Objective To establish a method for rapid determination of nitrate in air. Methods Nitrate in air was absorbed using Na2CO3-NaHCO3 solution and the content of nitrate in the absorption liquid was determined by ion chromatography. Results The detection limit of NO3- was 0.008 mg/m3 when the sampling volume of air was 100 L. The linear correlation coefficient was 0.999 6. The relative standard deviation of the method was less than 5% and the recovery rates was 92.0%-96.7%. Conclusion The method had good selectivity and was simple and rapid for the determination of nitrate in air.

Objective To investigate the effects of high-affinity tyrosine kinase receptors TrkA, TrkC and the low-affinity neurotrophin receptor p75 (p75~ NTR) protein in laser-induced retinal injury. Methods The Wistar rats were anesthetized and exposed to frequency doubling Neodymium:Yttrium,aluminum garnet(ND:YAG,?=532nm) laser for 100 plus per eye, which were sacrificed on 12 hours,1,3,7,14 and 28 days after laser exposure and eyeball was taken out. We investigated retinal histology by hematoxylin and eosin staining, and the expression of TrkA, TrkC and p75~ NTR protein was studied by means of immunohistochemistry. Results Immunohistochemistry results showed a differential distribution for these three neurotrophin receptors in the laser injuried retina. TrkA was enhanced in nerve fiber layer (NFL), ganglion cell layer(GCL) and inner nuclear layer(INL) ,which is the most nuclei of the ganglion cells, proximal M?ller cell end feet and a little cells in the innermost part of the INL, its peak of up-regulation was after day 1-3, after day 28 there was sustained. Whereas TrkC and p75~ NTR expression was enhanced in the outer nuclear layer(ONL), which is distal M?ller cell processes, TrkC up-regulated after 12 hours, its peak was on day 1-3, after day 28 there was sustained, p75~ NTR up-regulated after 24 hours, its peak was on day 3, on day 14-28 there was sustained in the GCL, which is proximal M?ller cell processes. Conclusion The expression of TrkA, TrkC and p75~ NTR participated in the course of laser injuried retinal pathology.

Objective:To study the feasibility,safety and effectiveness of intrapericardial injection with a trans-diaphragmatic approach in rats and its value in the study of heart diseases. Methods:Blue-black ink,recombinant adeno-associated virus carrying enhanced green fluorescent protein((eGFP)) gene,0.9% sodium chloride solution were respectively injected into pericardium of rats in three different groups(Group ink,Group eGFP and Group sodium chloride) by intrapericardial injection with a trans-diaphragmatic approach.Autopsy was done and hemodynamic parameters were measured and cryosection was analyzed by fluorescence microscopy. Results:The injection was proved successful in all rats in Group ink.Green fluorescence was detected in cryosection of all hearts in Group eGFP and the expression of green fluorescent protein was ubiquitously,but not homongeneous.No rat died during and after the operation among the operated rats(rats in Group eGFP and Group sodium chloride).There was no difference between hemodynamic parameters of the operated rats and those of the controls.Conclusion:The intrapericardial injection with a trans-diaphragmatic approach is a simple,feasible,safe and valid operation and suitable for small experimental animals.And it suggests an easy, safe,efficient and cheap technique in the study of heart diseases.

Objective To design a calculation method for medical equipment dynamic capability usage rate to provide guidance for capability development and purchasing demonstration during the utilization of large medical equipment.Methods Statistical analysis was executed on the application of all the capabilities of some medical equipment,and the utilization rates were obtained on each capability and dynamic capability respectively.Results The proposed method reflected accurately the application of each capability of the equipment when compared with the conventional way.Conclusion The dynamic calculation method can accurately reflect the capability utilization of a single device,and can be further applied to the evaluation of the capability utilization of all the equipment,which provides guidance for the development of equipment capabilities and procurement.

