Wide Variety Of Synthetic Materials Research Articles

Synthetic biomaterials based on hydroxyapatite and tricalcium phosphate: analysis of current clinical trials

Introduction To date, a wide variety of synthetic materials, including metals, polymers and ceramics, have been proposed and used as a substitute for bone grafts in the field of traumatology/orthopedics, neurosurgery and oral and maxillofacial surgery (OMFS). However, the most studied materials are calcium phosphate ceramics (CPC), in particular hydroxyapatite and tricalcium phosphate, as well as their mixtures, called byphasic calcium phosphates. This interest stems from the fact that the main component of bone is the apatite mineral calcium phosphate. Hydroxyapatite and tricalcium phosphate are among the most commonly used and effective synthetic substitutes for bone grafts. They have not only osteoconductive properties, but also osteoinductive. These properties, combined with cell-mediated resorption, ensure complete regeneration of bone defects. This study will analyze existing clinical trials, registered on the clinicaltirals.gov website, on the use of hydroxyapatite and tricalcium phosphate in the field of traumatology and orthopedics, neurosurgery and OMFS.Aim To identify the potential for clinical use, as well as possible side effects, of CPC as a replacement for bone grafts.Materials and methods The search strategy was to use material from the clinicaltrials.gov website, which focused on key terms such as hydroxyapatite, tricalcium phosphate, hydroxyapatite and tricalcium phosphate, traumatology and orthopedics, maxillofacial surgery, dentistry, neurosurgery, bone, и diseases of the musculoskeletal system.Results and discussion As of November 2022, there were approximately 85 clinical trials with hydroxyapatite application, approximately 49 clinical trials with tricalcium phosphate, and approximately 16 clinical trials with the hydroxyapatite/tricalcium phosphate combination. Most of the studies were Phase 1-2, Phase 2, or Phase 4. Most focused on tibial trauma therapy, osteoporosis/osteopenia, alveolar bone resorption, and spinal surgery. It was found that full results were published only in 3, 7 and 2 clinical trials on the use of hydroxyapatite, tricalcium phosphate and their combination, respectfully. All clinical trials had similar preparation methods and all of those clinical trials produced positive results without serious side effects.Conclusion There is a wide potential for clinical use of CPC as synthetic bone graft substitutes without reports of serious side effects. Many preclinical and clinical studies are currently underway on the use of hydroxyapatite and tricalcium phosphate, and their future results will further explore their clinical potential.

Health Impacts of Fire Smoke Inhalation

Most fatalities from fires are not due to burns, but are a result of inhalation of toxic gases produced during combustion. Fire produces a complex toxic environment involving flame, heat, oxygen depletion, smoke and toxic gases. As a wide variety of synthetic materials is used in buildings (insulation, furniture, carpeting, and decorative items) the potential for severe health impacts from inhalation of products of combustion during building fires is continuously increasing. In forest fires the burning of biomass leads to smoke emissions, the composition of which, as well as the relative health impacts from their inhalation, depends on the ecosystem's chemical and physical features and the local environmental parameters. In the present review, health problems that appear to people exposed to fire smoke and especially to firefighters are described and suggestions for fire management and prevention are made.

Toxicity of Parked Motor Vehicle Indoor Air

The interior of motor vehicles is made of a wide variety of synthetic materials, which emit volatile organic compounds (VOC). We tested the health effects of emissions from vehicles exposed to "parked in sunshine" conditions. A new and a 3 year old vehicle with identical interior were exposed to 14 000 W of light. Indoor air was analyzed by GC-MS. Toxicity of extracts of indoor air was assayed in human primary keratinocytes, human lung epithelial A549 cell line, and Chinese hamster V79 lung fibroblasts. In addition, toxicity after metabolic activation by CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, and CYP2E1 was assayed. The effect on type I allergic reaction (IgE-mediated immune response), type IV allergic reaction (T-cell mediated immune response), and irritative potential was evaluated also. A total of 10.9 and 1.2 mg/m(3) VOC were found in new and used motor vehicle indoor air, respectively. The major compounds in the new vehicle were o,m,p-xylenes, C3 and C4-alkylbenzenes, dodecane, tridecane, and methylpyrrolidinone. In the used vehicle they were acetone, methylpyrrolidinone, methylcyclohexane, acetaldehyde, o,m,p-xylenes, ethylhexanol, and toluene. No toxicity was observed in any cell line with or without metabolic activation. Neither did we find an effect on type IV sensitization or an irritative potential. A slight but statistically significant aggravating effect on IgE-mediated immune response of only the new vehicle indoor air was determined (p < 0.05). The IgE-response modulating effect of indoor air might be relevant for atopic individuals. Else no direct toxicity, no toxicity after metabolic activation by cytochrome P450, and no irritative or type IV sensitizing potential of motor vehicle indoor air were found, neither from the new nor used vehicle. Our investigations indicated no apparent health hazard of parked motor vehicle indoor air.

