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At least 19 recordsLinked to original sources

PubMed2001

[Photoluminescence from Er-doped silicon-rich silicon oxide film and Er-doped silicon-rich silicon nitride film and its annealing behavior].

Room temperature photoluminescence (PL) with a peak at 1.54 microns was observed from silicon oxide, silicon-rich silicon oxide, silicon nitride and silicon-rich silicon nitride films, all doped with Er and grown by the magnetron sputtering technique. To determine the optimum annealing temperature for the 1.54 microns PL, these films were annealed in the range of 600-1,100 degrees C with an interval of 100 degrees C. Among these four types of films annealed at an identical temperature, the intensity of 1.54 microns PL peak of the Er-doped silicon-rich silicon oxide film was always the strongest one, which arrived at a maximum in 800 degrees C annealing. A 1.38 microns PL band was also observed in each of these four types of films, and which in the silicon-rich silicon oxide or silicon-rich silicon nitride films was found to be correlated with the 1.54 microns PL band in intensity.

Chemical Phenomena↗

PubMed2003

Influence of silicon dioxide-silicon interface trap charges on the performance of monolithic metal-zinc oxide-silicon nitride-silicon dioxide-silicon convolver.

An enhancement in the convolution efficiency is obtained by annihilating the SiO2-Si interface trap charges in the metal-ZnO-Si3N4-SiO2-Si convolver structure. The annealing process uses a source of hydrogen created underneath the SiO2-Si interface by implanting H3(+) ion followed by rapid thermal anneal of 5s at 900 degrees C. The silicon nitride layer is inducted to protect ZnO films from hydrogen influx during low temperature oxygen anneal.

Letter↗

PubMed1996

Silicon and silicone levels in patients with silicone implants.

Although a potential link between silicone gel breast implants and autoimmune connective tissue disease has been suggested, none has been proven. The potential role of silicone as an immune adjuvant remains very controversial. Currently available techniques do not easily allow precise measurements of silicone in tissues. However, all compounds containing silicon (which would include silicone) can be measured accurately. The present study was designed to measure silicon levels in the fibrous capsules of patients with silicone-gel breast implants, saline breast implants and silicone inflatable penile prostheses. Baseline control silicon levels were obtained from the breast tissue of patients undergoing breast reduction, who had no exposure to breast implants. All silicon measurements were carried out using atomic absorption spectrometry with a graphite furnace. The mean silicon levels in 16 breast tissue control samples from 8 patients undergoing breast reduction varied from 0.046 to 0.742 micrograms/g dry weight, with the median mean being 0.0927. The median silicon level in capsules from 6 patients with saline implants was 7.7 micrograms/g (range 36.6). The median silicon level in capsules from 5 patients with silicone inflatable penile prostheses was 19.5 micrograms/g (range 34.8). Although the levels of silicon in capsules of patients with saline breast prostheses and penile implants were higher than in control samples, they were much lower than those from the capsules of the 58 gel implants (median 9979 micrograms/g). Of the 58 silicone gel breast implants (from 20 patients with bilateral implant removal and 18 patients with unilateral removal) which had been inserted from 1974 to 1990, 28 were intact, 8 had pinhole leaks, and 22 were ruptured. Median capsule silicon levels and ranges for all 58 implants, for intact only, for leaking, and for ruptured were: 9979 (152,000), 10,477 (88,703), 6592 (65,396), and 9922 (152,387) micrograms/g respectively. There were no significant differences in silicon levels associated with implant status, duration in situ, or year of implantation. Capsule contracture was not associated with higher levels of capsule silicon. Capsule silicon levels were about 10(6) times higher than previously assayed blood silicon levels. This may be because silicone released from implants remains localized in capsular tissue, or because blood-borne silicone is quickly excreted. Using 29Si nuclear magnetic resonance spectroscopy, no detectable silicone was found in the blood of 7 control women and 7 women with silicone-gel implants (5 with known implant rupture).

Breast Implants↗

PubMed1998

Breast milk contamination and silicone implants: preliminary results using silicon as a proxy measurement for silicone.