Objective To investigate the clinic application of micro-implant anchorage in the treatment of maxil-lary protrusion malocclusion. Methods Twenty-two patients,aged 18 to 25 years old,with maxillary protrusion were divid-ed into two groups:experimental group and control group with 11 patients in each group. All patients were treated with ex-traction. Micro-screw palatal implant was used in the cases of experimental group as orthodontic anchorage ,and traditional anchorage composed of extraoral arch used in the cases of control. The cephalometric films were measured before and after treatment. Statistical methods were utilized to analyze the morphological changes of facial profile and hard tissues in both groups. Results The values of U1-NA(mm:3.08±1.18 vs 8.15±3.05) and U1-SN(101.90°±3.50° vs 117.90°±6.05°) were sig-nificantly decreased after treatment compared with those before treatment in the experimental group ( P<0.01). The value of U1-L1(123.98°±5.78°vs 103.89°±8.95°) was significantly increased after treatment (P<0.01). In control group, the values of U1-NA (mm:5.01±1.34 vs 9.12±2.13) and U1-SN(101.90°±3.97° vs 114.87°±7.69°)were significantly decreased after treat-ment. The values of U1-L1(126.01°±3.12°vs 112.98°±5.98°) and U6-PtPNS(mm:21.45±2.43 vs 18.36±2.19)were significant-ly increased after treatment (P<0.05). The value of U1-L1(19.48°±8.90° vs 13.01°±5.90°) was significantly changed in exper-imental group than that of control group, but the value of U6-PtPNS(mm:0.90±0.29 vs 3.78±0.12)was significantly changed in control than that of experimental group (P<0.01). Conclusion The maxillary protrusion malocclusion with micro-im-plant anchorage can be used as treatment for patients with maxillary protrusion that needs strong anchorage.

Objective To investigate the effectiveness of panoramic mandibular index (PMI) in detecting the bone mineral density (BMD) of mandibular bone and whole-body bone in patients with chronic end-stage renal failure. Methods A total of thirty patients with peritoneal dialysis treatment were used as experimental group and 31 healthy adults were used as control group. The panoramic jaw tomography was taken for the measurement of superior PMI (sPMI) and inferior PMI (iPMI) in two groups. The dual-energy X-ray absorptiometry (DXA) was used to detect BMD of lumbar spine bone. Data were compared between two groups. The correlation of sPMI, iPMI and BMD of lumbar spine bone was analyzed. Results All indicators including sPMI(0.262 2 ± 0.026 7 vs 0.284 2 ± 0.025 4, t=3.301) , iPMI (0.314 1 ± 0.028 3 vs 0.334 1 ± 0.027 5, t=2.808) and BMD of lumbar spine bone (0.832 3 ± 0.101 0 vs 0.906 9 ± 0.113 6,t=2.709) were significantly lower in experimental group than those in control group (P＜0.01). There was a positive correlation between sPMI and iPMI with BMD of lumbar spine bone (r=0.439 and 0.389, P＜0.05). The BMD of lumbar spine bone was significantly lower in female patients than that of male patients in control group (0.849 7±0.114 7 vs 0.968 0±0.076 3,t=3.357). The BMD of lumbar spine bone was also significantly lower in female patients than that of male patients in experimental group (0.775 4±0.068 4 vs 0.882 1±0.099 9,t=3.365). There were no significant differences in values of sPMI and iPMI between male and female patients of two groups. Conclusion The BMD of mandibular bone is lower in patients with chronic end-stage renal failure than that of the normal people. PMI index is a simple and effective method to detect the BMD of mandibular bone, which can reflect the BMD of whole body bone in patients with chronic end-stage renal disease.

Oxygen is a mandatory for all aerobic organisms. Oxygen-containing free radicals are produced when oxygen is not completely reduced to water in energy-producing oxidation reaction.The radicals may also transform into other reactive compounds through electron transfer and all the compounds with similar functions are referred as reactive oxygen species(ROS).Increased ROS is known to cause damage to proteins,DNA and lipids.Much evidence showed that changes in partial oxygen pressure,hormone,cytokine and chemical stimulation could increase ROS,and ROS,acting as signaling molecules,mediates cell functions.Hypoxia-inducing factor(HIF),a key transcriptional factor for most hypoxia-inducible genes,is a heterodimer consisting of 2 subunits.Recent study found that ROS plays an important role in HIF activity regulation under hypoxic and non-hypoxic conditions.This paper reviews the production of ROS and its role in the regulation of HIF activity.

