Lykissa E D, Kala S V, Hurley J B, Lebovitz R M
Department of Pathology, Baylor College of Medicine, Houston, Texas 77030, USA.
Anal Chem. 1997 Dec 1;69(23):4912-6. doi: 10.1021/ac970710w.
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.
我们开展了一系列研究，涉及乳房植入物硅胶的化学成分，以及低分子量硅氧烷（LM - 硅氧烷）和重金属从完整植入物向各种周围介质的扩散情况，这些介质包括富含脂质的介质（大豆油）、水性组织培养基（改良的杜尔贝科培养基，DMEM），或由DMEM加10%大豆油组成的乳液。使用气相色谱（GC）结合原子发射（GC - AED）以及质谱（GC/MS）检测器对植入物和周围介质中的LM - 硅氧烷进行检测和定量，这些检测器能够检测纳克级别的硅氧烷。使用电感氩耦合等离子体/质谱（ICP - MS）对制备硅胶时使用的催化剂铂进行检测和定量，该方法能够检测万亿分之一级别的铂。我们的结果表明，GC可检测到的低分子量硅氧烷约占凝胶总质量的1 - 2%，主要由3至20个硅氧烷[（CH3）2 - Si - O]单元（分子量200 - 1500）的环状和线性聚（二甲基硅氧烷）组成。通过ICP - MS可在植入物凝胶中检测到铂的含量约为700微克/千克。植入物凝胶的主要成分似乎是分子量太大而无法被GC检测到的高分子量硅氧烷聚合物（HM - 硅氧烷）。然而，通过在150 - 180摄氏度下加热植入物凝胶数小时，这些HM - 硅氧烷几乎可以定量地（质量分数为80%）转化为LM - 硅氧烷。我们还研究了在各种条件下，LM - 硅氧烷和铂通过完整植入物外壳泄漏到周围介质中的速率。当周围介质富含脂质时，硅氧烷的泄漏最为严重，在37摄氏度下，每250克植入物中观察到高达10毫克/天的LM - 硅氧烷扩散到富含脂质的介质中。在为期7天的实验期间，这种泄漏速率保持不变。同样，在37摄氏度下，也观察到铂以约20 - 25微克/天/250克植入物的速率通过完整植入物泄漏到含脂质的介质中。已观察到的LM - 硅氧烷和铂从完整植入物中泄漏的速率可能导致在富含脂质的组织中大量积累，因此应在体内进行更全面的研究。
