bluuebunny/crossref_metadata_2025 huggingface dataset:
Zopiclone abuse in South Wales: Three case reports
Authors: Sullivan Gary , McBride Andrew J. , Clee William B.
Published: May 2005

Three cases of zopiclone abuse in South Wales are described. Two involve oral use with alcohol, and one of intravenous use. It appears that zopiclone has become widely available ‘on the street’ in parts of S. Wales where they are called ‘zim‐zims’. The implications are discussed.
Inositol may worsin attention deficit disorder with hyperactivity
Authors: Levine Joseph , Ring Aliza , Barak Yoram , Elizur Avner , Belmaker R. H.
Published: May 2005

Antidepressant drugs have been reported to improve ADDH symtomatology. Myoinositol is a simple isomer of glucose and is the precursor of the phosphatidylinositol second messenger system in brain. Both α1‐adrenergic and 5HT2 receptors activate this second messenger system. Recently, we found inositol to be effective in depression. Therefore we decided to evaluate the effects of oral inositol in children with ADDH in a double‐blind, cross‐over, placebo‐controlled manner. Eleven children, mean age 8.9 ± 3.6 years with a mean illness duration of 4.5 ± 2.8 years were enrolled in an 8‐week trial. Inositol or dextrose (placebo) was dispensed in powder form at a dose of 200 mg/kg aggravation of the syndrome with myo‐inositol as compared to placebo.
In vitro tendon cell colony growth rates on synthetic fibers
Authors: Ricci J. L. , Alexander H. , Gona A. G. , Lelah M. D.
Published: May 2005

Effective integration of synthetic fiber scaffold materials into connective tissues depends to a great degree on tissue attachment and ingrowth into the material. The authors have developed an experimental model that utilizes rat tendon explants to test the rates of cell colony formation on different types of synthetic fibers that are used as tendon and ligament scaffolds and for other medical uses. It was found that cell colony growth rates are linear on all 12 types of fibers tested. This agrees with the results of previous studies involving cell growth on synthetic fiber matrices. While most synthetic fibers showed similar colony growth rates, an overall trend was observed toward increased colony growth rates on fibers with relatively hydrophilic surfaces. One type of fiber that showed significantly increased colony growth rates was covalently coated with type I collagen. It was concluded that whereas most types of synthetic fibers had similar cell growth, a collagen coating can significantly enhance cell growth.
Use of carbon dioxide laser in improving knot security in polyester sutures
Authors: Gupta B. S. , Milam B. L. , Patty R. R.
Published: May 2005

Knot slippage continues to be a serious concern in surgery. This study explored the possibility of improving knot performance by exposing it to radiation from a CO2 laser. The specimens were mounted in a special device and exposed in a predetermined position for precisely controlled lengths of time. In the first set of experiments, the welding of ends was examined in nylon and polyester sutures. Although the welding was easily achieved, the joint was found brittle and its strength lower than that of a surgical knot. In the next set of experiments, the work was performed at a more fundamental level using oriented, high density, polyester films. The results showed that up to a certain level of exposure the tensile properties did not change, but beyond it a rapid decay took place. Shear tests on polyester sutures twisted together and then exposed to various levels of energy indicated that a bond of maximum strength developed at this exposure. Mersilene sutures of size 3/0 containing a two throw square knot when exposed to energy of this level produced optimal results. The knot strength increased by about 16% (from 13.4 N unexposed to 15.6 N exposed) and the slippage often known to occur in a two‐throw knot was completely absent. This work performed under standard atmospheric conditions provided a direction for greatly enhancing the performance of a two‐throw knot in terms of both the security and the strength. The investigation, however, must now be extended to other suture materials and sizes and to in vivo environments to realize the gain in actual surgery.
A method of analysis of cellular distribution in the membrane encapsulating surgically implanted biomaterials
Authors: Christel P. , Meunier A. , Therin M.
Published: May 2005

This article describes a method for analyzing the cell distribution occurring in the membrane encapsulating cylinders of specific polymers, metals, or ceramics when implanted in the paraspinal muscles in rats for periods between 2 weeks and 1 year. Using a computer‐assisted cell‐counting method, it is shown that the cell distribution exhibits a non‐Gaussian spectrum, which can be modeled by a three‐parameter statistical function. This observation was made possible because of the use of specific histological techniques, adapted to each particular material class, (polymer, metal, ceramic), keeping intact the implant‐tissue interface. The parameters arising from the histomorphometric and statistical analyses allow comprehensive and quantitative comparisons of the tissue response induced by the various implanted materials. This pattern of cell distribution was observed with all of the implanted materials to one year. This behavior has also been observed in rabbit muscle and reported by others in subcutaneous tissue in mice. This method provides both a way to evaluate the tissue response to a surgically implanted material on a quantitative basis and a research tool for the study of tissue‐implant compatibility.
The radioactivity of X‐ray contrast material in PMMA bone cement
Authors: Hopf Thomas W. , Glōbel Beowulf
Published: May 2005

