A set of L-band electron spin resonance imaging (ESRI) equipment suitable for biological species was developed and an ESRI experiment model for viable skin samples was established. The mechanic process of nitroxide free radical TEMPO (2,2, 6, 6-tetramethyl-1-piperidinyloxy) penetrating through skin sample and the spin density distribution of TEMPO after it interacted with skin sample were detected by the developed ESRI method. Skin samples were extracted from mice back. The experimental samples were prepared by cutting the skin pieces into square shape of 2 x 2 cm2 and then the samples were divided into three groups by treating them with three different methods: Method A, simple treatment by simply cutting the hair; method B, 8% Na2S depilation treatment for 10 min; method C, 8% Na2S depilation and then 5% pancreatic digestion treatment for 2 hours. The liposoluble solvent DMSO (dimethyl sulfoxide) and distilled water were used as two kinds of solvent for the TEMPO liquor. The results indicated that the skin-penetration properties of TEMPO were significantly different among samples treated with different methods and the surface cornifin of skin offered remarkable resistance to TEMPO. The TEMPO liquor of water could hardly penetrate through skins, whereas about 20%-30% of the original TEMPO compounds that solved in liposoluble solvent DMSO could penetrate through the skin sample treated with method C after 16 hours of interaction. Furthermore, the penetration rate of TEMPO through the skin tissue was a strong time dependent process. The preliminary application results suggested that ESRI technique could provide an effective and applicable method for dynamically researching skin-penetration properties of some special kinds of materials such as paramagnetic compounds.
Animals ; Cyclic N-Oxides ; pharmacokinetics ; Dimethyl Sulfoxide ; chemistry ; Electron Spin Resonance Spectroscopy ; methods ; Free Radical Scavengers ; pharmacokinetics ; Mice ; Piperidines ; pharmacokinetics ; Skin Absorption ; physiology ; Skin Physiological Phenomena ; drug effects ; Spin Labels

Objective:To explore the clinical effects of parallel combined flow-through perforator flaps in the treatment of circular hot crush injuries in limbs with blood supply disorder.Methods:The study was a retrospective observational study. From April 2016 to December 2022, 4 cases with circular hot crush injuries in limbs with blood supply disorder were admitted to the Department of Burns and Plastic Surgery of the 988 th Hospital of Joint Logistics Support Force of PLA, including 3 males and 1 female, aged from 24 to 48 years. Among them, 2 cases were injured in the calf and 2 cases were injured in the forearm. After emergency debridement, the area of skin and soft tissue defects was from 20 cm×20 cm to 44 cm×20 cm. The patients had defects in tibialis anterior and posterior tibial arteries with a length of 13 to 18 cm, and in ulnar and radial arteries with a length of 9 to 12 cm. Flaps were designed and cut, including a flow-through anterolateral thigh perforator flap with area of 20 cm×9 cm to 24 cm×21 cm carrying the descending branch of the lateral circumflex femoral artery and the accompanying veins of 8 to 18 cm in length; and a flow-through posterior tibial artery perforator flap with area of 21 cm×13 cm and 20 cm×14 cm carrying the posterior tibial artery, the accompanying veins with a length of 14 and 17 cm respectively, and the great saphenous vein with a length of 22 and 21 cm. The circular hot crush injury wounds in the calf with blood supply disorder were repaired by a parallel combination of flow-through posterior tibial artery perforator flap and flow-through anterolateral thigh perforator flap, and the circular hot crush injury wounds in the forearm with blood supply disorder were repaired by a parallel combination of bilateral flow-through anterolateral thigh perforator flap, and the injured main vessels were reconstructed. The donor site wounds of flap were closed directly or treated with split-thickness skin grafts from abdomen. After surgery, the blood supply and survival of the flap and distal affected limb, the healing of wounds in the donor and recipient sites, the survival of the skin graft in the flap donor site were observed. During follow-up, the condition of flaps, the appearance, blood supply, and function of affected limbs were observed. At the last follow-up, the foot and ankle functions were evaluated according to the scoring standards of American Orthopedic Foot and Ankle Association, and the wrist and hand function was evaluated according to the trial standard of replantation of amputated upper limb function assessment of the Hand Surgery of Chinese Medical Association. Results:The flaps and distal affected limbs of 4 patients had good blood circulation and successfully survived after surgery. The wounds of 3 cases successfully healed, while one patient with circular hot crush injury in the forearm experienced exudation in the recipient site in the later stage, and the wound healed after re-expansion and suturing. The donor site wounds healed smoothly, and the skin grafts successfully survived. During follow-up of 12 to 24 months after surgery, the flaps were slightly swollen, the limbs had good appearance, normal blood circulation, and fine functional recovery. At the last follow-up, the foot and ankle function of 2 patients with circular hot crush injuries in the calf was evaluated as good in 1 case and commonly in 1 case; the wrist and hand function of 2 patients with circular hot crush injuries in the forearm was evaluated as excellent in 1 case and good in 1 case.Conclusions:The parallel combined flow-through perforator flap can reconstruct the damaged main blood vessels and repair the wound at the same time. It can not only effectively save the limb, but also restore part of the function of the affected limb. It is one of the effective methods to treat the circular hot crush injuries in limbs with blood supply disorder.