bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of smoking abstinence and nicotine abstinence on heart rate, activity and cigarette craving under field conditions
Authors: Baldinger Beatrice , Hasenfratz Markus , Bättig Karl
Published: May 2005

In a field study heart rate, activity, cigarette consumption, craving for cigarettes, saliva cotinine and subjective ratings were assessed in 12 female subjects, smoking medium tar/medium nicotine cigarettes (TN). The habituated cigarettes were compared with a nearly nicotine‐free/medium tar (0·08 mg/9·3 mg) cigarette (Tn) and with abstinence. Two recording periods of 3 days each were conducted in two consecutive weeks. Heart rate was highest with the Tn cigarettes, 8 bpm lower on abstinence days and in between with the Tn cigarettes. A characteristic increase in heart rate and activity before cigarette lighting appeared with the TN and the Tn cigarettes and with button pressing indicating smoking desire on abstinence days. This response is attributed to an anticipative activation preceding lighting a cigarette. Subjective ratings assessing the craving to smoke differed between abstinence and the smoking condition but not between the two cigarette types, whereas saliva cotinine was significantly higher with the TN than with the Tn cigarettes or abstinence. Cigarette consumption was similar with both cigarette types, but taste and strength were rated better for the TN than the Tn cigarettes.

It is concluded that heart rate and saliva cotinine depend on the amount of nicotine absorbed, whereas subjective craving is reduced by smoking independently of the actual nicotine yield of the cigarette.
Zopiclone in elderly patients: Efficacy and safety
Authors: Kerr J. S. , Dawe R. A. , Parkin C. , Hindmarch I.
Published: May 2005

Zopiclone is an hypnotic medication belonging to the cyclopyrrolone family of drugs. It is chemically unrelated to the benzodiazepines and binds to a specific site of the GABAA receptor complex. Zopiclone has been found to be effective as an hypnotic for the elderly: single doses of 7.5 mg have been found to decrease sleep onset Latency and the number of nocturnal awakenings: to improve sleep duration and sleep quality, and to cause minimal impairment of psychomotor performance and mental alertness the morning after a normal bed‐time dose. Importantly, the drug has been shown to have little or no effect on short‐term memory, a function that is often impaired by earlier hypnotic drugs particularly in elderly patients. Furthermore, there is little evidence of dependency or rebound insomnia on withdrawal of the medication after continued use. The drug is well tolerated by patients of all ages, and adverse effects are infrequently reported, the majority of side‐effects being taste disturbance (3.6 per cent in the largest trial to date) and dry mouth (1.6 per cent). Zopiclone is now a well‐established alternative to the benzodiazepine hypnotics.
The effect of lithium on cholinergically mediated GH responses in healthy volunteers
Authors: Cooney J. M. , Dinan T. G.
Published: May 2005

The phosphoinositide (PI) cycle second messenger system mediates the effect of muscarinic receptor binding. Inositol, which is an essential substrate for phosphoinositide synthesis penetrates the blood‐brain barrier poorly, and is vulnerable to depletion. Lithium uncompetitively inhibits inositol‐1‐monophosphatase, a key enzyme in the recycling of inositol for the PI messanger system. There is evidence for cholinergic overactivity in depression from clinical and experimental observations. Among these, pyridostigmine (PYD) stimulated growth hormone (GH) release is found to be elevated relative to healthy controls. PYD/GH responses were examined in six healthy male volunteers before and after 10 days of lithium administration. GH responses did not differ significantly after lithium from those observed at baseline. These results suggest that lithium does not significantly inhibit cholinergically mediated GH secretion in healthy volunteers and provide further support for the selective action of lithium on upregulated cholinergic tracts, consistent with uncompetitive inhibition of the phosphoinositide cycle.
Exacerbation of migraine with paroxetine: Case report
Authors: Currie Alan , Ryman Ann , McAllister‐Williams R. Hamish
Published: May 2005

There has been one case reported in the literature (Medline search December 1994) of a serotonin selective re‐uptake inhibitor (SSRI), fluoxetine, being associated with the development of classic migrainous symptoms (Larson, 1993). We now report a case of severe exacerbation of migraine with another SSRI, paroxetine.
Temazepam impairs effortful but not automatic processing of stimulus elements
Authors: Joyce Eileen M. , File Sandra E.
Published: May 2005

The experiment investigated the effects in healthy volunteers of a single dose of temazepam (30 mg, oral) on effortful and automatic processing, by measuring memory for information and its context. Effortful processing was impaired, as shown by significant impairments in free recall of an 18‐item list, but automatic processing was spared, as evidenced by no impairments in recall of the frequency of presentation, the colour, size or form of the items. In a second task, temazepam significantly impaired both recognition and recency memory of 30 items, although these scores were not correlated. Temazepam caused significant sedation, measured by an objective test and by subjective ratings, but this did not correlate with the memory impairments. The pattern of results is discussed with reference to the hypothesis that the memory impairments resulting from benzodiazepines are due to a reduction in information processing resources and thus affect effortful processing more than automatic processing.
Responsiveness to environmental stimuli after destruction of the locus coeruleus noradrenergic system: A review
Authors: Zagrodzka Jolanta
Published: May 2005

The functional significance of the locus coeruleus noradrenergic system (LCNA) is still not fully understood. The aim of our work reviewed below, was to investigate the effects of the selective noradrenergic neurotoxin DSP‐4 on behaviours displayed during inter‐ and intraspecies encounters and in response to stressogenic stimuli on cats and rats. It has been found that the destruction of LC NA did not affect prey killing in either cats or rats. Also, well established dominance‐submissive order displayed during predatory competition remained unchaged, except for the situation when the stressful stimulus was presented to a pair of cats. In the presence of such a stimulus the DSP‐4‐treated cats attacked mice in front of their dominant partners, although they never did so before.

