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PubMed1996

Plasmacytoma development in mice injected with silicone gels.

Silicone gels derived from commercially obtained implants induce plasmacytomas in 60-70% of highly susceptible BALB/cAn.DBA/2-Idh1-Pep3 congenic mice. In contrast, dimethylpolysiloxane (DMPS) silicone oils with viscosities of 5, 1000 and 12,500 cs fail to elicit these tumors. 1000 cs vinylmethylpolysiloxane is also inactive. Silicone gels, in contrast to the oils, induce a highly inflammatory silicone granuloma. Silicone gels contain chemical components not found in the oils. The chemical component responsible for inducing the permissive environment for plasmacytoma formation has not yet been identified. Silicone gels are well tolerated for long periods of time in mice without adverse effects other than plasmacytoma formation. The response to different gel preparations varies; some are associated with relatively rapid formation of plasmacytomas resembling that seen with pristane, while in others the plasmacytoma formation is extended nearly over a two year period.

Animals↗
PubMed1995

Induction of plasmacytomas in genetically susceptible mice with silicone gels.

Silicone gels injected intraperitoneally into strains of mice related to BALB/c develop plasmacytomas in approximately the same numbers and with similar phenotypes as previously obtained with pristane. Silicone gels produce few side effects and are well tolerated for long periods. Silicone gels contain several components that are potentially biologically active: residual vinyl groups and platinum. Microscopic and histological evidence suggests the silicone gel is degraded over a long period of time. Preliminary studies with long chain liquid dimethylpolysiloxanes with viscosities of 1000 cSt and 12,500 cSt have not produced plasmacytomas as yet. The plasmacytomagenic action of the gel appears to be due to the release of liquids from the gel matrix.

Animals↗
PubMed1996

The adjuvant effect of silicone gel and silicone elastomer particles in rats.

This study examines the adjuvant properties of silicone oil, silicone gel and silicone elastomer using a foreign antigen, bovine serum albumin (BSA). Seventy male Harlan Sprague-Dawley rats, approximately 250 grams each, were divided into 7 groups: A- incomplete Freund's adjuvant (IFA) with BSA; B- silicone oil with BSA; C- IFA/silicone oil with BSA; D- 50% silicone gel/50% silicone oil with BSA; E- silicone oil/1000 microns elastomer particles with BSA; F- silicone oil/500 microns elastomer particles with BSA; G- saline with BSA. Rats were implanted intramuscularly with mixtures or emulsions of the above described treatment materials. Cardiac punctures were performed on days 0, 14, 28, 42, and 55. Serum IgG antibody response to BSA was determined by enzyme-linked immunosorbent assay (ELISA). Rats were sacrificed on day 55 and sections of the injection sites were collected and stained for histopathologic evaluation. The results demonstrated that silicone gel functions as a potent immunologic adjuvant as measured by a heightened IgG antibody response to BSA. In contrast silicone elastomer particles have no apparent adjuvant effect as determined by the low anti-BSA antibody levels in these treatment groups throughout the course of the study. Histologically, silicone gel and silicone elastomer elicit a moderate to severe "foreign body" granulomatous inflammatory response at the injection site. Silicone oil elicits mild or no local inflammatory response.

Adjuvants, Immunologic↗
PubMed1995

Simple technique for the preparation of silicone gel particles: the effect of silicone gel particles on oxidative responses of macrophages.

A simple technique was developed to prepare phagocytosable-size particles from the silicone gel used in breast implants. Sonication of silicone gel (1 g) in 5 ml of 20 mM sodium phosphate buffer (pH 7.2) containing 1% (wt/vol) polyoxypropylene-polyethylene block surfactant (F-68 or F-108) produced silicone gel particles ranging from 1-50 microns in diameter. Passage of the suspension through a series of filters yielded phagocytosable particles (1-5 microns in diameter) at a concentration of ca. 2 x 10(9) particles/ml. The particles remained as individual particles, did not coalesce to form large clumps, and were not pelleted by centrifugation (2000 x g, 20 min). They were not toxic for rabbit alveolar macrophages (AM) during 24 h of incubation at 37 degrees C, did not elicit an oxidative burst from AM in vitro in a luminol-enhanced chemiluminescent assay, and did not significantly increase the phorbol myristate acetate (PMA)-elicited oxidative burst by AM. AM isolated from rabbits 2 days after the intravenous injection of silicone particles were not primed or activated (i.e., the AM did not show an enhanced oxidative burst when elicited with PMA in vitro). However, AM isolated from rabbits 2 days after intratracheal injection of the particles were primed but only exhibited a 4-6-fold increase in the oxidative burst elicited with PMA.