Behandlungsstrategien des akuten Rauchgasinhalationstraumas

Most fatalities from fires are not due to burns, but are a result of inhalation of toxic gases produced during combustion. Fire produces a complex toxic environment, involving flame, heat, oxygen depletion, smoke and toxic gases such as carbon monoxide and cyanide. As a wide variety of synthetic materials is used in buildings, such as insulation, furniture, carpeting, electric wiring covering as well as decorative items, the potential for poisoning from inhalation of products of combustion is continuously increasing. The present review describes the pathophysiologic effects from smoke inhalation injury as well as strategies for emergency treatment on scene and in the intensive care setting.

Grafts in rhinoplasty: alloplastic vs. autogenous.

Over the past 15 years, grafts have been used with increasing frequency during rhinoplasty procedures as the transition has been made from reductive rhinoplasty to augmentation or restructuring rhinoplasty. There are a number of grafting materials available, including autogenous materials (bone, cartilage), homograft materials (rib cartilage, dermis), and a wide variety of synthetic or alloplastic materials. With regard to the autogenous materials, cartilage has been the mainstay for augmentation in rhinoplasty. Bone is used infrequently because it often yields unsatisfactory results in the aesthetic appearance of the nose, and has problems with graft resorption. I will therefore not discuss bone herein. This article focuses on the differences between autogenous cartilage implants and synthetic materials, in particular expanded PTFE (Gore-tex; WL Gore & Associates Inc, Flagstaff, Ariz). Certainly, there is no argument that autogenous grafts, in particular cartilaginous grafts, are superior as a grafting material in rhinoplasty for a variety of reasons. Cartilaginous grafts are considered the criterion standard by many authors. The more debatable issue is in the case where substantial dorsal augmentation is required: is autologous material preferable to synthetic? Arguments to both support and refute the notion that autologous cartilage is superior will be presented here. Overall, the ideal implant should have biocompatible physical properties. It should retain constant shape and volume and be nonresorbable. Removal should be easy, and migration should not be a problem. As well, the implant should be easily modified and molded, readily available, and cost-effective. On a microscopic level, there should be no inflammatory response, and there should be resistance to infection. The tissue should not degrade, transmit disease, or act as a carcinogen. These characteristics apply to implants throughout the body. Another desirable characteristic with respect to the nose is that in the area of thin skin over the upper dorsum, the implant should be easily camouflaged. These issues as they pertain to both the autogenous and synthetic graft will be addressed and conclusions offered. While comparison of the aesthetic results is impossible and has not been evaluated in a series, patient satisfaction and revision rates will be emphasized. The wide variety of synthetic materials that have been used for the purpose of rhinoplasty is an indication of the need for a perfect alloplastic implant. Through the years, numerous synthetic materials have had relatively high complication rates. I will address only 2 synthetic implants that continue to be used frequently: silicone and expanded PTFE. Silicone is widely used in rhinoplasty for the Asian patient, and the issues relative to this procedure will be addressed. Expanded PTFE has been gaining in popularity over the past 10 years, and results after long-term follow-up will be assessed. PRO

Concept and progress in the development of RGD‐containmg peptide pharmaceuticals

AbstractThe cell adhesion domain, arginine‐glycine‐aspartic acid (RGD), has been incorporated into synthetic peptides to perform either of two modes of drug action, antagonist or agonist. Short, conformationally constrained peptides have been developed as antagonists for the platelet membrane glycoprotein complex, the integrin α11b, β3, using cell‐based and integrin‐based assays. In combination with a comparative molecular modeling study, these results have helped identify common conformotional elements in the pharmacophore of this class of molecules. Peptides are presented that are highly potent, integrin specific, and that possess reduced pharmacological side effects. Also presented is the development of a peptide that modifies, noncovalently, the surfaces of a wide variety of synthetic materials used in medical implants. The agonist activity of this molecule is evident from its ability to stimulate cell attachment on these surfaces. This is shown to translate into an in vivo activity of faster and more complete tissue integration, and a reduction in foreign body response. © 1994 John Wiley &amp; Sons, Inc.

Vascularized polyvinyl sponge prosthesis. Its use to replace the canine common bile duct.

Studies to find a practical substitute for the common bile duct have attracted the interest of many investigators. A wide variety of synthetic materials have been tried and abandoned. Among these are polyethylene, 10,23,24,26 Vitallium, 15,18,26 Monel metal, 19 rubber, silicon, quills, catgut rolls, and absorbable magnesium. 27 In an attempt to find a more physiologic biliary substitute, various homologous tubular structures have been used experimentally. Among these are jejunum, 11,12,31 artery, 17,27,29 vein, 17,20,31 split-thickness skin grafts, 1,8,16,28 fascia, 7,15 bile duct homografts, 14,21 ureter, 17 fallopian tube, and appendix. 27 Varying success has attended these efforts, but most investigators have not advocated clinical application of their methods. 5 The experimental work has made certain points clear. Most free tissues interposed in the common bile duct lose their identity by a process of disintegration and replacement by scar tissue. 21 The cicatrization results in an obstructive biliary stricture which