BACKGROUND:Three-dimensional bioprinting technology is the emerging technology in recent years, which is one of the branches of tissue engineering. The three-dimensional bioprinting technology has been used in the reproduction process of in vitro tissues and organs, which has achieved surprising outcomes.
OBJECTIVE:To review the three-dimensional bioprinting technology in terms of its principles, operating steps, relationships with tissue engineering, advantages and chal enges, as wel as clinical applications.
METHODS:The first author did a computer-aided retrieval of the PubMed database, CNKI database, and CQVIP database for articles relevant to three-dimensional bioprinting technology used in tissue engineering published between January 2000 and October 2000. The key words were“three-dimensional bioprinting, tissue engineering, rapid prototyping technology, scaffold materials, selective laser sintering, fuseddeposition modeling, stereolithography”in English and Chinese. Repetitive studies were excluded, and 52 of 79 related literatures were adopted in result analysis.
RESULTS AND CONCLUSION:Three-dimensional bioprinting technology is one of the branches of tissue engineering, which can build a virtual three-dimensional structure layer by layer under the computer-aided design technology, with the help of imaging data information (including CT and MRI). This technology has the advantages of high precision, high building speed, fabrication on demand, and also has the chal enges in engineering mechanics and biological activities. In a word, it is a meaningful and promising technology in clinical application.

Objective:To compare therapeutic effects of Chinese medicine prescriptions for nourishing Yin to purge pathogenic fire,and prescriptions for relieving the depressed liver in treatment of sexual precocity of girls.Methods:The girls with sexual precocity were divided with random,double blind and control methods into a treatment group treated with the prescription for nourishing Yin to purge pathogenic fire,Zaoshu No.Ⅱ,and a control group treated with the prescription for relieving the depressed liver, Xiaoyao Pill.The medicines were given with double blind and double simulated methods.The mammary nucleus index,mammary Tanner phasing,cumulative scores of TCM syndromes,B type ultrasonography(volume of the uterus,ovary,the biggest follicle diameter),change of bone age were followed up and compared before and after treatment in the two groups.Follow-up was completed in 132 cases.Results:The treatment group in the mammary nucleus index,mammary Tanner phasing,decrease of cumulative scores of TCM syndromes after treatment was better than the control group(P0.05).Conclusion:Chinese medicine for nourishing Yin to purge pathogenic fire,Zaoshu No.Ⅱ,in therapeutic effect for treatment of sexual precocity of girls is better than the Chinese medicine for relieving the depressed liver,Xiaoyao Pill.

Objective To investigate the effect of cyclooxygenase-2(cox-2)on prostaglandin I2(PGI2)/thromboxane A2(TXA2)system in ischemia reperfusion(I/R)injury to small bowel in rat.Methods Forty-eight male SD rats were randomly divided into three groups:control group(n=8),I/R group(n=20)and intervention group(n=20).Small intestine I/R model was established with the animals of I/R group:after anesthesia,rats were split along the middle abdominal incision,the mesenteric artery was then bluntly separated and clipped with a blood vessel forceps at its root for 45 minutes to block the blood flow,then releasing the forceps for reperfusion.Animals of intervention group were lavaged with Nimeshulide 1h before operation,the remaining steps were the same as did in I/R group.The samples of blood and intestinal tissue were collected at 3,6,12 and 24 hours after operation.The content of plasma D-lactate was detected by ultraviolet spectrophotometric method.Radioimmunoassay was used to detect 6-keto-PGF1?(the stable metabolite of PGI2,reflected the level of PGI2)and thromboxane B2(TXB2,stable metabolite of TXA2,reflected the level of TXA2)in serum and tissues of small bowel.The expression of cox-2 mRNA was detected by RT-PCR.Results Compared with the control group,the levels of plasma D-lactate,cox-2,6-keto-PGF1? and TXB2 were significantly increased in I/R group,with more obvious increase of TXB2,and the value of 6-keto-PGF1?/TXB2 decreased significantly(P

