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.

AIM: To observe the efficacy of high concentrations of sodium hyaluronate ( 3g/L SH ) for moderate to severe dry eye.
METHODS: Forty moderate to severe dry eye patients were included in the study according to the diagnosis criteria and randomized into two groups. The patients of the trial group received topical administration of high concentration sodium hyaluronate (3g/L), and those of the control group received sodium hyaluronate ( 1g/L ) plus recombinant human epidermal growth factor. The dry eye symptom scores, ocular surface disease index ( OSDI) scores, tear film break-up time ( BUT) , SchirmerⅠ test and corneal fluorescein staining score were evaluated. All the indexes were compared between the two groups 2wk before and after treatment.
RESULTS: There were no significant differences of the indicators between the two groups before treatment. After 2wk treatment, the differences were statistically significant compared to former except for the SchirmerⅠtest. Compared with the control group, the symptom scores and the OSDI scores were lowered. No significant differences were found in the other indicators between these two groups.
CONCLUSION: Topical usage of highconcentrations of sodium hyaluronate (3g/L) is beneficial for remitting the ocular symptoms in moderate to severe dry eyes, and also improve the quality of life of patients.

Objective To evaluate the efficacy of different doses of dezocine for decreasing the minimum alveolar concentration (MAC) of desflurane.Methods ASA physical status Ⅰ or Ⅱ patients of both sexes,aged 50-70 yr,undergoing elective lower abdominal surgery performed under general anesthesia,were divided into 4 groups:control group (group C)and different doses of dezocine groups (D1,D2 and D3 groups).Before induction of anesthesia,in D1,D2 and D3 groups,dezocine 0.050,0.075 and 0.100 mg/kg were intravenously infused,respectively,while in group C,the equal volume of normal saline was given instead of dezocine.The adverse reactions were observed.Propofol 3 mg/kg was given for induction of anesthesia 15 min later until patient' s consciousness and spontaneous respiration disappeared.Laryngeal mask airway was inserted and the patients were mechanically ventilated.Up-and-down sequential allocation was used to determine the MAC of desflurane during maintenance of anesthesia.The end-tidal concentration of desflurane was set at 8.0％ and maintained at this level for at least 5 min before skin incision in the first patient.Each time the concentration of desflurane increased/decreased in the next patient depending on whether or not the body movement developed.The ratio between the two successive concentrations was 0.9.The point between the positive response and negative response served as a cross-over point.After at least 7 independent cross-over points were observed in each group,the experiment was stopped.The MAC and 95 ％ confidence interval of desflurane were calculated.Results No adverse reactions developed in each group.The MAC of desflurane was significantly lower in D1-3 groups than in group C,in groups D2.3 than in group D1,and in group D3 than in group D2.Conclusion Dezocine 0.100 mg/kg injected intravenously at 15 min before induction of anesthesia provides a better efficacy for decreasing the MAC of desflurane in the patients.

Objective To evatluate the effect of dexmedetomidine on intraoperative wake-up test during cerebral functional area operation performed under combined iv propofol-remifentanil anesthesia.Methods Twenty-seven ASA Ⅰ or Ⅱ patients (both sexes) aged 17-43 yr with a body mass index of 20-24 kg/m2 undergoing op-eration on cerebral functional area during which intraoperative wake-up test was performed were randomly divided into control group (group C,n =13) and dexmedetomidine group (group D,n =14).Anesthesia was induced with midazolam,sufentanil,etomidate and rocuronium and maintained with TCl of propofol (Cp =3-5 μg/ml) and remifentanil (Ce =2-6 ng/ml).BIS value was maintained at 55-65.In group D after dura of brain was opened,a loading dose of dexmedetomidine 0.3 μg/kg was administered iv over 15 min followed by continuous iv infusion at 0.2 μg· kg-1 · h-1 while TCI of propofol and remifentanil were suspended.In group C after opening of dura,Cp of propofol TCI was reduced to 0.5 μg/ml and Ce of remifentanil to 0.5 ng/ml.The wake-up time and development of hypertension,tachycardia,headache,dysphoria,delirium and awareness were recorded.Results All patients were successfully awakened.There was no significant difference in wake-up time between the 2 groups (P ＞0.05).The incidences of hypertension,tachycardia,headache and awareness were significantly lower in group D than in group C (P ＜ 0.05).Conclusion Dexmedetomidine does not affect intraoperative wake-up time during operation on cerebral functional area performed under iv propofol-remifentanil anesthesia,but can significantly reduce the incidence of adverse effects.

