Missing data plagues almost all surveys and researches. The occurrence of missing data will cause losses of original sample information and undermine the validity of the research results to some extents, so researchers should attach great importance to this problem. In this article, we introduced 3 kinds of missingness mechanism, namely missing completely at random, missing at random, and not missing at random. We summarized some common approaches to deal with missing data, including deletion, weighting approach, imputation and parameter likelihood method. Since these methods had its pros and cons , we should carefully select the proper way to handle missing data according to the missingness mechanism.

Atomic layer deposition has been employed for postsynthesis treatment of octadecyl bonded silica (ODS) as a typical reversed-phase stationary phase for high performance liquid chromatography (HPLC) ,in an effort to alleviate peak tailing for basic compounds. With hexamethyldisilazane( HMDS) as an endcapping agent,the ODS packing materials were heated to 250℃,and maintained at that temperature for 6 h,affording packing materials which are highly inert to basic compounds. Chromatographic performance in terms of retention factor and tailing factor of the resulting phases was evaluated using phenol/pyridine and naphthalene/ami-triptyline pairs as probes. The results were compared with those for the same packing treated by liquid phase method and for the commercial products including Zorbax SB-C_(18) and Kromasil C_(18). The separation characteristics of the ODS phase obtained by atomic layer deposition appear to be superior to that by liquid phase method and,comparable with or even better than the commercial products studied. Being solvent-free process amenable to mass production,the described method provides an economical and eco-friendly approach to manufacturing HPLC packing materials on industrial scale.

Objective To observe the effect of perioperative rehabilitation on anterior spinal cord syndrome caused by cervical hyper-flexion injury. Methods Sixty-nine inpatients with anterior spinal cord syndrome after cervical hyperflexion injury from January, 2012 to De-cember, 2014 were reviewed. 32 cases (group A) accepted systematic rehabilitations and other 37 cases (group B) did not. They were as-sessed with Japanese Orthopaedic Association (JOA) scores preoperatively and 1-year follow-up. Results All the patients succeeded in the operation. The JOA score improved more 1 year follow-up in group A than group B (t=2.538, P=0.044). Conclusion Systematic rehabilita-tion may work in the management of anterior spinal cord syndrome after cervical hyperflexion injury.

Objective To investigate the effect of rehabilitation on cervical fracture-dislocation following spinal cord injury.Methods126 patients with cervical fracture-dislocation following spinal cord injury from August, 2002 to March, 2009 in our hospital had undergone cervical anterior surgical treatment. 22 cases were picked up as control group, who missed rehabilitation after surgery. 22 cases were chosen randomly from the rest of 104 cases as rehabilitation group, who had undergone rehabilitation. Prognosis was evaluated by Japanese Orthopaedic Association Scores score(JOA).ResultsFollow-up time was 8-32 months，mean time 18 months. The limb function of rehabilitation group improved significantly. JOA score and quality of life were much higher in rehabilitation group than in control group.ConclusionRehabilitation is very beneficial to improve the quality of life and prognosis, and reduce complications of patients with cervical fracture-dislocation following spinal cord injury at the early stage.

Objective To study the mechanism, pathology, diagnosis and manage strategy of cervical fracture dislocation combined with anterior spinal cord syndrome (ASCS). Methods 32 cases of cervical fracture dislocation combined with ASCS from January 2012 to September 2014 were summarized. The mechanisms of injury and pathological characteristics were analyzed. All of them received surgical treatment. Anterior approach or anterior approach combined with posterior approach was chosen according to the characteristics of injury. Results All surgical treatments were successfully performed. There were 22 cases (68.75%) with hyperflexion, 5 cases (15.62%) with vertical hit, 1 case (3.12%) with hyperextension and 4 cases (12.5%) with multiple reasons. There were 4 cases (12.5%) with simple anterior dislocation, 28 cases (87.5%) with fracture combined with anterior dislocation. Only 8 cases were successfully diagnosed as ASCS, and the others (24 cases) were generally defined as spinal cord injury. Conclusion ASCS is not so rare. Hyperflexion injury is the most common mechanism. Anterior dislocation and fracture combined with anterior dislocation are the general types of pathology. Conscientious physical examination with CT and MRI can facilitate the diagnosis. Anterior approach or combined with posterior approach could be selected according to injury mechanism.