In rats treated with DSP‐4 a marked decrease in defensive episodes and an increase in offensive episodes was observed during social encounters in resident‐intruder paradigm. It was found that these rats spent more time in the stressogenic highly illuminated centre of the open field than did the controls. Biochemical analysis showed a significant reduction of noradrenaline content in the forebrain structures and some changes in serotonin and dopamine levels; the latter are considered as an effect secondary to noradrenaline depletion.

In light of other authors' data concerning the role of LC NA in brain and behavioural activity, three possible interpretations of our results are considered: (1) an increase in aggression; (2) fear reduction; (3) inadequate responsiveness to environmental cues.
Crossover reaction between mianserin and trazodone for restless legs syndrome
Authors: Otani Koichi , Kaneko Sunao
Published: May 2005

A 58‐year‐old woman with a past history of mianserin‐induced restless legs syndrome (RLS) developed the same syndrome on subtherapeutic doses of trazodone. However, neither nortriptyline nor imipramine at therapeutic doses caused RLS. The present report suggests that hyposerotonergic states are involved in the pathophysiology of RLS.
Development and application of modern devices in vascular surgery including comment on modern antithrombotic and lytic drug therapy
Authors: Sawyer Philip N.
Published: May 2005

Since modern vascular surgery started with the discovery of heparin and the development of modern vascular grafts including autogenous saphenous vein, the speciality has been technologically driven. At the outset, vascular surgery depended almost entirely on the development of specialized clamps, instruments, and tools to permit decisive attack on the problems of occlusion.

No less important was the development of insight into the basis of atherosclerosis, the discovery that atherogenesis with thrombosis is electrochemically identical to corrosion in pipes and therefore subject to chemical forces, which have not yet been delineated, as well as mechanical forces which have been delineated and permit one to attack the atheroma directly.

Thus, classic replumbing techniques including bypass and endarterectomy have long been a part of the fundamental firmament of vascular surgery.

Most recently, modern techniques in cleaning out blood vessels, removing occlusive processes, and modern thrombus‐dissolving enzymes have all come to the forefront. Frequently multiple techniques are used simultaneously. This article is an attempt to summarize various aspects of this activity and describe several of the patents which have been seminal in the ultimate application of the techniques in both experimental animals and man. This should be the first of a series of efforts to summarize this area. The process of change has never been more kinetic than now.
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 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 1990.
A method for preparation of etched collagen fibers that support neurite outgrowth
Authors: Wong Eric , Christiansen David , Rizvi Azam , Geller Herbert M. , Silver Frederick H.
Published: May 2005

Use of collagenous substrates for growth of attachment‐dependent and attachment‐independent cells have been reported in the literature. Growth of fibroblasts and epithelial cells on collagen sponges and fibers has been previously studied in our laboratory. This article reports the result of studies of neurite outgrowth on etched collagen fibers in cell culture. Collagen fibers with a mean diameter of about 134 μm were etched on glass coverslips using a collagenase solution until individual fibrils of 1 μm in diameter were observed. The kinetics of etching were optimized at a calcium chloride concentration of 5 mM and a collagenase activity of 300 unit/mL. At room temperature an etching time of 10 h maximized the number of fibrils exposed per fiber. Cell culture studies on etched collagen fibers indicate that neurites from rat fetal cortical neurons elongate along the longitudinal axes of collagen fibrils. In some instances the cell body observed was not on top of the collagen fibrils but situated between two parallel fibrils. Results of these experiments indicate that growth of neurites along collagen fibrils in cell culture may be a useful model to evaluate neurite extension in the presence of neurotrophic factors as well as to study optimization of substrates for nerve regeneration.
Performance of the polypropylene fiber tailstring on the copper 7 intrauterine device
Authors: Warner M. S. , Matsuno S. J. , Virgin C. J. , Masterson K. B. , Schneider G. A. , Wright T. E. , Robertson C. R. , Fives‐Taylor P.
Published: May 2005

New and used polypropylene tailstrings from the Copper 7 (Cu‐7) intrauterine device were examined by a combination of analytical techniques. Optical microscopy, scanning acoustic and electron microscopy, x‐ray diffraction, energy dispersive x‐ray analysis, and chemical etching were employed to elucidate both the surface and interior morphology of new Cu‐7 tailstrings. Tailstrings removed from women following varying periods of use were investigated with optical microscopy, scanning and transmission electron microscopy. In addition, a subset of the used tailstrings were cultured to identify the types of microorganisms associated with them. Our findings show that unused Cu‐7 tailstrings are in various stages of degradation owing to a combination of factors which include the high‐draw ratio employed during manufacturing, the method of packaging, and the use of a particulate colourant. Furthermore, it is evident that used Cu‐7 tailstrings undergo major deterioration while in situ because of the unfavorable interactions between the highly drawn polypropylene and the physiological environment. These results indicate that the polypropylene tailstrings as manufactured for use with the Cu‐7 IUD fail to meet accepted design criteria for biomedical implants.
Poly(vinyl alcohol) hydrogel as an artificial articular cartilage: Evaluation of biocompatibility
Authors: Noguchi Takashi , Yamamuro Takao , Oka Masanori , Kumar Praveen , Kotoura Yoshihiko , Hyonyt Suong‐Hyu , Ikadat Yoshito
Published: May 2005

