Toxicology and biocompatibility of bioglasses

Evidence for the lack of toxicity of various bioglass formulations has been deduced from studies carried out, both in vivo and in vitro, in several different centers. Recent studies of the authors, described here, include testing of solid bioglass implants in the soft tissues of rats and rabbits for time periods of up to eight weeks. Two new techniques are described for the toxicological testing of particulate biomaterials. These tests, which involve rat peritoneal macrophages in culture and a mouse pulmonary biomaterial embolus model, indicate the biocompatibility of bioglass powders. Thus, the surface activity so critical in bone adhesion is without toxic effect in non-osseous tissues in contact with solid bioglass implants. Should wear occur and produce particulate bioglass, the material should be eliminated without consequence.

Migration of silicone gel to axillary lymph nodes after prosthetic mammoplasty

Foreign-body reaction to material optically resembling silicone gel was evident in an axillary lymph node of a patient eight years after subcutaneous mastectomy for fibrocystic disease and breast reconstruction with a silicone gel-filled prosthesis. The lymph nodes. was removed as a component of a radical mastectomy for adenocarcinoma and Paget's disease of the nipple that had developed in the residual breast tissue and preserved nipple. Silicone gel may "bleed" through a structurally intact prosthetic envelope and subsequently migrate to regional lymph nodes

Porcine heterograft valve replacement in carcinoid heart disease

A 53-year-old man with a pancreatic carcinoid tumor and liver metastases had the carcinoid syndrome with involvement of the tricuspid valve by carcinoid plaque. The mitral valve was involved by unrelated myxomatous degeneration (floppy valve). Each valve was replaced by a Hancock glutaraldehyde-prepared porcine heterograft prosthesis. When the patient died of complications of the tumor 8 months postoperatively, both valves had clinically normal function. Nevertheless, the carcinoid plaque, which was present in all four cardiac chambers and almost completely covered the endocardial surfaces of both atria, extended onto both prostheses. This eventually might have interfered with prosthetic valve function.

Effect of alpha naphthylthiourea on uptake of 5-hydroxytryptamine from the pulmonary circulation

Pulmonary injury caused by alpha naphthylthiourea (ANTU) is characterized by alterations of the capillary endothelial barrier followed by lung edema. Because pulmonary uptake of 5-hydroxytryptamine (5-HT) is dependent upon active transcellular transport by lung endothelium, it may be an index of early impairment of endothelial function caused by ANTU. We studied the effect of a single intraperitoneal dose of 5 or of 10 mg/kg of ANTU on pulmonary uptake of 5-HT by isolated rat lungs. Four h after the administration of ANTU, when lung tissue structure and dry-to-wet-weight ratios were comparable to those of control animals, 5-HT uptakes were significantly reduced (p < 0.05). Twenty-four h after the administration of ANTU, when lung edema was present on histologic examination and by lung weights, 5-HT uptakes were further reduced. They returned to control values 14 days after the administration of ANTU. Depression of 5-HT uptake is an early and reversible alteration of lung endothelial cell function caused by ANTU. Uptake of 5-HT may provide a sensitive probe with which to detect and evaluate pulmonary endothelial cell injury caused by toxicants.

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.

Nodular pulmonary amyloidosis. Description of a case with ultrastructure

A 64-year-old man with a suspicious asymptomatic coin lesion received a thoracotomy that showed two foci of isolated nodular pulmonary amyloidosis. Ultrastructural analysis verified the amyloid nature of the lesion and suggested that the fibrils were produced by plasma cells and processed by macrophages. The pathogenesis of this lesion is discussed in light of recent studies.

Stress analysis of single-tooth implants. I. Effect of elastic parameters and geometry of implant

Five different implant materials and three different geometries of ankylosed single-tooth implants were investigated. The stress distributions within and around the implants were determined by finite element analysis. Results show that the optimal combination of implant material and geometry can reduce implant and alveolar stresses by a factor of three when compared to an arbitrary implant design.

Can a small blood vessel prosthesis be derived from heterologous foreign body reactive tissue?

This study investigated as a small diameter vascular replacement the tissue formed adjacent to an implanted cylindrical foreign body, heterologously transplanted. Grafts of 4 mm i.d. were grown in rabbits and transplanted to dogs as segmental carotid and femoral artery replacements. These maintained 50% patency after 3 weeks. Variables in the further development of this concept are discussed.

Foreign-body reaction to silicone gel in axillary lymph nodes after an augmentation mammaplasty

A radical mastectomy was performed for a breast adenocarcinoma occurring 10 years after a subpectoral augmentation mammaplasty with silicone gel-filled prostheses. A foreign-body reaction to silicone was seen in two of the axillary lymph nodes resected.

Objective evaluation of surface microreplication by dental impression materials

Twenty-two materials, including 19 dental impression elastomers, were compared in their ability to replicate microscopic detail. Some polysulfide, silicone, and polyether materials performed well. Curiously, microscopic replication ability generally correlated inversely with that expected from the nominal consistency. The test method developed appears to be a suitable microreplication evaluation standard.