And the Guidelines and Policies for Animal Surgery provided by the Animal Study Committee of the order 125-65-5 Central Institute for Experimental Animals and Keio University and were approved by the Animal Study Committee of Keio University (IRB approval number 09091-8).Magnetic resonance imagingMRI was performed with a 7.0-tesla magnet (BioSpec 70/16; Bruker BioSpin, Ettlingen, Germany) and a cryogenic quadrature RF surface probe (CryoProbe; Bruker BioSpin AG, Fallanden, ?Switzerland) to improve the sensitivity [16,18]. The cryoprobe technology can lower only the noise of the measurements; it does not affect the contribution of areas outside the paranodal junctions to the MR signal. T1 and T2 MRI scans were performed under general anesthesia 1418741-86-2 induced by intramuscular ketamine (50 mg/kg; Sankyo, Tokyo, Japan) and xylazine (5 mg/kg; Bayer, Leverkusen, Germany) injection, and maintained by isoflurane (Foren; Abbott, Tokyo, Japan). The animal’s pulse, arterial oxygen saturation, and rectal temperature were monitored during MRI. For ex vivo studies, the animals were euthanized by deep anesthesia (intravenous sodium pentobarbital, 100 mg/kg), and the spinal cord was removed and immersed in 4 paraformaldehyde (PFA) in 0.01 M phosphate-buffered saline (PBS) for 2 weeks. After fixation, the specimens were stored in PBS containing the contrast agent gadopentetate dimeglumine (1 mM; Magnevist, Schering, Berlin, Germany) for 2 weeks. The specimens were then embedded in 2 agarose gel and immediately subjected to MRI. In vivo high-resolution T1 mapping was conducted using rapid acquisition with relaxation enhancement (RARE) and the following parameters: echo time (TE), 18 ms; variable repetition time (TR), 200, 350, 500, 744, 1032, 1384, 2468, 3527, and 8000 ms; RARE factor, 4; number of averages (NA), 4. T2 mapping was conducted using multiple spin-echo with the following parameters: TE, 9, 18, 27, 37, 46, 55, 64, 73, 82, 91, 101, and 110 ms; TR, 3000 ms; RARE factor, 1; NA, 1. The T1and T2-mapping spatial resolution was 80 mm in-plane and 1.0 mm in thickness. For T2-weighted imaging (T2WI), we used RARE with the following parameters: TE, 31 ms; TR, 3000 ms; RARE factor, 8; NA, 4; spatial resolution, 60 mm in the plane and 1.0 mm in thickness. For both the WT and 24195657 CST-KO mice, we selected an ROI size sufficient to cover the ventral white matter. The ROI we used was elliptical, with an area of 0.144 mm2. Ex vivo DTI data sets were acquired with a spin-echo sequence based on the Stejskal-Tanner diffusion preparation [19], with the following parameters: TE/TR 22.3 ms/1500 ms; b-valueElectron microscopyWT and CST-KO mice were perfused with 4 PFA in 0.01 M PBS at pH 7.4. The spinal cord was dissected and post-fixed with 2.5 glutaraldehyde in 60 mM HEPES (pH 7.4) at 4uC overnight. The samples were fixed for 2 hours in 0.5 osmium tetroxide, dehydrated through ethanol, acetone, and QY1, and embedded in Epon. Ultrathin (80 nm) sagittal spinal cord sections were stained with uranyl acetate and lead citrate for 10 and 12 minutes, respectively. The sections were examined under a transmission electron microscope (JEOL model 1230) and photographed using a Digital Micrograph 3.3 (Gatan Inc., CA, USA).Behavioral analysesA Rotarod treadmill apparatus (Muromachi Kikai Co., Ltd., Tokyo, Japan) and a DigiGait Image Analysis System (Mouse Specifics, Quincy, MA, USA) were used to evaluate motor function in 8-week-old WT and CST-KO mice. In the Rotarod treadmill test, we