Characterization in Effective Stimulation on the Magnitude, Gating, Frequency Dependence, and Hysteresis of INa Exerted by Picaridin (or Icaridin), a Known Insect Repellent.

Picaridin (icaridin), a member of the piperidine chemical family, is a broad-spectrum arthropod repellent. Its actions have been largely thought to be due to its interaction with odorant receptor proteins. However, to our knowledge, to what extent the presence of picaridin can modify the magnitude, gating, and/or the strength of voltage-dependent hysteresis (Hys(V)) of plasmalemmal ionic currents, such as, voltage-gated Na+ current [INa], has not been entirely explored. In GH3 pituitary tumor cells, we demonstrated that with exposure to picaridin the transient (INa(T)) and late (INa(L)) components of voltage-gated Na+ current (INa) were differentially stimulated with effective EC50's of 32.7 and 2.8 µM, respectively. Upon cell exposure to it, the steady-state current versus voltage relationship INa(T) was shifted to more hyperpolarized potentials. Moreover, its presence caused a rightward shift in the midpoint for the steady-state inactivate curve of the current. The cumulative inhibition of INa(T) induced during repetitive stimuli became retarded during its exposure. The recovery time course from the INa block elicited, following the conditioning pulse stimulation, was satisfactorily fitted by two exponential processes. Moreover, the fast and slow time constants of recovery from the INa block by the same conditioning protocol were noticeably increased in the presence of picaridin. However, the fraction in fast or slow component of recovery time course was, respectively, increased or decreased with an increase in picaridin concentrations. The Hys(V)'s strength of persistent INa (INa(P)), responding to triangular ramp voltage, was also enhanced during cell exposure to picaridin. The magnitude of resurgent INa (INa(R)) was raised in its presence. Picaritin-induced increases of INa(P) or INa(R) intrinsically in GH3 cells could be attenuated by further addition of ranolazine. The predictions of molecular docking also disclosed that there are possible interactions of the picaridin molecule with the hNaV1.7 channel. Taken literally, the stimulation of INa exerted by the exposure to picaridin is expected to exert impacts on the functional activities residing in electrically excitable cells.

Laparoscopic retrieval of retained intraperitoneal drains in the immediate postoperative period.

Retained intraperitoneal Penrose drain secondary to fracture and adhesions in the immediate postoperative period happens on occasion. Most are unreported because of the fear of medico-legal problems. Previous management of such iatrogenic complications requires repeated laparotomy or wound exploration. Two patients who underwent appendectomy for ruptured appendicitis, with retained intraabdominal drains in the immediate postoperative period, managed eventually by laparoscopic retrieval are presented. Both patients had right low transverse incisions and intraabdominal drains exiting through a separate right lateral abdomen skin opening. Patient 1 had a stuck intraabdominal drain unable to be removed up to the second week. Patient 2's drain retracted intraperitoneally after its mobilization on the sixth post-op day. Both were managed by laparoscopy under general anesthesia with successful removal of both drains. Patient 1 underwent the procedure 3 weeks after the appendectomy, whereas Patient 2 had the procedure on her sixth post-op day. An additional new 1-cm wound in the periumbilical area was done for the introduction of pneumoperitoneum and 10-mm port for which the laparoscope was inserted. The second 5-mm port was inserted through the old drain site wound with peritoneal entry opening separate from the previous peritoneal defect viewed from laparoscope. Both drains had some marked adhesions from ingrowth of omentum to the side holes of the drain, causing it to get stuck in the pelvic cavity. This laparoscopic approach in the management of such iatrogenic complication, besides being cosmetically acceptable, contributes to early recovery and discharge of the patient, and helps to lessen the friction in the recently worsening doctor-patient relationship in Taiwan.