In vitro models of soft tissue damage by implant-associated frictional shear stresses

Silicone elastomer medical implants are ubiquitous in medicine, particularly for breast augmentation. However, when these devices are placed within the body, disruption of the natural biological interfaces occurs, which significantly changes the native energy-dissipation mechanisms of living systems. These new interfaces can introduce non-physiological contact pressures and tribological conditions that provoke inflammation and soft tissue damage. Despite their significance, the biotribological properties of implant-tissue and implant-extracellular matrix (ECM) interfaces remain poorly understood. Here, we developed an in vitro model of soft tissue damage using a custom-built in situ biotribometer mounted onto a confocal microscope. Sections of commercially-available silicone breast implants with distinct and clinically relevant surface roughness (Ra = 0.2 ± 0.03 μm, 2.7 ± 0.6 μm, and 32 ± 7.0 μm) were mounted to spherically-capped hydrogel probes and slid against collagen-coated hydrogel surfaces as well as healthy breast epithelial (MCF10A) cell monolayers to model implant-ECM and implant-tissue interfaces. In contrast to the "smooth" silicone implants (Ra < 10 μm), we demonstrate that the "microtextured" silicone implant (10 < Ra < 50 μm) induced higher frictional shear stress (τ > 100 Pa), which led to greater collagen removal and cell rupture/delamination. Our studies may provide insights into post-implantation tribological interactions between silicone breast implants and soft tissues.

Silicone Implant Surface Roughness, Friction, and Wear

Textured silicone breast implants with high average surface roughness ("macrotextured") have been associated with a rare cancer of the immune system, Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL). Silicone elastomer wear debris may lead to chronic inflammation, a key step in the development of this cancer. Here, we model the generation and release of silicone wear debris in the case of a folded implant-implant ("shell-shell") sliding interface for three different types of implants, characterized by their surface roughness. The "smooth" implant shell with the lowest average surface roughness tested (Ra = 2.7 ± 0.6 μm) resulted in average friction coefficients of μavg = 0.46 ± 0.11 across 1,000 mm of sliding distance and generated 1,304 particles with an average particle diameter of Davg = 8.3 ± 13.1 μm. The "microtextured" implant shell (Ra = 32 ± 7.0 μm) exhibited μavg = 1.20 ± 0.10 and generated 2,730 particles with Davg = 4.7 ± 9.1 μm. The "macrotextured" implant shell (Ra = 80 ± 10 μm) exhibited the highest friction coefficients, μavg = 2.82 ± 0.15 and the greatest number of wear debris particles, 11,699, with an average particle size of Davg = 5.3 ± 3.3 μm. Our data may provide guidance for the design of silicone breast implants with lower surface roughness, lower friction, and smaller quantities of wear debris.

[Esophageal cyst--a rare cause of backache]

Cysts of the esophagus are rare mediastinal tumors presenting a large variety of clinical symptoms. Even with modern methods of examination an exact diagnosis is difficult to obtain and often only possible after histological examination. Complications are perforation, or pulmonary, thoracic or esophageal haemorrhage. First choice of therapy is the exstirpation. We report on a 50 year old man with backache and the initial diagnosis of renal colic. Only the magnetic resonance image showed an isolated mediastinal esophageal cyst as the reason. The cyst was removed by thoracotomy. The operation and treatment were without complications. Symptomatology, diagnostical pitfalls and the therapy are described.

Effects of lysine clonixinate and ketorolac tromethamine on prostanoid release from various rat organs incubated ex vivo

The release of prostanoids from rat brain, gastric mucosa, lungs and kidneys incubated ex vivo has been investigated for up to 5 h after oral administration of 10 mg/kg lysine clonixinate or 1 mg/kg ketorolac tromethamine. Additionally, 60 min after drug administration, a time point of near-maximal inhibition of prostanoid release, the effects of 2.5, 10 and 30 mg/kg lysine clonixinate and of 0.0225, 0.15 and 1 mg/kg ketorolac tromethamine were compared. In all organs investigated both drugs inhibited fatty acid cyclooxygenase (COX) in a dose-dependent manner, but ketorolac tromethamine was more potent and had a longer-lasting effect than lysine clonixinate. While the ID50 values for lysine clonixinate were in the same order of magnitude for all 4 organs investigated, ketorolac tromethamine exhibited some organ selectivity with a particularly high activity in the kidneys. This effect might be related to the renal toxicity of ketorolac tromethamine. On the other hand, the difference in potency was smallest in brain suggesting that inhibition of central prostanoid biosynthesis could contribute to the rapid and effective inhibition of pain by both drugs. IC50 values for inhibition of purified COX-1 and COX-2 in vitro were slightly lower for lysine clonixinate (2.4 and 24.6 micrograms/ml, respectively) than for ketorolac tromethamine (3.7 and 25.6 micrograms/ml, respectively).

Natural Dermatophilus congolensis infection in camels (Camelus dromedarius) from Kenya

Natural Dermatophilus congolensis infection is found in many species of livestock and wild animals. It is, however, rarely described in camels and there are no details of bacterial isolation. In an investigation of both arid and semi-arid areas in Kenya, an outbreak of dermatophilosis was observed in camel calves being reared on a commercial farm in a semi-arid area. Histopathology and bacterial isolation were used to diagnose the diseases. The potential impact of the disease in camels is discussed.