In response to concerns about contamination of human breast milk from silicone gel-filled breast implants, and because silicon levels are assumed to be a proxy measurement for silicone, we compared silicon levels in milk from lactating women with and without implants. Two other sources of infant nutrition, cow's milk and infant formulas, were also analyzed for silicon. The survey took place at the Breast-feeding Clinic at Women's College Hospital in Toronto. A convenience sample of lactating women, 15 with bilateral silicone gel-filled implants and 34 with no implants, was selected. Women with foam-covered or saline implants or with medically related silicone exposures were ineligible. Collection of samples was scrupulously controlled to avoid contamination. Samples were prepared in a class 100 "ultraclean" laboratory and analyzed using graphite furnace atomic absorption spectrophotometry. Silicon levels were analyzed in breast milk, whole blood, cow's milk, and 26 brands of infant formulas. Comparing implanted women to controls, mean silicon levels were not significantly different in breast milk (55.45 +/- 35 and 51.05 +/- 31 ng/ml, respectively) or in blood (79.29 +/- 87 and 103.76 +/- 112 ng/ml, respectively). Mean silicon level measured in store-bought cow's milk was 708.94 ng/ml, and that for 26 brands of commercially available infant formula was 4402.5 ng/ml (ng/ml = parts per billion). We concluded that lactating women with silicone implants are similar to control women with respect to levels of silicon in their breast milk and blood. Silicon levels are 10 times higher in cow's milk and even higher in infant formulas.

Adult↗

PubMed1996

The prognostic utility of the Silicone Study Classification System. Silicone Study Report 9. Silicone Study Group.

OBJECTIVE: To evaluate the reproducibility and the prognostic utility of the Retina Society and Silicone Study Classification Systems in eyes after surgery for severe proliferative vitreoretinopathy (PVR). DESIGN: Subgroup analysis of the Silicone Study--a randomized, multicentered, surgical trial. SETTING: Community and university-based ophthalmology clinics. MATERIALS: Three hundred forty eyes with preoperative and intraoperative evaluations using both systems of grading PVR (reproducibility study), and 287 eyes with preoperative and intraoperative evaluations using both systems of grading PVR and with a 24-month follow-up examination (prognosis study). INTERVENTIONS: Vitrectomy for PVR with long-acting perfluoropropane gas or silicone oil as the intraocular tamponade. OUTCOME MEASURES: Retinal reattachment, visual acuity ( > or = 5/200), intraocular pressure, corneal clarity, and the need for reoperation. RESULTS: The reproducibility of the Silicone Study Classification System was 64% (type of contraction), 77% (number of clock hours), 67% (posterior PVR), 88% anterior and posterior PVR), and 94% (anterior, posterior, and subretinal PVR). The reproducibility of the Retina Society Classification System was 99%. Using the Silicone Study Classification System, location of PVR predicted visual acuity (P=.004, chi 2 test for trend) and hypotony (P=.03, chi 2 test for trend). Using the Retina Society Classification System, the grade of PVR predicted only visual acuity (P=.01, chi 2 test for trend). For eyes with anterior and posterior PVR, there was a decreasing trend in successful visual acuity outcome with increasing severity of PVR (from C-3 to D-3, P=.02, chi 2 test for trend). CONCLUSIONS: Although the classification of PVR using the Silicone Study classification System was not reproducible for the type of contraction or for posterior PVR, identification of the anteroposterior extent of the PVR was prognostic of visual acuity and hypotony at 24 months. The joint knowledge of the location of PVR (using the Silicone Study Classification System) and the tightness of the funnel for retinas with 9 to 12 clock hours involved by fixed folds (using the Retina Society Classification System) has prognostic utility for eyes with anterior and posterior PVR.

Adult↗

PubMed1993

Relaxing retinotomy with silicone oil or long-acting gas in eyes with severe proliferative vitreoretinopathy. Silicone Study Report 5. The Silicone Study Group.