Animals↗
PubMed1995

The effect of molecular weight and gel preparation on humoral adjuvancy of silicone oils and silicone gels.

Silicone gels from commercial breast implants have been shown previously by our laboratory to be potent humoral adjuvants, while the low molecular size 20 centistoke (cs) silicone oil (M.W. 1900) possesses no measurable adjuvant properties. It became necessary to shear the silicone gel during our previous experiments in order to facilitate injection through a syringe and needle, it is conceivable that shearing may reduce the molecular weight of the silicone gel used. This investigation was undertaken to determine whether humoral adjuvancy of silicone oils is dependent on molecular weight and whether the method of shearing the silicone gel affects its adjuvancy. Four Dow Corning 360 Medical silicone oils (100 cs, M.W. approximately 5,000; 350 cs, M.W. approximately 10,000; 1000 cs, M.W. approximately 16,500 and 12,500 cs, M.W. approximately 60,000) and Dow Corning octamethylcyclotetrasiloxane (D4, M.W. 296) were tested for their humoral adjuvancy by immunizing 64 Sprague Dawley rats with 50 micrograms of bovine serum albumin (BSA) mixed with each oil. The rats were periodically bled and the sera were analyzed for anti-BSA antibodies by ELISA. In a separate experiment, three silicone gel preparations with reproducible characteristics were prepared by using a tissue homogenizer and varying the applied shear force. Each of these preparations was tested for its humoral adjuvancy as previously described for silicone oils. Rats immunized with BSA mixed with the highest molecular size silicone oil tested (M.W. approximately 60,000) showed a significant increase in anti-BSA antibodies as compared to the lower molecular size oils. The three silicone gel preparations showed no difference in their adjuvancy effect. Thus, the humoral adjuvancy of silicone oil appears to be dependent on molecular weight. Differential shearing of the silicone gel does not alter its humoral adjuvancy.

Adjuvants, Immunologic↗
PubMed1990

Treatment of dermal depth burn wounds with an antimicrobial agent-releasing silicone gel sheet.

Silicone gel sheets containing 0.02 per cent Ofloxacin were used in the treatment of 24 patients with a total of 27 dermal depth burn wounds. The gel provided a continuing drug delivery system from the dressing to the wound. Clinically the silicone gel sheets did not adhere to the wound and could be removed easily without pain. No infection developed in any of the dermal depth burn wounds treated with the gel sheets. The silicone gel sheets were found to promote prompt epithelialization in 16 burn wounds of superficial dermal depth (mean 8.4 days) compared with ointment-impregnated gauze dressings (mean 14 days, P less than 0.01). There was less pain and discharge by macroscopic observation of the absorbent materials from both dressings. In nine wounds of mixed superficial and deep dermal burn, the silicone gel also provided prompt epithelialization (mean 12 days) compared to the control wounds (mean 22 days, P less than 0.01).

Adolescent↗
PubMed2001

Silicone gel breast implant rupture, extracapsular silicone, and health status in a population of women.

OBJECTIVE: To assess whether breast implant rupture or extracapsular silicone are associated with selected symptoms of self-reported physician-diagnosed connective tissue disease (CTD). METHODS: Women with silicone gel breast implants responded to a questionnaire that included questions on health status, satisfaction with implants, symptoms of CTD, and physician-diagnosed disease. These women then had magnetic resonance imaging (MRI) of their breasts to determine the status of the implants with respect to rupture and extracapsular silicone. RESULTS: Women with breast implant rupture diagnosed by MRI were no more likely to report a diagnosis of selected CTD than those with intact implants or those with implants of indeterminate status. Women with extracapsular silicone (silicone gel outside of the fibrous scar that forms around breast implants) were more likely to report having fibromyalgia (FM, p = 0.004) or other CTD, which included dermatomyositis, polymyositis, Hashimoto's thyroiditis, mixed CTD, pulmonary fibrosis, eosinophilic fasciitis, and polymyalgia (p = 0.008) than other women in the study. The association with FM remained statistically significant when adjusted for multiple comparisons (7 diagnoses) and implant age, implant location, or implant manufacturer (p < 0.05 in all cases), but became of borderline statistical significance when adjusted for multiple comparisons and self-perceived health status (p = 0.094) or self-perceived rupture status (p = 0.051). The association with other CTD remained statistically significant when adjusted for multiple comparisons and implant location or implant manufacturer, but became borderline or insignificant when adjusted for multiple comparisons and for implant age (p = 0.051), self-perceived health status (p = 0.434), or self-perceived rupture status (p = 0.145). Logistic regression was used to compute odds ratios of self-reported diagnoses comparing women with and without extracapsular silicone. The odds ratios were 2.8 (95% CI 1.2 to 6.3) for FM, and 2.6 (95% CI 0.8 to 8.5) for other CTD after adjustment for implant age, implant location, implant manufacturer, implant type, self-perceived health, self-perceived rupture status, and site of surgery practice. CONCLUSION: These data suggest an association between extracapsular silicone from ruptured silicone breast implants and FM. If this association persists in other studies, women with silicone gel breast implants should be informed of the potential risk of developing fibromyalgia if their breast implants rupture and the silicone gel escapes the fibrous scar capsule.

