putty was used in combination with the resorbable Lactosorb membrane had 67.7% new bone fill at 6 weeks and 84.0% at 12 weeks. Resorption of DBM particles was evidenced by the presence of osteoclastic activity and by the significant decrease in the size of the demineralized bone particles. In the calcium phosphate groups where BMP was added to the bioimplant there was 45.8% new bone formation at 12 weeks. The utilization of a composite consisting of DBM with resorbable Lactosorb membrane or a composite of calcium phosphate cement composite with BMP promoted complete closure of critical-sized calvarial defects in New Zealand white rabbits with viable new bone at 12 weeks. The complete bone bridging observed with these composites suggests that they could be used to enhance the protection of intracranial contents following craniofacial surgical procedures.

Animals↗

PubMed2006

Unilateral facial swelling caused by Ramsay Hunt syndrome resembles odontogenic infection.

Facial cellulitis and swellings of the head and neck are worrisome signs of odontogenic infection, which can be life threatening. Most head and neck infections are caused by bacterial pathogens. When treating such infections, dentists must also be aware of possible viral or fungal causes and their associated presentations. This report documents a case of viral infection that initially resembled a bacterial odontogenic infection. It is intended to familiarize dentists with the Ramsay Hunt syndrome and the need for prompt recognition and early definitive treatment.

Acyclovir↗

PubMed2005

Role of bovine bone morphogenetic proteins in bone matrix protein and osteoblast-related gene expression during rat bone marrow stromal cell differentiation.

Bone morphogenetic proteins (BMPs) are known to promote osteogenesis, and clinical trials are currently underway evaluating the ability of certain BMPs to promote bone graft and fracture healing. To observe the mechanism of osteoinductive and bone formation, 100 microg of bovine BMP was tested during osteogenic differentiation of rat bone marrow stromal cells (MSCs) and C2C12 line culture for 14 and 28 days. We examined alkaline phosphatase (ALP) by assay, immunohistochemical studies for bone matrix proteins, and mRNA expression of bone matrix proteins and osteoblast-related analysis by reverse-transcription polymerase chain reaction. ALP activity in MSC cultures was elevated by bovine BMP by two to fivefold (P < 0.05-0.001). DNA and protein content increased over 14 days. BMP significantly increased the mRNA expression of type I collagen, ALP, osterix, osteocalcin, osteopontin, vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF)-A, and parathyroid hormone receptor time dependently during the osteoblastic differentiation. There was no markedly enhanced mRNA expression of bone sialoprotein (BSP) and glyceraldehyde-3-phosphate dehydrogenase compared with that of control. Immunohistochemical results also showed BMP increased immunoreactive positivity of type I collagen, osteocalcin, osteonectin, osteopontin, and BSP during the C2C12 differentiation. These data indicated that BMP enhances our ability to stimulate the differentiation of osteoblast-like cells and increases osteoinductivity, bone matrix protein formation and mineralization, angiogenesis, and chondrogenesis during osteoblast progenitor cell differentiation in vitro and that the role of chondrogenic is weak.

Alkaline Phosphatase↗

PubMed2004

Histomorphometric evaluation of bone regeneration using allogeneic and alloplastic bone substitutes.

PURPOSE: The purpose of this investigation was to assess bone regeneration in critical sized defects in the rabbit calvarium using allogeneic and alloplastic bone substitutes. MATERIALS AND METHODS: Thirty New Zealand White rabbits were divided into 3 groups of 10 animals each. Bilateral 15 mm x 17 mm calvarial defects were made in the parietal bones of each animal. Group 1 had demineralized bone matrix (DBM) gel placed in one defect, while the other defect was left unfilled and served as the control. Group 2 had one defect filled with calcium hydroxide (CaOH)-treated DBM gel and the other defect filled with DBM gel. Group 3, the calcium-phosphate cement group, had Norian CRS (Norian Corp, Cupertino, CA) placed on one side and Bone Source (Howmedica Leibinger, Dallas, TX) placed on the contralateral side. Five animals in each group were killed at 6 and 12 weeks. Data analysis included qualitative assessment of the calvarial specimens and radiographic evaluation. Histomorphometric analysis was used to quantify the amount of new bone within the defects. RESULTS: Histomorphometric analysis showed that DBM gel-treated defects had significantly more new bone at 12 weeks compared with all other groups. There was no significant difference between defects filled with CaOH-treated DBM gel and those filled with DBM gel at 12 weeks. In group 3, Norian CRS- and Bone Source-treated defects were not statistically different from the unfilled controls. CONCLUSION: DBM gel was an effective allogeneic bone substitute that showed reliable osseous healing of critical size defects in the rabbit calvarium. The addition of CaOH to DBM gel did not significantly improve the bone regenerative capacity of the DBM gel. Both Norian CRS and Bone Source did not promote bone regeneration in this animal model.