Objective To evaluate the X-ray diagnosis value of intestinal malrotation in adults.Methods The X-ray findings of 16 cases with intestinal malrotation confirmed by surgery were analyzed retrospectively. All of them were taken X-ray plain films, 11 cases were taken alimentary tract barium meal,and 5 cases were taken barium enema. Results Eight cases were found incomplete obstruction of the duodenum, and 2 cases were found low small intestine obstruction on the X-ray plain films. The alimentary tract barium meal showed 4 cases with dilatation and incomplete obstruction of the duodenal bulb to horizontal segment,and the distal end of narrowing intestine appeared as a rat tail,7 cases showed the abnormal duodenal location and shape,called "strip" sign. Four cases were found abnormal duodenojejunal flexure by barium enema examination. Conclusion The alimentary tract barium meal and barium enema examination has great diagnosis value for intestinal malrotation in adults.

Objective: To compare the effects of different types of strength training on upper limbs’ body composition and maximum strength and bone density of male university students, so as to provide a reference for college students to choose reasonable resistance training methods. Methods: Forty-two male university students were randomly divided into three experimental groups: maximum-strength group, MS(n=12); speed-strength group, SS(n=15); strength-endurance group, SE(n=15). All subjects were subject to resistance training for 6 weeks, twice a week. Incremental load method was used to determine the maximum strength of the subject to develop a training program. Upper limbs’ Body Composition and BMD were performed by Dual energy X-ray absorptionmetry. Results: After the continuous training for 6 weeks, maximum strength of upper limbs increased significantly with training time，SE grows faster[(51.00±4.81)(67.20±5.66)(76.87±6.21)kg]; The body fat percentage of SS group and SE group decreased significantly[(13.50±4.10)%，(12.60±2.80)%；(13.70±3.80)%，(12.70±3.10)%](t=2.35，2.30，P<0.05), while LM of upper limb increased significantly[(5.19±0.59)(5.86±0.61)；(5.27±0.72)(6.21±0.59)kg](t=-2.48，-2.94，P<0.05). There was no significant difference in the body fat percentage and LM of upper limb between MS group[(14.0±3.3)%，(13.6±2.3)%] and SE group[(5.33±0.81)(5.41±0.79)kg](t=0.31，-0.22，P>0.05); BMC and BMD of upper limbs increased in all groups, but the increase of SS group and SE group was statistically significant(t=-3.07，-2.43，P<0.05). Conclusion Strength endurance resistance training for male college students can effectively promote muscle strength growth, increase bone density and improve upper limb composition.

Objective To investigate the effect and underlying mechanism of Qingguang’an Granules (青光安颗粒剂, QGAG) on mitochondrial autophagy (mitophagy) of retinal ganglion cells (RGCs) in rats with chronic ocular hypertension (COH). Methods Sixty Sprague Dawley (SD) rats, half males and half females, were randomly assigned to three groups: the control, model, and QGAG (2.5 g/kg) groups, with 20 rats in each group. Rats’ model of COH was established by cauterizing episcleral veins in the model group and QGAG group. Three weeks after successful modeling, rats in the QGAG group were intragastrically administered with QGAG, while rats in the control group and the model group received an equal dose of normal saline. After three months of intragastric administration, intraocular pressure (IOP) of all rats was measured. The mitophagy was monitored by the immunofluorescence method, the mitochondrial membrane potential was measured using the JC-1 method, and the morphological changes of mitophagy in RGCs were observed by transmission electron microscopy. Meanwhile, rat RGCs were labeled using the fluorescent gold method, and RGCs density in each group was calculated. Moreover, RGCs apoptosis was observed by TdT-mediated dUTP Nick-End Labeling (TUNEL) assay. Finally, the expression levels of Parkin, optineurin, microtubule-associated protein 1 light chain 3-II/microtubule-associated protein 1 light chain 3-I (LC3-II/LC3-I), recombinant lysosomal associated membrane protein 1 (LAMP1), and B-cell lymphoma-2 (Bcl-2) in RGCs were determined by Western blot assay. The corresponding mRNAs were detected through quantitative real-time polymerase chain reaction (qRT-PCR). Results The QGAG reduced IOP in COH rats, and inhibited mitophagy and apoptosis of RGCs (P < 0.05). Besides, the QGAG significantly increased the expression levels of Parkin and Bcl-2 (P < 0.05), and inhibited the expression levels of optineurin, LAMP1, and LC3-II/LC3-I (P < 0.05) in RGCs of COH rats. Conclusion The QGAG can inhibit mitophagy in RGCs of COH rats and show a protective effect against optic nerve damage caused by glaucoma, which may be mediated through the mitophagy ubiquitination via the Parkin/PINK1-related pathway.