Silicon and silicone: theoretical and clinical implications of breast implants

Emphasis on heat strain to the ocular surface: A functional and clinical study of a modified goggle

Purpose

The limitations of conventional goggles have caused immense inconvenience, and even damage, to the physical and mental health of healthcare workers. Hence, this study aimed to build a modified goggle (MG) with better physical performance. The temperature-humidity index (THI) was used as an indicator to investigate the impact of goggle-related heat strain on the ocular surface.

Methods

The basic functions of antifog, anti-ultraviolet (UV), and anti-blue-light radiation capabilities were evaluated. Furthermore, the clinical impact on noninvasive keratography tear film break-up time (NIKBUT), intraocular pressure, central corneal thickness, Schirmer test I, and the Dry Eye-related Quality of life Score (DEQS) were assessed in 40 healthcare workers by comparing MG with standard goggles (SG). The relationships between THI and the above parameters were explored.

Results

MG had a significantly longer antifog time than SG (212.75 ± 23.95 vs. 138.35 ± 5.54 min, p < 0.05), stronger antiultraviolet ability at 400 nm (99.99 vs. 45.55%), and optimal anti-blue-light performance at 440 nm (33.32 vs. 13.31%). Tear film stability after wearing the goggle was significantly worse than that before wearing them (p < 0.05). Both goggles achieved moderate to strong heat strain, with a THI of >80 at all timepoints. The MG group showed lower THI and DEQS and higher NIKBUT than the SG group (p < 0.05). THI was significantly correlated with DEQS, NIKBUT, and real fogging time (r = 0.876, −0.532, −0.406; all p < 0.05).

Conclusion

Wearing goggles for a long time may cause heat strain to the eyes, thereby leading to eye discomfort and changes in the microenvironment of the ocular surface. Our MG exhibited better antifog, antiultraviolet, and optimal anti-blue-light performance and lower heat strain than SG, thus making it ideally suited for healthcare workers.

Autoinflammatory/autoimmunity syndrome induced by adjuvants (ASIA; Shoenfeld's syndrome): A new flame

In the present review, recent findings regarding autoimmune/inflammatory syndrome by adjuvants (ASIA) are described. Patients with ASIA present with complaints such as fatigue, cognitive impairment, arthralgias, myalgias, pyrexia, dry eyes and dry mouth. During the last few years, it has been postulated that these symptoms in patients with foreign body implants are due to a chronic inflammatory process and an adjuvant effect of the implanted biomaterial. Ultimately, these inflammatory reactions result in (an increase of) allergies, autoimmune diseases, immune deficiency and/or lymphomas. Pre-existent allergic disease has been found to be an important risk factor for the development of ASIA after foreign body implantation. Explantation of the foreign body results in the majority of patients in an amelioration of the symptoms. There is an urgent need to start adequately adjusted epidemiological studies to obtain better evidence which percentage of patients does develop symptoms and/or diseases such as ASIA, immune deficiency, and/or autoimmune diseases after implant surgery.

Breast Implant-Associated Anaplastic Large Cell Lymphoma (ALCL): A Case Report

BACKGROUND Anaplastic large cell lymphomas (ALCL) are a rare type of primary breast lymphoma. The association between breast implants and ALCL was first described in 1997 and since then 34-173 cases have been presented. The annual incidence of breast implant-associated ALCL (BI-ALCL) is 0.1-0.3 per 100 000 women who undergo breast reconstruction, and cases are often underreported due to the rarity of these tumors. BI-ALCL arises from the inflammatory T cells surrounding the fibrous capsule, and most tumors are in situ. CASE REPORT Here, we present the case of a 51-year-old woman with ALCL following bilateral silicone breast implants. The patient presented with breast enlargement and tenderness 9 years following reconstructive surgery. Imagining studies showed fluid collection surrounding the affected breast implant. Staging studies and histocytopathology examination confirmed the presence BI-ALCL without capsular invasion or metastasis. Complete surgical excision was performed. The patient continues to be in complete remission. CONCLUSIONS Due to the rarity of these tumors, establishing the diagnosis of BI-ALCL can be challenging and requires a multidisciplinary approach. Clinicians should be aware of the relationship between breast implants and BI-ALCL.