Animals↗

PubMed2004

The osteoinductive activity of bone morphogenetic protein (BMP) purified by repeated extracts of bovine bone.

Native bone morphogenetic proteins (BMPs) extracted from bone have been used clinically to stimulate bone regeneration and repair. However, preparation of purified BMP is a laborious process. This study investigated the yield, activity and cost effectiveness of repeatedly extracting the same bone matrix to produce purified BMP. While repeated extraction was able to increase the yield 62% the activity of the partially purified BMP in later extracts decreased both in vitro and in vivo. This decline in activity appears to be due to an increase in non-BMP contaminants, such as collagen, in the extracts. When the first three extracts were combined and processed together activity was equivalent to that of the first extract. A simple analysis based on the cost of reagents used and the time required for purification indicates that separate processing of the extracts is inefficient while combining the first and second extracts and processing them together would result in a small cost saving. Based on this study we would recommend that the demineralized bone matrix be extracted no more than twice and that the extracts be combined for further processing.

Alkaline Phosphatase↗

PubMed2004

Osteoinductivity assay of the variability of repeated extractions of bone morphogenetic proteins from bovine bone at different times.

OBJECTIVE: To observe the activity of repeated extracts of bone matrix and the production of purified bone morphogenetic proteins (BMPs). METHODS: BMPs were extracted 1- 4 times from fresh bovine cortical bone by the modified Urist's method, with each collected precipitate separated and lyophilized as partially purified BMPs. Another fresh bovine bone was extracted three times and the precipitates were mixed and lyophilized. Meanwhile,the alkaline phosphatase (ALP) activity was measured by an in vitro assay employing cultured C2C12 mouse myoblast cells through the osteoinductivity of bovine BMPs extracted four times at days 1, 4, 7, and 14, and the correlation between BMPs quantities and costing during extraction processes was analyzed. RESULTS: The BMPs purified and the cost showed a positive correlation (r=0.969). To separate and lyophilize each collected precipitate as partially purified BMPs raised the cost, and mixed precipitates also cost much. ALP activities of the 1st and mixed extractions of BMPs were shown to be highly osteoinductive and keep a significantly high level (P<0.05-0.01) 4 days after culturing, compared with the 2nd, 3rd and 4th extractions, especially the control group. However, the more times the extraction was done, the less activity of BMPs was shown and more costing was. The x-ray and histological analysis also showed that the 1st extraction of BMPs induced more ossicles and new bone formation. CONCLUSIONS: The results indicated that BMPs enhanced the abilities of osteoinductivity in C2C12 culture in vitro. The first extraction of BMPs from bone is fitfull, the second extraction should be enough, while, the 3rd and 4th extractions are unnecessary for they cost more and waste more time, say nothing of mixed extractions.

Alkaline Phosphatase↗

PubMed2003

Clinical success in harvesting autogenous bone using a minimally invasive trephine.

PURPOSE: Autogenous bone grafting is well established for use in the maxillofacial skeleton. We present our experience with minimally invasive bone harvesting using a power-driven trephine, with favorable patient and clinical results. MATERIALS AND METHODS: This retrospective study evaluation patients requiring autogenous bone harvested using a trephine, treated consecutively over a 3-year period. Mean patient age was 27.2 years (range, 8 to 77 years). Only those patients requiring elective surgery and admission on the same day were included in the study. Intraoperative assessment included the description of complications and the quantity and volume of the bone cores harvested. The complications monitored included bleeding, nerve injury, and perforation of the medial or lateral walls of the ilium. Postoperatively, patients were assessed for ambulation, pain, bleeding, and suitability for discharge. The patients were evaluated 1 week after surgery and were examined for wound complications (incision breakdown, infection, paresthesia, pain) and ambulatory deficits. All patients were then surveyed using a questionnaire outlining short-term (1 to 14 days), and long-term (>6 months postoperative) deficits, pain, and general remarks about the procedure. RESULTS: A total of 84 patients underwent bone harvesting using a power-driven trephine. Bone was harvested from a total of 86 anterior iliac crest sites, for a total of 333 cores (3.96 cores per patient). Forty-one patients were discharged on the day of surgery. Intraoperatively, the volume of bone obtained ranged from 3 to 21 mL per harvest site (1 to 7 cores, 4 mm x 30 to 38 mm). The bone volume obtained was dependent on the size of the defect to be filled. Intraoperatively, 1 complication occurred (1 of 333 cores; 0.3%)-a broken instrument-and there were no perforations of the medial or lateral walls of the ilium or excessive bleeding. The complications totaled 3 (3.6%); none of these produced long term effects. Patients surveyed up to 6 months postoperatively noted positive results. CONCLUSIONS: The harvesting of bone from the anterior iliac crest using a power driven trephine appears to be safe and results in minimal morbidity and ample bone volume for many maxillofacial procedures, without delaying discharge from hospital.