We have developed a new poly(vinyl alcohol) hydrogel (PVA‐H) of increased physical strength through a new manufacturing process. Its mechanical properties have been found to be preferable as a substitute for articular cartilage. To evaluate its biocompatibility as an artificial articular cartilage, a series of in vivo tests within the intraarticular, as well as the intramuscular, environment were conducted. Tissue reactions of cartilage, bone, synovium, and muscle to PVA‐H were studied histologically. In the experimental group, in which PVA‐H was implanted, inflammatory reactions of all of these tissues were very slight. In the control group, in which ultra‐high molecular weight polyethylene (UHMWPE) was implanted, although tissue reactions of bone and muscle were as slight as in the experimental group, those of cartilage and synovium were somewhat more conspicuous. By way of these findings, the better biocompatibility of PVA‐H was documented.
Orthopedic implant devices: Prevalence and sociodemographic findings from the 1988 National Health Interview Survey
Authors: Moore Roscoe M. , Hamburger Stanford , Jeng Lana L. , Hamilton Peggy M.
Published: May 2005

National population‐based estimates on the magnitude and distribution of orthopedic implant devices in the United States have not been available to date. The Food and Drug Administration's Center for Devices and Radiological Health (FDA/CDRH) collaborated with the Centers for Disease Control's National Center for Health Statistics (CDC/NCHS) in the design and conduct of a nationwide medical device implant survey to generate the first national population‐based prevalence estimates of orthopedic implant devices. A Medical Device Implant Supplement to the 1988 National Health Interview Survey was administered in personal household interviews to a national sample of 47,485 households, which included 122,310 individuals.

An estimated 6.5 million orthopedic implants were in use in the general US population in 1988, including 1.6 million artificial joints and 4.9 million fixation devices. As a group, orthopedic implants comprised nearly half of all medical device implants in use, 43.4%. The majority of artificial joint recipients were 65 years of age or older, white, and male. the majority of fixation device recipients were less than 45 years of age, white, and male. The limitations and strengths of these population‐based estimates are discussed.
Application of extracorporeal shock wave lithotripter (ECSWL) in orthopaedics. III. In Vitro and In Vivo studies
Authors: Weinstein J. N. , Loening S. , Park J. B. , Park S. H. , Oster D.
Published: May 2005

The present study was conducted to compare the push‐out strength of the treated and control samples obtained after implantation of intramedullary rod in canine femurs with bone cement to simulate the femoral stem implantation for 2 weeks, 3 and 6 months. Contralateral femur served as control. The result showed a significant decrease in push‐out interfacial strength after shock wave treatment (average 48.4% decrease compared with control, p < 0.0001) which is similar to the in vitro results. There was no significant difference if the shock treatment was applied and left for 2 weeks or 4 weeks compared to the ones tested immediately after sacrifice. There were some soft tissue damage immediately following shock treatment in the focal area but this returned to normal in 2 weeks. Human cadaveric femoral bones and the canine bone (the dosage level was higher for the human bone than canine). The number of impacts used to extract the bone cement plug out of a human femur segment (5‐cm long) decreased about 68% at 23 and 25 kV treatment power level. These preliminary studies indicate that the shock wave can be utilized to reduce the interfacial strength of the bone and bone cement although more studies are needed to assess its efficacy in terms of cost, long‐term effect on patients and the exact mechanism of the loosening before this technique can be used clinically.
The effect of thermoforming on the properties of fiber‐reinforced composite wires
Authors: Patel Anil P. , Jon Goldberg A. , Burstone Charles J.
Published: May 2005

The effects of thermoforming on the instantaneous flexural properties and structure of thermoplastic fiber‐reinforced composite (FRC) wires were studied to determine the preferred temperature range for clinical forming. Five different formulations of FRC wires were heated to clinically relevant thermoforming temperatures in a special mold that was designed to maintain their shape. In addition, one formulation was also heated without the restraining effect of the mold. Flexural properties were determined. A temperature above the Tg is necessary to allow sufficient softening and avoidance of distortion in shape during clinical forming. However, higher temperatures will result in significant structural disintegration of the wires with consequent decrease in flexural modulus. Thus, for every material, there is a heating range or “working range” where the material can be properly formed with minimal changes in the physical properties. This was primarily related to the Tg of the matrix used.
Histologic analysis of a retrieved expanded polytetrafluoroethylene posterior cruciate ligament
Authors: Mantas John P. , Bloebaum Roy D. , Hofmann Aaron A.
Published: May 2005

