[Study on preparation of 3D printing degradable tissue engineering ossicles].

Objective: In combination with 3D printing technology and degradable composite materials, to discuss the preparation method of tissue engineering ossicles for middle ear hearing reconstruction. Methods: Domestic polymer (polylactic acid-glycolic acid copolymer, PLGA) and degradable ceramic material (ß-tricalcium phosphate, ß-TCP) were selected and prepared by low temperature deposition method according to the design ratio to Program according to the outline design code of the required scaffold to generate appropriate print files, and then the self-developed low-temperature deposition printing device was used to prepare tissue-engineered osseous scaffolds in accordance with the print files in a low-temperature environment. The scaffolds was freeze-dried and sterilized for later use after printing. Light microscopy and scanning electron microscopy were used to observe the apparent characteristics and internal structure of the scaffolds and to check its pore size, porosity and mechanical properties. Results: After printing, a degradable scaffold was obtained. Under the optical microscope, it was a small cylindrical shape with a diameter of 1.5 mm and a length of 6.0 mm, and its surface had micropores. The degradable scaffold had a horizontal and vertical interlaced warp and weft structure, the wire spacing was 1.2 mm, and the pores were connected to each other. The surface could see circular or quadrangular pores with a pore size of about 100-400 µm. The diameter of the inter-pore cross-linked channels was about 50 µm and the diameter of the surrounding circular micropores was about 10-40 µm. ß-TCP particles with a size of about 700 nm were attached to the surface of the PLGA material. The average porosity of the whole scaffolds was (83.43±0.01)%, and the content of BMP-2 loaded was about 0.7 µg/mm(3). After freeze-drying, the mechanical strength of the scaffold was moderate, and there was no obvious deformation during stretching and compression, which met the mechanical requirements of tissue engineering ossicles. Conclusions: Using the low-temperature deposition printing method and strictly controlled processes and conditions, a polymer-degradable ceramic ossicle tissue engineering scaffold can be prepared for implantation experiments. The scaffold has suitable porosity and mechanical properties, and can be loaded with osteoinductive factors.

[In vivo dynamic changes of inner ear guinea pigs with 9.4 T esla MRI].

Objective: To observe the imaging characteristics of guinea pig cochlear structure using 9.4 Tesla magnetic resonance imaging system at different time intervals of contrast agent distribution in the inner ear. Methods: Form May 2015 to October 2015, five albino guinea pigs were injected with Gd-DTPA via the right internal jugular vein (3 ml/kg). Inner ears were scanned with 9.4T MRI. At the 10 th, 30 th, 60 th, 90 th and 120 th minutes post-Gd-DTPA, we took inner ear images to detect changes of endolymph and perilymph. Using Image J software, we acquired MRI gray value through the first, second, third and apical turn of cochlear at different time points. Analysis by one-way ANOVA was taken to analyze the resultsusing GraphPad Prism 5 software. Results: Only outlines of the cochlea and vestibule were visible before Gd-DTPA injection and there was no clear distinction between endolymph and perilymph. Cochlea vestibule on T1 weighted images was enhanced at the 10 th (the first turn of cochlear 8 203±819) after injection, and then imaging of each part of cochlea, including cochlea, vestibule, semicircular canal and even endolymph and perilymph, can be distinguished clearly, because they enhanced gradually at the 30 th(10 489±819), 60 th(13 965±591), and at 90 th(18 050±1 250) after injection. While at the 120 th(18 952±1 185) minute, imaging was not significantly enhanced than at the 90 th minute. The speed and volume of contrast agent spreaded into the various parts of the inner ear were different, and changes with distribution of contrast agent in each part of the inner ear showed a rising process in a certain period of time. The distribution of contrast agent in the inner ear had concentration gradient via basal turn higher and apical turn lower. Conclusions: Endolymph of inner ear can be distinguished from the perilymph using a 9.4T MRI system with Gd-DTPA, and the best observation timer was 90 minutes after intravenous injection of contrast agent. In summary, our study provides the clearly visualized imaging evidence of the changes of the lymphatic fluid, which may be useful for diagnosis of inner ear diseases such as Meniere's Disease.

[Surgical management of elderly patients with medial wall pyriform sinus cancer].

Objective: To investigate the clinical efficacy of preoperative-, postoperative-radiotherapy and surgery for preserving laryngeal function in patient over 70 years of age with medial wall pyriform sinus cancer. Methods: Clinical data of 48 patients over 70 years of age with medial wall pyriform sinus cancer who received surgical treatment from January 2001 to December 2010 were retrospectively analyzed. Among them, 21 cases were given preoperative radiotherapy and surgery (R+ S). The radiation therapy dose was 45 Gy. And 14 cases' larynx is preserved. In addition, 27 cases were given postoperative radiotherapy and surgery (S+ R). The radiation therapy dose was 65 Gy. And 10 cases had preserved laryngeal function. Survival rates were analyzed by the Kaplan-Meier method. Chi-square test was used to compare complications between two groups. Results: The larynx preservation rate in R+ S group [66.7% (14/21)] was significantly higher than that in S+ R group [37.0% (10/27), P<0.05]. The complication rate and decannulation rate in R+ S group were 42.9% (9/21) and 64.3% (9/14), respectively, showing no difference compared with those in S+ R group [37.0% (10/27) and 50.0% (5/10), respectively] (all P>0.05). The complication rates of patients with and without larynx preservation were 41.7% (10/24) and 37.5% (9/24), respectively, showing no difference between two groups (P>0.05). The overall 3-years and 5-years survival rates for all patients were 54.2% (26/48) and 35.4% (17/48), respectively. There was no significant difference in survival rates between R+ S [38.1% (8/21)] group and S+ R group [33.3% (9/27), P>0.05)]. In the R+ S group, the survival rates in patients with and without larynx preservation were 40.0% (4/10) and 29.4% (5/17), respectively, showing no significant difference between two groups (P>0.05). Conclusions: It is secure and effective to choose the operation with laryngeal preservation for patient over 70 years of age with medial wall pyriform sinus cancer based on their physical conditions and the tumor extension. The preoperative- and postoperative-radiotherapy have the similar effect. Preoperative radiotherapy and surgery increases the laryngeal preservation rate.

Productivity and carcass characteristics of pure and crossbred Chinese Yellow Cattle.

The carcass characteristics of 334 Chinese Yellow Cattle, and their Simmental and Limousin crosses, were investigated in abattoirs in Hebei and Sandong provinces of China. The overall slaughter age was 4.8±2.2 years at a mean liveweight of 527.28±77.0 kg. Mean ages and liveweights for Yellow Cattle and its crosses were, respectively, 5.29±2.03 and 2.85±1.71 years and 519.43±78.7 and 563.13±56.8 kg. Carcass weights varied considerably and, consequently, so did subcutaneous fat depths and dressing percentages. Overall, mean carcass weights, subcutaneous fat depths and, dressing percentages and eyemuscle areas were 283.9±64.1 kg, 14.0±8.0 mm, 54.0±4.0%, and 62.7 ±13.3 cm(2), respectively. Compared with pure Yellow Cattle, the crosses were slaughtered at younger age, and had larger live and carcass weights, higher dressing percentages, less subcutaneous fat depth and bigger eyemuscle areas. It is concluded that crossbreeding can significantly improve Yellow Cattle' meat productivity, however feeding systems need to be improved and an appropriate grading system developed to improve beef production and quality in China.