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Biomedical subjects

D M Toriumi

Publications and source records attributed to D M Toriumi.

At least 37 records · Page 2Linked to original sources
PubMed1995

The enhancement of nerve regeneration using growth factors: a brief review.

The management of peripheral nerve injuries continues to challenge the surgeon. Despite advances in surgical technique, return of normal function is uncommon after the repair of a transected nerve. It is now possible to enhance the process of nerve regeneration in animals using growth factors carried in silicone nerve guides. In this article the biological process of nerve regeneration is described and contemporary research involving the use of growth factor implants to facilitate nerve regeneration is reviewed.

Animals↗
PubMed1994

Surgical tissue adhesives in otolaryngology-head and neck surgery.

The primary surgical tissue adhesives used in otolaryngology-head and neck surgery include the cyanoacrylate derivatives and the fibrin tissue adhesives. The cyanoacrylate derivatives are effective for superficial skin closure. Use of this material below the level of the skin can result in acute and chronic inflammation and tissue necrosis. Fibrin tissue adhesives can be used for wound closure, tissue sealing, and hemostasis. Drawbacks noted with the fibrin tissue adhesives include method of preparation, relatively low binding strength, and variable resorption time. This article discusses the properties, methods of preparation, and clinical indications of the cyanoacrylate derivatives and fibrin tissue adhesives.

Cyanoacrylates↗
PubMed1994

Injectable filler materials for soft-tissue augmentation.

The concept of non-surgical implantation of injectable filler materials for soft-tissue augmentation has always been an attractive option for the head and neck surgeon. The ideal injectable soft tissue filler material would be easy to use, biocompatible, nontoxic, and long-lasting. Presently available filler materials present significant drawbacks to their use. The most favorable filler materials appear to be autologous fat and microparticulate alloplasts. This article reviews presently used injectable filler materials and those that may be used in the future.

Biocompatible Materials↗
PubMed1992

The current status of cyanoacrylate and fibrin tissue adhesives.

Surgical tissue adhesives could simplify complex surgical procedures by stabilizing tissue surfaces through hemostasis, sealing wounds, and fixating tissue in areas inaccessible to suture placement. The most common surgical tissue adhesives available to the surgeon include the cyanoacrylate derivatives and the fibrin tissue adhesives. Butyl-2 cyanoacrylate (Histoacryl) is a cyanoacrylate derivative that is frequently used in Canada and Europe. This adhesive has excellent binding strength for skin closure; however, subcutaneous implantation can result in inflammation and foreign body giant cell reaction. Fibrin tissue adhesives use a fibrin clot as the binding moiety and vary in adhesive strength depending on the fibrinogen concentration of the preparation. Autologous fibrin tissue adhesives are prepared using one of several different methods, which vary in fibrinogen yield and concentration. The currently available autologous fibrin tissue adhesives demonstrate good hemostatic properties with relatively low binding strengths. This article reviews the status of cyanoacrylate adhesives and the preparation, efficacy, and clinical applications of the fibrin tissue adhesives.

Animals↗
PubMed1992

Considerations in the use of biologic grafts and alloplastic implants in facial plastic and reconstructive surgery.

Surgical changes in the contour of soft tissue and bone of the craniomaxillofacial structures may require use of a biologic graft or alloplastic implant. Autologous materials are preferred; however, the harvesting procedure, donor site, and its associated morbidity are the disadvantages of using autografts. There are numerous types of alloplastic implants and they all differ in how they interact with host tissues. Factors such as implant texture, ability to integrate with host tissues, and rate of resorption all influence the overall success of different implants. In this article, we discuss some considerations in the use of biologic grafts and alloplastic implants in facial plastic and reconstructive surgery.

Animals↗
PubMed1991

Mandibular reconstruction with a recombinant bone-inducing factor. Functional, histologic, and biomechanical evaluation.