An expanded polytetrafluoroethylene (PTFE) prosthesis used to reconstruct the posterior cruciate ligament in a 37‐year‐old Caucasian male was retrieved and histologically examined in this study. Backscattered electron (BSE) microscopy, utilized to observe the mineralized tissue ingrowth into the retrieved specimen, revealed an absence of bony ingrowth within the graft. Light microscopy demonstrated an exuberant foreign body giant cell response surrounding and invading the substance of the graft, and also revealed evidence of graft degradation. These observations indicate that PTFE may not be as favorable a material for reconstruction of ligamentous tissues as previously reported.
Biomaterials education: An academic viewpoint
Authors: Black Jonathan , Shalaby Shalaby W. , Laberge Martine
Published: May 2005

Biomaterials is emerging as an identifiable intellectual field of study. There are necessary preparatory studies to equip individuals to work within the field at various levels. The formal and informal instructional requirements are considered within the context of the academic program of the Department of Bioengineering at Clemson University, one of the first US university programs to focus on instruction and research in biomaterials.
The effect of egg phosphatidylcholine on antibiotics retention and release from hydroxyapatite
Authors: Iwata Hisashi , Yamamura Keiko , Zhao Xue Zhu
Published: May 2005

Hydroxyapatite (HAP) has been used in orthopedics as an aid in bone grafts following surgery of bone tumors and osteoarthrosis, often promoting osteoconduction. The incorporation of antibiotics into HAP beads to prevent local infection would seem to be therapeutically effective. This report describes in vitro and in vivo release rate of cefotiam hydrochloride (CTM, 3.5 mg/bead) loaded into HAP beads (8.48 mm in diameter). Egg phosphatidylcholine (EPC) was also incorporated into HAP to control the rate of release of CTM. In vitro, 100% of CTM was released within 3 h from the EPC‐free HAP beads. The rate of diffusion of CTM from HAP was prlonged with the incorporation of EPC. In vivo, 100% of CTM of the EPC‐free CTM was released within 7 h but the rate of release of CTM from the EPC‐CTM was extended. In vivo, the serum level of CTM reflected the rate of release of the antibiotics from the HAP bead. We conclude that EPC is useful in controlling the diffusion rate of CTM from HAP. © 1992 John Wiley & Sons, Inc.
Biological response of intramedullary bone to poly‐L‐lactic acid
Authors: Suganuma Jun , Alexander Harold
Published: May 2005

This study focuses on examining the biological response of intramedullary bone to poly‐L‐lactic acid (PLLA), particularly during the PLLA degradation phase. To study the influence of spherical crystals (spherulites) of PLLA on intramedullary bone response, two different types of PLLA coupon, with and without spherulites but with the same molecular weight, were used. Chambers containing PLLA coupons were implanted into the right femur of eight dogs, four with and four without spherulites; chambers containing stainless steel (SS) coupons (as a control) were implanted in the left femurs of all eight. Two dogs, one with and one without spherulites, were sacrificed at 3, 6, 12, and 24 weeks postoperatively. Histomorphometric evaluation and histophathological assessment were used to compare the response to PLLA and SS. Scanning electron micrographs showed that there were minimal changes in the surface of PLLA coupons at 3 and 6 weeks. But at 12 and 24 weeks, there were many cracks and holes on the surfaces of the coupons, and some parts of the surface were scaling off. The cross‐sectional area of PLLA coupons showed no change at 3 and 6 weeks, but started to decrease by 12 weeks. The amount of ingrown bone between PLLA coupons was significantly greater than that between SS coupons at 3 and 6 weeks, but had decreased dramatically by 12 weeks. Extensive bone resorption around PLLA coupons occurred by 12 weeks accompanied by infiltration of inflammatory cells. An abundance of histiocytes, giant cells, and leucocytes were seen, along with a few histiocytes that had phagocytized PLLA particles of less than 2 μm. By contrast, no inflammatory reaction was seen in SS samples at any period up to and including 24 weeks. PLLA demonstrated excellent biocompatibility with intramedullary bone for the first 6 weeks in this model. Once degradation commenced, however, biocompatibility decreased dramatically. Our study detected no difference between coupons with and without spherulites. It thus appears that the existence of relatively large PLLA particles did not influence the response of intramedullary bone to PLLA, but rather that it was the smaller particles (< 2 μm) released from the PLLA that induced foreign‐body inflammatory reactions and bone resorption. It is also possible that a local decrease in pH occurred around PLLA coupons, which could have influenced vital kinetics. © 1993 John Wiley & Sons, Inc.
Hydroxyapatite‐coated strain gauges for long‐term in vivo bone strain measurements
Authors: Maliniak Mary M. , Szivek John A. , DeYoung Donald W. , Emmanual Janson
Published: May 2005

The aim of this study was to examine the bonding process between hydroxyapatite‐coated strain gauges and bone in order to continue development of a long term in vivo strain measurement device. Two types of commercially available hydroxyapatite (HA) particles were applied to the sensing surface of uniaxial strain gauges using a polysulfone solution as an adhesive. Characterization by scanning electron microscopy and x‐ray diffraction (XRD) was used to determine materials property differences between the two powders. Interfacial strengths between the HA coatings and the strain gauges were tested and found comparable to interfacial strength obtained by a plasma sprayed HA coating on the surface of a titanium implant.