Debates over PBL have never stopped since its introduction to medical education in 1969 and are even becoming more heated.This paper expounds on the origin and definition of PBL,and then describes and analyzes the application of the clinical teaching in orthopedic surgery.

The efficacy of laparoscopic Dixon operation for the treatment of rectal cancer has been proven,while at the same time there are opportunities to make the procedure less invasive.From January 2010 to March 2011,9 cases of single access laparoscopic Dixon operation have been performed at the Shengjing Hospital.An incision with the length of 3 cm was created in umbilicus and 3 trocars were inserted through the fascia on the abdominal wall.The dissection and anastomosis were performed through the incision.The resected tumors were removed through the umbilical incision or anus.The operation was successfully performed on 9 patients,and one more incision with the length of 12 mm was created on the lower abdominal wall in 1 patient in order to install the stapling device.The average operation time was 202 minutes.No postoperative bleeding,intestinal obstruction or anastomosis leakage was found.

Objective To investigate the effects of different concentrations of dexmedetomidine on the expression of Toll-like receptor 4 (TLR4) mRNA in rat peripheral blood monocytes exposed to lipopolysaccharide ( LPS ). Methods Peripheral blood monocytes isolated from male Wistar rats were seeded in 24-well plate in RPMI 1640 liquid culture medium in CO2 incubator at 37 ℃ and 5% CO2 for 2 h, and were randomly divided into 5 groups ( n = 8 each): group A negative control; group B was exposed to LPS 1 μg/ml and C, D and E groups were exposed to LPS 1 μg/ml + dexmetomidine 0.5, 5.0 and 50.0 ng/ml respectively. The monocytes were then incubated for 24 h. The concentrations of TNF-α, IL-1β and IL-6 in the supernatant of the cultured monocytes were detected by ELISA. The expression of TLR4 mRNA in the monocytes was detected by RT-PCR.Results Exposure to LPS significantly increased the expression of TLR4 mRNA and the concentrations of TNF-α, IL-1β and IL -6 in group B as compared with group A ( P ＜ 0.01 ). Dexmedetomidine attenuated the LPS-induced increase in the expression of TLR 4 mRNA and the concentrations of TNF-α, IL-1β and IL-6 in a dose-dependent manner ( P ＜0.05or 0.01 ). Conclusion Dexmedetomidine can inhibit the synthesis of TLR4 and inhibit the secretion and dilivery of TNF-α, IL-1β and IL-6 by down-regulating the gene expression of TLR4 in rat peripheral blood monocytes exposed to LPS.