Various x‐ray contrast materials, barium sulphate (BaSO4) and zirconium oxide (ZrO2), were tested for their radioactivity by means of a gamma spectrometer. While BaSO4 showed no detectable radiation emission, the ZrO2 materials of various makes showed slight to partially high radioactive emission. From all zirconium oxides, only the pharmaceutic agent OPTIPUR® (MERCK) showed no detectable radioactivity. Taking into account that these x‐ray contrast materials remain in the body for decades as components of the bone cement, it would seem prudent to urge cement manufacturers to substitute high purity radiation‐free zirconium in place of radioactive zirconium oxide.
A bioactive glass powder‐ammonium hydrogen phosphate composite for repairing bone defects
Authors: Taguchi Yasushi , Yamamuro Takao , Nakamura Takashi , Nishimura Naomi , Kokubo Tadashi , Takahata Eiji , Yoshihara Satoru
Published: May 2005

Bioactive glass powder (AW‐G) was made into a rigid compound by mixing with ammonium hydrogen phosphate and was evaluated as a bone‐defect filler. The proximal metaphysis of the rat tibia was drilled and packed with (a) polymethyl‐methacrylate (PMMA) bone cement, (b) AW‐G powder, (c) AW‐G powder with ammonium hydrogen phosphate (AW‐G)‐(A‐P), or (d) nothing, as a control. The animals, with different implantation periods up to 24 weeks, were sacrificed and the defective sites were histologically analyzed. The results revealed direct bonding between the bone tissue and the (AW‐G)‐(A‐P). The general inflammatory reaction of (AW‐G)‐(A‐P) was less than that of PMMA bone cement. The compressive strength of (AW‐G)‐(A‐P) implanted subcutaneously into rats was measured chronologically and deterioration did not occur during a period of 24 weeks. The rigidity increased to 1.6 times 6 months after implantation as compared with the initial value.

This compound can be used as paste and is transformed into a rigid compound in about 4 min without noticeable elevation of the temperature. Thus, this (AW‐G)‐(A‐P) composite can be used as a bone defect filler, and there is a possibility that it can even be used as a bone cement if higher rigidity can be attained.
The effects of different steam‐sterilization programs on material properties of poly(L‐lactide)
Authors: Rozema F. R. , Bos R. R. M. , Boering G. , van Asten J. A. A. M. , Nijenhuis A. J. , Pennings A. J.
Published: May 2005

As‐polymerized poly(L‐lactide) test rods were sterilized by seven different specially designed computer‐operated autoclaving programs. As a control, common hospital sterilization was performed. In all cases, the molecular weight decreased after sterilization. A short time high‐temperature sterilization lead to less molecular weight decrease than a low sterilization temperature cycle with a longer sterilization time. Regular hospital sterilization significantly reduced the elongation at break and also resulted in a decrease of 35% in tensile strength. The program causing minimal damage to the material properties was studied in detail. This program, with a steriliztioan period of 60 s and 129°C, was effective for PLLA steriliztation and also looks very promising for sterilization of other thermo‐ and moisture‐labile polymers.
Determination of the ratio of HA/TCP mixtures by x‐ray diffraction
Authors: Toth Jeffrey M. , Hirthe Walter M. , Hubbard William G. , Brantley William A. , Lynch Kenneth L.
Published: May 2005

Previous studies have shown that synthetic calcium phosphate ceramics are biocompatible materials capable of providing scaffolding for new bone growth as well as osteogenesis. In particular, hydroxylapatite (HA) is less soluble than β‐tricalcium phosphate (β‐TCP) which has a higher degree of bioactivity. An implant made of dense hydroxylapatite shows substantially less bone growth than an implant made of a suitable HA/TCP ratio.1 Therefore, since biological response to the two materials is different, it is essential to have some means of determining the ratio of hydroxylapatite to β‐tricalcium phosphate to ensure quality control of the synthetic ceramic as well as optimum biological response. In this study, a calibration curve was developed for x‐ray diffractometer examination of mixtures of HA and β‐TCP. The accuracy of using the diffractometer was compared to the accuracy of a powder camera, and it was determined that the diffractometer correctly identified the ratio within a range of 3% while the powder camera was accurate within a 20% range. This study showed that with an appropriate calibration curve, the HA/TCP ratio can be determined to a greater degree of accuracy using an x‐ray diffractometer than by powder camera methods.
Application of a device to lower pulpal temperatures in vivo
Authors: Goodis H. E. , White J. M. , Watanabe L. G.
Published: May 2005

Heat generated by tooth reduction and restoration procedures may be harmful to the pulp. Water spray during those procedures aids in maintaining lowered pulpal temperatures. A device that lowers intrapulpal temperatures has been developed and tested in an animal model. The animal's pulp chamber temperatures were lowered to 15.5°C and 12.4°C and maintained at those temperatures for 20 min. Histological examination disclosed no inflammatory reaction to the testing. Therefore, this device may aid in reducing the trauma of dental preparation procedures as well as other effects of lowered temperature on the biology of the dental pulp.
Preparation and properties of barium sulphate and methyl iothalamate loaded poly(vinyl alcohol) microspheres as radiopaque particulate emboli
Authors: Thanoo B. Chithambara , Sunny M. C. , Jayakrishnan A.
Published: May 2005