Bone morphogenetic protein-2 (BMP-2) is a human recombinant bone-inducing factor that stimulates bone formation within 14 days. Twenty-six dogs underwent reconstruction of 3-cm full-thickness mandibular defects. After stabilizing the defects with stainless steel reconstruction plates, test implants composed of inactive dog bone matrix carrier and human recombinant BMP-2 were placed in defects of 12 animals (group 1). Control implants (carrier without BMP-2) were used in 10 animals (group 2), and no implants were placed in mandibular defects of four animals (group 3). Animals were killed at 3 and 6 months. The reconstructed segments were evaluated by roentgenography, analysis of functional stability, histology, histomorphometry, and analysis of biomechanical strength using three-point bend testing. In group 1, reconstruction plates were removed at 10 weeks because stiff, noncompressible mineralized bone formed across the defects, allowing the animals to chew a solid diet. The defects from groups 2 and 3 showed minimal, if any, bone formation and remained grossly unstable, prohibiting plate removal or advancement to a solid diet. Histomorphometric analysis at 6 months revealed that 68% of the group 1 implants were replaced by mineralized bone, whereas mineralized bone occupied less than 4% of the implants in groups 2 and 3. Biomechanical testing at 6 months revealed that the average bending strength of the reconstructed hemimandibles (expressed as a percentage of the contralateral hemimandible) was 27% for group 1 and 0% for group 2. The biomechanical strength of the defects reconstructed with BMP-2 increased significantly from 3 to 6 months and was related to degree of mineralization and thickness of bone bridging the defect.

Animals↗
PubMed1991

Variable histotoxicity of histoacryl when used in a subcutaneous site: an experimental study.

Histoacryl (butyl-2-cyanoacrylate) is one of the least histotoxic cyanoacrylate derivatives and is used as a tissue adhesive. Clinical applications primarily include skin closure (blepharoplasty incisions, etc.). In a recent study, we demonstrated that Histoacryl elicits minimal histotoxicity when used to glue bone grafts to rabbit-ear cartilage. Acute inflammation was limited to areas where Histoacryl escaped from between the bone graft and ear cartilage to contact well-vascularized soft tissue. In this study, Histoacryl was applied between bone graft and cartilage in one rabbit ear and adjacent to well-vascularized soft tissue with no graft in the opposite ear. Histologic analysis revealed minimal if any inflammation when small amounts of glue was used in the nonvascular region between bone graft and cartilage. However, subcutaneous implantation contacting well-vascularized soft tissue resulted in increased acute inflammation and prolonged foreign-body giant-cell response. Further studies are required to rule out any long-term problems associated with subcutaneous implantation of Histoacryl.

Administration, Cutaneous↗
PubMed1991

Bone-inducing implants in head and neck surgery: an experimental study.

The use of autologous bone for head and neck reconstruction requires a separate harvesting procedure which provides limited quantities of bone that may become infected or undergo resorption after being implanted. In this study, a collagen/ceramic carrier containing osteoinductive factor extract (OFE) was used in a rabbit facial augmentation model. Bone-inducing activity of these implants were evaluated in subcutaneous, intramuscular, and subperiosteal sites. Implants with (test) and without OFE (control) were placed on opposite sides of the face in 40 rabbits, and were harvested at 21 days. Bone formation was evaluated by implant alkaline phosphatase determinations and histomorphometry. Osteoblastic activity, bone formation, and preservation of facial augmentation were noted in the OFE implants, showing maximal bone formation when implanted subperiosteally. Control (no OFE) and demineralized bone implants showed no bone formation. Before these implants can be used clinically, novel bone-inducing factors must be manufactured by recombinant deoxyribonucleic acid (DNA) methodology to verify activity of the homogeneous molecule which would be free of other proteins or infectious agents.

Alkaline Phosphatase↗
PubMed1991

Osteoinductive biomaterials for medical implantation.

The search for the ideal implant material continues since presently available implants all have significant drawbacks. This paper reviews three studies that we recently completed with bone-inducing implants. Long-term clinical follow-up of 75 allogeneic demineralized bone implants showed an average degree of resorption of 49%. Implants used for dorsal nasal augmentation showed an average degree of resorption of 50.7%, increasing to 82.5% after a 24-month follow-up. The efficacy of demineralized bone implants is dependent on many factors including site of implantation, method of preparation, etc. Transforming growth factor-beta 1 (TGF-beta 1) is a regulator of bone formation. We combined recombinant TGF-beta 1 with demineralized bone powder in a rabbit facial augmentation model. At 6 weeks, there was evidence of increased bone formation in the implants containing TGF-beta 1. Even though TGF-beta 1 can increase bone formation in demineralized bone implants, the overall bone-inducing activity in these implants seems to be suboptimal. Osteoinductive factor extract (OFE) is a partially purified bone factor preparation that has been shown to form bone when implanted into rats. Using a collagen/ceramic carrier, we implanted OFE into a rabbit facial augmentation model. At 21 d, histomorphometry revealed numerous osteoblasts and bone formation in the OFE implants. The bone-inducing activity of many partially purified osteoinductive preparations such as OFE is probably due to Bone Morphogenetic Protein-2A (BMP-2A), which has been shown to induce bone formation in its recombinant form. Recombinant DNA methodology provides the technology necessary to produce these molecules in their homogeneous form, permitting evaluation of bone-inducing activity in a preparation free of contaminants. Finally, the ideal carrier must be devised to permit safe and effective delivery of recombinant bone-inducing factors.