Objective To evaluate pharmacodynamics of prepared long-circulating superparamagnetic iron oxide (SPIO) liposomes. Methods Control and experimental groups were established after adding SPIO or long-circulating SPIO liposomes as agents. (1)Macrophages experiment in vitro: the RAW 264.7 macrophage cell strains were recovered, cultured and seeded in the culture plate at a density of 2.5×105 cells/well until they reached 80%-90% confluence. The intracellular Fe uptake of control and experimental group cells were quantified by Ferrozine assay after incubation with different concentrations of drugs. Factorial design analysis of variance was used as statistics method. Prussian blue staining method was used to detect staining of experimental cells.(2)Drug biodistribution in mice: C57BL/6J(n=6) were classified into blank control group (n=2), control group(n=2) and experimental group(n=2).Saline, SPIO and long circulating SPIO were injected via the tail vein in the blank control group, control group and experimental group respectively. Then distribution of drugs in the body was observed by pathological examination.(3) MR imaging of tumor-bearing nude mice: 20 BALB/c nude mice bearing lung cancer models were established and classified into control group and experimental group. After administration of drugs, all animals underwent MR scanning. Signal intensities of livers and tumors were measured, SNR-time dynamic curves were drew. Covariance analysis was used to compare post-enhanced SNR at the 12th hour. (4)Cytotoxicity studies (MTT): cytotoxicity of both drugs on human liver cell line HL-7702 was studied, and statistically analyzed using factorial design analysis of variance. Results (1) Macrophages experiment in vitro: The nanoparticle uptake by macrophage cells evaluated by ferrozine assay showed the uptake of blank SPIO was higher than long-circulating SPIO liposomes. Compared with the blank control group, there was strong blue staining in the macrophages with Prussian staining in the control group and little blue staining in the experimental group. (2) Drug biodistribution in mice: for blue stained cells composed of iron particles, the amounts in the liver, spleen, lung, kidney of the control group were more than those in the experimental group. (3) MR imaging of tumor-bearing nude mice: the non-enhanced SNR of livers and tumors in the control group and experimental group were 31.47 ± 0.56, 30.89 ± 1.41, 58.41 ± 0.61, 58.44 ± 1.08, respectively. After injecting of contrast agents, SNR of livers and tumors in the control group and experimental group were 17.00 ± 0.96, 22.29 ± 0.73, 58.50 ± 0.63, 52.47 ± 1.18, respectively. The covariance analysis showed that SNR of the livers in the control group after 12 hours was significantly lower than the experimental group (F=167.022, P=0.000); while the SNR of the tumors in the experimental group was significantly lower than the control group (F=266.106, P=0.000).(4) Cytotoxicity of nanoparticles by MTT method: the viability of HL-7702 cells tend to decrease with the increase of Fe concentration. Cytotoxicity in the long-circulating SPIO liposomes was lower than the SPIO(F=2256.204,P=0.000). Conclusions Long-circulating SPIO liposomes we prepared reveal suitable sizes, even distribution, and good anti-macrophage ability in vitro and in vivo. They have long circulation characteristic and T2 negative enhancement effect in the transplanted lung cancers, while they still maintain low cytotoxicity.

Objective To investigate the clinical features of primary retroperitoneal fibrosis (RPF), and to find out better method for diagnosis and therapy. Methods Nine patients with primary RPF in Peking Union Medical College Hospital since 1990 to 2003 were analyzed retrospectively. Results All patients had abnormal findings in CT or MRI, and 8 of them had chronic non-specific inflammation of the retroperitoneum in pathology. Six patients had renal involvement and 2 of them had severe renal failure. Eight of the patients had received therapy with corticosteroid or tamoxifene. Conclusions RPF is an uncommon collagen vascular disease characterized by a chronic non-specific inflammation of the retroperitoneum.Because of the atypical manifestations of RPF, awareness of the disease is important.CT and (or) open biopsy remains the gold standard for diagnosis.Management typically includes surgery and drug treatment.Corticosteroid therapy or more recently,tamoxifen has been used successfully. The clinical and radiographic improvement with drug treatment has been seen in several patients and confirmed the diagnosis,thereby early diagnosis and treatment can bring the patient more excellent renal and general outcome.

Objective To investigate the change of plasma marinobufagenin (MBG) level and the expression of its receptor Na+-K+-ATPase (NKA) in renal biopsy specimens of chronic glomerulonephritis (CGN) patients. Methods Twenty-eight CGN patients and 14 healthy people were enrolled in the study. The plasma MBG concentration was measured by competitive inhibition ELISA system. Immunofluorescence and immunohistochemistry staining were applied to detect the expression of NKA in renal biopsy specimens of 28 CGN patients and analyzed by semi quantitively. Results Compared with healthy controls, CGN patients had significant lower plasma MBG concentration [(0.579±0.214) nmol/L vs (0.715±0.154) nmol/L, P＜0.05], without further significant difference between CGN patients with hypertension and with normal blood pressure [(0.595±0.231) nmol/L vs (0.557±0.197) nmol/L, P＞0.05]. Meanwhile, proximal tubular staining of NKA was decreased compared with normal controls. The NKA positive staining area of the CGN group was lower than that of normal controls [2.1% (0.5%-6.2%) vs 5.6% (3.5%-10.8%), P＜0.01] and correlated with 24-hour urinary sodium excretion (r=0.551, P＜0.01).Conclusion Decreased plasma MBG level and its receptor expression on proximal tubules may play a role in the regulation of sodium in CGN.