Adolescent↗

PubMed2003

Recombinant human transforming growth factor beta-1 and its effects on osseointegration.

Dental implant failures are still a common occurrence, especially in areas of poor bone quality. The purpose of this study was to observe whether the application of a growth factor, recombinant human transforming growth factor beta-1 (rhTGF-beta1), would improve the healing of bone adjacent to titanium dental implants. Four adult male Yucatan minipigs had four titanium dental implants placed into the inferior border of each hemimandible. On the control side, the implants were placed in standard fashion. On the experimental side, rhTGF-beta1 within a carrier gel was placed into the recipient site before implant placement. After a 6-week healing period, two implants from each side were evaluated by pull-out testing and histomorphometric analysis. The mean pull-out force for experimental implants was 1,124.01 N and 818.12 N (P = 0.5015) for controls. The mean percentage of bone between adjacent threads on the implant surface was 49.74% for the experimental group and 36.50% for controls (P = 0.0783). The mean percentage of bone-implant surface contact was 41.86% for the experimental implant sites and 24.60% for the control implant sites (P = 0.0452). The application of rhTGF-beta1 to implant sites appears to increase the amount of bone healing adjacent to a titanium dental implants in minipig mandibles at the 6-week period. Further studies are required to quantify better the amount of growth factor required and to study its effects over a broader period of time to see whether these differences are maintained.

Animals↗

PubMed2003

In search of the ideal bone morphogenetic protein delivery system: in vitro studies on demineralized bone matrix, purified, and recombinant bone morphogenetic protein.

The clinical use of recombinant bone morphogenetic protein (rBMP) is limited by the lack of a suitable delivery system. The bone morphogenetic protein (BMP) delivery system provided by nature is highly effective, and by studying purified BMP (BMP/NCP) and demineralized bone matrix (DBM), it may be possible to learn how to emulate nature's success. The current study used an in vitro muscle cell model to study the activity of BMP/NCP and DBM and the effects of extracellular matrix on BMP activity. C2C12 cells transiently exposed to recombinant human BMP-4 (rhBMP-4) rapidly increased their alkaline phosphatase (AP) activity to day 5, after which it steadily declined. Cells exposed to BMP/NCP or DBM continued to increase their AP activity over the 14-day culture. If BMP/NCP was treated to remove a 22-kd protein, it became water-soluble and exhibited a similar activity pattern to rhBMP-4. Cells cultured on collagen type I, fibronectin, and hyaluronic-coated surfaces demonstrated increased AP activity when exposed to rhBMP-4 or BMP/NCP compared with cells cultured on bovine serum albumin or poly-l-lysine. These results suggest that the natural BMP delivery system operates both by binding to the BMP molecule and slowly releasing it into the extracellular milieu and by interacting with the responding cells through cell-matrix receptors to enhance the cellular response to BMP.

Alkaline Phosphatase↗

PubMed2002

Closure of critical sized defects with allogenic and alloplastic bone substitutes.

