Mice that lack the angiogenesis inhibitor, thrombospondin 2, mount an altered foreign body reaction characterized by increased vascularity.
Disruption of the thrombospondin 2 gene (Thbs2) in mice results in a complex phenotype characterized chiefly by abnormalities in fibroblasts, connective tissues, and blood vessels. Consideration of this phenotype suggested to us that the foreign body reaction (FBR) might be altered in thrombospondin 2 (TSP2)-null mice. To investigate the participation of TSP2 in the FBR, polydimethylsiloxane (PDMS) and oxidized PDMS (ox-PDMS) disks were implanted in TSP2-null and control mice. Growth of TSP2-null and control skin fibroblasts in vitro also was evaluated on both types of disks. Normal fibroblasts grew as a monolayer on both surfaces, but attachment of the cells to ox-PDMS was weak and sensitive to movement. TSP2-null fibroblasts grew as aggregates on both surfaces, and their attachment was further compromised on ox-PDMS. After a 4-week implantation period, both types of PDMS elicited a similar FBR with a collagenous capsule in both TSP2-null and control mice. However, strikingly, the collagenous capsule that formed in TSP2-null mice was highly vascularized and thicker than that formed in normal mice. In addition, abnormally shaped collagen fibers were observed in capsules from mutant mice. These observations indicate that the presence or absence of an extracellular matrix component, TSP2, can influence the nature of the FBR, in particular its vascularity. The expression of TSP2 therefore could represent a molecular target for local inhibitory measures when vascularization of the tissue surrounding an implanted device is desired. (+info)
The purpose of this study was to assess the value of 99mTc-pertechnetate scanning in the diagnosis of gastric banding leaks. METHODS: Three patients with morbid obesity received laparoscopic adjustable silicone gastric banding (ASGB), but no significant weight reduction was obtained. To exclude band leakage as the cause, four scintigraphic procedures were performed, consisting of imaging the upper abdomen 30 min and 3 h after injection of 3 mL (111 MBq) pertechnetate solution into the ASGB reservoir. In one patient, the integrity of the ASGB device was first assessed radiologically after injection of a water-soluble contrast agent into the ASGB reservoir. RESULTS: In two normally functioning ASGB devices, radiotracer was observed within the device on both early and late images. In two patients with a surgically proven small leak in the reservoir or the connecting tube, late images showed little tracer in the reservoir and the connecting tube. However, intense tracer accumulation was observed in the stomach as a result of resorption of pertechnetate in the subcutaneous or peritoneal blood vessels and subsequent gastric uptake. In one of the latter patients, radiographic assessment of the ASGB device revealed no abnormalities. CONCLUSION: 99mTc-pertechnetate scanning is a valuable technique to diagnose small leaks in an ASGB device. (+info)
Temporary endovascular balloon occlusion of the internal carotid artery with a nondetachable silicone balloon catheter: analysis of technique and cost.
BACKGROUND AND PURPOSE: Temporary balloon occlusion has become a routine and medically accepted technique for the management of patients with aneurysms or intracranial or head/neck tumors. We describe our experience using a nondetachable silicone balloon (NDSB) catheter in 103 endovascular temporary balloon occlusions of the internal carotid artery, with attention focused on technique, complications, and cost. METHODS: Between 1993 and 1998, 103 patients underwent preoperative temporary balloon occlusion testing with a 1.5-mm NDSB catheter. Clinical testing during endovascular blockade was combined with qualitative cerebral blood flow analysis using technetium-99m HMPAO SPECT. Cost-effective analysis was performed, emphasizing cost and complication rates in comparison with those in previously reported series in which multiple types of temporary balloon occlusion catheters were used, predominantly not of the NDSB type. RESULTS: No carotid artery injury or complication, including cerebral infarction due to NDSB use, was encountered. Despite the increased cost of the NDSB catheter system, cost-effective analysis showed up to 40% reduction in cost per quality adjusted life years. CONCLUSION: Temporary balloon occlusion using the NDSB catheter is safe and cost-effective, owing to the low rate of complications. (+info)
Plastic migration from implanted central venous access devices.
BACKGROUND: This is the first reported study of histologically confirmed migration from intravenous access devices in children. METHODS: The capsules from around intravenous access devices were examined by light microscopy to determine the extent of the foreign body response; energy dispersive x ray analysis was performed to document the elemental content of the foreign material. RESULTS: A fibroconnective tissue capsule was found around all the samples. Elemental silicon was found in six of 13 tissue samples, and a foreign body giant cell reaction was seen in three of these. CONCLUSIONS: The pseudocapsule that surrounds an implanted vascular access device often has residual foreign material, including silicone. (+info)
Influence of long term silicone implantation on type II collagen induced arthritis in mice.
