Tumor Targeting and Pharmacokinetics of a Near-Infrared Fluorescent-Labeled δ-Opioid Receptor Antagonist Agent, Dmt-Tic-Cy5.

Fluorescence molecular imaging can be employed for the development of novel cancer targeting agents. Herein, we investigated the pharmacokinetics (PK) and cellular uptake of Dmt-Tic-Cy5, a delta-opioid receptor (δOR) antagonist-fluorescent dye conjugate, as a tumor-targeting molecular imaging agent. δOR expression is observed normally in the CNS, and pathologically in some tumors, including lung liver and breast cancers. In vitro, in vivo, and ex vivo experiments were conducted to image and quantify the fluorescence signal associated with Dmt-Tic-Cy5 over time using in vitro and intravital fluorescence microscopy and small animal fluorescence imaging of tumor-bearing mice. We observed specific retention of Dmt-Tic-Cy5 in tumors with maximum uptake in δOR-expressing positive tumors at 3 h and observable persistence for >96 h; clearance from δOR nonexpressing negative tumors by 6 h; and systemic clearance from normal organs by 24 h. Live-cell and intravital fluorescence microscopy demonstrated that Dmt-Tic-Cy5 had sustained cell-surface binding lasting at least 24 h with gradual internalization over the initial 6 h following administration. Dmt-Tic-Cy5 is a δOR-targeted agent that exhibits long-lasting and specific signal in δOR-expressing tumors, is rapidly cleared from systemic circulation, and is not retained in non-δOR-expressing tissues. Hence, Dmt-Tic-Cy5 has potential as a fluorescent tumor imaging agent.

Monitoring and mitigating isoflurane emissions during inhalational anesthesia of mice.

Establishing a program to monitor waste anesthetic gas (WAG) in order to limit personnel exposure requires measuring the levels of WAG emitted and determining the effectiveness of scavenging methods to reduce such levels. In this study, the authors used infrared spectroscopy to measure levels of WAG emitted while anesthetizing mice with isoflurane for 15 min. They evaluated four different WAG scavenging conditions during induction and maintenance anesthesia: two conditions that used passive techniques and two that used active techniques. Isoflurane concentrations were measured at three different locations: in the operator's vicinity, at the mouse-facemask interface and in the room environment. Passive scavenging of WAG improved when chambers were purged with oxygen after induction and when a diaphragm-sealed facemask delivered a reduced anesthetic flow rate during maintenance anesthesia. Active scavenging of WAG improved when a relief intake opening was provided in the induction chamber's vacuum line, vacuum draw after induction was regulated and the anesthetic flow rate and vacuum scavenging draw were balanced during maintenance anesthesia using a facemask that separated the breathing space from the scavenging zone. Additionally, time-weighted average isoflurane WAG levels detected by personal dosimeters correlated with real-time measurements made using infrared spectroscopy. These observations contribute to the development of a substantiated program for monitoring WAG air quality.