体外培养乳牙牙髓干细胞向血管内皮细胞定向分化的实验研究

目的研究体外培养乳牙牙髓干细胞向血管内皮细胞的定向分化。方法选取南方医科大学口腔医院29例健康儿童的滞留乳牙,在4 h内进行乳牙牙髓干细胞的原代提取。采用免疫磁珠分选法进行细胞分选,并对分选出的细胞进行特定的血管内皮细胞定向诱导。对乳牙牙髓干细胞及血管内皮细胞定向诱导后的细胞进行镜下形态观察、血管生成实验,以及免疫表型鉴定。结果镜下形态观察显示,经过血管内皮定向诱导的乳牙牙髓干细胞呈典型血管内皮细胞的形态特征;血管生成实验表明,经过血管内皮定向诱导的乳牙牙髓干细胞可呈现明显的血管样结构;免疫表型鉴定显示经过血管内皮定向诱导的乳牙牙髓干细胞血管内皮细胞表面抗原呈阳性。结论乳牙牙髓干细胞可定向分化为血管内皮细胞。

Main technical innovations of Songke Well No.2 Drilling Project

Songke Well No.2,one of the main part of the scientific drilling project in Songliao Basin,which was drilled 7018 m and acquired the part of cores continuously from the Low Cretaceous to the Carboniferous and the Permian from the 2843 m deep,can be considered as the deepest continental drilling project in Asia.Aiming at the features of longer well sections,larger diameters and multiple spud-ins for coring of Songke Well No.2,this project broke through the "coring in small diameter and reaming in large diameter"spud-in drilling-completion procedures which are always used in large-diameter-well coring for continental scientific drilling projects in domestic and overseas and the drilling method of short-singlecylinder roundtrip footage.At the same time,"coring in the same diameter and completing drilling at one single diameter"was achieved at all φ311 mm and φ216 mm coring sections of more than one thousand meters long,high-efficient operation with "drilling long footage with drill tools combined in multicylinders"was achieved at deep coring section.Four world drilling records were created which include more than a thousand meters continuous coring at φ311 mm,and the footage per roundtrip footage at φ311 mm,φ216 mm and φ152 mm is all more than 30 m,all of these breakthroughs reduced at least 300 days for this project;moreover,considering the characteristics of formations that the geothermal gradient is high in the drilled sections and the inside-well temperature is over 240℃ after drilling completion,a formate-polymer water-based mud system was developed by compounding attapulgite and sodium bentonite and by adding independently developed high-temperature stabilizer,which can provide critical technical support for successful well completion at 7018 m in the super-high-temperature environment It is the first time that the water-based mud is operated at the working temperature higher than 240℃ in China;Besides,considering the high-quality requirement on cores imposed by the project,the method "mechanical cored is charge"to discharge core nondestructively on the ground was worked out,and more than 4000 m scatheless cores were discharged out of the drill pipes while maintaining original stratum structures.

Visual performance with accommodating and multifocal intraocular lenses

AIM： To compare the visual functional outcomes with accommodating and multifocal intraocular lenses（IOLs）.METHODS： Our retrospective comparative study included 51 patients（60 eyes） received implantation of an accommodating IOL（Tetraflex;16 patients,20 eyes）,a refractive multifocal IOL（Re Zoom;18 patients,20 eyes）,or a diffractive multifocal IOL（ZMA00;17 patients,20 eyes）.Subjective refraction,visual acuity,contrast sensitivity（CS）,intraocular aberration,and subjective photic phenomena were detected at 3mo after surgery.RESULTS： The spherical equivalent in the three groups was-0.38±0.54 D,0.14±0.56 D,and 0.35±0.41 D,respectively.No statistically significant differences were found in uncorrected and corrected distance visual acuity and uncorrected intermediate visual acuity among the groups（P=0.39）.The Re Zoom group had significantly better distance-corrected intermediate visual acuity than the ZMA00 group（P=0.003）.The ZMA00 group had significantly better near visual acuity than the other groups（P〈0.05）.Better contrast sensitivity values were observed in the Tetraflex group under most of the spatial frequencies conditions（P=0.025）.The total aberration was lowest in the ZMA00 group（P=0.000）,and the spherical aberration was highest in the Tetraflex group（P=0.000）.The three groups had similar frequency of ghosting and glare,and the Tetraflex group had a low rate of halos（P=0.01）.CONCLUSION： Both accommodating and multifocal IOLs can successfully restore distance and uncorrected intermediate visual acuities.Tetraflex accommodating IOLs perform better in CS and with less halos of photic phenomena.Re Zoom refractive multifocal IOLs havebetter performance in distance-corrected intermediate visual acuity than ZMA00 diffractive multifocal IOLs,and the latter achieved better near visual acuity and efficiently decreased the optical aberration.