Adult↗
PubMed1997

Adjuvancy effect of different types of silicone gel.

Women with silicone gel-filled breast implants (SBIs) are likely to be at a slightly higher risk of developing an autoimmune-like syndrome. This risk, although small, may be associated with the immunological adjuvancy property of the silicone gel. However, not all silicone gels are chemically formulated exactly the same and their adjuvancy behavior may vary. This study compared, in rats, the adjuvant effect of three different lots of silicone gel using ovalbumin (OVA) as the test antigen. Test bleeds were taken at 21, 48, 62, and 84 days post immunization and the rat sera were analyzed for anti-OVA antibodies by enzyme linked immunosorbent assay (ELISA). A delayed type hypersensitivity (DTH) test was performed on all the treated rats beginning at 14 post-immunization days. The results showed that silicone gel #3 (McGhan lot #S0400488) produced the highest mean anti-OVA antibody titer followed by silicone gel #1 (DC lot #HH019581) and silicone gel #2 (McGhan lot #DP9339). The DTH results showed that rats treated with silicone gel #1 and #3 had a clear positive response, whereas silicone gel #2 caused only a minimal response. These results demonstrate the immunological adjuvancy difference among three types of silicone gel. The chemical composition of each of these silicone gels, that would help explain these results, is yet to be determined.

Adjuvants, Immunologic↗
PubMed2002

Epidemiology of silicone-gel breast implants.

Silicone breast implants have been marketed in the United States since 1963. Questions remain unanswered on the safety of these medical devices despite their popularity and availability. In 1992, the Food and Drug Administration restricted the availability of silicone-gel breast implants to women requiring them for reconstruction after breast cancer or for other medical indications. Inflatable saline breast implants have remained available for either reconstruction or for cosmetic augmentation while manufacturers completed studies addressing issues of safety and effectiveness. The Food and Drug Administration (FDA) has less concern today regarding a putative association between breast implants and autoimmune disease because of epidemiologic studies that have indicated that there is not a large increase in risk for connective tissue disease in women with breast implants. These studies have not ruled out a small increase in risk of connective tissue disease to these women nor have they addressed the issue of an atypical syndrome related to silicone. The FDA has continuing concerns over local complications that are related to breast implants. The current review provides a brief discussion of the regulatory history of silicone implants and of FDA concerns over breast implants, implant prevalence, studies of systemic and local complications related to breast implants, and a brief description of the FDA study of silicone-gel breast implant rupture.

Autoimmune Diseases↗
PubMed1995

Lack of lymph node reaction to subcutaneously injected silicone gel: histological and computer aided morphometric study in rats.

The gel of silicone implants may bleed through the elastomeric envelope or may come into contact with the body because of rupture of the implant. We have studied the effects of free silicone gel injected into the subcutaneous space in rats and analysed the morphological features of the axillary and inguinal lymph nodes. Ninety six Wistar rats had 3 cm3 of silicone gel injected into their subcutaneous space and 96 Wistar rats (the control group) had distilled water injected into their subcutaneous space. The animals were killed on days 1,3,7,9,15, 30,60,90,120,180,270, and 365 after the injection. There was no detectable silicone and no damage to the lymph nodes on routine histopathological analysis. Small amounts of silicone that could migrate to lymph nodes could result in hyperplasia. To evaluate this possibility, a morphometric study based on a computer aided system compared the area of lymph node sections between treated and control animals, and showed no difference between treated and control groups. If silicone did migrate, it did not provoke morphological signs or hyperplasia in the lymph nodes.

Animals↗
PubMed2004

Effect of chemical treatment of silicon gel on tissue compatibility.