In the Silicone Study, 117 of 404 eyes (29%) with severe proliferative vitreoretinopathy (> or = C-3, full-thickness retinal folds in three or more quadrants) enrolled in the study were treated with vitrectomy, underwent a relaxing retinotomy, and were randomly assigned to treatment with long-acting gas or silicone oil. Forty-six eyes (20%) had undergone no previous vitrectomy (group 1); 71 eyes (42%) had undergone previous vitrectomy (group 2) with intraocular gas tamponade (P < .001). Group 1 eyes not undergoing retinotomy had better anatomic (six months) and visual (six and 24 months) outcomes and less hypotony (six months) than eyes that did regardless of tamponade (P < .05). For eyes undergoing retinotomy, silicone oil decreased the likelihood of hypotony (six months, P < .05). These differences were not found in group 2 eyes. We conclude that eyes undergoing a vitreous operation for the first time for the treatment of proliferative vitreoretinopathy can in most instances be successfully treated by conventional techniques without the need for relaxing retinotomy. Retinotomy may be required more often in patients undergoing repeat vitreous surgery for proliferative vitreoretinopathy, in which case both silicone oil and long-acting perflouropropane gas appear to be equally effective.

Eye Diseases↗

PubMed1993

Bicanalicular silicone intubation using three-piece silicone tubing: direct silicone intubation.

The special silicone tube (50-120 mm in length) consists of three pieces. One piece is the thinner central segment [20-40 mm long, 0.64 mm outer diameter (OD), 0.30 mm inner diameter (ID)], and the other two are thicker bilateral segments (10-50 mm long, 0.94 mm OD, 0.51 mm ID). Both ends of the three-piece silicone tubing (TPST) were sealed by the silastic medical adhesive with or without the silicone rod (2 mm long, 0.5 mm diameter) and diagonally cut to taper the end. To push the TPST from the upper and lower puncta into the lacrimal passage, a thin metal probe (0.4-0.6 mm diameter) was inserted into both sides of the tube through a small cut. In this new technique, there is no difficult procedure of retrieving the tip of a metal probe from the nasal cavity. The TPST requires no suture to secure it in position. The success rates were 63.6% (7/11), 100% (5/5) and 50% (1/2) for nasolacrimal-duct obstruction, canalicular obstruction, and canalicular and nasolacrimal-duct obstructions, respectively (follow-up: 3.4-12 months, mean 5.3 months).

Adult↗

PubMed2002

Formation of silicon carbide nanotubes and nanowires via reaction of silicon (from disproportionation of silicon monoxide) with carbon nanotubes.

One-dimensional silicon-carbon nanotubes and nanowires of various shapes and structures were synthesized via the reaction of silicon (produced by disproportionation reaction of SiO) with multiwalled carbon nanotubes (as templates) at different temperatures. A new type of multiwalled silicon carbide nanotube (SiCNT), with 3.5-4.5 A interlayer spacings, was observed in addition to the previously known beta-SiC (cubic zinc blende structure) nanowires and the biaxial SiC-SiO(x) nanowires. The SiCNT was identified by high-resolution transmission microscopy (HRTEM), elemental mapping, and electron energy loss spectroscopy (EELS). The multiwalled SiCNT was found to transform to a beta-SiC crystalline structure by electron beam annealing under TEM.

Journal Article↗

PubMed1999

Silicon assays in women with and without silicone gel breast implants--a review.