Effects of oxygen enriched tent by a new oxygen concentration machine on blood oxygen saturation and heart rate in tibet

Many people who live in the low altitude areas are often suffered from hypoxia when they entered the high plateau. This problem may seriously influence the physical and mental state and work efficacy for the travelers and workers. Oxygen enrichment of a small space air at high altitude is considered as a simple way to provide lowlanders enriched oxygen for sleeping and resting, improving work efficiency, so we developed an oxygen concentration machine based on the technology of oxygen enrichment membrane. This paper tested 8 healthy male lowlanders (age 21.63±1.77 yr) who have never exposed to plateau performed an incremental exercise on cycle ergometer at sea-level in order to be used as sea-level controls. Two days later, the same subjects were taken to Lhasa (3700 m) by air and exposed to the plateau, performed the same exercise as they did at sea-level. The next day, all subjects were asked to enter the experimental tent which was enriched with oxygen (higher than 24%) by the oxygen concentration machine and sleep for 10 hours at night, then exposed to plateau and performed the same exercise twice at different time (2 hours and 10 hours after oxygen enrichment). During the tests, subjects must cycled continuously at 60 rpm beginning with a 3 min exercise intensity of 0 W followed by incremental increases of 25 W every 3 min until 150 W, pulse oxygen saturation (SpO2) and heart rate (HR) were recorded. After sleeping in an oxygen enrichment of tent air, 2 hours later, the subjects’ load capacity had no difference compared with control group, but significant difference than before (higher SpO2 and lower HR), which indicated that oxygen concentration machine is effective in increasing the oxygen concentration of the air for the tent and sleeping in the oxygen enrichment tent for l0 h might be effective in improving exercise performance during high-altitude hypoxia. At the same time, 10 hours later, when work-load exceeded 125 W, the same effects were also found. The results indicated the effects of oxygen enrichment of tent air could last a certain period of time.

Comparison of 25-gauge sutureless vitrectomy and 20-gauge vitrectomy in the treatment of posterior capsule opacification in pseudophakic children

AIMTo compare the effectiveness and safety of pars plana capsulotomy and vitrectomy using 25-gauge tansconjunctival sutureless vitrectomy system and 20-gauge vitrectomy system for posterior capsule opacification (PCO) in pseudophakic children.METHODSRetrospectively study. Pars plana capsulotomy and vitrectomy using 25-gauge sutureless vitrectomy system was performed for PCO in the study group (32 eyes). Patients in the control group (34 eyes) underwent capsulotomy and vitrectomy using standard 20-gauge vitrectomy system, providing a comparison between 2 groups with regard to preoperative and postoperative best corrected visual acuity (BCVA), intraocular pressure (IOP), and intraoperative and postoperative complications. The two groups were performed consequentially. The patients ages ranged from 2 to 13y (means: 6.61±2.73y). Surgical technique, intraoperative and postoperative complications, visual acuity, IOP, and recurrent PCO were recorded.RESULTSThe surgical procedure was performed uneventfully in all patients. Visual acuity improved significantly in both groups. BCVA improved in 22 eyes (81.5%) in the study group and in 28 eyes (87.5%) in the control group. There was no statistical difference of visual acuity that were attainable in two groups (H=0.115, P=0.909). Mean postoperative IOP showed no significant difference between the groups at 1wk. All sort of PCO were accomplished by 20-gauge system, while 25-gauge system was effective for pearls style and 2 grade of fibrous PCO, and was insufficient to grade 3 of PCO. In the study group two cases were not accomplished by 25-gauge system while 20-gauge system conquered them. Compared with the control group, mean operative time for opening and closing the sclerotomy in the study group was considerably reduced. The mean follow-up was 38.2mo (range: 8-79mo). During the follow-up period, no incision leakage, corneal edema, vitreous loss, IOL damage, retinal detachment, recurrent PCO, or other complications were noted.CONCLUSIONPars plana capsulotomy and vitrectomy using 25-gauge transconjunctival sutureless vitrectomy appeared to be a safe and effective approach for PCO in pseudophakic children. Combined sutureless surgery needed shorter setup time for sclerotomy and caused less surgical trauma than combined surgery with 20-gauge vitrectomy. Therefore, this type of procedure would be a good option for selected cases with PCO in pseudophakic children.

Electroluminescence from the InGaN/GaN Superlattices Interlayer of Yellow LEDs with Large V-Pits Grown on Si(111)

A blue emission originated from In GaN/GaN superlattice（SL） interlayer is observed in the yellow LEDs with V-pits embedded in the quantum wells（QWs）, revealing that sufficient holes have penetrated through the QWs into SLs far away from the p-type layer. In the V-pits embedded LEDs, hole transport has two paths： via the flat c-plane region or via the sidewalls of V-pits. It is proved that the holes in SLs are injected from the sidewalls of V-pits, and the transportation process is significantly affected by working temperature, current density, and the size of V-pits. Four motion possibilities are discussed when the holes flow via the sidewalls. All these may contribute to a better understanding of hole transport and device design.

Carrier Dynamics Determined by Carrier-Phonon Coupling in InGaN/GaN Multiple Quantum Well Blue Light Emitting Diodes

Phonon sidebands in the electrolumiescence(EL) spectra of InGaN/GaN multiple quantum well blue light emitting diodes are investigated. S-shaped injection current dependence of the energy spacing(ES) between the zero-phonon and first-order phonon-assisted luminescence lines is observed in a temperature range of 100–150 K.The S-shape is suppressed with increasing temperature from 100 to 150 K, and vanishes at temperature above200 K. The S-shaped injection dependence of ES at low temperatures could be explained by the three stages of carrier dynamics related to localization states:(i) carrier relaxation from shallow into deep localization states,(ii) band filling of shallow and deep localization states, and(iii) carrier overflow from deep to shallow localization states and to higher energy states. The three stages show strong temperature dependence. It is proposed that the fast change of the carrier lifetime with temperature is responsible for the suppression of S-shaped feature.The proposed mechanisms reveal carrier recombination dynamics in the EL of InGaN/GaN MQWs at various injection current densities and temperatures.

Aging mechanism of GaN-based yellow LEDs with V-pits

GaN-based yellow light-emitting diodes(LEDs) on Si substrates are aged at a direct current density of 50 A/cm^2 for500 h. After the aging process, it can be found that the LEDs have a stable electrical property but their light output power is decayed by 4.01% at 35 A/cm^2. Additionally, the aging mechanism of GaN-based yellow LED is analyzed. It is found that the decay of light output power may be attributed to the following two reasons: one is the increase of Shockley–Rrad–Hall recombination and the other is the change of the transport path of holes via V-pits after aging, which may induce the radiative recombination current to decrease. In this paper, not only the aging mechanism of GaN-based yellow LED is investigated, but also a new possible research direction in LED aging is given.

Excretion and detection of SARS coronavirus and its nucleic acid from digestive system

AIM： To study whether severe acute respiratory syndrome coronavirus （SARS-CoV） could be excreted from digestive system.METHODS： Cell culture and semi-nested RT-PCR were used to detect SARS-CoV and its RNA from 21 stool and urine samples, and a kind of electropositive filter media particles was used to concentrate the virus in 10 sewage samples from two hospitals receiving SAILS patients in Beijing in China. RESULTS： It was demonstrated that there was no live SARS-CoV in all samples collected, but the RNA of SARS-CoV could be detected in seven stool samples from SARS patients with any one of the symptoms of fever, malaise, cough, or dyspnea, in 10 sewage samples before disinfection and 3 samples after disinfection from the two hospitals. The RNA could not be detected in urine and stool samples from patients recovered from SARS.CONCLUSION： Nucleic acid of SARS-CoV can be excreted through the stool of patients into sewage system, and the possibility of SARS-CoV transmitting through digestive system cannot be excluded.

Effect of Green Quantum Well Number on Properties of Green GaN-Based Light-Emitting Diodes

In GaN-based green light-emitting diodes（LEDs） with different green quantum well numbers grown on Si（111）substrates by metal organic chemical vapor deposition are investigated. It is observed that V-shaped pits appear in the AFM images with the green quantum well number increasing from 5 to 9, and results in larger reverse-bias leakage current. Meanwhile, in the case of the sample with the number from 5 to 7 then to 9, the external quantum efficiency increases firstly, and then decreases. These phenomena may be related to the size of V-shaped pits in the active area and the distribution of electrons and holes in the active area caused by V-shaped pits. The optimal number of green quantum wells is determined to be 7.

Multi-frequency bioimpedance measurements of rabbit shanks with stress fracture

Purpose: The objective of this research is to investigate whether bioimpedance is useful to indicate a shank’s physical condition during training. Methods: Bioimpedance was applied to monitor the condition of 8 rabbits’ shanks in 3 weeks, during which the rabbits were trained for regular excessive jump daily. Nine tibias in 16 developed stress fracture after the 3-week training. Results: According to the analysis of the bioimpedance data, we found that changing pattern of bioimpedance properties of shanks which were more liable to suffer from SF was different from that of shanks which were not during training. Conclusions: This suggests that bioimpedance may be used to monitor the physical condition of a limb, imply its liability to develop stress fracture, and indicate stress fracture during training.