Poly(vinyl alcohol) (PVA) microspheres impregnated with barium sulphate and methyl iothalamate, having diameters raning from 100 to 1500 μm were prepared by the glutaraldehyde cross‐linking of an aqueous dispersion of PVA containing the radiopaques in paraffin oil using dioctyl sulfosuccinate (DOS) as the stabilizing agent and thionyl chloride as the catalyst. while the use of thionyl chloride allowed the formation of spherical, nonaggregatory beads, other catalysts such as magnesium chloride and hydrochloric acid gave rise to an agglomerated product. The radiopaques were found to be firmly trapped inside the microspheres as they did not leach out on prolonged standing in water, on sonication, or on steam sterilization. Microspheres with pores and channels were also made by incorporating a fine powder of methyl methacrylate along with barium sulphate during their preparation and washing out the polymer after the microspheres were formed. The porous nature of such microspheres was confirmed by transmission electron microscopy (TEM). Microspheres containing the radiopaques exhibited hydrophilicity, swelling ability, and compressibility to a significant extent. the radiopaque nature of the microspheres was confirmed by their x‐ray images. In vitro tests using heparinized calf blood showed that the microspheres were nonhaemolytic in nature. These microspheres may find application as radiopaque emboli in particulate embolization.
The effect of screw fixation on initial rigidity of tibial knee components
Authors: Wyatt Ronald W. B. , Alpert Jeffrey P. , Daniels A. U. , Hofmann Aaron A. , Dunn Harold K.
Published: May 2005

Initial rigid fixation is essential for bone ingrowth into a porous‐coated prosthesis. In this study, the amount of micromotion between a cut tibial surface and a custom tibial base‐plate mounted with various types of screw fixation was measured. Motion transducers were placed at the corners of the baseplate to detect liftoff and subsidence. Central and eccentric loads were then applied. The variables tested included screw number and position, as well as screw length and type of bone purchase.

A four‐screw peripheral configuration had less micromotion than a three‐screw triangulated configuration, and both had less micromotion than a two‐screw central condyle configuration. Long screws with cancellous purchase and screws with cortical purchase had less micromotion than short screws with cancellous purchase.

These results indicate that important variables which contribute to the initial rigidity of a cementless tibial implant using screw fixation include screw number, configuration, length, and type of bone purchase.
Application of extracorporeal shock wave lithotripter (ECSWL) in orthopedics. I. Foundations and overview
Authors: Park S. H. , Park J. B. , Weinstein J. N. , Loening S.
Published: May 2005

In this paper we have reviewed the feasibility of using a shock wave lithotripter to loosen the interface between the bone and acrylic bone cement for revision arthroplasty. We have reviewed the physics of shock wave and its applications in medicine, especially its interaction with tissues. The calculations show that the energy is greatly reduced at the interface both in the soft tissue–bone interface and cement–bone interface. On the other hand, a tensile and compressive pressure can be operated at the cement–bone interface that can cause the interface to break if the pressure exceeds the tensile strength of the cement–bone interface.

Subsequent papers will deal with in vitro and in vivo application of the shock wave in the treatment of the cement‐bone interface in order to weaken it and consequently for easier extraction of bone cement from the intramedullary canal.
Biomaterials education: An academic and industrial viewpoint
Authors: Feldman Dale S. , Gombotz Wayne R.
Published: May 2005

The field of biomaterials has grown rapidly over the last three decades in the academic, industrial, and regulatory sectors. Beginning as a research thrust, which led to courses at a few universities, biomaterials education has evolved into distinct curriculum in over 60 institutions in the United States and Canada alone.

Rapid growth, however, can cause problems. In an effort to determine the present status and future needs in each sector, as well as begin to assess if the needs of industry are being met by present academic programs, two surveys were sent out.

As shown by the two surveys, academic programs have been increasing in both size and quality while industry has also been expanding, as indicated by the many small companies involved in biomaterials. The shift toward graduate programs is in keeping with the perceived educational needs of potential employers. The majority of academic programs appear to be providing the training and coursework desired by employers. Further information, however, is needed to determine if the number of graduates trained in biomaterials is adequate, or in fact excessive.

It is, therefore, recommended that a more comprehensive survey, sent to the biomaterials companies listed in the FDA registry, be undertaken. In addition, a survey to each academic program that addresses hiring of recent graduates would also be beneficial. It does appear that certain standards for curricula could be agreed upon, although the field has probably not evolved sufficiently for accreditation or professional registration to be addressed yet.
Applied Biomaterials Standards Report
Authors: Daniels A. U.“Dan”
Published: May 2005

The purpose of my column is to provide readers with current information on biomaterials‐related standards produced by both private groups and government agencies, and also on standards‐related activities. Standards are descriptive documents given official status by their producers, and in the case of biomaterials, they are generally intended to provide formalized descriptions of (a) materials used in the construction of medical devices, (b) materials used directly in surgical repairs, (c) test methods to evaluate materials for such applications, and (d) methods for handling or processing such materials.

Please consider this column not only a place to obtain biomaterials standards information, but also a place to submit news of biomaterials standards developments in order to get the information before the public. This invitation extends to members of all professional organizations and government agencies in the United States and abroad who are active in standards development and would like specific activities or standards publicized. I will present the information in this column to the extent that allotted space allows.