Gauges were surgically placed on the periosteal surface of greyhound femora. Three groups of dogs were implanted with gauges for periods of 3, 6, and 12 weeks using cyanoacrylate, resorbable sutures, and cable ties to initially hold the gauge against the surface of the bone.

Following euthanasia, the femora of the dogs were explanted and subjected to cantilever loading. Response of the implanted HA‐coated gauges were compared to a control set that had been freshly glued onto the contralateral femur. Full response, that is, 100h% of the strain measurement with respect to the control, was obtained after 12 weeks in vivo. Attachment of HA‐coated gauges with a circumferential suture showed bonding, while HA‐coated gauges attached with cyanoacrylate did not bond to bone.

After mechanical testing, femora were embedded in polymethylmethacrylate, cut, ground, and polished. Sections were stained using mineralized bone stain (MIBS) and optical microscopy was performed using transmitted and fluorescent light to allow analysis of remodeling occurring in the region of the strain gauges. Bone formation occurred at the HA surface of sutured gauges, and a fibrous tissue layer developed between the bone and HA coating when the tissue adhesive was used to initially bond the gauge. Fluorescence microscopy indicated an increase in the number of areas of bone remodeling adjacent to the gauge but a normal rate of remodeling of 0.93 ± 0.07 μm/day was observed. No gross bone remodeling due to strain gauge placement was observed. Backscattered electron imaging (BSE) indicated new bone apposition at all time periods. © 1993 John Wiley & Sons, Inc.
A synthetic membrane for testing needle penetration
Authors: Pavlovich Lucas J. , McClung W. Lyle , Thacker John G. , Edlich Richard F. , Rodeheaver George T.
Published: May 2005

Needle performance is primarily judged by its penetration through tissue. For detailed studies of needle performance, tissue is too heterogeneous and unstable and difficult to obtain. A homogeneous, stable, and readily available polyurethane substrate has been evaluated as a suitable alternative to biological tissue for evaluation of needle penetration. The needle penetration profiles through the synthetic substrate correlated very well with those through natural tissue. In addition, the synthetic substrate was sensitive enough to easily detect a 20% increase in the force necessary to penetrate natural tissue. This polyurethane substrate offers a valid alternative to biological tissue for the testing of needle penetration performance. © 1993 John Wiley & Sons, Inc.
Tensile and bend relationships of several surgical needle materials
Authors: Bendel Lee P. , Trozzo Lawrence P.
Published: May 2005

Four stainless steel alloys, commonly used for surgical needles were tensile and bend tested. The materials included: ASTM 42000, ASTM 45500, ASTM 30200, and a Fe–12Cr–8.5Ni–3.2Mo–1.9Ti alloy. Small diameter wires in a wide range of strength levels were produced using various heat treatments and/or cold drawing. Samples from each processing condition were tensile and bend tested. Calculated yield moment and ultimate moment were determined using tensile yield strength, the flexural formula (M(y) = σ(y) I/C), and the shape factor for circular cross sections (M(u)/M(y) = 1.7). A deviation was observed between the theoretically calculated yield moment and a 2° offset measured yield moment. This was expected because moment‐strain diagrams provide only an approximation of yield moment due to the gradual departure from linearity. The 2° offset yield was termed the surgical yield because it represents the strain at which a surgical needle would start to lose functionality. A nonlinear relationship (R) was observed between measured and calculated values. The relationship (R) proved to be a function of cold work by wire drawing as measured by the change in wire length (ΔL), R = a − b * In(ΔL). This suggests that engineers selecting materials for bending applications such as surgical needles cannot use tensile data alone to predict bend strength. Processing history must also be known. © 1993 John Wiley & Sons, Inc.
A comparison of a new polypropylene suture with prolene
Authors: Chu C. C. , Pratt L. , Zhang L. , Hsu A. , Chu A.
Published: May 2005

The purpose of this paper is to examine the performance of the newly available monofilament polypropylene suture (Surgipro) manufactured by U.S. Surgical and compared it with commercial Prolene sutures for determining the merit of this new suture. Two different sizes of Surgipro sutures were esused. They were 4/0 and 0 sizes and were tested in terms of their fundamental properties: level of crystallinity, melting temperature, fiber morphology, and mechanical properties including knot strength and knot security. The effect of three different sterilization methods on the mechanical and fundamental properties of the new polypropylene (PP) sutures was also examined. In general, the new Surgipro sutures performed as good as Prolene sutures in terms of mechanical properties; but there were some differences in fundamental properties between these two types of PP sutures, particularly in finer size PP sutures. The major differences were in interior fiber morphology, level of crystallinity, and melting temperature. Surgipro suture fibers showed homogeneous interior morphology, while Prolene fibers exhibited two distinctive fiber morphologies. These two types of PP suture fibers also responded differently to the three sterilization methods tested. Surgipro sutures are less affected by different sterilization methods than the same size Prolene control. Except for the Co60 gamma sterilization, Surgipro suture fibers did not exhibit statistically significant differences in tensile breaking strength between sterilized and control. Ethylene oxide and autoclave sterilized Prolene suture fibers, however, showed statistically (p < 0.05) consistently lower tensile breaking strength than their unsterilized controls. One should be aware of the fact that suture manufacturers are constantly improving their manufacturing processes. The difference between these two types of PP suture fibers may disappear in the future. © 1993 John Wiley & Sons, Inc.
Influence of surgeon's tying technique on knot security
Authors: Batra Erich K. , Franz David A. , Towler Mike A. , Rodeheaver George T. , Thacker John G. , Zimmer Christopher A. , Edlich Richard F.
Published: May 2005

