Analysis of the Necrosis-Inducing Components of the Venom of Naja atra and Assessment of the Neutralization Ability of Freeze-Dried Antivenom.

Patients bitten by Naja atra who are treated with bivalent freeze-dried neurotoxic antivenom in Taiwan have an improved survival rate but develop necrotic wound changes. The World Health Organization (WHO) has suggested using the minimum necrotizing dose (MND) of venom as a method of evaluating the neutralization effect of antivenom. The aim of this study was to evaluate the effectiveness of antivenom for the prevention of necrosis based on the MND and clarify which component of the venom of N. atra induces necrosis. The neurotoxins (NTXs) were removed from the crude venom (deNTXs), and different concentrations of deNTXs were injected intradermally into the dorsal skin of mice. After three days, the necrotic lesion diameter was found to be approximately 5 mm, and the MND was calculated. A reduction in the necrotic diameter of 50% was used to identify the MND50. Furthermore, both phospholipase A2 (PLA2) and cytotoxins (CTXs) were separately removed from the deNTXs to identify the major necrosis-inducing factor, and the necrotic lesions were scored. All mice injected with deNTXs survived for three days and developed necrotic wounds. The MND of the deNTXs for mice was 0.494 ± 0.029 µg/g, that of the deNTXs-dePLA2 (major component retained: CTXs) was 0.294 ± 0.05 µg/g, and that of the deNTX-deCTX (major component retained: PLA2) venom was greater than 1.25 µg/g. These values show that CTX is the major factor inducing necrosis. These results suggest that the use of the deNTXs is necessary to enable the mice to survive long enough to develop venom-induced cytolytic effects. CTXs play a major role in N. atra-related necrosis. However, the MND50 could not be identified in this study, which meant that the antivenom did not neutralize venom-induced necrosis.

Intraoperative Assessment of the Relationship Between Nipple Circulation and Incision Site in Nipple-Sparing Mastectomy With Implant Breast Reconstruction Using the SPY Imaging System.

INTRODUCTION: Nipple-sparing mastectomy (NSM) and immediate breast reconstruction with gel implants have grown in popularity because of superior aesthetic outcomes. One risk of this procedure is overexcision of the flap leading to inadequate circulation in the breast envelope. METHODS: We investigated 17 cases of NSM and gel implant breast reconstruction. Patients were divided into an infra-areolar incision group and a supra-areolar incision group. Nipple-areolar complex perfusion was evaluated using the SPY imaging system after NSM and gel implant breast reconstruction. We aimed to discover any relationships between the incision method and nipple-areolar complex (NAC) circulation in NSM and gel implant breast reconstruction. RESULTS: For successful breast surgery, awareness of the blood supply to the breast, especially the NAC, is very important. In our study, with the indocyanine green SPY imaging system, most ingress (arterial inflow) and egress (venous outflow) rates in the infra-areolar incision group were better than those in the supra-areolar incision group (P < 0.005). CONCLUSIONS: We have shown that an infra-areolar incision provides better blood flow following NSM and gel implant breast reconstruction. In our experience, in order to prevent the possible ischemia of NAC, we used the smaller gel implants, which is approximately 10 to 20 mL smaller than the original implant size measured by the sizer, if the egress rate of NAC is lower than 0.2. These findings have implications in the clinical setting as surgeons have a choice to provide a better outcome for patients.