Soft tissue materials

Bum victims who have lost large amounts of skin do not have enough cells to grow new skin, so a synthetic substitute must be used. The most promising artificial skin material is based on a polymer of lactic acid and glycolic acid. Both of these compounds contain an alcohol group (—OH) and a carboxy group (—COOH). so they can form a polyester copolymer in a condensation reaction that mirrors the formation of Dacron polyester (Section 25.1)  

This copolymer forms the structural mesh that supports the growth of skin tissue cells from a source other than the patient. Once the skin cells grow on the structural mesh, the artificial skin is applied to the patient, and the copolymer mesh eventually disappears as the ester linkages are hydrolyzed. During this treatment, the patients must take drugs that will suppress their immune systems, which ordinarily would attack these substances as foreign to prevent their bodies from rejecting the new skin. 

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In regard to Equation (5.4), we have to note that without the above mentioned assumptions the nonlinearities will contain weighting factors that are proportional to the corresponding wave-vector mismatch and inversely proportional to refractive index, thus suggesting that the THG signal is sensitive to the refractive index interface(s) as well. In order to differentiate between contrast mechanisms in THG imaging of soft tissue materials it would be important to know the relationships of the corresponding linear and nonlinear optical parameters. A nonlinear optical... 

X-rays were discovered by Wilhelm Roentgen in 1895. Soon after their discovery Roentgen used x-rays to image the bones in a human hand. The x-rays transmitted through the hand (phenomenon 1) were recorded on photographic film. The bones or other dense objects absorb x-rays more than do soft tissues or less dense materials (phenomenon 2). This method of imaging the internal stmcture of an object is known as x-ray radiography. 

The calcium chelate cements are limited to the use of a cavity liner. They may be placed directly over an exposed tooth pulp to protect the pulp and stimulate the growth of secondary dentin, or used as a therapeutic insulating base under permanent restorations. The high alkalinity and high solubihty of these materials prohibits use in close proximity to soft tissues or in contact with oral fluids. 

The concept of total body burden refers to the way a trace material accumulates in the human system. The components of the body that can store these materials are the blood, urine, soft tissue, hair, teeth, and bone. The blood and mine allow more rapid removal of trace materials than the soft tissue, hair, and bone (5). Accumulation results when trace materials are stored more rapidly than they can be eliminated. It can be reversed when the source of the material is reduced. The body may eliminate the trace material over a period of a few hours to days, or may take much longer— often years. 

Wang and coworkers first reported the use of these monomers as a novel elastomeric material for potential application in soft tissue engineering in 2002. The molar ratio of glycerol to sebacic acid they used was 1 1. The equimolar amounts of the two monomers were synthesized by polycondensation at 120°C for three days. The reaction scheme is shown in Scheme 8.1. To obtain the elastomers, they first synthesized a prepolymer and then poured an anhydrous 1,3-dioxolane solution of the prepolymer into a mold for curing and shaping under a high vacuum. 

Hydrogels have many potential uses in biomedicine, ranging from materials for the construction of soft-tissue prostheses or... 

Why are barium- and iodine-based materials selected for contrast media The production of X-ray images depends on the differences between the X-ray absorbing power of various tissues. This difference in absorbing power is called contrast and is directly dependent on tissue density. To artificially enhance the ability of a soft tissue to absorb X-rays, the density of that tissue must be increased. The absorption by targeted soft tissue of aqueous solutions of barium sulfate and iodized organic compounds provides this added density through the heavy metal barium and the heavy nonmetal iodine. 

Wang, M., Hench, L.L. and Bonfield, W. (1998) Bioglass/high density polyethylene composite for soft tissue applications Preparation and evaluation. Journal of Biomedical Materials Research, 42, 577-586. 

Schiraldi et al. [64] have developed this kind of material by combining silica particles and pHEMA. pHEMA is a biocompatible hydrogel that has been widely studied in the past decades due to its chemical-physical structure and mechanical properties. It has been widely used in ophthalmic prostheses (contact or intraocular lenses), vascular prostheses, drug delivery systems and soft-tissue replacement [65]. These authors have shown that by incorporating silica nanoparticles, the resulting hybrid material is highly biocompatible and promotes bone cell adhesion and proliferation of bone cells seeded on it.1 ... 

Nga ME, Lim G-L, Barbro N, et al. Successful retrieval of fine-needle aspiration biopsy material from previously stained smears for immunocytochemistry a novel technique applied to three soft tissue tumors. Mod. Pathol. 2005 18 728-732. 

This material is hazardous through inhalation, penetration through broken skin, and ingestion. Wound contamination results in death of skeletal muscles and soft tissue. Symptoms of ingestion include nausea and diarrhea usually without vomiting. Inhalation produces pulmonary complications. 

Apart from interference the greatest problem in the use of ion-selective electrodes is that of contamination. Any insoluble material deposited on the surface of the electrode will significantly reduce its sensitivity and oil films or protein deposits must be removed by frequent and thorough washing. It is possible to wipe membranes with soft tissue but they can be easily damaged. Solid-state membranes are more robust but they must not be used in any solution which might react with the membrane material. 

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