The purpose of this study was to determine the influence of the surgeon's tying techique on knot security using 0 and 2‐0 monofilament and multifilament nylon sutures. Using an Instron® Tensile Tester and a portable tensiometer, knot security was achieved with these sutures using four‐throw square knots (1=1=1=1). After didactic and psychomotor skill training, medical students were taught to construct the four‐throw square knot using either a two‐hand tie or an instrument tie. Using the portable tensionmeter, their knot tying techniques were judged to be superior to those used by surgeons. The surgeon's faulty technique can easily be corrected by didactic information and psychomotor skill training. © 1993 John Wiley & Sons, Inc.
Poly‐(2‐hydroxyethyl methacrylate) particles for preoprative endovascular occulusion of extensive angiodysplasias
Authors: Horák Daniel , Švec František , Adamyan Arnold A. , Titova Mariya I. , Dan Vasilii N. , Trostenyuk Nadezhda V. , Voronkova Olga S. , Gumargalieva Klara Z.
Published: May 2005

The application of superselective endovascular occlusion in vascular radiology has broadened the scope of possible radical surgery of giant angiodysplasias by reducing considerably the risk of severe haemorrhage during the surgery. Occlusion was performed on 229 patients using spherical and cylindrical particles of porous poly(2‐hydroxyethyl methacrylate). The treatment of a patient suffering from angiodysplasia of the pelvis is described as an example. The first day following endovascular occlusion a hypercoagulation reaction developed, with a decrease of both the level of fibrinolysis and of anticoagulant factors. This was mainly due to a decrease of the level of antithrombin III and activation of the factor XIII indicating a strong tendency of intravascular thrombosis. During the third day, the hypercoagulation reaction increased. However, on the fifteenth day, parameters of the haemostasis system were close to normal values. Only the activity of the factor XIII remained high suggesting the stabilization and the organization of fibrin clot in the embolized blood vessel territory. © 1993 John Wiley & Sons, Inc.
A comparison of peripheral nerve repair using an absorbable tubulization device and conventional suture in primates
Authors: Tountas Chris P. , Bergman Ronald A. , Lewis Terry W. , Stone Harold E. , Pyrek Janine D. , Mendenhall H. Vince
Published: May 2005

Median nerve regeneration was studied in 30 adult primates after repair by microsurgical suture or tubulization with a nonwoven, bioabsorbable, polyglycolic acid device. The two methods were compared electrophysiologically and histologically 6 and 12 months after repair. The electrophysiology included recording of electrically evoked compound action potentials and subsequent determination of threshold, conduction velocity, amplitude, and area above the baseline for each component. Measurements were obtained before nerve transection and at the time of biopsy by stimulating both proximal and distal to the transection site. Analysis of all electrophysiological parameters revealed no statistically significant differences (p < 0.05) between the two repair techniques. Histopathology included examination of cross sections proximal and distal to the repair sites and longitudinal sections through the coaptation site. End organs (Meissner's and Pacinian corpuscles and muscle) were sectioned to determine the degree of reinnervation. No significant differences between the repair techniques were observed by histological analysis of these sections. These evaluations indicated that the tubulization repair technique produced results comparable to that of the suture technique. © 1993 John Wiley & Sons, Inc.
Testing method for mechanical properties of fibrin glue
Authors: Duda Georg N. , Chao Edmund Y. S. , Grabowski John J. , Taswell Howard F.
Published: May 2005

A testing method was developed to evaluate the mechanical properties of a fibrin adhesive in an effort to correlate mechanical strength to fibrinogen content. Autologous fibrin adhesives with varying fibrinogen content were loaded to failure in shear using a mechanical testing machine. The method developed was capable of distinguishing a mechanical strength difference among the three fibrin sample lots used in the study. A number of parameters were evident that could lead to testing variability. The development of a more sophisticated component delivery system would greatly reduce the variability of these parameters and thus, the product reliability. Ultimately, the information gathered from the current and future studies will form a type of quality control standard to directly correlate the percentage of fibrinogen in a particular sample to its adhesive performance. © 1993 John Wiley & Sons, Inc.
Characterization of polyesterurethane degradation products
Authors: Luu H.‐M. D. , Biles J. , White K. D.
Published: May 2005

