BACKGROUND:Three-dimensional printing technique has been applied in medical fields since it was invented in the end of 20th century. Recently it has been widely used in manufacturing scaffolds for bone tissue engineering. OBJECTIVE:To review the basic concept of the scaffold for bone tissue engineering, the basic requirements for three-dimensional printing technique in scaffold engineering, different materials used in bone tissue engineering, the advantages and limitations of three-dimensional printing technique and the outlook of three-dimensional printing technique applied in manufacturing scaffold for bone tissue engineering. METHODS: The first author did a computer-aided retrieval of the MEDLINE database, Science Direct database, CNKI database, and CQVIP database for articles relevant to three-dimensional printing technique used in manufacturing scaffolds for bone tissue engineering published between January 1990 and February 2015. The key words were three-dimensional printing, tissue engineering, rapid prototyping technology, scaffold, materials in English and Chinese, respectively. Repetitive studies were excluded, and 33 of 52 related literatures were adopted in result analysis. RESULTS AND CONCLUSION: Three-dimensional printing technique has many advantages such as high resolution, high velocity and the freedom to build unlimited geometries. There are some requirements for the powder and binder used to construct bone tissue engineering scaffolds using the three-dimensional printing technique, such as the flowability, stability and wettability. A wide range of materials can be used: synthetic and natural polymers, ceramics, as wel as composites of the aforementioned. Various kinds of powder take responsibility of different features of scaffolds, resulting from the advantages and disadvantages of different materials. Although this technique has some limitations such as high cost and the difficulty of commercial production, its application stil has a bright future.

With the development of brain research, study of neural coding has attracted more attention. Neural coding by informatics entropy is a very important aspect in the research field. This paper presents an overview of typical entropy coding methods of neuronal spike train including binary string method, direct method, asymptotically unbiased estimator method, inter-spike interval and mutual information method. Related principles and application are reviwed.

Objective:To investigate the dynamic changes of thyroid function and risk factors of hypothyroidism and delayed thyroid stimulating hormone (TSH) elevation in late preterm infants.Methods:This study retrospectively recruited 782 late preterm infants admitted to Nanjing Medical University First Affiliated Hospital and performed thyroid function monitoring from January 2017 and December 2019. Thyroid function test was performed in all cases at 4-7 d after birth and repeated at 2-4 weeks of age for those with normal results or two weeks after the first test for those with abnormal. The test would be continued if the second test was abnormal and stopped until the thyroid function became normal or hypothyroidism was diagnosed, based on which, these infants were divided into hypothyroidism ( n=11) and non-hypothyroidism groups ( n=771), or delayed TSH elevation ( n=71) and normal thyroid function groups ( n=450). The characteristics of thyroid hormone changes and perinatal data were compared between different groups using two independent sample t-test and Chi-square test, and risk factors of hypothyroidism and delayed TSH elevation were analyzed using logistic regression tests. Results:(1) Dynamic changes of thyroid function: among these 782 late preterm infants, five infants were found with transient hypothyroxinemia at the first test, and became normal at the second test; 249 (31.8%) exhibited hyperthyrotropinemia, and four of them were diagnosed with hypothyroidism based on the second and the third results; 71(9.1%) with delayed TSH elevation all became normal later; 11(1.4%) were diagnosed with hypothyroidism and treated with thyroxine, among which, seven cases were diagnosed at the first test, three at the second test and one at the third test. (2) Risk factors for hypothyroidism: lower birth weight was noted for infants with hypothyroidism compared with those without [(2 140.9±455.1) vs (2 464.1±474.0) g, t=-2.247, P=0.025]. Multivariate logistic regression analysis found that for every one gram reduction in birth weight, the risk of hypothyroidism elevated by 0.002 times ( OR=1.002, 95% CI: 1.000-1.004, P=0.045). (3) Risk factors for delayed TSH elevation: the birth weight was lower [(2 395.4±420.9) vs (2 523.6±462.3) g, t=-2.200, P=0.028], and the proportion of small for gestational age and twin pregnancy were higher in the delayed TSH elevation group than those in the normal thyroid function group [15.5% (11/71) vs 7.1% (32/450), χ2=5.690, P=0.017; 29.6% (21/71) vs 18.7% (84/450), χ2=4.537, P=0.033]. Multivariate logistic regression analysis found that small for gestational age ( OR=4.366, 95% CI: 1.649-11.564, P=0.003) and twin pregnancy ( OR=1.943, 95% CI: 1.048-3.600, P=0.035) were independent risk factors for delayed TSH elevation. Conclusions:Late preterm infants have a high incidence of different kinds of thyroid dysfunction. Thyroid function monitoring is necessary for late preterm infants because those with lower birth weight are more susceptible to develop hypothyroidism, and those small for gestational age infants and twins are more susceptible to develop delayed TSH elevation.