During the past 5 years, as the failure properties of silicone gel breast implants have emerged, there has been considerable interest in measuring the levels of silicone and silicon in blood, serum, breast milk, and body tissues. Assays have been done in control patients without implant exposure, and in patients with silicone gel implants in an attempt to predict implant failure. Nuclear magnetic resonance measurements of silicone compounds have not been helpful because of their low sensitivity of detection. However, all compounds containing the element silicon, which includes silicone, have been measured accurately. Modern techniques, such as electrothermal atomic absorption spectrometry, direct-current plasma emission spectrometry, and inductively coupled plasma emission spectroscopy have allowed precise measurement of silicon in body fluids and tissues. Using these techniques, recent studies have demonstrated consistent levels of silicon in the blood and plasma of control women without exposure to implants. In one study, plasma silicon was shown to be 140 +/- 10 ng per milliliter. In four other studies, serum silicon levels in control patients were the following: mean, 130 +/- 70 ng per milliliter; mean, 170 +/- 100 ng per milliliter; median, 100 ng per milliliter (range, 30-209 ng per milliliter); and 10 to 250 ng per milliliter. Three independent studies have shown that women with silicone gel implants have higher blood and serum silicon levels than control subjects, but their values were still within the range of control subjects. One study has shown that the mean silicon level in breast milk was not significantly different between 15 implant patients and 34 control patients. The measurement of silicon in control breast tissue has shown consistent results in three different studies, with most tests varying from <0.2 to 2.2 microg per gram dry weight. Three studies have shown that capsules from women with silicone gel breast implants had markedly elevated silicon levels compared with control breast tissue. Median silicon levels varied from 9,980 to 14,390 microg per gram dry weight. There was no significant difference in capsule silicon level between intact and ruptured implants or associated with implant duration in situ or year of implantation. Four studies have shown that capsules from saline implants had elevated levels of silicon compared with control tissue, but their silicon levels were much lower than those of gel implants. The median levels of silicon in the capsules of these studies were as follows: 7.7, 71.5, 198, and 1,100 microg per gram dry weight. Based on current knowledge, because of the large variability among patients, the use of silicon measurements in blood, serum, breast milk, or implant capsule tissue has no clinical role for the effective monitoring of implant leakage in women with silicone gel breast implants.

Breast Implants↗

PubMed1996

Silicon analysis of breast and periprosthetic capsular tissue from patients with saline or silicone gel breast implants.

The ubiquitousness of silicon is well known. Recent work has demonstrated measurable baseline levels of silicon in nonaugmented cadavers, subsequent to numerous reports of significant elevations of such levels within patients with silicone breast implants and even more reports alleging a causal relation between silicone gel prostheses and connective-tissue diseases. Despite the lack of scientifically substantiated data that such a relation exists, the calamitous silicone breast implant controversy has ensued. Saline-filled breast implants are constructed with a silicone elastomer envelope that remains in direct contact with periprosthetic capsular tissue following implantation. Although there is no evidence to link saline implants with any disorders, it is important to know if saline breast implants contribute any silicon to human body baseline silicon levels. The present study measured tissue silicon levels in 28 breasts of 16 patients with saline-filled implants to determine if the silicone envelope of these prostheses can contribute to the elevation of such levels. These data were compared with data from 116 breasts of 65 patients with silicone gel-filled prostheses as well as breast tissue from 17 patients (controls) who had never been exposed to either type of implant. Samples of breast tissue and periprosthetic capsular tissue were obtained from patients with both intact and ruptured implants. Silicon levels of breast tissue specimens from patients with saline-filled implants were within the range of the controls if the implants were intact. Silicon levels in periprosthetic capsular tissue from patients with intact saline-filled implants were significantly higher than controls (p < 0.02); however, they were still 100-fold less than capsular tissue levels from patients with intact gel-filled implants. Silicon levels measured in both types of tissue were significantly elevated in patients with silicone gel-filled implants compared with controls (p < 0.01). In the case of ruptured gel implants, breast tissue demonstrated higher silicon levels than did similar specimens from patients with intact implants (p < 0.054); periprosthetic capsular tissue levels also were elevated, although the differences were not statistically significant (p = 0.54). These findings are independent of the implant brand or length of exposure to the particular prosthesis. The finding of elevated levels of silicon in both breast and periprosthetic capsular tissue in patients with silicone gel-filled implants in no way implies or substantiates any claim of a causal relationship between silicone and any reported illnesses.

Adult↗

PubMed1994

Antibody to silicone and native macromolecules in women with silicone breast implants.