Microthane foam, a poly(ester)urethane, used as a covering of some breast implants (Meme or Replicon by Surgitek) degrades readily in phosphate buffer pH 7.4 producing multiple unknown products in addition to 2,4 and 2,6 toluenediamine (TDA). The cumulative weight loss of the foam in buffer was 1.5% at 1 week and 2% at 2 weeks. Multiple peak molecular weights from 105 to 665 000 were found in the aqueous foam extracts following 2 weeks of incubation at 37°C using size exclusion chromatography (SEC). TDA was measured in the foam buffer extracts by high pressure liquid chromatography (HPLC) and confirmed by gas chromatography/mass spectroscopy (GC/MS). The total cumulative levels of 2,4 TDA and 2,6 TDA measured were 3 ± 0.65 μg/g of foam and 1.13 ± 0.19 μg/g of foam following 36 days of incubation at 37 °C. Higher amounts, 8.96 μg/g of 2,4 TDA and 3.3 μg/g of 2,6 TDA, were obtained at 50 °C. The cumulative release of TDA in aqueous extracts was found to correlate linearly with time suggesting a slow but continuous production of TDA under neutral conditions. However, less than 0.2 μg/g of TDA was detected as residual TDA in the methylene chloride extracts following up to 60 days at 37 °C. PU foam extracted with methylene chloride under similar conditions showed higher foam weight loss, 4.4 and 5% at 1 and 2 weeks, respectively. The results presented in this study provide further evidence that Microthane undergoes hydrolysis under neutral conditions in aqueous solutions producing TDA and other unknown low molecular weight components and oligomers. © 1994 John Wiley & Sons, Inc.
A method for transmission electron microscopy investigation of the osteoblast/hydroxyapatite interface
Authors: Garvey Brian T. , Bizios Rena
Published: May 2005

Neonatal rat calvaria osteoblasts were cultured on hydroxyapatite (as received or relatively‐rough surface and mechanically polished to a 0.3‐m̈m finish) and on glass (reference material) in Dulbecco's Modified Eagle Medium supplemented with 10% fetal bovine serum, 50 μg/mL ascorbic acid, and 10 mM β‐glycerophosphate under standard, sterile, cell‐culture conditions for 1, 3, 7, 14 and 21 days. At the end of the prescribed time periods, the cells were fixed and embedded in resin before removing the material substrates by exposure to acid solutions. Transmission electron microscopic examination of stained, ultrathin sections of the biological structures revealed osteoblast monolayers at 1 day of culture but multilayered cell structures at later time periods (14 and 21 days). The osteoblasts exhibited continuous contact and intimate apposition on polished hydroxyapatite and on glass; in contrast, osteoblasts on as received or rough hydroxyapatite made contact with discrete high points, spanned low regions of the material surface, and did not conform to all substrate contours. An electron dense layer (composed of mucopolysaccharides and proteins) was observed on all substrates tested after 7 days of culture. Collagen fibrils were seen interspersed among the osteoblasts as early as 3 days of culture; at later culture times, (i.e., 21 days) mineralized loci were observed in the extracellular matrix. © 1994 John Wiley & Sons, Inc.
Phosphonated polyurethanes that resist calcification
Authors: Joshi Ravi R. , Frautschi Jack R. , Phillips Richard E. , Levy Robert J.
Published: May 2005

Cardiovascular implant mineralization involving bioprosthetic materials, such as glutaraldehyde cross linked porcine aortic valves or synthetic materials such as polyurethanes, is an important problem that frequently leads to clinical failure of bioprosthetic heart valves, and complicates long‐term experimental artificial heart device implants. Novel, proprietary, calcification resistant polyetherurethanes (PEU) as an alternative to bioprosthetic materials were the subject of these investigations. A series of PEU was derivatized through a proprietary reaction mechanism to achieve covalent binding of 100 to 500 nM/mg of bisphosphonate (2‐hydroxyethane bisphosphonic acid, HEBP). The stability of HEBP (physically dispersed or covalently bound) verified by studying the release kinetics in physiological buffer (pH 7.4) at 37°C, demonstrated the covalent binding reaction to be stable, efficient, and permanent. Surface (FTIR‐ATR, ESCA, SEM/EDX) and bulk (solubility, GPC) properties demonstrated that the covalent binding of HEBP occurs in the soft segment of the PEU, reduces surface degradation, and does not affect the original material properties of the PEU (prior to derivatization). In vitro calcium diffusion of the derivatized PEU showed a decrease in calcium permeation as the concentration of HEBP covalent binding was increased. In vivo properties of underivatized and derivatized PEU (containing 100 nM of covalently bound HEBP) were studied with rat subdermal implants for 60 days. Explants demonstrated calcification resistance due to the covalently bound HEBP without any side effects. It is concluded that a PEU containing HEBP might serve as a calcification resistant candidate material for the fabrication of a heart valve prosthesis and other implantable devices. © 1994 John Wiley & Sons, Inc.
Physical properties of hyaluronic acid and hydroxypropylmethylcellulose in solution: Evaluation of coating ability
Authors: Silver Frederick H. , LiBrizzi Joseph , Pins George , Wang Ming‐Che , Benedetto Dominick
Published: May 2005

Hyaluronic acid (HA) and hydroxypropylmethylcellulose (HPMC) in buffered saline are “viscoelastics” used in ophthalmic surgery to prevent mechanical damage to delicate eye structures and to form a protective coating over corneal endothelium.

HA is a high molecular weight polysaccharide that exhibits decreasing viscosity at increased shear rates. HPMC is a cellulose derivative that exhibits low surface tension. This study examines the physical properties of HA and HPMC solutions and attempts to correlate these properties with the ability of those macromolecules to coat and protect ocular structures.