Safe human exposure limits for airborne linear siloxanes during spaceflight

Background

Low molecular weight siloxanes are used in industrial processes and consumer products, and their vapors have been detected in the atmospheres of the Space Shuttle and International Space Station. Therefore, the National Aeronautics and Space Administration (NASA) developed spacecraft maximum allowable concentrations (SMACs) for siloxane vapors to protect astronaut health. Since publication of these original SMACs, new studies and new risk assessment approaches have been published that warrant re-examination of the SMACs.

Objective

To reevaluate SMACs published for octamethyltrisiloxane (L3) for exposures ranging from 1 hour to 180 days, to develop a 1000-day SMAC, and to expand the applicability of those values to the family of linear siloxanes.

Methods

A literature review was conducted to identify studies conducted since the SMACs for L3 were set in 1994. The updated data were reviewed to determine the sensitive toxicity endpoints, and current risk assessment approaches and methods for dosimetric adjustments were evaluated.

Results

Recent data were used to update the original 1-hour, 24-hour, 30-day, and 180-day SMACs for L3, and a 1000-day SMAC was developed to protect crewmembers during future exploration beyond Earth orbit. Group SMACs for the linear siloxane family, including hexamethyldisiloxane (L2), L3, decamethyltetrasiloxane (L4), and dodecamethylpentasiloxane (L5), were set for exposures of 1-hour to 1000 days.

Conclusion

New SMACs, based on acute pulmonary and neurotoxicity at high doses only achievable with L2 and potential liver effects following longer-term exposures to L2 and L3, were established to protect crewmembers from the adverse effects of exposure to linear siloxanes.

An elderly 'kawara' craftsman with acute kidney injury and haemoptysis: a case of silica-induced autoimmunity

A 62-year-old Japanese ‘kawara’ (ceramic roof tile) craftsman presented with acute kidney injury and haemoptysis. This case met the systemic lupus erythematosus and microscopic polyangiitis criteria, with high titres of myeloperoxidase–antineutrophil cytoplasmic antibody (570 EU). Results showed the presence of antinuclear antibody at a high titre (1:2560), but detection of rheumatoid factor, anti-dsDNA, anti-SSA and anti-SSB antibodies was not apparent. This serology was similar to drug-induced, silicon-induced or silica-induced autoimmunity. The patient had been exposed to silica for > 40 years. The environmental aetiology of autoimmune diseases should be considered in cases that show atypical epidemiology and serology.

The association between silicone implants and both antibodies and autoimmune diseases

Silicones are widely used materials in many fields of medicine and largely are believed to be biologically inert. However, some investigators have reported that silicone implants are associated with an increased incidence of autoimmune disorders. In this study, we evaluated the capsular tissue of silicone implants and the sera of implant patients and controls for antisilicone antibodies and nonspecific immunoglobulins (IgG, IgA, IgM, and IgE). Our study group included 15 patients (eight men and seven women) undergoing reconstructive procedures for burn scars, in whom we used silicone implants, and 15 sex-matched controls undergoing reconstructive surgery for burn scars without using silicone implants. By immunofluorescence, we discovered strong capsular binding of IgG and weak capsular binding of IgM; antisilicone antibody levels were significantly higher in capsular tissue than elsewhere. Serum IgE also was higher in patient vs control subject sera. In conclusion, silicone materials do lead to an immune response consisting of antisilicone antibodies most evident immediately adjacent to the implant itself.

Controversies in neurotoxicology: current status

Several controversial neurotoxic syndromes have received notoriety in the past several decades. For each, the controversy involves the most fundamental question about the existence of the disorder as a clinically diagnosable entity. Interestingly, the most controversial of these syndromes share several features, including argument about the existence of each syndrome in the courtroom. The authors focus their discussion on three problems (painter's encephalopathy, silicone breast implant neurotoxicity, and the Gulf War syndrome) for which no scientific consensus has been reached that would establish them as diagnosable disorders. These syndromes do not meet traditional disease criteria, and until a clear set of symptoms and objective signs can be defined, a definite course and clear cause demonstrated, and specific tests and treatments identified, these syndromes are likely to remain highly controversial.

