ObjectiveTo explore the light sensitivity and kinetic of the new optogenetics tools Channelrhodopsin-XXM2.0 (XXM2.0) and Channelrhodopsin-PsCatCh2.0 (PsCatCh2.0), and analyze whether they could be used to restore the visual function by optogenetics.MethodsMolecular biology techniques were used to link the gene fragments of XXM2.0 and PsCatCh2.0 to the vector pCIG(c)-msFoxn3 containing ampicillin resistant screening gene and reporter gene to form new plasmid pCIG(c)-msFoxn3-XXM2.0 and pCIG(c)-msFoxn3-PsCatCh2.0. The constructed plasmids were transfected into HEK 293T cells, and light responses were recorded in the whole cell mode with the HEKA patch clamp system. The photocurrent was recorded under three light intensity included 2.7×1016, 4.7×1015, and 6.4×1014 photons/(cm2·s). And then, XXM2.0 and PsCatCh2.0 were stimulated with 2.7×1016 photons/(cm2·s) and fully recovered. The opening and closing time constants were analyzed with Clampfit 10.6 software. At the same light intensity, photocurrents of XXM2.0 and PsCatCh2.0 were recorded by the light pulse stimulating of 2-32 Hz. The current attenuation was analyzed at long intervals of 4000 ms and short intervals of 200 ms after repeated stimulation. Comparisons between groups were performed by independent samples t test.ResultsRestriction endonuclease sites of EcoRⅠ and EcoRⅤ were successfully introduced at XXM2.0 and PsCatCh2.0 sequences. When the digestion was completed, they were ligated by T4 DNA ligase to construct new plasmids pCIG(c)-msFoxn3-XXM2.0 and pCIG (c)-msFoxn3-PsCatCh2.0, and then transfected on HEK 293T cells. The light intensity dependence was showed in XXM2.0 and PsCatCh2.0. The greater light intensity was accompanied by the greater photocurrent. Under the light intensity 6.4×1014 photons/(cm2·s) below the retinal safety threshold, large photocurrent was still generated in XXM2.0 and PsCatCh2.0 with 92.8±142.0 and 13.9±5.6 pA (t=1.24, 1.24; P=0.28, 0.29). The opening time constants of XXM2.0 and PsCatCh2.0 were 23.9±6.7 and 2.4±0.8 ms, and the closing time constants were 5803.0±568.2 and 219.9±25.6 ms. Compared with PsCatCh2.0, the opening and closing time constant of XXM2.0 were both larger than PsCatCh2.0. The differences were statistically significant (t=7.10, 31.60; P=0.00, 0.00). In terms of response frequency, XXM2.0 and PsCatCh2.0 could follow to 32 Hz high-frequency pulsed light stimulation, and all could respond to repeated light stimulation at a long (4000 ms) and a short time (200 ms) interval with the small current decay rate.ConclusionXXM2.0 and PsCatCh2.0 could be activated under light intensity with safety for the retina, and could respond to high frequency (at least 32 Hz) pulsed light stimuli with low current attenuation, which could meet the characteristics of opsins required to restore the visual function by optogenetics.
ObjectiveTo design the channels of parallel screws and cross screws for fixation of symphysis pubis diastasis through a small sample anatomic study on pubic symphysis and its neighbor structures so as to provide anatomical basis for minimally invasive fixation of symphysis pubis diastasis. MethodsEight cadaveric pelvic specimens (6 men and 2 women) were transected along L5 and the proximal 1/3 of bilateral thighs, with intact lumbar spines. The spermatic cord, womb round ligament, and corona mortis were dissected; the distance to the ipsilateral pubic tubercle was measured and subsequently the distance between pubic tubercles, the height of pubic symphysis, the diameter of outer edge of pubic tubercle, the thickness of pubic symphysis and 2 cm outside the pubic symphysis (upper, central, and lower 1/3 thickness of pubic symphysis) were measured to provide anatomical basis for the design of channels of parallel screws and cross screws. ResultsParallel screw fixation: the entry point of first screw was on the outer edge of pubic tubercle, and its exit point was on the outer edge of contralateral pubic tubercle; a cannulated screw with a diameter of 4.5 mm or 6.5 mm can be suitable for this channel. The entry point of second screw was 20 mm outside the pubic symphysis and 23 mm beneath the pubic symphysis, and its exit point was symmetrical with entry point; a cannulated screw with a diameter of 4.5 mm can be appropriate for the second channel. The direction of two screws was perpendicular to the pubic symphysis. Cross screw fixation: the entry point of cross screws was on one side of the pubic tubercle, and its exit point was 20 mm outside the contralateral pubic symphysis and 23 mm beneath the contralateral pubic symphysis; two cannulated screws with a diameter of 4.5 mm can be chosen for cross screws channels. The direction of two cross screws was intersected with the horizontal line of two pubic tubercles at an angle of 25° respectively; besides, two cross screws formed an anteversion angle and retroversion angle of 5-10° with pubic body plane, respectively. ConclusionThe channels of parallel screws and cross screws are feasible for fixation of symphysis pubis diastasis by analyzing the anatomical data of the pubic symphysis and its neighbor structures, but further biomechanical research is need to confirm the stability of two fixation methods.
ObjectiveTo evaluate the effectiveness of channel-assisted minimally invasive repair (CAMIR) for acute closed Achilles tendon ruptures. MethodsBetween January 2011 and June 2012, 30 patients (30 sides)with acute closed Achilles tendon ruptures were treated with CAMIR technique. Among 30 patients, 18 were male and 12 were female with an average age of 30.4 years (range, 22-50 years); the locations were left side in 10 cases and right side in 20 cases. All the causes were sports injury. B-ultrasound was used to confirm the diagnosis, with the average distance from the rupture site to the Achilles tendon insertion of 4.4 cm (range, 2-8 cm). The time from injury to operation was 3 hours to 9 days (median, 4 days). All injuries were repaired by CAMIR technique. ResultsThe average operation time was 17.0 minutes (range, 10-25 minutes), and the mean incision length was 2.0 cm (range, 1.5-2.5 cm). All the incisions healed by first intention. There was no complication of wound problem, deep vein thrombosis, re-rupture, or sural nerve injury. All cases were followed up 12-24 months with an average of 16 months. At last follow-up, the patients could walk normally with powerful raising heels and restored to normal activity level. MRI imaging suggested the continuity and healing of ruptured tendon. The circumference difference between affected leg and normal leg was less than 1 cm, and the ankle dorsi-extension was 20-30°, plantar flexion was 20-30°. Arner Lindholm score showed that the surgical results were excellent in 28 cases and good in 2 cases, with an excellent and good rate of 100%. ConclusionCAMIR is a safe and reliable method to repair acute closed Achilles tendon rupture, with many advantages of minimal injury, low re-rupture and infection. Sural nerve injury can be minimized using CAMIR by carefully placing the suture channel with a stab incision and special trocar based on a modified Bunnel suture technique.
Aiming at the problem of low recognition accuracy of motor imagery electroencephalogram signal due to individual differences of subjects, an individual adaptive feature representation method of motor imagery electroencephalogram signal is proposed in this paper. Firstly, based on the individual differences and signal characteristics in different frequency bands, an adaptive channel selection method based on expansive relevant features with label F (ReliefF) was proposed. By extracting five time-frequency domain observation features of each frequency band signal, ReliefF algorithm was employed to evaluate the effectiveness of the frequency band signal in each channel, and then the corresponding signal channel was selected for each frequency band. Secondly, a feature representation method of common space pattern (CSP) based on fast correlation-based filter (FCBF) was proposed (CSP-FCBF). The features of electroencephalogram signal were extracted by CSP, and the best feature sets were obtained by using FCBF to optimize the features, so as to realize the effective state representation of motor imagery electroencephalogram signal. Finally, support vector machine (SVM) was adopted as a classifier to realize identification. Experimental results show that the proposed method in this research can effectively represent the states of motor imagery electroencephalogram signal, with an average identification accuracy of (83.0±5.5)% for four types of states, which is 6.6% higher than the traditional CSP feature representation method. The research results obtained in the feature representation of motor imagery electroencephalogram signal lay the foundation for the realization of adaptive electroencephalogram signal decoding and its application.
The electroencephalogram (EEG) signal is the key signal carrier of the brain-computer interface (BCI) system. The EEG data collected by the whole-brain electrode arrangement is conducive to obtaining higher information representation. Personalized electrode layout, while ensuring the accuracy of EEG signal decoding, can also shorten the calibration time of BCI and has become an important research direction. This paper reviews the EEG signal channel selection methods in recent years, conducts a comparative analysis of the combined effects of different channel selection methods and different classification algorithms, obtains the commonly used channel combinations in motor imagery, P300 and other paradigms in BCI, and explains the application scenarios of the channel selection method in different paradigms are discussed, in order to provide stronger support for a more accurate and portable BCI system.