And last, a caveat–since this is a column, it contains both factual information and opinions. I will make every effort to make it clear which is which. Also, as a frame of reference, please note that this column was written and submitted in March 1991.
A heat‐generating bioactive glass–ceramic for hyperthermia
Authors: Ohura Kouichiro , Ikenaga Minoru , Nakamura Takashi , Yamamuro Takao , Ebisawa Yukihiro , Kokubo Tadashi , Kotoura Yoshihiko , Oka Masanori
Published: May 2005

Glass plates of the chemical composition: CaO (29.0), SiO2 (31.0), Fe2O3 (40.0), B2O3 (3.0), P2O5 (3.0) in weight ratio were heated to 1050 °C at a rate of 5 °C/min and then cooled to laboratory temperature. The resulting glass–ceramic containing magnetite and wollastonite crystals showed high‐saturation magnetization. The bonding ability of this new glass–ceramic to bone tissue was evaluated using rabbit tibiae, and compared with glass of the same composition. This glass–ceramic formed a Ca, P‐rich layer on its surface and bonded tightly with bone within 8 weeks of implantation. However, the glass did not form this Ca, P‐rich layer, nor had it bonded with bone at 25 weeks. The bone‐heating ability of this glass–ceramic was investigated by applying a max. 300‐Oe, 100‐kHz magnetic field. The granules of the glass–ceramic filled in the rabbit tibiae heated the whole surrounding bone to more than 42 °C and maintained this temperature for 30 min. Bioactive ceramics reinforce the mechanical strength of bone tissue. Furthermore, this heat‐generating bioactive glass–ceramic can be used for hyperthermic treatment of bone tumors.
Stability of a cyclically loaded hydroxyapatite coating: Effect of substrate material, surface preparation, and testing environment
Authors: Kummer Frederick J. , Jaffe William L.
Published: May 2005

Cyclic loaing of Ti‐6‐4 and Co‐Cr‐Mo (cast) test samples with grit‐blasted or waffle‐textured surfaces coated with a plasma‐sprayed 50‐μm HA layer was performed in air, Ringer's solution (5% dextrose), 0.9% NaCl (Tris buffer, pH 7.40), and balanced Hank's solution. Maximum interfacial stresses in bending of 40 ksi (280 MPa) and 20 ksi (140 MPa) were utilized, and the speciments tested to 106 cycles at 5 Hz with a MTS servohydraulic machine. Tested samples were examined by optical microscopy to determine coating integrity and thickness and by scanning electron microscopy (electron backscatter mode and EDAX) to determine surface morphology and chemical changes.

The following observations were made: (1) Samples cyclically tested in solutions showed a general thinning of the coating, accentuated in the higher‐stressed regions. (2) Samples tested with an equivalent static load in the solutions did not show this centralization. (3) Bare metal interface surfaces were noted on most of the edges of highly stressed central specimen regions, in several entire central regions, and on the upper surfaces of some of the waffled samples. (4) The specimens tested in Ringer's solution (pH 4.70 initially) demonstrated the most dramatic coating deterioration. (5) The coatings on titanium appeared more stable than these on Co‐Cr as tested in all solution environments for both surface types.

The HA coating evaluated in this experiment demonstrated increased instability when cyclically loaded in in vitro solutions of lowered pH and depleted cations (Ca2+) at stress levels of 280 MPa. The more physiological solution (Hank's) did not show this increased dissolution at the lower stress level. It is suggested that this type of testing be performed on other HA coatings due to the possible implications for long‐term in vivo coating integrity.
Biocompatibility tests on a novel glass–ceramic system
Authors: Wolfe Leonora A. , Boyde Alan
Published: May 2005

The aim of this study was to look at the bone bonding potential of six formulations of a novel glass‐ceramic system. Cylinders of the ceramics were implanted in rabbit tibiae for 4 and 7 weeks. Histological tests, both quantitative and qualitative, as well as push‐out tests, were carried out during the bonding assessment. Bone growth was quite prolific, even at 4 weeks, as evidenced by growth up to and along the implant surfaces. The interfacial shear strengths compared well with other biomaterials in use as endosseous implants. Therefore it seems pertinent to pursue further long‐term experimentation with this material.
Glass–Ceramic implant in acetabular bone defect: An experimental study
Authors: Yoshii Satoru , Yamamuro Takao , Nakamura Takashi , Oka Masanori , Takagi Haruki , Kotani Seiya
Published: May 2005

Extensive acetabular defects produced surgically in 25 dogs were repaired using A ‐ W glass‐ceramic blocks. No dislocation of the femoral head, and no displacement or breakdown of the blocks was seen 1 year after surgery. All dogs were able to run normally shortly after surgery, except for one that limped for a short time. The failure load between the blocks and the bone had increased markedly 2 months after implantation. The failure load/unit area was 33.2 kgw/cm2 1 year after implantation. We conclude that glass‐ceramic supplementation of the acetabulum is successful experimentally, and that this may be a promising method for repair of large acetabular bone defects. © 1992 John Wiley & Sons, Inc.
Osteoconduction of bioceramics in normal and osteopenic rats: Comparison between bioactive and bioinert ceramics
Authors: Iwashita Yasushi , Yamamuro Takao , Kasai Ryuichi , Kitsugi Toshiaki , Nakamura Takashi , Okumura Hideo , Kokubo Tadashi
Published: May 2005