Silicone implants have been associated with the development of multiple organ system abnormalities, including rheumatic disorders, nervous system, pulmonary dysfunction associated with autoantibodies and abnormalities of cellular immunity. In this regards a number of case reports and series of articles have been described. We hypothesized that an immune reaction to silicone breast implants would include the host reactivity against silicone and the macromolecules within the microenvironment of the implant, and these autoantibodies may react with other tissue antigens far from the site of the implant. To test this hypothesis 520 Symptomatic women with Silicone Implants which have developed Silicone related Immunological disorders and have typically complained of breast pain, Myalgia-Arthralgia, fatigue, or generalized pain, were examined by their physician. Blood samples were obtained and examined for the presence of Silicone antibodies, Myelin Basic Protein and human serum albumin antibodies. These samples were then compared to 520 matched controls without implants. At least at the level of two standard deviation silicone specific antibodies, IgG, IgA IgM, IgE and IgG+IgA+IgM antibodies were detected above the mean of normal controls. When these antibodies were classified based on the specialty of the examining physician, the % of patients with Silicone Antibodies were varied; general practice 51.6, Rheumatology 58.7, and Plastic Surgery 83.3, which may relate to the severeness of the disease. Being that a large % of patients demonstrated very high levels of Myelin Basic Protein Antibodies, possible cross reactive antibodies were sought. However, absorption of highly positive sera for Silicone Antibodies with MBP did not change the levels of Silicone Antibodies. On the other hand, Silicone-HSA was able to reduce the antibody values significantly. This reduction in antibody levels by Silicone is the best indication for the specificity of these antibodies. Moreover when data for silicone antibodies and MBP antibodies was analyzed in patients some with high and others with medium or low levels of silicone antibodies, MBP antibodies did not correspond to the silicone antibody levels. Similarly human serum albumin antibodies which was significantly higher in patients with silicone implants did not correlate with levels of silicone antibodies. These results indicate that immune reaction to silicone and different tissue antigens do occur and they are initiated through different mechanisms. And since predominant antibody class against silicone, MBP and HSA was IgM, clonal activation of IgM is possible which certainly warrants further investigation.

Adult↗

PubMed1998

The effect of silicone ocular surgical devices on serum IgG binding to silicones.

PURPOSE: To determine whether silicone materials used in retinal detachment repair and cataract surgery increase serum IgG binding to silicone and identify correlations with complications of ocular surgery. METHODS: Serum from 49 patients who had ocular surgery using silicone materials was examined. Patient groups included scleral buckling (n = 25), silicone oil tamponade (n = 3), scleral buckling and silicone oil tamponade (n = 9), and silicone lens implants after cataract extraction (n = 12). Convalescent samples for all patients and preoperative samples from 19 patients (18 scleral buckling and one silicone oil tamponade) were examined. Postoperative complications were monitored for up to 108 months (mean, 10.7 months; mode, 1.5 months; range, 1 to 108 months). Samples were evaluated for the extent of IgG binding to silicones using a micromodification of a previously described enzyme-linked immunosorbent assay method. RESULTS: In 19 patients, IgG binding levels in preoperative samples were 21 arbitrary units (AU) or less. Of the 25 buckling patients, one developed complications; however, in all patients the postoperative levels of IgG binding to silicone were low (2.2 to 20.0 AU). Although four silicone lens patients developed mild complications, none displayed postoperative IgG binding levels of greater than 20 AU. Three patients who underwent both scleral buckling and silicone oil tamponade developed complications; one of these patients, who was also noted to have systemic connective tissue disease, had a significant elevation in postoperative serum IgG binding to silicone. CONCLUSIONS: Statistically significant elevations of serum IgG binding to silicone were noted postoperatively in only one patient who had a systemic connective tissue disease. The complication rate and frequency of enhanced serum IgG binding to silicone was low, making correlations to surgical complications difficult. Examination of matched samples suggested that if ocular exposure to silicone implants enhances the level of serum IgG binding to silicones, it must be a rare event that should not alter the clinical use of these important devices.

Adult↗

PubMed1998

Silicon analysis of breast and capsular tissue from patients with saline or silicone gel breast implants: II. Correlation with connective-tissue disease.