OBJECTIVES: The use of silicone implants in cosmetic and reconstructive surgery has been implicated in the development of autoimmune connective tissue diseases. Previous investigation of the influence of short-term silicone implantation using an experimental model of rheumatoid arthritis revealed no adverse influence upon disease despite the generation of autoantibodies against silicone bound proteins. This study was designed to examine the influence of long term implantation of different forms of silicone in collagen induced arthritis. METHODS: DBA/1 mice were surgically implanted with silicone elastomers, gel or oil nine months before immunisation with type II collagen emulsified in Freund's incomplete adjuvant. The incidence and severity of arthritis, antibodies to type II collagen, and serum cytokines were assessed and compared with sham implanted mice. Silicone implants were recovered, and autoantibodies to silicone bound proteins evaluated in arthritic and non-arthritic mice. RESULTS: Immunisation with CII/FIA resulted in a 30% arthritis incidence in sham implanted DBA/1 mice. Long term silicone implantation resulted in an increased incidence of arthritis, with a significant increase of 90% arthritis in animals implanted with silicone elastomers. Animals implanted with silicone elastomer also developed foreign body sarcomas during the study. Serum concentrations of interleukin 10 were increased in mice implanted with elastomers and immunised with CII/FIA, while interleukin 5 concentrations were significantly diminished in these mice. The production of autoantibodies to autologous silicone bound proteins, including anti-type I collagen antibody, was also attributed to the implantation of either silicone gel or silicone elastomer in type II collagen immunised animals. CONCLUSIONS: These data suggest that long term silicone implantation results in both the production of autoantibodies to connective tissue antigens and increased susceptibility to an experimental model of autoimmune disease. (+info)
Extended field-of-view two-dimensional ultrasonography of the breast: improvement in lesion documentation.
The purpose of this study was to evaluate the use of extended field-of-view two-dimensional ultrasonographic imaging for improvement in overall breast lesion documentation. Sonographic images of 59 patients with breast lesions or silicone implants were evaluated by three radiologists retrospectively to compare traditional static linear array images alone with images obtained with the addition of an extended field of view to determine if documentation of lesions was improved. The addition of extended field-of-view imaging improved lesion conspicuity by 21% over traditional images. It provided overall improvement in lesion documentation by including a reference point (nipple) or by more completely imaging large masses in 79% and implants in 69%. The larger field of view of this technique is promising as an adjunct to traditional sonography for breast lesion documentation. (+info)
Epidemiologic studies of environmental agents and systemic autoimmune diseases.
Systemic lupus erythematosus and systemic scleroderma are autoimmune diseases thought to have an exogenous trigger. This review summarizes relevant case-control and cohort studies that investigated exogenous sex hormones, silica, silicone, solvents, pesticides, mercuric chloride, and hair dyes as putative risk factors for the development of these diseases. These studies indicate that estrogen replacement therapy in postmenopausal women increases the risk of developing lupus, scleroderma, and Raynaud disease, although the increase in risk is relatively modest. Oral contraceptives may also play a role in disease susceptibility in lupus but not apparently in scleroderma. Environmental endocrine modulators, in the form of pesticides, may represent another opportunity for estrogenlike effects to occur, but there is scant evidence that these agents play a role in human systemic autoimmune disease. Although exposure to silica dust increases the risk of scleroderma in men occupied in the industry, this does not explain most male scleroderma cases. When this exposure was investigated among women, no significant risk was found. Additionally, silicone in implanted devices as well as occupational exposure to silicone-containing compounds did not pose an increased risk among women for scleroderma. The role of solvent exposure has been investigated as a risk factor for scleroderma with mixed findings. One study suggested a potential role in male patients or in those individuals with Scl-70 antibody positivity either male or female. Two other studies were unable to corroborate this finding. Mercuric chloride causes antifibrillarin antibodies and immune complex glomerulonephritis in susceptible mouse strains. Antifibrillarin antibodies, but not glomerulonephritis, occur in a subset of scleroderma patients and preliminary evidence suggests that mercury levels may be higher in this group of individuals. Hair products have been studied as possibly raising the risk of developing lupus, since such products contain an aromatic amine similar to a compound known to cause drug-induced lupus. A 1986 study suggested a positive association, but two subsequent studies did not support this association. (+info)
Neutrophil chemotaxis on silicone and polyurethane surfaces.
Silicone vascular catheters have a greater risk of infection and produce greater inflammation in vivo and greater complement activation in vitro than other vascular catheter polymer materials. This study investigated whether polymorphonuclear leukocyte (PMNL) chemotaxis under agarose on silicone surfaces is different than on polyurethane (PU). Glass slides were coated with silicone and PU by use of a constant-speed dipping apparatus. Chemotaxis (3 h) in response to (10-7 mL) FMLP, zymosan-activated serum, and fresh serum (100%) was greater on silicone than on PU (P<.05). Polyclonal antibody to C5a blocked >50% of the movement toward serum (P<.05). Serum in the PMNL well significantly decreased chemotaxis toward FMLP on silicone (P<.05) but not on PU. These findings suggest that excessive complement activation by silicone may interfere with chemotaxis, but further work is necessary to determine whether this is relevant to an increased risk of catheter-related infection. (+info)