Rats with experimental osteopenia, which was induced by resecting both ovaries and sciatic nerves (OVX + NX), were used to evaluate osteoconduction of an apatite and wollastonite‐containing glass‐ceramic (designated A‐W.GC) and an alumina ceramic. The bone mineral densities (BMDs) of the femurs were measured by dural energy X‐ray absorptiometry (DEXA) and determination of the ash weight. Twelve weeks after the first operation, when the BMDs in the OVX + NX groups were about 20% less than that in the sham‐treated groups (Sham), the bioceramics were implanted into the proximal tibiae. The bone mineral masses around the implants in the proximal tibiae were evaluated by histological examination of undecalcified specimens and DEXA. Both types of implants in the OVX + NX groups showed less reactive bone than those in the Sham groups. However, a histomorphological study revealed that the direct contact area between bone and implant was larger with bioactive ceramic A‐W.GC than with the bioinert alumina ceramic even under osteopenic conditions while two types of ceramic made no difference on the bone at distance from the implant. The direct contact area with A‐W.GC did not show any difference between the Sham and the osteopenic OVX + NX groups. The bioactive ceramic A‐W.GC appears to have good osteoconductivity solely on its surface even under osteopenic conditions.
The surface treatment of polypropylene molds and its effect on the quality of cast contact lenses
Authors: Lukášk J. , Fenclová T. , Tyráčkková V. , Vacík J.
Published: May 2005

An investigation of the surface by XPS photoelectron spectroscopy has shown that the process of production of cast contact lenses based on poly(2‐hydroxyethyl methacrylateco‐diethyleneglycol methacrylate) is accompanied by mass transfer at the lens‐mold boundary. This phenomenon, which impairs the compatibility of the lens during its application, can be considerably suppressed by employing a suitable surface modification of polypropylene molds. The surface treatment consisting in the oxidation of the mold surface by an AC corona discharge in the oxygen atmosphere increased hydrophilicity of the material, thus facilitating separation of the lens from the mold. The results of the XPS study were also confirmed microscopically by employing the SEM method. © 1992 John Wiley & Sons, Inc.
A versatile alginate droplet generator applicable for microencapsulation of pancreatic islets
Authors: Wolters Gerrit H. J. , Fritschy Wilbert M. , Gerrits Dick , Van Schilfgaarde Reinout
Published: May 2005

Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, smooth, and spherical in order to ensure that around the islets a strong alginate‐polylysine‐alginate capsule will be formed with optimal biocompatibility and diffusion of nutrients and hormones. However, the preparation of small capsules around islets is difficult. Our newly designed air jet droplet generator allows for variations in the length and diameter of the alginate nozzle and the air jacket and is in this way adaptable to a required bead size. Alginate droplets are converted into rigid beads in a 100 mM CaCl2 solution. Their size depends upon the diameter of the jacket, the air flow rate, and the outer diameter of the nozzle, whereas the production rate depends upon the pressure on the alginate, and on the diameter and the length of the nozzle. When the air flow or the alginate flow surpasses a certain rate, the droplets are fragmented. Thus study describes the mutual relationship of these variables and defines their optimal range for reproducible production of smooth and spherical beads for microencapsulation of islets at an acceptable production rate. © 1992 John Wiley & Sons, Inc.
Strain analysis of flexing blood pump diaphragms
Authors: Kesavan S. K. , Yazdani S. A.
Published: May 2005

Blood pumps usually use elastomer diaphragms that undergo repeated small‐strain flexing (deformation). The stresses and strains that develop in the mechanically actuated diaphragms dictate the useful life and fluid‐solid interactions of the diaphragm. A knowledge of these stresses and strains is essential for proper design of the pump's elastomer diaphragm. A nonlinear axisymmetric finite‐element stress‐strain analysis has been carried out on a Hexsyn rubber diaphragm used in a blood pump to illustrate a finite‐element modeling technique. A situation involving the application of an axial deformation load on the diaphragm has been considered. In particular, the strains developed in a blood pump diaphragm during pumping have been quantified to illustrate the analysis technique. © 1992 John Wiley & Sons, Inc.
Preliminary biocompatibility screening of several biodegradable phosphate fiber reinforced polymers
Authors: Andriano Kirk P. , Daniels A. U. , Smutz W. Paul , Wyatt Ronald W. B. , Heller Jorge
Published: May 2005

This article describes preliminary biocompatibility screening of three degradable phosphate fibers containing K+, Ca+2/Na+ and Na+/Ca+2/Al+3 ions in the polymer chain, and of several different degradable polymers reinforced with these fibers. Biodegradable phosphate fibers of calcium–sodium–metaphosphate (CSM) and sodium–calcium–aluminum–polyphosphate (NCAP) were acutely nontoxic in cellular, tissue, and whole animal evaluations, as determined by standard acute toxicity tests. Histological studies of bone implants sites fabricated from composites of copolymers of poly(E‐caprolactone/L‐lactide) and poly(ortho ester) reinforced with either CSM or NCAP fibers showed these composite materials to be nontoxic, with no abnormal inflammatory response. However, histological evaluation of muscle implants sites revealed the appearance of necrotic foci associated with implant sites in 12 of 22 NCAP containing composite specimens (p < 0.05). Results of this preliminary biocompatibility screening suggest CSM fibers may be useful in reinforcing degradable polymers for production of completely biodegradable composites for implant use. © 1993 John Wiley & Sons, Inc.
In vivo behavior of a high performance duplex stainless steel
Authors: Cigada A. , Santis G. De , Gatti A. M. , Roos A. , Zaffe D.
Published: May 2005