The silicone breast implant controversy rages on. Recent work has demonstrated that normal or baseline breast tissue silicon levels in women who had had no prior exposure to any type of breast implant may be as high as 446 microg/gm of tissue. These data ranged from 4 to 446 microg/gm of tissue, with a median of 27.0 microg/gm of tissue. In addition, numerous other epidemiologic and rheumatologic studies have demonstrated no association between silicone breast implants and any connective-tissue diseases. Despite these reports, the use of silicone implants remains restricted. The present study measured breast and capsular tissue silicon levels from 23 breasts in 14 patients with saline implants, and from 42 breasts in 29 patients with silicone implants. No patient in the saline implant group presented with signs or symptoms of connective-tissue disease. Patients with silicone implants, however, were divided into three groups based on the presence or absence of signs or symptoms of connective-tissue disease: group I, no symptoms or signs; group II, + symptoms, no signs; and group III, + symptoms, + signs. Six patients in group III were diagnosed with a specific connective-tissue disease, including systemic lupus erythematosus, rheumatoid arthritis, or scleroderma. The most common indications for implant removal or exchange were capsular contracture and implant rupture, although 41 percent of patients with silicone implants expressed media-related concern over the implant issue. The most common symptoms described by patients in groups II and III were joint pain and stiffness, arm pain and numbness, and fatigue. In all groups, capsular tissue silicon levels were significantly greater than breast tissue levels. This finding may indicate that the capsule serves as a barrier to the distribution of silicone from the implant into adjacent breast tissue. Although breast tissue silicon levels in patients with silicone implants were not significantly greater than those in patients with saline implants (p = 0.48), capsular tissue levels in patients with silicone implants were, indeed, significantly greater than those in patients with saline implants (p < 0.001). However, no statistically significant differences in tissue silicon levels were observed with relation to the presence or absence of connective-tissue disease signs or symptoms in patients with silicone implants (groups I to III). Therefore, these data strengthen the conclusion that there is no association between tissue silicon levels and connective-tissue disease.

Breast↗

PubMed1995

Migration and accumulation of silicone in the liver of women with silicone gel-filled breast implants.

1H NMR localized spectroscopy (STEAM), combined with echocardiography (ECG), respiratory gating, and water and fat suppression, was used to quantify silicone concentrations in the liver of women with silicone gel-filled breast implants. Localized spectroscopy was performed on 15 patients with silicone gel-filled breast prostheses and on eight volunteers with no implants. The 1H spectra in the liver of patients showed silicone resonances from 0.3 to -0.8 ppm, attributable to protons in the methyl groups of silicone. The presence of silicone in the liver could first be detected 3-4 years after breast prostheses implantation. No correlation between silicone concentrations and implantation times was observed. However, our results indicated that silicone concentrations may reflect implant integrity: detectable silicone concentrations in the liver appeared to be higher when the implants were ruptured than when the implants appeared intact. Moreover, new resonances in the range of -2.6 to -4 ppm were observed in most patients after long-term implantation. As these species increase with implantation time, the new resonances may reflect chemically changed silicone (paramagnetically shifted silicon complexes bound to iron) accumulated over time. The sensitivity of 1H NMR localized spectroscopy is sufficient to detect silicon concentrations as low as 0.20 mM. Results from one patient whose implants had been removed 14 months prior to the NMR examination showed no detectable silicone in the liver, indicating that it may have been excreted via bile or degraded to silica and high coordinated silicon complexes. Quantitative 1H localized spectroscopy of the liver in women with silicone gel-filled breast implants may provide valuable information concerning silicone accumulation and degradation in vivo, as well as about the kinetics of its elimination from the body after implant removal.

Breast Implants↗

PubMedDate not supplied

Release and skin distribution of silicone-related compound(s) from a silicone gel sheet in vitro.

The efficacy of topical silicone gel sheeting in prevention and/or reduction of keloids and hypertrophic scars is well recognized. In the present study, we reexamined the possible release of silicone-related compound(s) from a commercially available silicone gel sheet (Cica-Care, Smith and Nephew, Hull, England) in aqueous media in vitro. The silicone gel sheet was also applied on the excised skin surface to examine the possible distribution of silicone-related compounds into the skin in vitro. Silicone-related compounds were measured as silicon by an inductively coupled plasma-atomic emission spectrophotometer. When a piece of silicone gel sheet was placed in phosphate buffer solution (pH 3-9) at 37 degrees C for 7 days, the concentration of silicon in the medium increased with time, depending on the pH of the medium. This indicates that the released silicone-related compounds are water-soluble. When Cica-Care was applied on the surface of excised rat skin, human axilla skin and hypertrophic scars under hydrated conditions in vitro, silicon was detected in all skin samples. Greater distribution was observed in rat skin than in human axilla skin and hypertrophic scars. The release of silicone-related compounds from a silicone gel sheet (Cica-Care) and their distribution into the skin were demonstrated in vitro. Silicone-related compounds distributed into the skin may have pharmacological effects on the skin. Further investigation will be necessary to investigate in detail the action of silicone-related compounds on the proliferation of fibroblasts and excessive production of collagen.