Animals↗
PubMed1990

Histotoxicity of cyanoacrylate tissue adhesives. A comparative study.

Cyanoacrylate derivatives have been used as surgical adhesives for many years. Shorter-chain derivatives (methyl- and ethyl-cyanoacrylate) have proved to be histotoxic. Longer-chain derivatives (butyl- and isobutyl-cyanoacrylate) are much less histotoxic. Many surgeons continue to use ethyl-2-cyanoacrylate (Krazy Glue) despite the availability of a less toxic derivative, butyl-2-cyanoacrylate (Histoacryl). In this study, the histotoxicity and bone graft-cartilage binding ability of Krazy Glue and Histoacryl were compared. Bone grafts harvested from the anterior wall of the maxillary sinus were placed in a subcutaneous pocket and glued to auricular cartilage in the rabbit. Krazy Glue and Histoacryl were used in opposite ears, harvesting specimens at 1, 2, 4, 12, 24, and 48 weeks. The Krazy Glue-treated ears developed seromas with histologic evidence of acute inflammation, tissue necrosis, and chronic foreign body giant cell reaction. The Histoacryl-treated ears showed mild acute inflammation and mild foreign body giant cell reaction. The Krazy Glue was completely degraded within 12 months, while some Histoacryl was still present at 1 year. Histoacryl had minimal histotoxic effect and good bone graft-cartilage binding ability, whereas Krazy Glue demonstrated severe histotoxicity.

Animals↗
PubMed1990

Demineralized bone. Implant resorption with long-term follow-up.

The osteoinductive properties of demineralized bone have stimulated its use in facial skeletal augmentation and reconstruction. Demineralized bone has been shown to induce phenotypic conversion of mesenchymal cells into osteoblasts, with bone formation within 29 days (osteoinduction). In this clinical study, 75 demineralized bone implants were followed up from 1 to 48 months (average follow-up, 14.3 months). There were 41 major dorsal implants, with an average degree of resorption of 50.7%. Eight dorsal implants were followed up for more than 24 months, with an 82.5% degree of resorption. Overall resorption for all implants was 49%. Major factors contributing to implant resorption included lack of surrounding mesenchymal cells and inadequate contact between host tissue and bone-inducing surface area. Other factors included infection, poor vascularity, and compression of the implant. Demineralized bone has an unacceptably high resorption rate and should only be used in highly selective cases where the implant can be positioned in a site rich in primitive mesenchymal or bone-forming cells.

Bone Density↗
PubMed1990

Management of the aging forehead.

Browlifting and forehead procedures are a critical element in the contemporary surgical management of the aging face. Esthetics of the upper third of the face will dictate brow position and its relationship to the supraorbital rim and eyes. Treatment of deformities of the upper third of the face can be varied according to the sex and age of the patient as well as contour of the hairline and forehead. The indications, advantages, disadvantages, and techniques of the coronal forehead, modified pretrichal forehead, midforehead, and direct browlifting procedures are discussed.

Aged↗
PubMed1990

Rationale for elective neck dissection in 1990.

Elective neck dissection has long been a subject of debate among surgeons. The proponents of elective neck dissection base their rationale on studies that show a 30% incidence of occult disease in those situations for which elective neck dissection is recommended. One hundred eighty-two patients with advanced stages of squamous cell carcinoma of the head and neck were studied. All patients had preoperative computed tomography or magnetic resonance imaging, and all patients had some form of radical neck dissection. The sensitivity of clinical exam was compared with the sensitivity of computed tomography or magnetic resonance imaging in ability to detect nodal disease. The sensitivity of clinical exam alone was 71.7%, while the sensitivity of computed tomography or magnetic resonance imaging was 91.1%. Based on physical exam alone, there would be a 39% rate of occult disease; if computed tomography or magnetic resonance imaging data is combined with physical exam, the occult disease rate would drop to 12%. All centers performing elective neck dissection must reassess their rationale or restudy their occult disease rate with computed tomography or magnetic resonance imaging.

Carcinoma, Squamous Cell↗