Results presented in this article suggest mixtures of HA and HPMC exhibit low surface tension and ease of aspiration characteristics that are desired in viscoelastic materials. For this reason a blend of these two macromoleculars offers handling advantages over each of these individual macromolecules. © 1994 John Wiley & Sons, Inc.
Processing and characterization of absorbable polylactide polymers for use in surgical implants
Authors: Andriano Kirk P. , Pohjonen Timo , Törmälä Pertti
Published: May 2005

Absorbable fibers of linear poly‐α‐hydroxy acids have been used successfully in providing temporary scaffolds for tissue regeneration. In some surgical applications, degradation rates for poly(glycolide) (PGA) are too high, but implants of poly(L‐lactide) (PLLA) fibers may degrade too slowly for optimal function. Polymers produced by copolymerization of L‐lactide with varying amounts of D‐lactide may offer an alternative choice for absorbable fiber based implants. Poly(L/D‐lactide) stereocopolymers with L/D lactide molar ratios of 95/5, 90/10, and 85/15 were considered. Melt‐spun/hot‐drawn fibers with L/D molar ratios of 90/10 and 85/15 and draw ratios ranging from 3.0 to 8.9 were further evaluated by mechanical testing, differential scanning calorimetry, birefringence, x‐ray diffraction, and in vitro exposure to pH 7.4 phosphate buffered saline at 37°C. Fabrication was reproducible and results indicated that tensile strength, modulus, and birefringence all increased with increasing draw ratio up to a draw ratio of 6.7 and declined thereafter; elongation to failure decreased for the entire range studied. For fibers with a draw ratio of 6.7, there was a 10% relative difference in crystallinity between the 90/10 and 85/15 lactide fibers (90/10 was higher). Wet strength retention after 12 weeks in vitro exposure was approximately 10% for the 90/10 fibers and 30% for the 85/15 fibers. The intermediate wet strength retention of lactide stereocopolymer fibers when compared to reported values for PGA and PLLA fibers, suggests these materials may be useful in absorbable surgical implants for tissue repair and regeneration. © 1994 John Wiley & Sons, Inc.
Six bioabsorbable polymers: In vitro acute toxicity of accumulated degradation products
Authors: Taylor M. S. , Daniels A. U. , Andriano K. P. , Heller J.
Published: May 2005

Bioabsorbable polymer implants may provide a viable alternative to metal implants for internal fracture fixation. One of the potential difficulties with absorbable implants is the possible toxicity of the polymeric degradation products especially if they accumulate and become concentrated. Accordingly, material evaluation must involve dose–response toxicity data as well as mechanical properties and degradation rates. In this study the toxicity and rates of degradation for six polymers were determined, along with the toxicity of their degradation product components. The polymers studied were poly(glycolic acid) (PGA), two samples of poly(L‐lactic acid) (PLA) having different molecular weights, poly(ortho ester) (POE), poly(ϵ‐caprolactone) (PCL), and poly(hydroxy butyrate valerate) (5% valerate) (PHBV). Polymeric specimens were incubated at 37°C in 0.05 M Tris buffer (pH 7.4 at 37°C) and sterile deionized water. The solutions were not changed during the incubation intervals, providing a worst‐case model of the effects of accumulation of degradation products. The pH and acute toxicity of the incubation solutions and the mass loss and logarithmic viscosity number of the polymer samples were measured at 10 days, 4, 8, 12, and 16 weeks. Toxicity was measured using a bioluminescent bacteria, acute toxicity assay system. The acute toxicity of pure PGA, PLA, POE, and PCL degradation product components was also determined. Degradation products for PHBV were not tested. PGA incubation solutions were toxic at 10 days and at all following intervals. The lower molecular weight PLA incubation solutions were not toxic in buffer but were toxic by 4 weeks in water. The other materials did not produce toxic responses during the 16‐week exposures. The degradation products components in order from most toxic to least toxic are: lactic acid (PLA), ϵ‐caproic acid (PCL), glycolic acid (PGA), cyclohexane dimethanol (POE), propionic acid (POE), 1,6 hexane diol (POE), pentaerythritol dipropionate (POE), and pentaerythritol (POE). © 1994 John Wiley & Sons, Inc.
Creep behavior of hand‐mixed simplex P bone cement under cyclic tensile loading
Authors: Verdonschot Nico , Huiskes Rik
Published: May 2005

Acrylic cement, used for the fixation of total hip replacements and other orthopedic implants, is a subject of renewed scientific interest as a result of recent hypotheses about dynamic, longterm mechanical failure mechanisms suspected to play a role in prosthetic loosening. Little is known, however, about the long‐term mechanical behavior of cement. In this study, the dynamic creep deformation of hand mixed acrylic cement was examined in laboratory tests. Strain patterns found represented the familiar creep process consisting of a primary, a secondary, and a tertiary creep phase. Specimens dynamically loaded with a maximum stress of 3 MPa from 0 were subject to creep of about 50% of the elastic strain after 250 000 loading cycles. A linear relationship between the logarithmic values of the creep‐strain and the number of loading cycles was found. Specimens exposed to higher loads showed significantly higher creep‐strains. No relationship could be established between the strain levels and the porosity of the specimens. Specimens dynamically loaded with a maximal stress of 7 or 11 MPa from 0 failed during the tests. The number of loading cycles to failure was similar to fatigue strength data reported in earlier literature. © 1994 John Wiley & Sons, Inc.