Long-term complications of polyurethane-covered breast implants

The authors's personal experience using an earlier manufactured polyurethane-covered gel prosthesis is presented. Very long-term follow-up did not validate the author's initial enthusiasm. It is to be hoped that the newer polyurethane-covered implants will give more satisfactory long-term results.     

Late breast pain following reconstruction with polyurethane-covered implants

Two patients of 56 who were reconstructed with polyurethane-coated implants developed breast pain as a late complication and eventually required implant removal for relief. Although the cause of pain was not proven, it may have been due to contracture of the fibrous capsule which formed between the polyurethane and the shell of the implant. The complication of late pain has not been stressed previously in the literature on reconstruction.     

Use of stacked polyurethane-covered mammary implants in aesthetic and reconstructive breast surgery

The use of stacked polyurethane-covered mammary implants has proven useful in improving results in the correction of deficiencies of mammary form and projection that can occur in certain cases of congenital and acquired breast deformity. The method has been used in 57 patients (102 breasts). The rate of significant complications, including seroma, rash, infection, hematoma, and capsular contracture, has been low (1 to 6 percent). Polyurethane-covered implants will maintain their position when used in a stacked system because of their unique biophysical characteristics, which include tissue bonding and a high friction coefficient between the implant surfaces.     

Treatment of breast contractures with open capsulotomy and replacement of gel prostheses with polyurethane-covered implants

Capsular contracture around gel and gel-saline implants is the most common complication following breast augmentation and reconstruction. Thirty-one patients with postaugmentation gel-implant contractures were treated with open capsulotomy and replacement with polyurethane-covered implants. Eighty-seven percent remain soft after a minimum follow-up of 14 months. Results of replacement after subcutaneous mastectomy and reconstruction are more varied and less successful. Results in 14 patients are presented.     

PHEMA as a fibrous capsule-resistant breast prosthesis

The presence of a silicone (poly-dimethyl siloxane) breast prosthesis in a breast reconstruction patient typically leads to fibrous tissue encapsulation of the prosthesis. Fibrous capsular contracture forces the prosthesis into a hardened sphere. The initially satisfactory cosmetic result can thus be changed into a deformed mass of inappropriate compliance. It is the author's hope with the present study to identify a material for implantation with a diminished tendency to form fibrous encapsulation, to improve the long-term results of prosthetic implants. The purpose of this investigation was to compare the early capsule production quality of poly-2-hydroxyethyl methacrylate (PHEMA) and poly-dimethyl siloxane (silicone). Each of five rats subcutaneously underwent implantation with both a disk of poly-dimethyl siloxane (control) and a similar disk of PHEMA. In this study, the extent of fibrous encapsulation was assessed at 6 weeks after implantation of the two disk types. The five disks of poly-dimethyl siloxane were embedded in fibrous tissue, whereas there was no apparent fibrous tissue surrounding the implants of PHEMA. The author concludes that the results for PHEMA were superior to those for silicone at 6 weeks with regard to fibrous encapsulation (p = 0.0312).     

"Anticipated" nucleosome positioning pattern in prokaryotes

Linguistic (word count) analysis of prokaryotic genome sequences, by Shannon N-gram extension, reveals that the dominant hidden motifs in A+T rich genomes are T(A)(T)A and G(A)(T)C with uncertain number of repeating A and T. Since prokaryotic sequences are largely protein-coding, the motifs would correspond to amphipathic alpha-helices with alternating lysine and phenylalanine as preferential polar and non-polar residues. The motifs are also known in eukaryotes, as nucleosome positioning patterns. Their existence in prokaryotes as well may serve for binding of histone-like proteins to DNA. In this case the above patterns in prokaryotes may be considered as "anticipated" nucleosome positioning patterns which, quite likely, existed in prokaryotic genomes before the evolutionary separation between eukaryotes and prokaryotes.     

Paget's disease of the breast after subcutaneous mastectomy and reconstruction with a silicone prosthesis

Eight years after subcutaneous mastectomy for extensive fibrocystic disease, a patient developed Paget's disease of the breast associated with an underlying infiltrating duct cell adenocarcinoma. We emphasize the need for meticulous examination of the subcutaneous mastectomy specimen and long-term follow-up examination of the breasts in patients treated with subcutaneous mastectomy.