Objective: To establish N-methyl-N-nitrosourea (MNU)-induced bladder cancer model in Wistar rats, and to investigate the preventive and therapeutic effects of curcumin on bladder cancer, as well as to explore its potential mechanism. Methods: The bladder cancer in Wistar rats was induced by intravesical infusion of 1.5 mg MNU at 0, 2, 4, 6 and 8 weeks. The rats were divided into two groups, including the preventive group [receiving 0.2 mL curcumin (160 μmol/L) at 1, 3, 5, 7 and 9 weeks] and the therapeutic group [receiving 0.2 mL curcumin (160 μmol/L) at 10, 12, 14, 16 and 18 weeks]. The rats in the preventive group and the therapeutic group were sacrificed at 13 weeks and 23 weeks, respectively. The bladder cancer tissues were stained with hematoxylin and eosin (HE) for pathological examination. The apoptosis of tumor cells in the bladder cancer tissues was detected by fluorescence staining. Results: In the preventive group, three rats developed bladder cancer at 13 weeks (23.1%, 3/13), and the muscle invasion of superficial transitional cell carcinoma of bladder (TCC) was not observed. In the vehicle control group, the incidence of bladder cancer was 66.7% (8/12). Six rats had superficial TCC, and two rats had TCC with muscle invasion. There were significant differences in the incidence and histologic staging of bladder cancer between the preventive group and the vehicle control group. The pathological results of the preventive group revealed that curcumin could not decrease the histologic stage of the developed cancer, but evidently increase the apoptosis rate of bladder cancer cells. Conclusion: Curcumin can effectively inhibit the tumorigenicity and progression of rat bladder cancer induced by MNU, and this mechanism may be related to apoptosis of tumor cells, but it has no effect on the developed bladder cancer. Copyright© 2011 by TUMOR.

Objective To investigate the prevalence of benign prostatic hyperplasia (BPH) in Beijing. Methods A cross-sectional study was performed at Beijing communities in men aged over 50 years. The International Prostate Symptom Score (IPSS) questionnaire was used to evaluate the symptoms. Transabdominal ultrasonography was used to measure prostate size and the residual urine volume(RUV). Uroflowmetry was performed to record the maximum flow(Q_(max)). One-way ANOVA was used to analysis the differences. Results 1644 subjects were enrolled and the mean age was 64. 5 years (range 50 - 93 years). The mean IPSS, prostate weight andQ_(max) were 9. 9±8. 2, (30. 8± 19.4) and (14. 7 ± 7. 5)ml/s, respectively. They had correlation with age (r=0. 388,0. 262, - 0.371). The prevalence of moderate-severe lower urinary tract symptoms (LUTS) was 50. 8% (835/1644). Prostate volume was greater than 20 ml in 69. 7%(1146/1644) of the subjects.Q_(max) was less than 15 ml/s in 53. 8% (883/1642) of the subjects. Conclusions In men age over 50 years in Beijing, there is positive correlation between LUTS, prostate size and age, and negative correlation between Q_(max) and age. The prevalence of BPH, defined as IPSS greater than 7, maxium flow rate less than 15 ml/s and prostate size greater than 20 ml, is 26. 8%(441/1644).

Objective To investigate the concentration changes of vascular endothelial growth factor(VEGF), nitric oxide(NO) and endothelin (ET) in elderly patients with obstructive sleep apnea syndrome (OSAS) combined with eerebrovascular disease.Methods One hundred and thirty-two subjects were divided into four groups: OSAS with cerebrovaseular disease group (OC group), OSAS without cerebrovascular disease group (O group), cerebrovascular disease without OSAS group (C group) and normal control group (N group).The concentrations of VEGF, NO and ET in the plasma were compared in each subgroup.Results The concentration of VEGF was significantly increased in OC group and O group compared with C group and N group[(195.34±56.7)ng/L, (162.34±48.7)ng/L, (156.4 4±51.8) ng/L, (114.1 ± 54.2) ng/L, F= 21.02, P< 0.05].The concentration of NO was increased gradually in OC group, C group, O group and N group[(62.3±4.9)mmol/L,(64.7±5.1) mmol/L, (66.2± 4.2)retool/L, (77.5 ± 6.8) mmol/L, F= 17.35, P<0.05], and the concentration of ET was decreased gradually in OC group, C group, O group and N group[(59.8±9.6)ng/L, (56.5±4.3)ng/L, (54.7±7.9)ng/L, (37.2±8.5)ng/L, F= 4.27, P<0.05].Conclusions The concentrations of VEGF and ET are increased and the concentration of NO is decreased in patients with OSAS.Patients with OSAS combined with cerebrovascular disease have higher VEGF and ET concentrations and lower NO concentration than in patients with simple OSAS.The results indicate that vascular endothelial dysfunction may play an important role in the development of cerebrovascular disease in patients with OSAS.

