摘要:

AbstractWe describe the preparation and some of the properties of heparin‐bound α‐chymotrypsin that were obtained via activation of heparin with water‐soluble carbodiimide. Immobilized enzyme has unchanged kinetic characteristics toward low‐molecular‐weight and macromolecular substrates. The heparin‐bound enzymes could have a wide range of medical

ISSN:0021-9304    

DOI:10.1002/jbm.820120502

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractMeasurements of the permeability coefficients of various compounds up to a molecular weight of about 70,000 have shown clearly that membranes prepared from hydrolyzed polyacrylonitrile are about 10 times more permeable than those made of poly(2‐hydroxyethyl) methacrylate. The higher permeability is probably due more to the higher water content (about 75%) than to the type of network. The high mechanical strength of the membranes and their good permeability to compounds possessing a comparatively high molecular weight seem to designate the material for some new applications in medicin

ISSN:0021-9304    

DOI:10.1002/jbm.820120503

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractSurface configurations are vessels fabricated from tubing and plate, films deposited on the surface of vessels, and beads confined in vessels. The average association constant between thrombin and sites on commercial poly(methyl methacrylate) surface (Lucite) is near 4 × 108liters/mole at 22°C, pH 7.0, and ionic strength 0.15. Depending on Lucite composition, average adsorptionU, in molecules/cm2of apparent solution‐surface interface, ranges from 0.7 to 8.8 × 1011. Analysis based on the assumptions that solution dimensions are preserved, adsorption is random, and surface rearrangement is negligible indicates a paucity of surface sites. Plasma albumin competes with thrombin for surface sites. Attempts to detect, by thrombin adsorption, the presence of free sites at 4.5 × 10−9Malbumin or the displacement of bound albumin indicate an albumin‐site association contrast greater than 1.6 × 109. Cross‐linked poly(methyl acrylate) bead surface hasUless than 5 × 1010. In contrast to acrylic resins are silicone gum, polypropylene, and polyisobutylene, for whichUranges from 15 to 20 × 1011. Analysis as above indicates that sites are of frequent occurrence. Material composition suggests that thrombin can interact with nonpolar groups. Further characteristics of low‐energy surfaces are that progressive surface denaturation is small and there is a large variance between nominally equivalen

ISSN:0021-9304    

DOI:10.1002/jbm.820120504

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA previously derived cubic equation describing the release of drugs from matrix tablets is compared with a more complex equation recently presented. Using data obtained from cylindrical hydrocortisone matrix tablets, it is shown that the simpler cubic equation affords an equally acceptable description of drug release. Because the cubic equation contains a release‐rate constantKrthat is independent of tablet shape, a congruency between this equation and other historical models of diffusion may be demonstrated. It is suggested, given the complexity of drug dispositionin vivo, that simplicity in modeling is a desirable goa

ISSN:0021-9304    

DOI:10.1002/jbm.820120505

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA study has been made of the fractures and associated material from 34 prostheses broken in service. All the fractures appear to be of the fatigue type. Search by me‐tallographic analysis for cracklike generating defects in material near the fracture reveals such conditions as abnormally coarse crystals, large nonmetallic inclusions, large inclusion population, undissolved master alloy particles, abnormal carbide segregation, interdendritic segregation, shrinkage, and gas porosity. Recommendations are made for the choice of metallic alloys for femoral stem applicatio

ISSN:0021-9304    

DOI:10.1002/jbm.820120506

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA method is shown for deducing the surface area of a pendant drop from the same profile photograph as is normally used to determine interfacial tension. Manipulation of such drops by a micrometer syringe then enables the pendant drop to be used as a surface balance for studying adsorption from bulk solutions. Results are given for the compression of films from solutions of albumin, γ‐globulin, fibrinogen, albumin–γ‐globulin mixture and albumin–γ‐globulin–fibrinogen mixture, and from serum, plasma, and blood at the isooctane–buffer interface. It is suggested that γ‐globulin and fibrinogen films are unfolded at the interface but that albumin films are different in that they consist of an inner, unfolded layer and an outer, globular layer. A film from serum resembles that from γ‐globulin alone, and not that from albumin–γ‐globulin mixture, whereas a film from plasma resembles that of fibrinogen at low compression and that of albumin–γ‐globulin–fibrinogen mixture at high compression. A film from blood is

ISSN:0021-9304    

DOI:10.1002/jbm.820120507

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA high‐modulus polymer, polysulfone, was evaluated as a porous bone implant material. The bone ingrowth into canine cortical pellets of sintered polysulfone particles was assessed by microradiography and histology. The shear strength of the porous polysulfone–bone interface was determined by push‐out and pull‐out tests of cortical and trochanteric implants, respectively. Results indicated that the bone in‐growth into porous polysulfone specimens proceeded in such a fashion as to mimic the normal repair at the site. Mechanical testing of cortical and cancellous implants revealed that the interfacial shear strength of the porous polysulfone‐bone composite was similar to that achieved using po

ISSN:0021-9304    

DOI:10.1002/jbm.820120508

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effect of combining gentamicin and cephalothin with Surgical Simplex bone cement was testedin vitro.Experiments were designed to determine (1) quantitative elution rates and period of time the antibiotics were eluted and (2) effective bactericidal qualities. Both antibiotics were eluted from polymerized acrylic cement in large quantities within 24–48 hr after coming in contact with fluid and continued to be released in smaller amounts for 21 days to more than 175 days. This varied with the antibiotic, concentration of antibiotic in the cement, surface area of cement, and volume of elution fluid. Quantitative determinations of numbers of bacteria in broth cultures demonstrated that sufficient quantities of antibiotics were released to be bactericidal to microorganisms within 45 min to 20 hr. This was dependent on the type of antibiotic, type of bacteria, concentration of antibiotic in the cement, and time of contac

ISSN:0021-9304    

DOI:10.1002/jbm.820120509

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe rates of adhesion of melanoma cells (carcinogenic) onto nonionic polymer surfaces were studied by using radioactively labeled cells and measuring the fraction of cells which adhered to the surface in a given time. Glow discharge (plasma) polymerization of 1,1,3,3‐tetramethyldisiloxane and of nitrogen‐acetylene‐water (mole ratio 0.4:1.0:0.2) was used to modify the surface energy of the substrate. The cell adhesion rate was found to be given byY= 1 − exp [−k0(γs− γ0)t], whereYis the fraction of cells adhered, −k0is a characteristic rate constant, γsis the total surface energy of the substrate, γ0is the threshold surface energy of cell adhe

ISSN:0021-9304    

DOI:10.1002/jbm.820120510

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractLiquid–air and liquid–liquid interfaces were used as models for the liquid‐solid system of plasma proteins and hydrophobic surfaces in the study of adsorption of serum, plasma, and blood onto these surfaces. The interfacial tension is determined for three phases: air, methylene iodide, and isooctane. Curves of interfacial tension versus time for the various systems are given from which a triple‐intersection point, where the protein solution is in equilibrium with each surface, is found. It is shown that albumin, γ‐globulin, and a mixed solution of these atin vivoconcentrations behave in characteristic and constant manners at the three interfaces of air, methylene iodide, and isooctane. A range of synthetic surfaces which have constant behavior at equilibrium is deduced and it is concluded that any soft tissue response differences between such surfaces could not be the result of albumin or

ISSN:0021-9304    

DOI:10.1002/jbm.820120511

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY