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Biomedical subjects

V L Young

Publications and source records attributed to V L Young.

At least 19 recordsLinked to original sources
PubMed2002

The effect of cyclic swelling (octamethylcyclotetrasiloxane) on the physical properties of silicone breast implant shells.

Changes in the physical and mechanical properties of silica filled silicone elastomeric films were studied as a function of repeated sorption extraction cycling. The sorption of octamethylcyclotetrasiloxane (D4) on the properties of three silicone filled elastomeric films was analyzed. Two of the films, SILASTIC I and SILASTIC II, were shells of explanted breast implants and the third, a calendered film, prepared with similar composition to the elastomer used for the breast prosthesis were studied. The as-received (AR) SILASTIC I and II films contained 20 and 26.5 wt% non-cross-linked material that was removed by extraction with hexane. The failure properties of the extracted films are significantly higher than those of the AR films. The amount of swelling, weight gain, volumetric change, and the stress- and strain-to-fail of the films were measured in the as-received condition, and after a series of extractions and swellings. Repeated cycling (up to 5 cycles) of extraction-swelling had essentially no effect on the failure properties of films when all the diluent was removed. The effect of diluent on the failure properties of all three films was quite large. The stress-to fail of the swollen film was reduced a factor of 6 compared to baseline extracted samples while the corresponding strain values were reduced a factor of 5. The energy to fail of the swollen compared to baseline films was reduced almost a factor of 50. However, the overall mechanical properties of the films are restored when the diluent was removed. The mechanical forces involved in the swelling process do not degrade the polymer even when cycled through five swell-extract cycles.

Absorption↗
PubMed2001

Variability in the properties of silicone gel breast implants.

Several generations of silicone gel breast implants have been produced by implant manufacturers. The primary material usually viewed as the base material in the manufacture of implants is polydimethylsiloxane. Polymeric reactions are notorious for their variability and nonuniformity. The elastomer used in different types of implants can have vastly different properties. Furthermore, the material properties associated with a particular type of implant can vary considerably from one lot to the next. Considering the various designs, styles, and manufacturing techniques associated with silicone gel implants, knowledge of the original properties of the implants before implantation is important in determining the effects of aging in vivo. This study was conducted to investigate differences in key mechanical and chemical properties of silicone gel breast implant materials. The two types of implants chosen for analysis were Silastic I and Silastic II control implants. Material property data were determined for both types of controls and significant differences were found in their values. Lot-to-lot variability was also investigated and found to be significant.

Breast Implants↗
PubMed2001

Scanning electron microscopy characterization of surgical instrument damage to breast implants.

In this article, mechanisms of breast-implant failure caused by surgical instruments commonly used to perform implantation, breast biopsies, needle localization procedures, cyst aspirations, and explantation are described. Failure was artificially induced in breast-implant shells using various types of surgical instruments, including scalpels, suture needles, hypodermic needles, hemostats, and Adson forceps. Field-emission scanning electron microscopy (SEM) was used to document the morphology of the failure sites produced by these instruments. Micrographs were used to categorize failure according to a specific type of surgical instrument. SEM micrographs were also obtained on explants that failed in situ, and the morphology of the corresponding failure sites was examined. The study was designed to document a range of failure mechanisms associated with gel-filled, saline-filled, double-lumen (saline-gel), and soybean oil-filled implants. The results of the study also demonstrate that SEM can often be used to determine the cause of breast-implant failure.

Breast Implants↗
PubMed2001

The transport of octamethylcyclotetrasiloxane (D4) and polydimethylsiloxane (PDMS) in lightly cross-linked silicone rubber.

The transport of octamethylcyclotetrasiloxane (D4), one of the major constituents of silicone fluids and rubbers, and low viscosity polydimethylsiloxane oil into a silica filled cross-linked silicone elastomeric rubber was measured as a function of temperature, cross-link density of the rubber, and concentration of the D4 in methanol solution. A small amount of material, approximately 3 wt%, is extracted from the rubber with hexane. The extraction process has a large effect upon D4 solubility in the rubber, increasing from approximately 160 to 180 wt% after extraction. The heats of solution for both penetrants into the rubber are essentially zero and the activation energies for diffusion are small, approximately 8 and 15 kJ molt(-1) for D4 and PDMS, respectively. The diffusion process is Fickian and the diffusion coefficient of D4 into silicone/silica rubbers is essentially independent of concentration over the concentration investigated, i.e. from 1 to 100 vol% D4 in methanol. The permeability, i.e. the product of the diffusion coefficient and the solubility, decreases rapidly for D4 concentrations less than 50 vol% (0.1 mol fraction). This suggests that the permeation of D4 out of any encapsulation device, such as a silicone breast implant, is linearly dependent upon the concentration of D4 in the prosthesis. Swelling is isotropic and was measured by dimensional changes in rectangular samples and correlates well with the volume of D4 sorbed.