Objective To compare the clinical effect of simple volar or dorsal plate fixation of intra-articular distal radius fracture.Methods This retrospective study included 42 patients with closed intra-articular distal radius fracture treated surgically using the dorsal or volar plate.Out of the 15 patients in dorsal plating group 5 were males and 10 females at age of (55 ± 7)years (range, 48-62 years), 13 were injured from falls and 2 traffic accidents, 10 were classified as AO type C3 and 5 AO type C2.Out of the 27 patients in volar plating group 8 were males and 19 females at age of (56 ± 6)years (range, 50-62 years), 24 were injured from falls and 3 traffic accidents, 17 were classified as AO type C3 and 10 AO type C2.Between-group differences were compared with respect to wrist range of motion, postoperative radiographic parameters, postoperative complications, disabilities of the ann, shoulder and hand (DASH) score and Gartland-Werley score.Results All the patients were followed up for 11-25 months.There were no significant differences in the wrist range of motion and radiographic parameters between the two groups (P ＞ 0.05).Volar plating group resulted in a significantly better Gartland-Werley score compared to dorsal plating group [1 vs 4 points, P ＜ 0.05], but no significant difference was noted in DASH score (P ＞ 0.05).Four patients (27％) in dorsal plating group developed tendon adhesions and tenolysis was in demand, but one patients (4％) in volar plating group was complicated by median nerve symptoms (P ＜ 0.05).Conclusions Although the DASH score of the two methods was similar, volar plating yields better results in Gartland-Werley score and complication incidence.Thus the volar plating is recommended for intra-articular distal radius fracture.

Objective To investigate the therapeutic effects of TNF and IL 2 recombinant adenoviruses via intra arterial injection on metastatic liver cancer in rat model. Methods Recombinant adenoviruses harboring hTNF ? or hIL 2 gene were amplified in 293 cells and subjected to titration by the pathogenetic effects on 293 cell. The rats bearing metastatic liver cancer of Walker 256 breast carcinoma were randomly grouped and administered via gastra intestinal artery with hTNF ? recombinant adenoviruses alone, or hIL 2 recombinant adenoviruses alone, or at the dose of 1.0?10 9 pfu/rat. The therapeutic effects were observed including their survival time. Results The prepared recombinant adenoviruses of hTNF ? and hIL 2 were with the titers of 2.0?10 9 pfu/ml and 2.1?10 9 pfu/ml, respectively. 1.0 ?10 9 pfu hTNF was the proper dose. Administration of hTNF ? or hIL 2 recombinant adenoviruses via hepatic artery could extend the survival time of metastatic liver cancer bearing rats, with the better therapeutic effects achieved by combinatorial administration of these two adenoviruses. Conclusion Arterial administration of adenoviruses may be an effective approach to targeted immunogene therapy for cancer.

Objective To investigate the gene transfer efficiency and lasted time in rat organs by hepatic artery injection with LacZ reporter gene recombinant adenoviruses. Methods Seven groups of rats were injected with Ad.LacZ (2?10 9 pfu/ml) and two groups of rats were injected with PBS 1 ml as control separately through gastra intestinal artery, and liver, spleen, lung, and kidney were gotten at 12 hrs, 18 hrs, 72 hrs, 7 day, 14 day, 21 day, and 28day, respectively. X gal staining was used to check up expression of LacZ gene. Results Expression of LacZ gene was detected in liver 12 hrs after injection, but none were done in spleen, lung, and kidney. Up to 21days, LacZ gene expressed in liver, but the gene expression lasted for only 14 days in spleen, lung, and kidney LacZ gene was not detected in the two control groups in all organs at 7 day. Conclusion When recombinant adenovirus was administrated through hepatic artery, the introduced gene expressed preferentially in liver. This result was the basis of intraarterial administration of cytokines gene to treat liver tumor.

Objective To evaluate the feasibility, safety and efficacy of selective portal vein embolization (SPVE) in treatment of liver tumor in rats and to provide the groundwork for its future clinical applications. Methods 24 healthy rats underwent the embolization. Pre and post SPVE portogram and liver chemical profile were obtained. Four rats were sacrificed at 10 min, 7,14, 21 and 28 days respectively following follow up portography. The liver, heart, lungs and kidneys were examined macroscopically and microscopically. Fifteen rats implanted with Walker 256 tumor sized from 3 to 10 mm in liver were scanned with MRI and portography pre SPVE taken. Post SPVE 3 rats were examined with MRI for each group at the same interval as above and the lives were examined microscopically. Results (1) The blood flow to the target portal branches were immediately halted after SPVE. These vessels remained occluded without collateral formation up to 28 days. (2) The liver indexes and BUN level increased after embolization, but returned to normal within 21 d. Macroscopic and microscopic changes were not found in the heart, lungs or kidneys. (3) In the healthy rats, the affected segment was atrophic and the remaining liver underwent compensatory hypertrophy. Histologic examination revealed that the targeted portal veins were coagulated, the endothelium were degenerated and the local hepatocytes were necrotic after embolization. (4) In the rats with implanted liver tumor, the affected segment including the tumor was necrotic and atrophic. The tumors were completely necrotic, and no viable tumor cell was seen under microscope in 12 among the 15 rats. Three tumors 10 mm in diameter were not completely necrotic. Part of tumor cells were still alive and infiltrated into the surrounding liver. Conclusion SPVE with ethanol is effective in the treatment of small liver tumor in rats. However,in case of bigger tumors involving several segments, SPVE should be combined with other treatment.