Prestin-Mediated Frequency Selectivity Does not Cover Ultrahigh Frequencies in Mice / 神经科学通报·英文版

In mammals, the piezoelectric protein, Prestin, endows the outer hair cells (OHCs) with electromotility (eM), which confers the capacity to change cellular length in response to alterations in membrane potential. Together with basilar membrane resonance and possible stereociliary motility, Prestin-based OHC eM lays the foundation for enhancing cochlear sensitivity and frequency selectivity. However, it remains debatable whether Prestin contributes to ultrahigh-frequency hearing due to the intrinsic nature of the cell's low-pass features. The low-pass property of mouse OHC eM is based on the finding that eM magnitude dissipates within the frequency bandwidth of human speech. In this study, we examined the role of Prestin in sensing broad-range frequencies (4-80 kHz) in mice that use ultrasonic hearing and vocalization (to >100 kHz) for social communication. The audiometric measurements in mice showed that ablation of Prestin did not abolish hearing at frequencies >40 kHz. Acoustic associative behavior tests confirmed that Prestin-knockout mice can learn ultrahigh-frequency sound-coupled tasks, similar to control mice. Ex vivo cochlear Ca2+ imaging experiments demonstrated that without Prestin, the OHCs still exhibit ultrahigh-frequency transduction, which in contrast, can be abolished by a universal cation channel blocker, Gadolinium. In vivo salicylate treatment disrupts hearing at frequencies <40 kHz but not ultrahigh-frequency hearing. By pharmacogenetic manipulation, we showed that specific ablation of the OHCs largely abolished hearing at frequencies >40 kHz. These findings demonstrate that cochlear OHCs are the target cells that support ultrahigh-frequency transduction, which does not require Prestin.

An imaging study on effect of total artificial disc replacement on lumbar sagittal alignment / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate effect of Activ L total lumbar disc replacement on lumbar sagittal alignment.</p><p><b>METHODS</b>The imaging data of patients with degenerative disc disease received Activ L total lumbar disc replacement at Department of Orthopedics, Beijing Chao-Yang Hospital, Capital Medical University from March 2009 to March 2013 were retrospectively analyzed. The average age was 45.6 years(range, 35-60 years)and the surgery levels were as follows: L3-4 2 cases, L4-5 15 cases, L5/S1 5 cases, L3-4+ L4-5 3 cases, L4-5+ L5/S1 7 cases. All patients were followed up for 15 to 63 months(average, 32 months). Radiographic parameters such as lumbar lordosis angle(LL), segment lordosis angle(SL) and sacral slope angle(SS) were recorded. All the radiographic parameters were compared using one-way ANOVA at different stage. Lumbar lordosis angle of the two-level was compared with the one of one-level by using independent sample t-test before and after the operation. A partial correction test was carried out to determine the corrections between the parameters preoperatively, one month after the operation and at final follow-up.</p><p><b>RESULTS</b>One month after the operation, the lumbar lordosis angle decreased by an average of 1.8°, but there was no statistically significant(P>0.05). Compared with one month postoperation, the lumbar lordosis angle increased by an average of 6.8°(P<0.05), which also increased a lot compared with preoperation(P<0.05). The value of segment lordosis angle was rising up from preoperation to the final follow-up(P<0.05), so was the value of sacral slope angle, but there was no statistically significant between different stage(P>0.05). The lumbar lordosis angle showed no significant difference between double-level ones and single-level ones at different stage(P<0.05). The lumbar lordosis angle showed positive correlation with the sacral slope(P<0.001), however, the lumbar lordosis angle showed no corrected with the segment angle all the time(P>0.05).</p><p><b>CONCLUSIONS</b>The total lumbar disc replacement with Activ L prosthesis had contributed to maintain and improve the lumbar alignment in the short and medium term. Double- or single-level total lumbar disc replacement had no significant effect on the value of lumbar lordosis angle. The lumbar lordosis angle showed positive correlation with the sacral slope all the time with no correlation between lumbar lordosis angle and sacral slope.</p>

Study on the morphology of sagittal of lumbar endplate in healthy adult / 中华外科杂志

<p><b>OBJECTIVE</b>To provide a theoretical basis for designing of lumbar intervertebral disc prosthesis by collecting the data of the lumbar endplate morphology.</p><p><b>METHODS</b>A total of 100 healthy adults were measured about the following parameters: lumbar lordosis, the Cobb angle of each segment, the concavity depth (ECD) of the endplate, the location of concavity apex (ECA) of the endplate. And a correlation analysis on lumbar lordosis and ECD, ECA was made, respectively.</p><p><b>RESULTS</b>In total, 100 volunteers were measured. The mean age of the volunteer was 40 years (range 20 - 50 years); the average depth of ECD was (2. 37 ± 1. 42) mm, the average location of ECA was (52. 21 ± 9. 70) %; the average depth of ECD of inferior endplate (IEP) was (2. 81 ± 1. 52) mm (0. 54 - 7. 60 mm), and the parameter of the superior endplate (SEP) was (1. 94 ± 1. 16)mm(0. 39 - 6. 10 mm). The average depth of ECD of the IEP was bigger than of the SEP for each lumbar vertebral body. Most of the location of ECA was at the back of the intervertebral body, the average location of ECA of IEP was (49. 60 ± 8. 78) % (22. 57% - 75. 58%), and the parameter of the SEP was (55. 03 ± 9. 90) % (16. 03% -75. 58%); the mean angle of lumbar lordosis was 39. 760 11. 25°(13. 8° - 72. 00°). There was no obvious correlation between the lumbar lordosis and the ECD (r -0. 193, P =0. 195), neither was the location of ECA(r =0. 080, P =0. 592).</p><p><b>CONCLUSION</b>Most of the location of ECA is at the back of the intervertebral body, the average depth of ECD is 2. 37 mm, the average location of ECA is 52. 21%.</p>