An in vivo investigation of a new high molybdenum and nitrogen duplex stainless steel (25Cr7Ni4Mo0.3N) has been performed. Cylindrical pins and specially developed devices, to test in static conditions the in vivo localized corrosion resistance, made of this new duplex steel and of a common austenitic stainless steel were implanted in rabbit's femurs for 6 and 12 months. After sacrifice, SEM observations and EDS microanalyses to detect metallic ion release were carried out on the femur sections surrounding the pins. Morphologic observations with stereoscope and SEM were performed on the metallic surfaces of the special devices in order to detect the presence of localized corrosion. Both ion release and localized corrosion were observed for the specimens made of austentic stainless steel, but not for those made of 25Cr7Ni4Mo0.3N duplex stainless steel. © 1993 John Wiley & Sons, Inc.
Effects of pulsed electromagnetic fields on the foreign body response to particulate debris in a rabbit model
Authors: DoVan T. , Zimmerman M. C. , Bednarz P. , Alexander N. , Deehan M.
Published: May 2005

The effect of pulsed electromagnetic fields (PEMFs) on the foreign body response to particulate debris, similar in morphology and quantity to wear debris present in the tissues around loose total joint prostheses, was investigated using a rabbit model. Cobalt chrome pins were inserted into the femurs along with particulate debris consisting of ultra high molecular weight polyethylene (UHMWPE), polymethylmethacrylate (PMMA), and cobalt chrome (CC). The particles induced a significant cellular response compared to the control animals that did not receive any debris. The application of PEMFs did not increase this foreign body response, nor did it have an effect on the number of resorption cavities, cortical area, or cortical thickness. © 1993 John Wiley & Sons, Inc.
Surface dependent antigens identified by high binding avidity of serum antibodies in a subpopulation of patients with breast prostheses
Authors: Kossovsky Nir , Zeidler Michelle , Chun Grace , Papasian Nora , Nguyen Anhthu , Rajguru Samir , Stassi John , Gelman Andrew , Sponsler Ed
Published: May 2005

There is growing concern in the medical community that silicones, ubiquitous in health care, may exhibit antigenic, immunogenic, and/or adjuvant activity. Sera from women with silicone breast prostheses were assayed by ELISA for humoral immunoreactivity to a variety of common interstitial and cellular components. In decreasing order of frequency, significant IgG avidities were found against silicone surfaces treated with fibronectin–laminin, phospholipids, no treatment, and fibrinogen when compared with sera obtained from healthy, age‐matched, nonimplanted women and a population of nonimplanted women with previously diagnosed autoimmune diseases. Moreover, the sera from approximately 15% of the positive responders were found to react to matrix proteins independent of the siloxane polymer. The data show human antibody production to native macromolecules with antibody avidity being related to molecular conformation. Silicone may function as an adjuvant by inducing changes in the conformation of native molecules. © 1993 John Wiley & Sons, Inc.
Light microscopic identification of submicron polyethylene wear debris
Authors: Guttmann Dan , Schmalzried Thomas P. , Jasty Murali , Harris William H.
Published: May 2005

A simple, yet specific, means to identify submicron polyethylene (PE) particles in routine histologic sections would be practically useful. We have previously reported a very fine, diffuse, birefringence (when viewed under polarized light) in the cytoplasm of phagocytic cells from around total hip replacements (THRs) with a PE acetabular bearing and proposed that this finding was caused by multiple submocron PE particles. In order to determine the specificity of this light microscopie finding, we have analyzed a wide range of specimens (N = 27), characterized by a foreign‐body inflammatory response to both biologic and prosthetic material, that do not contain PE. In no case was there any suggestion of the diffuse cytoplasmic birefringence that is characteristic of specimens from THRs with a PE acetabular bearing surface. This study indicates that, within the range of orthopedic implant materials and designs currently in use, this diffuse birefringence is a specific finding and it represents a simple, practical, and useful method for ligh microscopic identification of submicron PE. © 1993 John Wiley & Sons, Inc.
Porous polyurethane tubes as vascular graft
Authors: Fujimoto Keiji , Minato Masao , Miyamoto Susumu , Kaneko Takaaki , Kikuchi Haruhiko , Sakai Kazuhiko , Okada Masao , Ikada Yoshito
Published: May 2005

A vascular graft with the inner diameter of about 3 mm was prepared from segmented poly (ether urethane) with an extrusion technique. To make the wall of the vascular grafts porous, NaCl salts were added to the polyurethane solution to be extruded and removed with water extraction after evaporating the solvent in the extruded tube. The wall was reinforced with elastic fiber to prevent dilation. The compliance of the vascular graft measured with the method of Hayashi et al. ranged from 0.2 to 0.3% mmHg−1. The initial Young's modulus was close to that of canine carotic artery, to which the porous polyurethane graft 4‐cm long was anastomosed. Vascular grafts were occluded within 2 weeks after implantation, when their pore size was 0, 1.7, or 4.4 m̈m, whereas those with the pore size of 5.5, 7.4, and 30 m̈m were patent for longer than 4 weeks. When the vascular graft with the pore size of 30 m̈m was implanted for 6 months, the luminal surface was covered with neointima, but the endothelium‐like cells appearing in the middle of the intima of the vascular graft were immature and sometimes had a very big nucleus. In addition, spindle‐shaped, modified smooth muscle cells were noticed in the deep layer of the neointima, especially in the tissue where anastomotic intimal hyperplasia occurred. © 1993 John Wiley & Sons, Inc.
Effects of metallic debris on adult bovine articular chondrocyte metabolism in vitro
Authors: Maloney William J. , Castro Frank , Schurman David J. , Smith R. Lane
Published: May 2005