CREST syndrome: clinical manifestations and dental management

Scleroderma is a multisystem connective tissue disease of unknown etiology, which is characterized by inflammation, vascular, and fibrotic changes of the skin as well as various internal organs. This article will review the systemic form of scleroderma known as CREST syndrome, its clinical manifestations including the dentofacial complications, as well as provide information to assist the prosthodontist in managing the dental treatment for patients with this disease.

Silicon and matrix macromolecules: new research opportunities for old diseases from analysis of potential mechanisms of breast implant toxicity

An understanding of the normal and essential integration of the element silicon in biosystems, as well as knowledge of its fundamental chemistry, are crucial to understanding its role in health and disease. Modern organosilicon chemistry, based in part on the artificial silicon-carbon bond, coincided with the emergence of the biomaterials and bioengineering fields fifty years ago, and was thought to be a fortunate coincidence according to conventional wisdom that high-molecular-weight polymeric siloxanes were chemically and biologically inert. These concepts have been challenged by reports of silicone migration and degradation following insertion of gel-filled breast implants, claims of a novel systemic illness appearing in many breast implant recipients, and investigations implicating varied and permeating immunotoxic mechanisms of disease causation by breast devices. The present study develops additional potential pathogenetic ideas based on alterations of cell biochemistry by silicon-containing compounds, and offers correlation of the patients' diverse clinical features with plausable disruption of basic biological processes. This in turn raises new questions concerning everyday environmental exposure, has broad implications for multiple other diseases, can provide alternative directions for future investigative research, and may contribute to the ongoing redefinition of immune dysfunction and inflammation.

Silicone elastomer cerebrospinal fluid shunt systems. Council on Scientific Affairs, American Medical Association

A 1995 resolution of the American Medical Association House of Delegates, introduced by the American Academy of Neurology, the American Association of Neurological Surgeons, and the Congress of Neurological Surgeons, asked the American Medical Association Council on Scientific Affairs to add the use of hardened silicone shunts to its study of the effects of silicone gel used in breast implants. On consideration of the important differences between the two materials, silicone elastomer ("hardened silicone") and silicone gel, the Council on Scientific Affairs elected to address the subject of silicone elastomer shunt systems separately. This report describes the different types of medical-grade silicone used in medical devices, the incidence of hydrocephalus and its causes and treatment, and the use of cerebrospinal fluid shunt systems made of silicone elastomer. Published case reports of possible immunological disease in patients who have had silicone elastomer cerebrospinal fluid shunt systems implanted are reviewed. The Council on Scientific Affairs concluded that the evidence presented does not support the occurrence of immune-mediated systemic reactions to implanted silicone elastomer cerebrospinal fluid shunt systems. The local granulomatous or inflammatory responses observed in some patients with silicone shunt systems have not been shown to be immunologically mediated; similar reactions have been described with other implanted foreign bodies.

A review of the possible health implications of silicone breast implants

BACKGROUND

The silicone gel breast implant has long been an important method of reconstruction for the mastectomy patient. Because of concerns about possible health implications of the implant, the Food and Drug Administration banned its use for augmentation mammaplasty and limited its use in the mastectomy patient to a research protocol study. This article reviews the recent literature about the possible health hazards of the silicone implant.

METHODS

In this review of the literature, specific attention was directed toward structural failure of the device as well as the diagnosis of rupture, tissue response to silicone, systemic immunologic response to silicone, the relationship of silicone to connective tissue diseases, and the association of the silicone implant with breast carcinoma in both the augmentation mammaplasty patient and the patient undergoing postmastectomy reconstruction. A total of 88 works were reviewed.