Objective To study the expression of cyclooxygenase2 in hepatic inflammatory reaction of rats with sepsis and its effect on metabolism.Methods Fifty-four Wistar rats were randomly divided into 3 groups:Sham(A)group,sepsis model(B)group,and NS398 intervention(C)group.The rats were subjected to cecal ligation and puncture(CLP)for sepsis model or sham operation.RT-PCR was used to determine COX-2 mRNA expression,serum prealbumin(PA)and transferrin(TF)by radioimmunity.At the same time,ALT,AST,albumin determination and liver pathological changes were determined.Results(1)The expression of COX-2 mRNA was low in A group,higher in B and C groups,and higher in B than C group at each time period(P

Objective To explore the CT manifestations of pediatric mesenechymal hamartoma of liver (MHL).Methods Clinical data of 15 cases with MHL confirmed by surgery and pathology were retrospectively analyzed.All children were performed with CT scans including plain and enhanced scans,and the imaging features were analyzed.Results All the lesions were solitary,and 9 masses located at the right lobe of liver,4 located at the left lobe,the others located at both right and left lobe.The maximum diameter of lesions was from 5 cm to 30 cm,with an average of (11.52±6.84) cm.Ten cases were cystic and solid mixed,5 cases were solid.After contrast administration,the solid component and the septa of the masses showed enhancement while no enhancement was observed in the cystic component.Two cases had the spot-like calcification.Conclusion MHL has some special characteristics in the CT scan before surgery,which should be differentiated from other cystic and solid tumors of live.Some MHLs can be diagnosed when combined with the clinical information and CT images.

Objective To assess the dose reduction potential of adaptive statistical iterative reconstruction(ASiR)and model-based iterative reconstruction(MBIR)in pelvic CT with a standard male phantom.Methods A Fluke Biomedical RANDO standard male phantom was scanned with discovery CT750 HD using different tube currents.CT images were reconstructed with FBP,50％ASiR and MBIR.The CT value,the image noise and the contrast-to-noise ratio(CNR)for the sacral vertebra relative to muscle were measured.The volume CT dose indexes(CTDIvo1)and dose-length product(DLP)were recorded.Results Compared with FBP,using 50％ASiR and MBIR had significant reduced image noise and greater CNR.The effective minimal tube currents for displaying sacral vertebra were 250 mA(FBP),180 mA(50％ASiR),and 100 mA(MBIR).With the similar image quality using FBP,the dose was reduced by 28.0％ and 59.9％ using 50％ASiR and MBIR,respectively.Conclusions Using advanced iterative algorithms can reduce image noise,improve CNR,and reduce the radiation dose in pelvic CT examination.

Objective To investigate the effect of acupuncture combined with human amniotic mesenchymal stem cells ( HAMCs ) transplantation on the osteoporosis in ovariectomized rats.Methods Forty-five healthy female non-pregnant Wistar rats were randomly divided into sham operated group, model group and experimental group ( acupuncture+HAMC transplantation), 15 rats in each group.At 7 days after the surgical wound healing, the rats received acupuncture every day and intravenous injection of HAMCs suspension ( except the sham operated group) once a week for consecutive 12 weeks.The body weight was measured every week.24 hours after the last intervention, the rats were killed and specimens were collected.Specimens of the mid-, proximal-and distal femur were taken to measure the bone mineral density using a dual energy X-ray absorptiometer.At 12 weeks after the intervention, changes of the expression of serum 25-hydroxy-vitamin D (25-HVD), C-terminal peptide of type I collagen (CTX-I), bone specific alkaline phosphatase ( BAP) and human tartrate-resistant acid phosphatase 5b ( TRACP 5b) were determined by ELISA, the biomechanical properties of the removed femur was measured, and the expression of transforming growth factor-β( TGF-β) in the vertebrae was assessed by RT-PCR assay.Results Body weight of rats in the sham operation group was increased gradually in accordance with the natural growth of animals, that of the model group was significantly higher than that of the sham operated group since two months after modeling, and the body weight of the experimental group was similar to that of the sham operated group.The bone mineral density and calcium content of the model group were significantly decreased compared with that of the sham operated group ( P<0.05) , and the bone mineral density and bone calcium content of the experimental group were significantly higher than that of the model group ( P <0.05 ) .The ELISA showed that the expressions of serum 25-HVD, CTX I, BAP, and TRAP5b in the model group were significantly lower than that of the sham operated group, and those of the experimental group were significantly higher than that of the model group ( P<0.05 ) . Measurement of biomechanical properties showed that the limit load, limit stress and elastic modulus of the femur of the sham operated group were significantly higher than that of the model group ( P<0.05 ) , and the limit load and elastic modulus of the experimental group were significantly higher than that of the sham operated group ( P <0.05 ) .T-PCR showed that the expression of TGF-β1 m-RNA in the experimental group was significantly up-regulated than that of the sham operated and model groups ( P<0.05) .Conclusions Acupuncture combined with human amniotic mesenchymal stem cell ( HAMCs) transplantation has a synergistic effect on the treatment of osteoporosis, and can improve the conditions in ovariectomized rats.