The purpose of this study was to examine the effects of particles, derived from metals commonly used in joint prostheses, on chondrocyte proliferation, metabolism, and morphology in vitro. Chondrocyte viability was influenced by the type and concentration of metal particle added. Cobalt was toxic to chondrocytes at all particle concentrations (0.83–0.000083%, v/v), whereas the chromium, titanium and titanium‐aluminum particles only effected chondrocyte viability at high concentrations. The metabolic response of chondrocytes to particulate debris as assessed by caseinase, collagenase, and hexosaminidase activities were variable at low concentrations but were always reduced at high concentrations (0.83% v/v). Prostaglandin E2 levels in the medium showed a steady increase when particle load increased, except in the medium of chondrocytes exposed to titanium‐aluminum. Scanning electron microscopy of chondrocytes exposed to titanium showed ruffled cell borders and frequent membrane blebbings. This was in contrast to chondrocytes exposed to cobalt, where the crenated appearance indicated cell death, and titanium‐aluminum, where the cells appeared quiescent. These findings show that metal particles alter chondrocyte viability and metabolism and suggest that particulate debris may influence the integrity and stability of articular cartilage following hemiarthroplasty. © 1994 John Wiley & Sons, Inc.
Effects of intermittent micromotion versus polymer particles on tissue ingrowth: Experiment using a micromotion chamber implanted in rabbits
Authors: Goodman Stuart , Aspenberg Per , Song Yong , Regula Donald , Doshi Amol , Lidgren Lars
Published: May 2005

Both micromotion and particulate debris have been implicated in the process of aseptic loosening of joint arthroplasties and the failure of bone ingrowth into porous coated prostheses. In the present study, we compare the histological and histomorphometric results of tissue ingrowth into titanium chambers in the presence of interfacial micromotion versus phagocytosable particles of two polymers used in orthopedic surgery. The micromotion chamber, having a 1 × 1 × 5 mm transverse canal for tissue ingrowth was implanted into the proximal right tibia of five mature male New Zealand white rabbits. In the first series, the chambers were manipulated at 40 cycles per day (cpd) at 1 Hz, using an amplitude of 0.5 mm. The tissue within the chamber was harvested after 3 weeks. In the following series, fabricated particles of bone cement or highdensity polyethylene (HDPE) were mixed with the carrier, 1% sodium hyaluronate (Healon) to obtain a concentration of 108 particles/mL; this solution was implanted in the canal of the chamber but micromotion was not instituted. Histological sections from control, nonmoved chambers, or those implanted with the carrier Healon alone contained extensive trabecular and woven bone embedded in a fibrovascular stroma. The application of 40 cpd resulted in less formation of bone and more fibrous tissue within the chamber. The sections containing particles of bone cement were infiltrated by numerous foamy, mononuclear, and multinuclear histiocytes. HDPE particles were associated with more fibrosis and a less aggressive foreign body response compared to cement particles. Chambers manipulated at 40 cpd and those containing cement or HDPE particles contained less bone compared to nonmoved chambers or those containing Healon alone. Despite evoking different histological reactions, the presence of micromotion or polymer particles appears to inhibit the formation of bone in this experimental model. © 1994 John Wiley & Sons, Inc.
Corrosion and cell culture evaluations of nickel‐chromium dental casting alloys
Authors: Bumgardner J. D. , Lucas L. C.
Published: May 2005

In this study, the corrosion and surface properties of four commercially available nickel‐chromium dental casting alloys, were evaluated using electrochemical corrosion testing and Auger electron microscopy. The corrosion tests were conducted under cell culture conditions of 5% CO2 humidified atmosphere at 37°C in minimum essential medium (MEM) balanced salt solution, 95% MEM–5% FBS (fetal bovine serum) cell culture media, and in 95% MEM–5% FBS media after cold solution sterilization of test samples. The results of the surface and corrosion analyses were correlated to cytotoxicity and metal ion release from the alloys using agarose overlay and direct contact cell culture tests. The surface and electrochemical corrosion analyses demonstrated that the non‐beryllium containing alloys were more resistant to accelerated corrosion processes as compared to the beryllium‐containing alloys. All alloys demonstrated decreased corrosion rates in cell culture solutions after cold solution sterilization treatment. The corrosion products released from the nickel‐based alloys failed to alter the cellular morphology and viability of human gingival fibroblasts, however they did cause reductions in cellular proliferation. The potential for accelerated corrosion and the exposure of local and systemic tissues to elevated levels of corrosion products raises concerns over the biocompatibility of these alloys. © 1994 John Wiley & Sons, Inc.
Inhibition of in vitro calcium phosphate precipitation in presence of polyurethane via surface modification and drug delivery
Authors: Chandy Thomas , Kumar B. Ajith , Sharma Chandra P.
Published: May 2005

Biomaterial associated calcification is the principal cause of the clinical failure of bioprosthetic implants. The present investigation describes the mineralization of polymeric substrate in an extracirculatory environment and the possible methods of prevention. Calcification was examined on various polyurethane films (and bioprosthetic tissue) incubated in metastable solutions of calcium phosphate and the role of polymer casting and precipitation was evaluated. The formulation and the in vitro efficacy of prolonged controlled‐release chitosan matrices, containing the novel anticalcification agents, such as Fe+++ or protamine sulfate (PS), were also attempted. The in vitro release profiles of PS from chitosan beads was performed in a rotating shaker (100 rpm) in 0.1 M phosphate buffer (pH 7.4) and was monitored spectrophotometrically. The amount and percentage of drug release were much higher initially, which was controlled with the incorporation of egg phosphatidyl choline (EPC). The PS loaded chitosan beads (coincubated in calcium phosphate solution with the calcifiable polyurethane films) significantly inhibited biomaterial calcification (about 40–50% inhibition). Surface modification of polyurethanes with Fe+++ or PS also inhibited the calcification profile of the material. These findings suggest the possibility of a combination therapy for prevention of biomaterial associated calcification via surface modifications in conjunction with long‐term controlled release of the anticalcifying drugs. © 1994 John Wiley & Sons, Inc.
Mixed mode fracture characterization of hydroxylapatite–titanium alloy interface
Authors: Mann Kenneth A. , Edidin Avram A. , Kinoshita Roy K. , Manley Michael T.
Published: May 2005

