Inflammatory nodules are likely to be caused by a low-grade infection maintained within a biogfilm surrounding the hydrophobic silicone gel and the combination gels. Aquamid gel may prevent formation of a biofilm through its high water-binding capacity, explaining why late inflammatory nodules are not seen after injection of this polyacrylamide hydrogel product.

It has become evident that aggregation or biofilm formation is an important survival mechanism for bacteria in almost any environment. In this review, we summarize recent visualizations of bacterial aggregates in several chronic infections (chronic otitis media, cystic fibrosis, infection due to permanent tissue fillers and chronic wounds) both as to distribution (such as where in the wound bed) and organization (monospecies or multispecies microcolonies). We correlate these biofilm observations to observations of commensal biofilms (dental and intestine) and biofilms in natural ecosystems (soil). The observations of the chronic biofilm infections point toward a trend of low bacterial diversity and sovereign monospecies biofilm aggregates even though the infection in which they reside are multispecies. In contrast to this, commensal and natural biofilm aggregates contain multiple species that are believed to coexist, interact and form biofilms with high bacterial and niche diversity. We discuss these differences from both the diagnostic and the scientific point of view.

No abstract

Polyacrylamide hydrogel is an atoxic, stable, nonresorbable sterile watery gel consisting of approximately 2.5% cross-linked polyacrylamide and nonpyrogenic water. Polyacrylamide hydrogel is widely used in ophthalmic operations, drug treatment, food packaging products, and water purification. In the former Soviet Union, polyacrylamide hydrogel has been used in plastic and aesthetic surgery for more than 10 years, and Kiev City Hospital treats approximately 300 women a year for breast augmentation using the polyacrylamide hydrogel Interfall (Contura SA, Montreux, Switzerland). Capsule shrinkage following these injections has never been observed. The authors examined breast tissue samples from a total of 27 women who had polyacrylamide hydrogel injected at Kiev City Hospital up to 8 years and 10 months earlier. Age at operation, duration of polyacrylamide hydrogel implantation, history of possible side effects to the gel injection, other intercurrent diseases, the reason for present open breast operation, and breast palpation findings before operation were in each case compared with the histological findings on samples taken from breast tissue bordering the gel. The gel presented itself as a dark violet, homogenous mass with a rounded or ragged outline in large or medium-size deposits and as elongated strands, which mimicked the extracellular matrix, in small deposits. Histological findings of the breast tissue bordering the gel showed three different patterns: large collections of gel gave rise to a thick, soft-looking cellular membrane of macrophages and foreign-body giant cells; medium-size deposits were surrounded by just a thin layer of macrophages; and small deposits were not associated with any reaction in the surrounding tissue. Projections of the cellular soft membrane, known as granulomas, were seen in six patients. The granulomas were composed of macrophages, foreign-body giant cells, lymphocytes, and blood cells. A thin layer of fibrous connective tissue was occasionally present around the foreign-body membrane, but the thick fibrous capsule, which has been described in connection with silicone implants, was completely absent. The gel changes could be correlated to neither time since gel injection nor a history of recent injury or inflammation. It is concluded that the polyacrylamide hydrogel Interfall, which has been used in the former Soviet Union, is stable over time, nondegradable, confined to the breast, and diffusion and migration resistant. When the hydrogel is injected in medium-size or large quantities a cellular foreign-body reaction occurs, but in small amounts it is capable of splitting up individual connective tissue fibers and fat cells, substituting for the extracellular connective tissue matrix without eliciting any foreign-body reaction. As far as these data are concerned, polyacrylamide hydrogel is well tolerated by the breast and does not give rise to severe fibrosis, pain, or capsule shrinkage. However, to determine safety with more certainty, a larger sample size would be necessary.

No abstract

Complications following homogenous hydrogels are caused by infection with bacteria, which have been inserted into the gel during injection. If not treated with relevant antibiotics (but instead steroids or large doses of NSAIDs) the bacteria form a biofilm, which gives rise to a low-grade chronic infection that is resistant to antibiotics. Complications following particulated gels and silicone oil are not known, but bacteria in a biofilm and/or endotoxins released by these is a possibility which deserves further investigations, primarily by using the fluorescence in situ hybridization (FISH) technique.

Objectives: The aim of the study was to examine the overall risk factors for epithelial ovarian cancer and according to histologic subtypes. Materials and Methods: Ovarian cancer cases and controls were recruited from 1995 to 1999, and personal interviews were conducted. A total of 554 cases and 1,564 randomly selected controls were included. The analyses were done using multiple logistic regression models. Results: The overall risk of ovarian cancer decreased with ever being pregnant [odds ratios (OR), 0.40; 95% confidence intervals (CI), 0.30-0.55], with increasing pregnancies (OR, 0.63; 95% CI, 0.45-0.87 and OR, 0.51; 95% CI, 0.37-0.69 for two and three pregnancies as compared with one), and with older age at first and last pregnancy, respectively. Increasing years of ovulation was a very strong risk factor with a 7% to 8% increase in risk for each year of ovulation. Use of oral contraceptives (OR, 0.67, 95% CI, 0.53-0.85) and longer duration of use were associated with a decreased risk of ovarian cancer. Ever use of hormone replacement therapy increased the overall risk (OR, 1.30; 95% CI, 1.05-1.61). For all those variables, the effect was present for serous tumors, endometrioid tumors, and tumors of other histologies, but not for mucinous tumors. In contrast, current smoking was a risk factor only for mucinous tumors (OR, 1.78; 95% CI, 1.01-3.15) and increasing body mass index tended to increase the risk especially for mucinous and endometrioid tumors. Conclusions: We confirmed already known risk factors for ovarian cancer, and we observed significant differences in the risk profiles between mucinous and nonmucinous tumors indicating different etiologies. (Cancer Epidemiol Biomarkers Prev 2007;16(6):1160 -6)

This study supports the assumption that infection with bacteria in aggregates causes culture-negative late adverse reactions to polyacrylamide gel, suggesting a biofilm environment.