Adsorption↗
PubMed2001

Breast implant research: where we have been, where we are, where we need to go.

This article summarizes the current state and future needs of research into saline-filled and silicone gel breast implants. The authors describe recent investigations into possible causes and potential risk factors for silicone gel and saline implant failure. Also discussed are local complications of breast implantation and the need for revisional operations in augmentation and reconstruction patients. In addition, the effects that surgical, implant, and patient variables have on the aesthetic outcome of surgery are addressed. The last portion of the article lays out future research needs, such as determining the incidence rate of implant failure, reducing the frequency of revisional surgery, and the difficulty of designing better breast implants in the current strict regulatory climate.

Breast Implants↗
PubMed2000

Effect of surgical insertion on the local shell properties of SILASTIC II silicone gel breast implants.

The reasons for the failure of silicone gel breast implants are unclear. One potential failure mechanism is the weakening of the implant shell during its insertion into the breast. Such local weakening could eventually lead to implant failure. We recently reported on the effect of implant surgery on the overall mechanical properties of SILASTIC II gel-filled implants. In the earlier study, the mechanical properties of 34 Dow Corning SILASTIC II gel-filled breast implants from the same manufacturing lot were measured. Twenty of the thirty four implants were not implanted but were evaluated to establish a baseline of control data. The other fourteen lot-matched implants were inserted into a subglandular pocket through an inframammary incision in a cadaver breast and then removed. The experimental augmentation scenario was designed to represent actual breast implantation as closely as possible. The mechanical properties of the anterior and posterior sides of the control implants (not implanted) and explants (implanted in a cadaver) were measured and compared to determine whether differences existed between the explant and control groups. We found that the implantation surgery process did slightly reduce the average tensile strength. Although not as statistically significant, other mechanical properties such as breaking energy and moduli were less for the explants than the controls. The reduction was a relatively small percentage in the context of overall shell properties. Elongation and tear resistance were unaffected. Our findings suggested that the surgical act of implanting a breast implant has a small but detectable weakening effect on the average tensile strength, breaking energy and moduli of the elastomeric shell of the device. The present study is an extension of the previous investigation. Here we have analyzed the explant shell region where the surgeon's fingers forced the implant through the incision. Our results indicate that the implant shell can be locally damaged due to the implantation process.

Breast Implantation↗
PubMed1999

Analysis of periprosthetic capsular tissue from women with silicone breast implants by magic-angle spinning NMR.

The amount of silicone (polydimethylsiloxane [PDMS]) in capsular tissue surgically removed from women with breast implants was measured by using (29)Si and (1)H magic-angle spinning solid-state NMR spectroscopy. Twelve women having smooth surface silicone gel-filled implants, including a subject with "low-bleed" double-lumen implants, had detectable levels of PDMS ranging from 0. 05 to 9.8% silicon in wet tissue (w/w). No silicon-containing compounds other than PDMS were detected. No correlation was found between the amount of PDMS measured in the capsular tissue and the length of implantation time (Pearson correlation coefficient, r = 0. 22). The results showed no relationship between higher amounts of PDMS and capsular contracture (p = 0.74) or other symptoms (p = 0. 53). Magn Reson Med 42:436-441, 1999.

Breast↗
PubMed1999

Elemental analysis and clinical implications of calcification deposits associated with silicone breast implants.

Calcification of the fibrous capsule surrounding silicone breast implants is a well-recognized occurrence that increases with time following implantation. These mineralized deposits potentially confound mammographic breast cancer surveillance already made difficult by the obscuring effects of silicone breast implants. The authors performed elemental analysis of silicone breast implant-associated calcifications to define better their chemical composition as related to mammographic and clinical significance. Electron probe microanalysis and infrared spectroscopy revealed all of the calcification deposits to be calcium complexed with tribasic phosphate. No evidence of calcium oxalate, calcium carbonate, silicone, or talc was observed. Caution must be employed in interpreting mammograms in women with silicone breast implants as well as those who have had their silicone breast implants removed. High-density mammographic calcifications indicative of calcium phosphate associated with a silicone breast implant may represent an accepted consequence of implantation or nearby carcinoma. We recommend baseline mammography on women who have had their silicone breast implants removed to prevent unnecessary fine-needle aspiration or tissue biopsy of retained breast capsule calcifications during subsequent routine surveillance for carcinoma.