Objective:To explore the mechanism of Trametes Robinioplila on regulating the imbalance of Th1 and Th2 ratio in gene and protein level,and to find the theoretical basis of the fungus for treating asthma in remission stage.Methods:The PBMC from asthmatic children were divided into three groups(blank group,middle-dose group,large-dose group),and then treated respectively with Trametes Robinioplila(0g/L,3g/L,6g/L) and culture medium for 48 hours respectively.The expression of IL-4 and IFN-? mRNA in cellular precipitation were measured,and the expression of IL-4 and IFN-? in supernatant were measured too.Results:After PBMC cultured with Trametes Robinioplila for 48 hours,the expressions of IL-4 mRNA,IFN-?,IFN-?/IL-4 mRNA ratios and IFN-?/IL-4 ratios were significantly different(P0.05) between large-dose group and middle-dose group.Conclusion:Trametes Robinioplila markedly increased the expression of IFN-? and decreased the expression of IL-4 mRNA,then regulated the imbalance of IFN-?/IL-4 and Thl/Th2 ratios in asthmatic children in remission stage.

Objective To study the pathological features and developmental tendency of gastric carcinoma(GC) in Wuwei City. Methods The clinical data of 7346 cases of GC found in 85427 cases undergoing endoscopy in Wuwei City from 1977 to 2000 were retrospectively analysed. Results The detectation rate of GC by endoscopy in Wuwei City was 8.7%. GC developed to a peak at 40～70 years of age(92.0%).In the GC cases, the Hp infection rate was 64.6%, which is higher than that in the area of low incidence of GC and the general population. Hp infection rate in poorly differentiated adenocarcinoma was higher than that in well differenciated type.Most GC(43.8%) were located in the proximal portion of the stomach. Poorly differentiated adenocarcinoma appeared to be the most common pathological type. Conclusions GC in Wuwei City is related to Hp infection. GC location has shifted from the distal to the proximal portion of the stomach in the last 23 years.

Objective To investigate the expression and role of cyclooxygenase-2(COX-2)in the ischemia reperfusion in"ury in liver transplantation in rat.Methods Fifty-four male Wistar rats were divided into control group(n=6),liver transplantation group(n=24)and NS398 treated group(n=24)according to random number table.The expression of COX-2 mRNA was detected by RT-PCR,the distribution of COX-2 positive cells by immunohistochemistry.and the content of serum TNF-αand IL-10 by enzyme-linked immunosorbent assay.All the data were processed by one-way ANOVA.Results The serum indexes and changes of TNF-α.expression were in accordance with the histological injury of liver graft.The expression of COX-2 mRNA was essential to the ischemia reperfusion injury of the liver graft.Inhibition of the expression of COX-2 mRNA would aggravate the isehemia reperfusion injury of the liver graft.Conclusions COX-2 plays an important role in the ischemia reperfusion injury in liver transplantation.COX-2 may decrease the isehemia repertusion injury of liver graft.