Incidence and Consequence of Close Margins in Patients with Ductal Carcinoma-In Situ Treated with Mastectomy: Is Further Therapy Warranted?

Background

The impact of close margins in patients with ductal carcinoma-in situ (DCIS) treated with mastectomy is unclear; however, this finding may lead to a recommendation for postmastectomy radiotherapy (PMRT). We sought to determine the incidence and consequences of close margins in patients with DCIS treated with mastectomy.

Methods

The records of 810 patients with DCIS treated with mastectomy from 1996 through 2009 were reviewed. Clinical and pathologic factors were analyzed with respect to final margin status. Median follow-up was 6.3 years.

Results

Overall, 94 patients (11.7 %) had close margins (positive, n = 5; negative but ≤1 mm, n = 54; 1.1–2.9 mm, n = 35). Independent risk factors for close margins included multicentricity, pathologic lesion size ≥1.5 cm, and necrosis, but not age, use of skin-sparing mastectomy, or immediate reconstruction (p > 0.05). Seven patients received PMRT, and none had a locoregional recurrence (LRR). Among the remaining 803 patients, the 10-year LRR rate was 1 % (5.0 % for margins ≤1 mm, 3.6 % for margins 1.1–2.9 mm, and 0.7 % for margins ≥3 mm [p < 0.001]). The 10-year rate of contralateral breast cancer was 6.4 %. On multivariate analysis, close margins was the only independent predictor of LRR (p = 0.005).

Conclusions

Close margins occur in a minority of patients undergoing mastectomy for DCIS and is the only independent risk factor for LRR. As the LRR rate in patients with close margins is low and less than the rate of contralateral breast cancer, PMRT is not warranted except for patients with multiple close/positive margins that cannot be surgically excised.     

Prolonged treatment of Salmonella enterica serovar Typhimurium with commercial disinfectants selects for multiple antibiotic resistance, increased efflux and reduced invasiveness

OBJECTIVES: To study how disinfectants affect antimicrobial susceptibility and phenotype of Salmonella enterica serovar Typhimurium SL1,344. METHODS: Wild-type strain SL1,344 and its isogenic gyrA mutant were passaged daily for 7 days in subinhibitory concentrations, and separately for 16 days in gradually increasing concentrations of a quaternary ammonium disinfectant containing formaldehyde and glutaraldehyde (QACFG), an oxidizing compound blend (OXC), a phenolic tar acids-based disinfectant (TOP) and triclosan. The MICs of antimicrobials and antibiotics for populations and representative isolates and the proportion of cells resistant to the MICs for the wild-type were determined. Expression of acrB gene, growth at 37 degrees C and invasiveness of populations in Caco-2 intestinal epithelial cells were assessed. RESULTS: QACFG and triclosan showed the highest selectivity for variants with reduced susceptibility to chloramphenicol, tetracycline, ampicillin, acriflavine and triclosan. Populations treated with the above biocides had reduced invasiveness in Caco-2 cells, and altered growth kinetics. Resistance to disinfectants was observed only after exposure to gradually increasing concentrations of triclosan, accompanied with a 2000-fold increase in its MIC. Growth in OXC and TOP did not affect the MICs of antibiotics, but resulted in the appearance of a proportion of cells resistant to the MIC of acriflavine and triclosan for the wild-type. Randomly selected stable variants from all populations, except the one treated with TOP, over-expressed acrB. CONCLUSIONS: In vitro exposure to QACFG and triclosan selects for Salmonella Typhimurium cells with reduced susceptibility to several antibiotics. This is associated with overexpression of AcrAB efflux pump, but accompanied with reduced invasiveness.     

Pancreatic islets engineered with a FasL protein induce systemic tolerance at the induction phase that evolves into long‐term graft‐localized immune privilege

We have previously shown that pancreatic islets engineered to transiently display a modified form of FasL protein (SA‐FasL) on their surface survive indefinitely in allogeneic recipients without a need for chronic immunosuppression. Mechanisms that confer long‐term protection to allograft are yet to be elucidated. We herein demonstrated that immune protection evolves in two distinct phases; induction and maintenance. SA‐FasL‐engineered allogeneic islets survived indefinitely and conferred protection to a second set of donor‐matched, but not third‐party, unmanipulated islet grafts simultaneously transplanted under the contralateral kidney capsule. Protection at the induction phase involved a reduction in the frequency of proliferating alloreactive T cells in the graft‐draining lymph nodes, and required phagocytes and TGF‐β. At the maintenance phase, immune protection evolved into graft site‐restricted immune privilege as the destruction of long‐surviving SA‐FasL‐islet grafts by streptozotocin followed by the transplantation of a second set of unmanipulated islet grafts into the same site from the donor, but not third party, resulted in indefinite survival. The induced immune privilege required both CD4⁺CD25⁺Foxp3⁺ Treg cells and persistent presence of donor antigens. Engineering cell and tissue surfaces with SA‐FasL protein provides a practical, efficient, and safe means of localized immunomodulation with important implications for autoimmunity and transplantation.     

An inhibitory monoclonal antibody to factor X that blocks prothrombin activation but not prothrombinase enzyme assembly

A monoclonal antibody (designated alpha BFX-2b) prepared against bovine factor X inhibited factor X activity in human, bovine, porcine, rabbit, and canine plasma. In assays using purified prothrombinase components, factor Xa, factor Va, phospholipid vesicles, and calcium ion with the fluorescent active site thrombin inhibitor dansylarginyl-N-(3-ethyl-1,5- pentanediyl)amide, the antibody inhibited the conversion of prothrombin to thrombin. Antibody alpha BFX-2b also blocked prothrombinase cleavage of the macromolecular substrates prethrombin 1 and prethrombin 2 but did not inhibit factor Xa hydrolysis of the synthetic substrate benzoyl- Ile-Glu-Gly-Arg-p-nitroanilide. The antibody also prevented the inactivation of factor Xa by antithrombin III but did not prevent the inactivation by soybean trypsin inhibitor. Antibody alpha BFX-2b bound factor Xa with a stoichiometry of 1:1 and an apparent dissociation constant of 9.0 x 10(-11) mol/L as estimated from its inhibition of prothrombinase activity. Antibody alpha BFX-2b did not prevent binding of factor Xa to factor Va-phospholipid as measured by using fluorescence polarization or high-pressure liquid gel chromatography with the fluorescent Factor Xa analogue dansyl-glutamyl-glycyl-arginyl- Xa. Immunoblotting of factor X following electrophoresis on sodium dodecyl sulphate-polyacrylamide gels and transfer to nitrocellulose indicated that the antigenic determinant recognized by antibody alpha BFX-2b was found on the heavy chain of factors X and Xa. From these observations it can be concluded that antibody alpha BFX-2b recognizes a highly conserved epitope on the factor X heavy chain that is remote from the topographic sites required for prothrombinase complex assembly and substrate hydrolysis but may be located at or near a portion of the macromolecular substrate binding site.