Objective To determine the difference in blood microcirculation recovery between normal frostbite and high-altitude frostbite during the wound healing.Methods Twenty four male rats were randomly divided into control group (n=8), normal frostbite group (n=8), and high-altitude group (n=8). The normal frostbite group rats were frozen to produce mid-degree frostbite models by controlling the freezing time with liquid nitrogen penetration equipment. The high-altitude frostbite group rats were acclimated to a hypoxic and low-pressure environment for 1 week, and then the high-altitude frostbite models were constructed by the same way with liquid nitrogen penetration apparatus. On days 3, 7, 11, 15, 19, and 23 after modeling, the recovery situation of blood circulation of each group was observed with contrast ultrasonography by injecting SonoVue micro-bubble into rats' tail. Finally, the micro-bubble concentration (MC) was calculated to confirm the blood circulation recovery with software Image Pro. ResultsAt different time points, the wound area of the high-altitude frostbite group was bigger than that of the normal frostbite group, and the MC of control group was always about (27±0.2)×109/ml. On day 3, 7, 11, 15, 19, and 23, the MC was significantly lower in the high-altitude frostbite group than in the control group and normal frostbite group (P<0.05). The MC of normal frostbite group was significantly lower than that of the control group on day 3, 7, 11, 15 and 19 (P<0.05). In addition, no obvious difference in MC was found between normal group and control group on the 23th day (P<0.05).Conclusion The blood microcirculation recovery after high-altitude frostbite is significantly slower than the normal frostbite.

Plateau frostbite (PF) treatments have remained a clinical challenge because this condition injures tissues in deep layers and affected tissues exhibit unique pathological characteristics. For instance, low-frequency pulsed electromagnetic field (PEMF) can affect tissue restoration and penetrate tissues. Therefore, the effect of PEMF on PF healing should be investigated. This study aimed to evaluate the effects of low-frequency PEMF on PF healing systematically. Ninety-six Sprague-Dawley rats were randomly and equally divided into three groups: normal control, partial thickness plateau frostbite (PTPF), and PTPF with low-frequency PEMF exposure (PTPF + PEMF). PTPF wounds were induced in the dorsum of the rats. The PTPF + PEMF group was exposed to low-frequency PEMF daily. During PF healing, wound microcirculation in each group was monitored through contrast ultrasonography. Wound appearance, histological observation, and wound tensile strength were also evaluated. Results showed that the rate of the microcirculation restoration of the PTPF + PEMF group was nearly 25% faster than that of the PTPF group, and wound appearance suggested that the healing of the PTPF group was slower than that of the PTPF + PEMF group. Histological observation revealed that PEMF accelerated the growth of different deep tissues, as confirmed by tensile strength examination. Low-frequency PEMF could penetrate PF tissues, promote their restoration, and provide a beneficial effect on PF healing. Therefore, this technique may be a potential alternative to treat PF.

目的:研制空间聚焦和频率强度可调的低频脉冲电磁场(Pulsed Electromagnetic Fields,PEMF)发生装置.方法:采用以单片机STC89C52为基础的智能可调低频脉冲信号发生器产生不同频率占空比的低频脉冲信号;该信号经预放大滤波后,由PA19构成的功率放大电路进行放大,驱动后级可调空间聚焦电磁场发射架;PEMF强度和空间分布通过特斯拉计HT108进行测量.结果:PEMF发生装置能够产生频率0～2 kHz、占空比10％～80％和强度0～400 mT可调的PEMF,且空间聚焦效果明显.结论:PEMF发生装置具有输出PEMF各参数可调范围大、电磁场聚焦范围空间可调等优点,适合用于电磁场非热生物效应研究.

目的:研究评估20 Hz、25 mT低频脉冲电磁场(low frequency pulsed electromagnetic fields,LFPEF)对高原冻伤伤口愈合过程中各组织层血液循环恢复情况的影响.方法:雄性SD大鼠24只,随机等分为3组:空白对照组(CG组)、高原冻伤组(PF组)和高原冻伤照射组(PF+LFPEF组).PF组和PF+LFPEF组大鼠缺氧习服1周后,采用液氮冻伤的方法构建中度冻伤模型.采用低频脉冲电磁场发生器产生20 Hz、25 mT低频脉冲电磁场对PF+LFPEF组进行照射治疗.于造模后第4、7、10、13、16、19、22d,采用超声微泡造影方法对各组大鼠冻伤伤口血液循环恢复情况进行观察检测,并计算对比各组冻伤部位微泡浓度.结果:在不同的时间点,PF+LFPEF组微泡浓度明显高于PF组,且在第22 d微泡浓度与CG组已无明显差别.结论:该低频脉冲电磁场能够有效促进高原冻伤血液循环的恢复和血管网络的形成.

目的:研究观察频率为15 Hz、强度150 mT占空比一定的低频脉冲电磁场（Pulsed electromagnetic fields,PEMFs）对SD大鼠冻伤部位组织血液循环的影响。方法:设计以高精度、低输出阻抗信号发生器芯片MAX038为核心的低频脉冲电磁场发生器,装置可产生频率为15 Hz,强度150 mT的电磁场;在大鼠的背部区域,采用液氮冷却的方法,建立中度冻伤的SD大鼠冻伤模型。将24只大鼠分为3组,空白对照组,单纯冻伤组,冻伤照射治疗组。采用该低频脉冲电磁场照射冻伤治疗组,6 h/d,持续10 d。然后,采用动物B超检查各组大鼠冻伤部位组织血液循环情况,并测量各组大鼠冻伤部位存活面积。结果:各组SD大鼠冻伤后存活面积测量显示照射组存活面积最大（P＜0.05）;对比各组大鼠冻伤部位B超图像,表明照射组血液循环明显优于单纯冻伤组。结论:一定强度的低频脉冲电磁场能有效改善冻伤部位组织血液循环,促进冻伤恢复。