measured t.And the Guidelines and Policies for Animal Surgery provided by the Animal Study Committee of the Central Institute for Experimental Animals and Keio University and were approved by the Animal Study Committee of Keio University (IRB approval number 09091-8).Magnetic resonance imagingMRI was performed with a 7.0-tesla magnet (BioSpec 70/16; Bruker BioSpin, Ettlingen, Germany) and a cryogenic quadrature RF surface probe (CryoProbe; Bruker BioSpin AG, Fallanden, ?Switzerland) to improve the sensitivity [16,18]. The cryoprobe technology can lower only the noise of the measurements; it does not affect the contribution of areas outside the paranodal junctions to the MR signal. T1 and T2 MRI scans were performed under general anesthesia induced by intramuscular ketamine (50 mg/kg; Sankyo, Tokyo, Japan) and xylazine (5 mg/kg; Bayer, Leverkusen, Germany) injection, and maintained by isoflurane (Foren; Abbott, Tokyo, Japan). The animal’s pulse, arterial oxygen saturation, and rectal temperature were monitored during MRI. For ex vivo studies, the animals were euthanized by deep anesthesia (intravenous sodium pentobarbital, 100 mg/kg), and the spinal cord was removed and immersed in 4 paraformaldehyde (PFA) in 0.01 M phosphate-buffered saline (PBS) for 2 weeks. After fixation, the specimens were stored in PBS containing the contrast agent gadopentetate dimeglumine (1 mM; Magnevist, Schering, Berlin, Germany) for 2 weeks. The specimens were then embedded in 2 agarose gel and immediately subjected to MRI. In vivo high-resolution T1 mapping was conducted using rapid acquisition with relaxation enhancement (RARE) and the following parameters: echo time (TE), 18 ms; variable repetition time (TR), 200, 350, 500, 744, 1032, 1384, 2468, 3527, and 8000 ms; RARE factor, 4; number of averages (NA), 4. T2 mapping was conducted using multiple spin-echo with the following parameters: TE, 9, 18, 27, 37, 46, 55, 64, 73, 82, 91, 101, and 110 ms; TR, 3000 ms; RARE factor, 1; NA, 1. The T1and T2-mapping spatial resolution was 80 mm in-plane and 1.0 mm in thickness. For T2-weighted imaging (T2WI), we used RARE with the following parameters: TE, 31 ms; TR, 3000 ms; RARE factor, 8; NA, 4; spatial resolution, 60 mm in the plane and 1.0 mm in thickness. For both the WT and 24195657 CST-KO mice, we selected an ROI size sufficient to cover the ventral white matter. The ROI we used was elliptical, with an area of 0.144 mm2. Ex vivo DTI data sets were acquired with a spin-echo sequence based on the Stejskal-Tanner diffusion preparation [19], with the following parameters: TE/TR 22.3 ms/1500 ms; b-valueElectron microscopyWT and CST-KO mice were perfused with 4 PFA in 0.01 M PBS at pH 7.4. The spinal cord was dissected and post-fixed with 2.5 glutaraldehyde in 60 mM HEPES (pH 7.4) at 4uC overnight. The samples were fixed for 2 hours in 0.5 osmium tetroxide, dehydrated through ethanol, acetone, and QY1, and embedded in Epon. Ultrathin (80 nm) sagittal spinal cord sections were stained with uranyl acetate and lead citrate for 10 and 12 minutes, respectively. The sections were examined under a transmission electron microscope (JEOL model 1230) and photographed using a Digital Micrograph 3.3 (Gatan Inc., CA, USA).Behavioral analysesA Rotarod treadmill apparatus (Muromachi Kikai Co., Ltd., Tokyo, Japan) and a DigiGait Image Analysis System (Mouse Specifics, Quincy, MA, USA) were used to evaluate motor function in 8-week-old WT and CST-KO mice. In the Rotarod treadmill test, we measured t.