PURPOSE: This study evaluates bone regeneration of critical sized cranial vault defects in New Zealand white rabbits using four commercially available bone substitutes: OsteoSet (calcium sulphate pellets), DynaGraft Putty (demineralized bone matrix delivered in a poloxmer excipient), Norian CRS, and Bone Source (two commercially available calcium phosphate cements). MATERIALS AND METHODS: Critical sized defects 15 mm in diameter were created bilaterally in the parietal bones of 30 adult male New Zealand White rabbits. They were divided into three groups with ten animals in each. Bone healing was assessed clinically, radiographically, and histomorphometrically. Group 1 had calcium sulfate bioimplant on one side of the calvarium and an unfilled defect on the contralateral side. Group 2 had DBM putty on one side and Poloxamer gel on the contralateral side. Group 3, the Calcium phosphate cements (CPC), had Norian CRS on one side and Bone Source on the contralateral side. Five animals in each group were killed at 6 weeks and 12 weeks post operatively. RESULTS: All unfilled defects healed with fibrous scar, as did the Plaster of Paris and the poloxamer gel defects. Defects reconstructed with the demineralized bone matrix putty healed with bone throughout the entire defect. This was obvious clinically and radiographically where the defects appeared completely filled with a dense radiopaque tissue. The six-week group displayed new bone formation (87.1%) surrounding the remaining allogeneic particles. Resorption was evidenced by the presence of osteoclastic activity and by the significant decrease in the size of the demineralized bone particles. By 12 weeks, the demineralized bone putty bioimplant was almost completely replaced by new bone (95.5%). Both calcium phosphate cement groups (Norian CRS and Bone Source) had identical patterns of healing. They clinically were visible and firm and uniformly radiopaque with little evidence of new bone formation. Histologically the cement remained unresorbed with little new bone with in the defect at 12 weeks. CONCLUSIONS: The utilization of a demineralized bone matrix putty appeared to allow for complete closure of critical sized calvarial defects in New Zealand white rabbits with viable new bone at 12 weeks.

Analysis of Variance↗

PubMedDate not supplied

Differences in the location and multiplicity of mandibular fractures in Kuwait, Canada and Finland during the 1990s.

OBJECTIVE: To compare the location and multiplicity of mandibular fractures in Kuwait, Canada and Finland during the 1990s. SUBJECTS AND METHODS: Data were collected from several hospitals in Kuwait (1991-2000), Toronto General Hospital in Canada (1995-2000) and Oulu University Hospital in Finland (1990-1999). The data were analyzed statistically using chi-square test, ANOVA, t test and logistic regression. RESULTS: Condylar fractures were more common in Finnish patients (41%) than Canadian (35%) or Kuwaiti patients (21%). Condylar fractures caused by falls were about 3.4 times more common in Kuwait and Finland compared to Canada. In Finland the risk of road traffic accidents caused by condylar fracture was about 4 times higher than those caused by other etiologies. In Canada male gender was about 2 times higher for the condylar fracture than female gender. Female patients often had more multiple injuries than men in all three countries and multiple fractures were observed especially in traumas caused by falling. CONCLUSION: Differences in location and multiplicity of mandibular fractures are due to differences in etiologies and demographic patterns.

Accidental Falls↗

PubMedDate not supplied

Zygomatic bone: an additional donor site for alveolar bone reconstruction. Technical note.

This article describes a procedure to harvest bone from the zygoma for alveolar bone reconstruction. A detailed description of the bone harvesting procedure and a preliminary report of 3 patients undergoing alveolar bone reconstruction and simultaneous dental implant placement in the maxillary anterior area is presented. The technique is indicated when a modest amount of bone is needed, for example, to cover exposed implant threads and expand a narrow alveolar ridge. It also could be used as an additional source of bone with other intraoral donor sites. Surgical access to the zygoma is simple and can be performed using local anesthesia. Postoperative complications after zygomatic bone harvest are minimal.

Adult↗

PubMedDate not supplied

Fractures of the supraorbital rim: principles and management.

Dentists may be asked to provide consultations for patients who have sustained trauma to their facial structures. Supraorbital rim fractures, although uncommon, must be recognized and promptly referred to an oral and maxillofacial surgeon or other specialist skilled in the management of facial bone fractures. Supraorbital rim fractures commonly coexist with other craniomaxillofacial injuries, especially with fractures of the anterior table of the frontal sinus. In this article, we review the frequency, management and complications associated with the treatment of supraorbital rim fractures in adults. A series of 5 cases was reviewed; 4 of the 5 patients were male, with a mean age of 21.6 years (range 17-28 years). All injuries involved the supraorbital rim and the anterior table of the frontal sinus and occurred concurrently with other facial injuries. Treatment ranged from conservative observation to open reduction and internal fixation of the fractures. No associated perioperative or postoperative complications occurred. The follow-up ranged from 6 months to 26 years, with satisfactory subjective esthetic outcomes in all cases.

Adolescent↗