BACKGROUND: Silicon gel is unfavourable for cell attachment and growth. This study was to study if pretreating the surface of silicon gel with chemical agents affects the proliferation of epithelial cells. METHODS: Silicon gel was made and treated with either mixed acid solution (containing 232 g/dm(3) of H(2)SO(4) and 8 g/dm(3) of K(2)Cr(2)O(7)) or 300 cm(3)/dm(3) peroxide for 5, 10, and 15 minutes or 10, 15, and 20 minutes, respectively. The cultured corneal epithelial cells were seeded onto those silicon gels and kept for 13 days. Immunohistochemical investigations were then carried out for integrin (alpha 6 or beta 4) and actin. RESULTS: Growth of the epithelial cells in silicon gels treated with mixed acid solution for 10 minutes and 15 minutes was much significant than that in the untreated gels. After a 12-hour culture, a small number of corneal epithelial cells were proliferated on the surface of the silicon gels that had been treated with peroxide for 15 minutes. After a 3-day culture, those cells were further proliferated and fused together. The corneal epithelial cells did not grow well in the silicon gels treated with peroxide for 10 or 20 minutes. Immunostaining revealed the expression of actin and integrin alpha 6 or beta 4 on the silicon gels that were treated with mixed acid solution for 10 minutes or peroxide for 15 minutes. CONCLUSION: Silicon gels treated either with mixed acid solution for 10 or 15 minutes or with peroxide for 15 minutes improves cell proliferation.

Animals↗
PubMed1990

Silicone gel including antimicrobial agent.

Silicone gel sheets containing Ofloxacin (OFLX), that provide a continual drug delivery system from a wound dressing to the wound so as to prevent infection and to promote healing, are described. It was found that silicone gel sheets without added medication did not inhibit microbial growth but that gel sheets containing 0.02% and 0.2% of OFLX had a positive antimicrobial effect against Staphylococcus aureus and Pseudomonas aeruginosa in a dose-dependent fashion in vitro. Further, this antimicrobial efficacy was greatly increased in a silicone gel sheet that contained 0.02% of OFLX and an additional 10% of silicone oil. In animal experiments, a silicone gel sheet containing OFLX prevented microbiol growth and promoted rapid epithelialisation in wounds to which Staphylococcus aureus had been applied, whereas wounds covered only with OpSite all resulted in continued infection.

Administration, Topical↗
PubMed1995

Induction of type II collagen arthritis in the DA rat using silicone gels and oils as adjuvant.

The relative safety (or otherwise) of silicone gel filled breast implants remains a controversial issue. The Dark Agouti (DA) rat has been shown recently to have a high susceptibility for developing arthritis. This study determined the arthritogenic potential of silicone gel, silicone oil, and the low molecular weight octamethylcyclotetrasiloxane (D4), by either mixing it with bovine collagen II (BII) or by injecting silicone gel alone in DA rats. Three separate experiments were performed using 110 female DA rats with 10 rats per treatment group. The incidence of collagen induced arthritis was as follows: Experiment I (6 micrograms BII)- PBS = 0/10, silicone gel = 4/10, and IFA = 8/9; Experiment II (125 micrograms BII)- PBS = 0/10, silicone gel = 7/10, IFA = 10/10, 1,000 cs silicone oil = 3/10, D4 = 0/10, and 1% D4 in 1,000 cs silicone oil = 1/10; Experiment III (adjuvant alone)-IFA = 8/10, silicone gel = 0/10. Anti-BII antibodies were formed in most of the rats treated with either silicone gel or IFA mixed with BII and these groups of rats showed a positive DTH reaction. The PBS treated rats were negative for both anti-BII antibodies and DTH reaction. Silicone gel taken from a commercial breast implant thus is capable of mediating collagen induced arthritis in the DA rat. However, silicone gel alone does not appear to be arthritogenic.

Adjuvants, Immunologic↗
PubMed2002

Shur-clens: an agent to remove silicone gel after breast implant rupture.

Removal of silicone gel from surrounding tissues after implant rupture is difficult. Local inflammation, infection, and silicone granulomas warrant thorough removal of the silicone gel. Shur-Clens (20% solution of the surfactant poloxamer 188), povidone-iodine, and saline are agents that are used to aid in the removal of silicone gel from tissue. The purpose of this study was to compare the efficacy of silicone gel removal by these three agents in vitro. Shur-Clens, povidone-iodine, and saline were compared as solvents for silicone gel. Four weight increments of silicone gel (0.02 g, 0.04 g, 0.06 g, and 0.08 g) were placed on glass slides. These slides were placed in separate beakers containing 40 ml test solution. The slides were soaked for 1 minute with gentle agitation. The slides were removed, rinsed gently with de-ionized water, and placed in a vacuum desiccator to dry. The slides were weighed to determine the amount of silicone removed after soaking in the solution. Analysis of variance was used to determine the significance between the three solvents. The percentages of silicone gel removed for the four weight increments (0.02 g, 0.04 g, 0.06 g, and 0.08 g) in saline were 5.6%, 2.9%, 2.1%, and 5.8%, respectively. In povidone-iodine solution, the percentages were 18.9%, 25.4%, 28.8%, and 51.9%. In Shur-Clens, the percentages were 31.3%, 43.0%, 63.5%, and 79.9%. The greater percentage of silicone gel removed by Shur-Clens was significant compared with the other solutions (p < or = 0.05). Shur-Clens was shown to be a more effective solvent for removal of silicone gel in vitro. This enhanced efficacy is a result of the fact that Shur-Clens contains 20% of the surfactant poloxamer 188. The authors' clinical experience with 7 patients who underwent ruptured silicone breast implant removal demonstrated the superiority of Shur-Clens. Shur-Clens is a surfactant cleanser that is widely available, is inexpensive, and has a good safety profile. They propose the use of Shur-Clens to clean silicone gel spillage to decrease local complications resulting from residual silicone gel.