Breast↗
PubMed1999

Analysis of breast implant capsular tissue for crystalline silica and other refractile phases.

This study questions previous reports of the presence of micrometer-sized areas of crystalline silica in pathologic tissue sections that are based exclusively on polarized-light microscopy. By using optical principles, it can be argued that it is impossible to identify unambiguously or to detect the birefringence of crystalline silica in 5-microm-thin sections. To clarify whether silicone, amorphous silica, or crystalline silica occurs in micrometer-sized moieties in standard 5-microm-thick tissue sections, one needs to apply a structural means of analysis in addition to optical microscopy. This study recommends the use of the laser Raman spectroscopic technique, which is very well suited to clarify this highly controversial issue in future pathologic studies.

Breast↗
PubMed1999

Vilray P. Blair, his surgical descendants, and their roles in plastic surgical development.

Perhaps one of the most historically well-known plastic surgeons is Vilray P. Blair. As commander of the U.S. Army corps of head and neck surgeons during World War I, he became well known for his work in posttraumatic reconstruction. Blair's efforts in the early part of this century helped to develop plastic surgery as a distinct surgical subspecialty in the United States. His prowess as a surgeon allowed him to build one of the largest plastic surgery centers in the country and to train many of the top young American surgeons. Blair excelled as a teacher. He produced academic surgeons such as James Barrett Brown and Bradford Cannon, who took the lead in the care of wartime injuries during World War II. At Valley Forge General Hospital, Blair's trainees dedicated themselves to the reconstruction of injured patients and trained other young plastic surgeons in the care of postwar trauma. This exceptional level of patient care resulted in the U.S. government recognizing plastic surgery as a subspecialty following World War II. Since that time, Blair's surgical descendants at Washington University have led the country in the development of new training concepts and ideals and have gone on to become leaders in plastic surgery worldwide.

History, 19th Century↗
PubMed1999

Silicone gel-filled breast and testicular implant capsules: a histologic and immunophenotypic study.

The immunophenotypic characteristics of silicone gel-filled breast and testicular implant capsules have not been well described. Therefore, we studied 17 paraffin-embedded tissue sections from 9 breast implant patients and 1 testicular implant patient to assess the type and extent of inflammatory responses present. Immunohistochemical analyses were performed on paraffin-embedded tissue sections for expression of CD20, CD45RO, betaF1, CD68, CD44, kappa and A immunoglobulin light chains, and bcl-XL (a member of the bcl-2 family of proteins involved in apoptosis). The most common histologic features included prominent T-cell and foamy macrophage reactions with foreign body giant cells and granulomas in a dense fibrovascular connective tissue. Foci of polyclonal plasma cells and acute inflammatory cells were variably present. In one case, there was reactive germinal center formation, a novel finding. A "pseudosynovium" at the implant capsule interface was present in the majority of cases as previously described; it showed reactivity with CD68. Thin strands of highly refractile, nonpolarizable material, consistent with silicone, were regularly noted in intra- and extracellular locations. The immunohistochemical results included reactivity of the majority of lymphocytes with CD45RO and/or betaF1 (confirming an anamnestic reactive T-cell phenotype), and reactivity of the macrophages, giant cells, and "pseudosynovium" with the macrophage/histiocyte marker, CD68. The reactive germinal centers were positive for CD20. Reactivity for CD44, an activation and intracellular adhesion marker, was frequently observed in the foamy macrophages and foreign body giant cells and has not been previously reported. The plasma cells demonstrated polyclonal immunoglobulin light-chain reactivity, consistent with a reactive process. These findings suggest that silicone implants induce chronic inflammatory responses in many adjacent capsules, which consist of anamnestically responding T cells, reactive B-lymphocytes, and macrophages.

Adult↗
PubMed1999

Report from the conference on ultrasound-assisted liposuction safety and effects.

The authors report on the Ultrasound-Assisted Liposuction (UAL) Safety and Effects conference held in St. Louis, Missouri, in November 1998. The meeting was convened to discuss how internal UAL works (its physics and mechanisms of action), gain a basic knowledge of the interaction between acoustic energy and tissue, identify safety concerns potentially related to thermal effects and free radical production, and define future research questions. Those attending represented multiple scientific disciplines: plastic surgery, physics, lipid chemistry, cancer biology, and medical biophysics. Participants agreed that scientists do not yet understand the mechanisms of UAL action, although multiple mechanisms are probably involved, such as mechanical forces, cavitation, and thermal effects. Additional research has revealed that long-term complications or negative bioeffects--including DNA damage and oxidation-free radical attack--are probably not serious safety concerns with UAL. Several areas deserving future investigation were proposed.