Cantilever beam and four‐point bend specimen geometries were used to experimentally determine the critical energy release rates for a plasma sprayed hydroxylapatite‐titanium alloy (HA–Ti alloy) interface. A locus of energy release rates as a function of crack tip phase angle was determined where a 0° phase angle represented tensile opening (mode I) loading and a 90° phase angle represented in‐plane shear (mode II) loading. Energy release rates were found to increase substantially with an increase in phase angle. An energy release rate of 0.108 N/mm was determined for a phase angle of 0° (mode I). Energy release rates of 0.221, 0.686, and 1.212 N/mm were determined for phase angles of 66°, 69°, and 72°, respectively. The experimental data was matched to a phenomenological model for which crack propagation depended on mode I loading alone indicating that crack propagation at the Ha‐Ti alloy interface is dominated by the mode I loading alone indicating that crack propagation at the Ha–Ti alloy interface is dominated by the mode I loading component. Therefore, regions of HA coated implants that experience compressive or shear loading across the HA–Ti alloy interface may be much less likely to debond than regions that experience tensile loading. © 1994 John Wiley & Sons, Inc.
Load transfer through a hydroxyapatite‐coated canine hip implant
Authors: Szivek J. A. , Kersey R. C. , De Young D. W. , Ruth J. T.
Published: May 2005

Strain transfer near hydroxyapatite (HA) coated canine hip implants was examined using simulated anatomical loading based on in vivo strain measurements. Strain changes near implants relative to intact control values were in excess of 100% for transverse and principal strains for zero time period (immediate postimplant) specimens. They were generally smaller (100% or less) for axial, transverse, and principal minimums in the same locations for 4 months postimplantation specimens.

Cortical bone loss occurred in all implanted femora. The most extensive loss, up to 47%, occurred adjacent to the proximal section of the implant. Extensive trabecular bone formation, over 300% in some regions of each femur, was noted in all implanted femora.

Backscattered electron imaging along the HA‐coated sections of the implants showed extensive bone bonded to the coating. Normal light and UV light micrographs showed direct bone apposition to the implant surfaces and extensive bone formation in all test animals. Microscopy revealed no evidence of any soft tissue layer between the implant and bone. Bone was typically found in direct contact with the implant surface.

Histomorphometry indicated that bone formation rates in the implanted femora were elevated, up to 850%, relative to controls. Fewer formation sites were noted on the posterior and lateral (in two cases zero sites). Mineral apposition rates (MAR) from two of the dogs were slightly elevated (from 110–113%) in the implanted femora relative to controls and depressed (to about 83% of controls) in a third. © 1994 John Wiley & Sons, Inc.
Mechanical properties of vacuum‐mixed acrylic bone cement
Authors: Lewis Gladius , Ed Austin G.
Published: May 2005

The thrust of the present work was the experimental determination of the uniaxial static compressive and fully reversed tension‐compression fatigue properties of CMWTM 3 acrylic bone cement whose consituents were mixed in a properietary chamber while simultaneously subjected to a vacuum. Selected indices of performance in this material are: mean static compressive strength, 81.4 MPa; mean compressive modulus of elasticity, 1.95 GPa; endurance limit, 8.1 MPa; and characteristic fatigue life (using a three‐parameter Weibull fit to the fatigue test data obtained at a stress of ±10 MPa), 238 712 cycles. The difficulties in comparing results obtained using different cement formulations, preparation conditions, and test conditions are detailed. With this in mind, it is suggested that the present results are within the range of values reported by previous workers for other formulations mixed using a variety of methods. The clinical significance of the present results is discussed. © 1994 John Wiley & Sons, Inc.
Use of a compact sandwich specimen to evaluate fracture toughness and interfacial bonding of bone
Authors: Wang Xiaodu , Lankford Jim , Agrawal C. Mauli
Published: May 2005

The objective of the present study was to develop a reliable and statistically valid test to measure the fracture toughness of small specimens of bone, and by extension, prosthetic materials, using a compact sandwich specimen. Samples of bone were sandwiched between holders of a different material and using this specimen configuration a new technique was developed to test the fracture toughness of the bone interlayer. The effects of different speciments sizes and holder materials were investigated empirically. Using finite element analysis a correction factor was determined to account for the finite thickness of the interlayer and the analytical solutions governing the test specimen were accordingly modified. Bulk compact tension specimens of bone were tested for comparison. Both wet and dry bone were evaluated and the fracture surface morphology characterized using scanning electron microscopy. The results indicate no statistically significant differences between the fracture toughness values obtained from the compact tension and sandwich specimens. The application of this technique to the testing of interfacial bonding between bone and biomaterials is discussed. © 1994 John Wiley & Sons, Inc.