Breast↗
PubMed1995

The effect of silicone-gel on the immune response.

Silicone materials have been used in medical applications for at least 30 years. Despite this long history of use the question whether silicones can mediate an immunological reaction that may be detrimental to the host remains unanswered. Most studies on the biocompatability of silicones conclude that silicones are chemically stable compounds, which however are often capable of eliciting a benign chronic inflammatory response. Recently, our laboratory has conducted a series of animal experiments aimed at determining the immunological adjuvancy potential of silicone-gel taken from commercial breast implants. Our previous studies have indicated that silicone-gel is a potent humoral (antibody) adjuvant. Our present studies have found that silicone-gel is capable of eliciting auto-antibodies to rat thyroglobulin and bovine collagen II. However this immune response did not produce any histological evidence of thyroiditis or arthritis. Theories to explain why silicone-gel behaves as an adjuvant are discussed along with discussion of the hypothesis on the desirability of replacing silicone-gel with a more hydrophilic material in bioimplants.

Adjuvants, Immunologic↗
PubMed2000

Induction of hypergammaglobulinemia and macrophage activation by silicone gels and oils in female A.SW mice.

Although most published epidemiological studies have found little evidence of systemic autoimmune disease associated with silicone breast implants, there still remains a question of whether silicones can cause local and/or systemic immune dysfunction. This study further investigates the effects of silicones on autoantibody and immunoglobulin production and macrophage activation in female A.SW mice. Sixty mice were divided among four treatment groups receiving a 0.5-ml intraperitoneal injection of either phosphate-buffered saline (PBS), pristane, silicone gel, or silicone oil. Test bleeds were taken periodically for 6 months. In contrast to pristane, neither silicone gel nor silicone oil induced lupus-associated antinuclear autoantibodies (immunoglobulin G [IgG] anti-nRNP/Sm, Su, and ribosomal P) or lupus nephritis. However, serum IgM became elevated persistently within 1 month of silicone gel or silicone oil administration. Also, the level of IgG3 was clearly elevated in silicone oil-treated mice. In contrast, IgG1, IgG2a, and IgG2b levels were not affected greatly by either silicone gel or oil. Furthermore, peritoneal macrophages from silicone- and pristane-treated mice produced higher levels of interleukin-1beta (IL-1beta) and IL-6 than those from PBS-treated mice after lipopolysaccharide stimulation. These results suggest that silicone gels and oils are capable of inducing hypergammaglobulinemia and activating macrophages in female A.SW mice.

Animals↗
PubMed1994

Light microscopy techniques for the demonstration of silicone gel.

Because of the difficulty in identifying silicone gel in histologic and cytologic specimens by means of conventional light microscopy, we investigated alternative light microscopy techniques, as well as specimen staining and preparation. Specimens from six periprosthetic capsules, one silicone granuloma specimen, and one synovial biopsy specimen obtained from women with silicone breast implants were cut at 4-, 10-, 20-, and 30-microns sections, stained with a variety of common stains, and correlated with electron probe microanalysis. In addition, a commercial silicone gel and silicone gel extracted from a previously implanted silicone breast prosthesis were smeared and examined unstained or stained with Papanicolaou and Diff Quik. Silicone was noted to be refractile, nonpolarizable, and nonstainable. Thicker sections prevented silicone "dropout" during processing and increased the contrast between stained tissue and unstained silicone (negative staining). The relative ease of silicone identification was greatly increased with non-Koehler, phase contrast, and darkfield microscopy. Staining the mounting media of hematoxylin-eosin-stained sections with a nonparticulate commercial ink allowed enhanced negative staining detection of silicone gel.

Breast↗