Acoustics↗
PubMed1998

Long-term results of total penile reconstruction with a prefabricated lateral arm free flap.

PURPOSE: We present 5-year followup results of patients who underwent total penile reconstruction with a prefabricated lateral arm free flap technique. MATERIALS AND METHODS: We treated 3 female-to-male transsexuals and a man with penile amputation with a 2-stage technique of total penile reconstruction. In the first stage the neourethra is constructed as a tubed skin graft incorporated in the territory of the lateral arm flap. Three to 6 months later the lateral arm flap with its well epithelialized conduit is fashioned into a penis, an inflatable prosthesis is incorporated and the construction is transferred to the pubis with vascular, urethral and nerve repairs. RESULTS: In addition to the 2 surgical procedures required to construct the penis, the patients have required an average of 3 revisions. There were no complications beyond the first year postoperatively. All 4 patients are able to void in the standing position and are free of fistulas or strictures. The inflatable prosthesis allows them to achieve penetration during sexual intercourse. All reconstructed penises have recovered erogenous and tactile sensibility. Patient satisfaction with the reconstructed penis is high. All transsexuals are married and fully integrated as men. CONCLUSIONS: With the prefabricated lateral arm free flap technique it is possible to achieve a fully functional penis with stable long-term results and excellent patient satisfaction. To our knowledge our series represents the first report of a technique for functional penile reconstruction with at least 5 years of followup.

Adult↗
PubMed1998

Guidelines and indications for breast implant capsulectomy.

This article discusses indications for performing a capsulectomy in conjunction with explantation of breast implants. This issue has rarely been addressed in the literature, and there is no consensus on guidelines to assist surgeons in deciding whether a capsulectomy is warranted. The many factors that must be weighed when considering performance of a capsulectomy are outlined, and recommendations for the explantation contexts in which capsulectomy may be considered optional or should usually be performed are given. Capsulectomy may be indicated in the majority of instances when breast implants are removed or exchanged, but the potential risks of capsule removal must always be balanced against the potential benefits.

Breast Implantation↗
PubMed1997

Mammographic visualization of a nonpalpable breast mass through a radiolucent breast implant.

We report a woman who underwent augmentation mammaplasty as part of a clinical trial of the Trilucent (soybean oil-filled) breast implant in Genoa, Italy. Five months after surgery a mammography was performed in response to the patient's complaints of pressure and tightness in the area of her left breast. The mammogram clearly demonstrated a 5-mm fibroadenoma of the left breast. This is the first documented case of a nonpalpable breast lesion that was detected by mammography through the new radiolucent, triglyceride-filled implant.

Adult↗
PubMed1997

Microbial growth inside saline-filled breast implants.

In vitro and in vivo experiments were conducted to determine whether intraluminal saline in breast implants can support the growth of common wound-infecting microorganisms over a prolonged period of time. The bacteria tested were Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Corynebacterium jeikeium, Enterobacter cloacae, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Three fungal species also were tested: Aspergillus fumigatus, Paecilomyces variotii, and Candida albicans. In the in vitro study, four organisms survived in flasks of sterile saline for the 2 weeks in which serial cultures were performed: K. pneumoniae, C. albicans, A. fumigatus, and P. variotii. In the in vivo study, 61 white rabbits (122 implants) received both an experimental implant inoculated with one of the test organisms and a control implant containing only sterile saline. They were sacrificed at 1-, 3-, or 6-month scheduled endpoints. None of the control implants containing sterile saline had positive cultures. In contrast, the intraluminal saline was culture positive for 7 of the 10 inoculated organisms after varying lengths of time: S. epidermidis, E. coli, E. cloacae, K. pneumoniae, P. aeruginosa, A. fumigatus, and P. variotii. Samples of capsular tissue also were cultured. Of the 122 capsular tissue specimens, 21 (17 percent) had positive cultures and surrounded both inoculated and sterile implants. In most instances, capsules that were culture positive contained an organism different from the one that had been inoculated in the group. In only 3 cases was the same organism cultured from both the periprosthetic tissue and the intraluminal saline, and these may represent instances of the inoculated organism migrating through the implants filler valves. The data show that several types of bacteria (particularly gram-negative species) and fungi can grow and reproduce in a restricted saline environment for extended periods of time.

Animals↗