BACKGROUND:Studies addressing reconstruction of tooth tissue engineering have shown that tooth structure can be constructed using tissue engineering technology. Tooth root and its periodontal attachment are critical for tooth survival and functions, based on which, whether we can target root tissues with simple structure for tissue engineering construction by bypassing a complex dental tissue engineering concept with the structural integrity?
OBJECTIVE:To construct a tissue-engineered dental root by seeding dental papil a cells, as seed cells, into poly(lactic-co-glycolic acid)/sodium alginate hydrogel.
METHODS:Rabbit dental papil a cells were isolated and cultured. The cells were then mixed with 1%sodium alginate hydrogel at a final density of 6×109/L. The cellsuspension was seeded into a poly(lactic-co-glycolic acid) scaffold with predetermined shape of human tooth and solidified with calcium chloride. Final y, the cel-scaffold composites were subcutaneously implanted into the back of nude mice. The specimens were harvested after 4 and 8 weeks respectively and processed for gross inspection, X-ray and CT examination and histological observation.
RESULTS AND CONCLUSION:The newly formed tissue kept the original shape of human dental root 4 and 8 weeks post-implantation. After 4 weeks of implantation, the specimen density was low;the root implants appeared to be incompletely mineralized, alginate hydrogels were degraded, but the copolymer scaffold was not degraded;a number of dentin-like structure appeared, and a fibrous membrane structure was visible on the surface of specimens paral el to the root surface, but the structure was not continuous, and no pulp cavity formed. After 8 weeks, the newly formed tissue was highly mineralized close to root tissue of the nature tooth;the copolymer scaffold was mostly degraded;specimens appeared to have a large number of mature dentin-like structure, and form continuous fibers membrane on the surface paral el to the root surface, below which, cementum-like structure formed. Artificial dental root with biological y similar structures of human dental roots can be constructed using the method of tissue engineering.

Objective To evaluate the orthodontic effect of surgery on mixed dentition period class Ⅲ malocclusion and to investigate the effective therapeutic method of the skeletal class Ⅲ malocclusion.Methods A total of 20 patients aged 8.5 to 9.1 years with early mixed dentition class Ⅲ skeletal malocclusion.The treatment was divided into two phases.During the first phase,the entire stuffy group was treated with a bonded maxillary expansion and protraction.During the second phase,the entire study group received multiple loop edgewise arch wire (MEAW) treatment until an ideal occlusion relationship achieved.Comparison of the pre-and post-orthodontic treatment cephalometric radiographs had been done after maxillary protraction and MEAW were applied for patients.Results In the 20 patients after orthodontic treatment,Class Ⅲ skeletal facial profile was improved,the retraction of anterior teeth was obvious,and there were significant changes in dentition; the profile of soft tissue and satisfactory occlusion relationship were significantly improved,as compared with the changes between pre-treatment and post-treatment.Conclusions Skeletal Ⅲ malocclusion in early mixed dentition can be successfully treated.The results can be satisfied with improved class Ⅲ skeletal and molar relationship,high-angle and profile of soft tissue.

Objective To investigate the effect of blood-flow-activating and blood-stasis-removing herbal medicine on the vision of primary glaucoma patients.Methods A retrospective study was carried out in 60 eyes of primary glaucoma from 32 cases.The cases were allocated to Group A and Group B.Group A(n=33 eyes)was treated with routine drugs of lowering intraocular pressure and operation and Group B(n=27 eyes)with blood-flow-activating and blood-stasis-removing herbal medicine additionally.Results After treatment,the vision of 8 eyes( 24.24%)in Group A and 16 eyes ( 59.26%)in Group B was improved,and the difference was significant(P 0.05).Conclusion Blood-flow-activating and blood-stasis-removing herbal medicine combined with routine treatment is helpful for the increase of vision of primary glaucoma.