RESULTS

The literature fails to support an association between silicone gel breast implants and systemic diseases. Although implants may cause local symptoms, rupture over time, or be associated with an immunologic reaction, comprehensive epidemiologic studies have concluded that there is no connection between breast implants and the known connective tissue diseases or between the implants and breast carcinoma. There is no increase in the risk of recurrence in mastectomy patients reconstructed with implants and no delay in the detection of recurrences. Recent laboratory studies in animals suggest that silicone may have anticarcinogenic effects.

CONCLUSIONS

Silicone gel breast implants may rupture and cause local symptoms, but they have not been demonstrated to be a systemic health hazard for patients who have undergone augmentation mammaplasty or postmastectomy reconstruction.

Serum silicon levels are elevated in women with silicone gel implants

The metabolic fate of silicone gel leaked into the body from an implant is unknown. In this study, serum from 72 women with silicone gel breast implants and 55 control women was blindly assayed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) for elemental silicon. Samples were processed using materials free of silicon. The mean silicon level in controls was 0.13 +/- 0.07 mg/l (range 0.06-0.35 mg/l), while in implant patients, the mean was significantly higher at 0.28 +/- 0.22 mg/l (range 0.06-0.87 mg/l) (P < 0.01, Student's t-test with correction for unequal variances). Using the mean of the control group + 2 SD as a cutoff for normal range (0.27 mg/l), 25/72 (34.7%) implant patients exceeded this value, compared with 2/55 (3.6%) controls. There was no significant correlation between past rupture of one or both implants, current rupture at the time of the blood draw or the number of years with implants and silicon levels. The results suggest that elevations of serum silicon are seen in many women with silicone gel breast implants. The kinetics of this elevation and the actual chemical species of the measured silicon remain to be determined.

Elevated serum silicon levels in women with silicone gel breast implants

The metabolic fate of silicone gel leaked from an intact or ruptured prosthesis is unknown. In this study, serum was blindly assayed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) for elemental silicon in 72 women with silicone gel breast implants and 55 control women (mean age 48 yr, both groups). Blood was drawn and processed using silicon-free materials. The mean silicon level in controls was 0.13 +/- 0.07 mg/L (range 0.06-0.35 mg/L), whereas in implant patients, the mean was significantly higher at 0.28 +/- 0.22 mg/L (range 0.06-0.87 mg/L) (P < 0.01, Student's t-test with correction for unequal variances). Using the mean of the control group + 2 SD as a cutoff for normal range (0.27 mg/L), 25/72 (34.7%) implant patients exceeded this value, compared with 2/55 (3.6%) controls. There was no significant correlation between past rupture of one or both implants, current rupture at the time of the blood draw, or the number of years with implants and silicon levels. The results suggest that serum silicon levels are elevated in many women with silicone gel breast implants. The chemical species involved and kinetics of this elevation remain to be determined.

Silicone injection granulomas of the breast: treatment by subcutaneous mastectomy and immediate subpectoral breast implant

Silicone leakage from silicone breast prostheses with or without rupture of the prostheses is of great concern. Silicone injection for breast augmentation is still common in Asia, even though silicone injection induced granulomas and associated malignancy have been reported. A series of 24 women who had bilateral silicone injection granulomas in their breasts, requiring subcutaneous mastectomies and immediate breast reconstruction, is presented. Most of the patients had had one silicone injection into each breast. The patients' average age was 37.5 years and removal of the granulomas was done 3-20 years (mean 8.4 years) after the silicone injections. All patients had breast lumps and some had mastitis (21%) and dermatitis (16%) but none had palpable axillary lymph nodes. Mammograms showed diffuse, multiple granulomas of various sizes. Subcutaneous mastectomies were done via inframammary incisions. Immediate breast reconstruction was carried out with double-lumen silicone/saline implants or textured saline-filled implants inserted subpectorally via a separate axillary incision. The implants were entirely covered by the pectoralis major muscle and partially dissected serratus anterior fascia. Two cases had wound infections (8%) as early complications, and two cases developed hypertrophic scars (8%). At 6-41 months follow-up (mean 21.4 months), 69% of the patients had Baker II and 31% of the patients had Baker III breast capsular contractures.

