A new bioartificial pancreas utilizing amphiphilic membranes for the immunoisolation of porcine islets: a pilot study in the canine.

We have developed a replaceable bioartificial pancreas to treat diabetes utilizing a unique cocontinous amphiphilic conetwork membrane created for macroencapsulation and immunoisolation of porcine islet cells (PICs). The membrane is assembled from hydrophilic poly(N,N-dimethyl acrylamide) and hydrophobic/oxyphilic polydimethylsiloxane chains cross-linked with hydrophobic/oxyphilic polymethylhydrosiloxane chains. Our hypothesis is that this membrane allows the survival of xenotransplanted PICs in the absence of prevascularization or immunosuppression because of its extraordinarily high-oxygen permeability and small hydrophilic channel dimensions (3-4 nm). The key components are a 5-10 microm thick semipermeable amphiphilic conetwork membrane reinforced with an electrospun nanomat of polydimethylsiloxane-containing polyurethane, and a laser-perforated nitinol scaffold to provide geometric stability. Devices were loaded with PICs and tested for their ability to maintain islet viability without prevascularization, prevent rejection, and reverse hyperglycemia in three pancreatectomized dogs without immunosuppression. Tissue tolerance was good and there was no systemic toxicity. The bioartificial pancreas protected PICs from toxic environments in vitro and in vivo. Islets remained viable for up to 3 weeks without signs of rejection. Neovascularization was observed. Hyperglycemia was not reversed, most likely because of insufficient islet mass. Further studies to determine long-term islet viability and correction of hyperglycemia are warranted.

Does core needle breast biopsy accurately reflect breast pathology?

BACKGROUND: Core needle breast biopsy (CB) has replaced excisional biopsy as the initial diagnostic biopsy procedure for many suspicious breast lesions; however, CB remains a sampling procedure. The purpose of this study was to determine the degree of agreement between histology obtained at CB and that obtained at a subsequent excisional procedure (EP). We hypothesized a high degree of agreement. METHODS: Data were collected prospectively for 3035 CBs performed by breast radiologists using either ultrasound or stereotactic guidance between January 1995 and July 2002, 1410 (46%) of which had a subsequent EP within 1 year. Histologic categories were defined as invasive breast cancer, duct carcinoma in-situ, atypia/lobular carcinoma in-situ, and benign. The principal histology (PH) from CB and EP was identified and compared. RESULTS: Overall, there was moderate agreement (kappa=0.669) between CB and EP histology. Complete agreement occurred in 1168 (83%) procedures. For the remaining 242, the PH was identified only at CB for 78 (5%) procedures, and only after EP for 164 (12%) procedures. CONCLUSIONS: Although the majority (83%) of CB and EP demonstrated exact histologic agreement, CB was diagnostic for 1246 (88%) procedures.