Adolescent↗

PubMed2001

Laser resurfacing of silicone-injected skin: the "silicone flash" revisited.

OBJECTIVE: To determine whether prior silicone injection increases the risks associated with carbon dioxide laser resurfacing. DESIGN: Laboratory determination of the effect of laser energy on liquid silicone; histologic evaluation of silicone-injected skin after lasing; and histologic demonstration of silicone deposits in all layers of dermis years after injection of silicone as filler fluid. SETTING: Tertiary care medical center. PATIENT-RELATED DATA: Histologic examination of freshly excised skin injected with microdroplets of liquid silicone and subjected to application of carbon dioxide laser energy; histologic examination of skin excised years after silicone injection. INTERVENTIONS: High-speed clinical photographic imaging of the effect of laser energy on silicone fluid; histologic examination of hematoxylin-eosin-stained sections of skin injected with liquid silicone and subsequently lased. MAIN OUTCOME MEASURES: Response of liquid silicone to application of laser energy; effect of this response on surrounding normal skin. RESULTS: Exposure of microdroplets of liquid silicone to carbon dioxide laser energy produced flaring with frank flame. Flaring of dermal silicone caused collateral skin damage. CONCLUSIONS: Prior injection with liquid silicone is a relative contraindication to cutaneous resurfacing with the carbon dioxide laser. Surgical excision of silicone-injected skin may be preferable for many patients. A strenuous needs assessment should be done, alternatives for skin rejuvenation considered, and comprehensive informed consent obtained from the patient before embarking on laser resurfacing of silicone-injected skin.

Carbon Dioxide↗

PubMed1997

Release of low molecular weight silicones and platinum from silicone breast implants.

We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was also observed to leak through intact implants into lipid-containing media at rates of approximately 20-25 micrograms/day/250 g of implant at 37 degrees C. The rates at which both LM-silicones and platinum have been observed to leak from intact implants could lead to significant accumulation within lipid-rich tissues and should be investigated more fully in vivo.

Breast Implants↗

PubMedDate not supplied

The non-specific binding of immunoglobulins to silicone implant materials: the lack of a detectable silicone specific antibody.

Recent studies have suggested that anti-silicone antibodies develop in patients implanted with silicone materials. The majority of these studies have utilized enzyme-linked immunosorbent assay (ELISA) methodology with a silicone material substrate as a means to detect the presence of the anti-silicone antibody. The current studies were undertaken to determine whether the binding of IgG to a silicone substrate was consistent with an antigen-specific antibody interaction or the result of non-specific hydrophobic interactions. While significant differences were detected in serum from silicone antibody "positive" and "negative" patients when the ELISA was conducted using a phosphate buffered saline (PBS)-0.05% Tween 20 (Tween) blocking system, the difference in the responses was attenuated when protein blocking systems were used or when incubation times were decreased. Furthermore, ELISA studies, using purified mouse and human IgG, demonstrated a concentration-dependent binding of IgG to silicone elastomer substrate which was also attenuated when a protein blocking system was used in lieu of Tween. In controlled animals studies in which female B6C3F1 mice were implanted with silicone gel or silicone elastomer for 180 days, no difference was observed between the implanted animals and the PBS control animals with respect to binding of IgG to the silicone substrate. Similar studies in female Fischer 344 rats implanted with silicone gel for 84 days also failed to demonstrate the presence of anti-silicone antibody. Collectively, the results suggest that the binding of IgG to silicone implant materials is non-specific in nature, consistent with the well-recognized interactions between hydrophobic molecules (IgGs) and hydrophobic surfaces (silicones) in an aqueous-based system.

Animals↗