Silicone-specific blood lymphocyte response in women with silicone breast implants

A blinded cross-sectional study was carried out with 99 women, 44 of whom had silicone breast implants. Group I consisted of 55 healthy volunteer women without breast implants; group II comprised 13 volunteer women with breast implants or explants who felt healthy; group III comprised 21 volunteer women with breast implants who had chronic fatigue, musculoskeletal symptoms, and skin disorders; and group IV comprised 10 women who had their prostheses explanted but still presented with clinical symptoms similar to those of the women in group III. Proliferative responses of peripheral blood mononuclear cells from all 99 women were measured by [3H]thymidine uptake after exposure to SiO2 silicon, or silicone gel. The levels of proliferative responses were expressed as stimulation indices, which were obtained by dividing the counts per minute of stimulated cells by the counts per minute of unstimulated cells. Abnormal responses to SiO2, silicon, or silicone gel were defined as a stimulation index of > 2.8, > 2.1, or > 2.4, respectively. Abnormal responses were observed in 0% of group I, 15% of group II, 29% of group III, and 30% of group IV (P < 0.0005 for group I versus groups II and IV). Thirty-one percent of symptomatic women with silicone gel breast implants had elevated serum silicon levels ( > 0.18 mg/liter); however, there was no significant correlation between abnormal cellular responses and silicon levels in blood serum, type of implant, time since first implantation, prosthesis explantation, number of implants, or report of implant leakage or rupture.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunotoxicity of silicone: implications of oxidant balance towards adjuvant activity

A variety of mechanisms can be proposed to explain the potential effects of silicone and silicone by-products on the immune response. In this paper, we discuss information on the chemistry of silicon and silicone gels/elastomers, and the manufacture of silicone breast implants as they pertain to the bioreactivity of silicone. Moreover, with reference to silicone-mediated human adjuvant disease, an overview of experimental adjuvant-induced arthritis is presented; comparisons with graft-versus-host disease and chemically induced autoimmunity then follow. Particular attention is paid to similarities in the characteristics of silicone and classic lipid adjuvants. For example, macrophage activation is presumed to be a central event in silicone-induced autoimmunity. Since those genes uniquely expressed in macrophages activated by plastic adherence are similar to those induced by lipopolysaccharide, adherence to silicone rubber may initiate an inflammatory response by the same mechanism. Macrophage effects would also include the erosion of implants through the generation of oxidants and localized pH changes. The degradation products of silicone are also implicated in the adjuvant effects of silicone implants. There is evidence to suggest that oxidants produced by inflammatory cells preferentially inactivate CD8+ suppressor T cells. This could then lead to an inflammatory state, perhaps through oxidant-induced transcription factors such as NF-kB, resulting in a long-term pro-oxidant imbalance that manifests itself as a breakdown in immunological self-tolerance. The authors hypothesize that autoreactivity following oxidant stress evolved to enhance inflammatory repair mechanisms after tissue, cell or molecular damage by oxidants.

Current status of silicone gel breast implants

There are currently three main areas of concern regarding the safety of silicone gel implants: implant failure; a potential link to autoimmune connective tissue disease; and a possible link to breast cancer. All silicone gel implants ‘bleed’ small levels of silicone. In addition, silicone gel implants appear to fail (leak or rupture) with time. Most implants in place for less than seven years appear to be intact. It appears that many silicone gel implants implanted for over seven years are probably ruptured or leaking. Implant failure may occur simply from deterioration. Implants can also rupture following closed capsulotomy. Mammography and ultrasound studies are generally not helpful in predicting implant failure. Magnetic resonance imaging (MRI) studies appear to be useful, but the ‘breast coil’ necessary to perform these studies is not currently available in most MRI units in Canada. The significance of implant failure is not known. There is a growing (but unproven) concern that immunological sensitization to silicone could develop in women with silicone gel implants. An extensive review of all clinical and immunological studies in the current literature has failed to demonstrate any conclusive link between silicone gel implants (whether intact or nonintact) and the development of autoimmune connective tissue disease or other disease process. However, large scale epidemiological studies remain to be done. Several large studies have proven that there is no relationship between silicone gel implants and the development of breast cancer.