Recently,tissue-engineered chondrocyte transplantation has been tried to treat full-thickness cartilage defects.Of the many scaffold materials being investigated,collagen,with good biocompatibility,biodegradable and biological activity,has been shown to have many advantageous features for the proliferation,the attachment and the differentiation.The present article reviews the applications and prospects of collagen in cartilage tissue engineering.

[Objective]Porous collagen type Ⅱ matrices crosslinked by 1-ethyl-3-(3-dimethyl aminopropyl)carbodⅡmide(EDC) and N-hydroxysucinimide(NHS) were developed as scaffolds for cartilage tissue engineering.[Method]Collagen type Ⅱ matrix was crosslinked by EDC/NHS,and then freeze-dried to achieve collagen scaffolds.The porous characteristics of the prepared scaffolds were tested by using diffenent methods,including laser scanning confocal microscopy (LSCM),scanning electron microscopy (SEM) and mechanical testing machine.The chondrocytes labeled by GFP were planted in crosslinked collagen type Ⅱ,and observed by LSCM.[Result](1) The mechanical properties of cross-linked matrices increased significantly,reaching 2.18?0.47MPa.(2)The degradation of cross-linked matrices decreased by 8.28% after 4 hours.The pore size was about 90?m,and their average porosity and water capacity reached 93.39% and 97.78%,respectively.3.Chondrocytes were in good condition in the crosslinked collagen.[Conclusion]The present work indicates that EDC/NHS-crosslinked collagen type Ⅱ could keep the properties and biocompatibility of collagen,besides,the mechanical strength increased and the degradation was decreased.It will be suitable for cartilage tissue engineering purposes.

Objective To evaluate the relative quantities of flt-1, KDR, endostatin mRNA in tissue specimens of human hemangioma and great saphfenous vein with the modified reverse transcriptase-polymerase chain reaction (RT-PCR). Methods Total RNA from human specimens by Trizol was reverse-transcribed and amplified by PCR in 4 deffirent tubes containing one of the primer pairs such as flt-1, KDR, endostatin or ?-actin. The target genes and beta-actin PCR products were about 200 bp in length. The ratio of the yield of the target gene PCR product to the beta-actin PCR product could be calculated after 35 cycles of amplification.Results These ratios were correlated positively ( P=0.014,P=0.019) in two groups, but no relationship in endostatine level was observed (P=0.436).Conclusions VEGFR may play a very important role in the pathogenesis of the congenital hemangioma in children. But the endostatin may take little effect on it.

Objective To study the 2244G→A, 2299 A→G single nucleotide polymorphism (SNP) in the 5' regulatory regions of Toll-like receptor 4 (TLR4) in patients with Gram negative bacteria infection in Shenzhen locality, and to discuss the occurrence, course and prognosis of patients with sepsis. Method Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to detect the genotype of TLR4. After the whole blood DNA of patient was extracted and PCR was amplified, the products were 500bp and 599 bp, and were cut by endonuclease Mae Ⅱ and Sph Ⅰ respectively to determine the SNP 2244G→A and 2299 A→G in TLR4. These two kinds of allele frequencies were statistically calculated in all patients. In the meantime, the incidence of septic shock, average hospitalized days, cost and prognosis of all patients were recorded. Statistical analysis was performed with SPSS version 16 software. ANOVA was used for comparison among multiple groups, and t -test and Sighed rank test were used for paired comparison. Results The 2299 and 2244 sites in the 5' regulatory regions of TLR4 gene of patients with Gram negative bacteria infection in Shenzhen locality had various degrees of changes in single nucleotide. Compared with the documented data from Chinese people in general, there was a significant difference in 2299A→G genotype frequency in residents of Shenzhen locality ( P < 0.05). But there were no statistically significant difference in mortality, incidence of septic shock, average days of ICU stay or ICU cost between TLR4 SNP positive and negative groups of patients. Conclusions There is a wide range of genetic variation in the 2299 and 2244 sites in the 5' regulatory regions of TLR4 among citizens of Shenzhen locality with unique distribution. The 2299A→G genotype frequency probably has differences in distribution and population. The pathogenesis and the prognostic factors of sepsis are complicated, whereas the gene polymorphism may be just one of the factors affecting the prognosis of patients with Gram negative bacteria infection.

Phase angle (PA), derived by bioelectrical impedance analysis, has been used to evaluate nutritional status.It has a unique advantage in diagnosing early malnutrition related to diseases by the detection of human body cell membrane integrity and fluid composition change, and being associated with bad disease prognosis in part of clinical research.Because of its non-invasive, convenient, accurate and affordable technique, it has a wide prospect of clinical application.However, lack of uniform PA reference value somehow limited its application.We summarize the latest clinical research and application situation of PA, and explore the characteristics and the influence factors of PA in different disease group, in order to provide theoretical basis for the Chinese PA reference range.

Aim To investigate the vasodilatory effect and the mechanisms of urocortin(Ucn) on the thoracic aorta of spontaneously hypertensive rats(SHR).Methods Rings cut from SHR thoracic aorta were used in vitro.The endothelium dependent and independent vasorelaxing effects of Ucn were measured.Furthermore,it was also explored whether the relaxing effects of Ucn were affected by N~((?)) nitro-L-arginine methyl ester(L-NAME), methylene blue(MB) and glybenclamide.Results Ucn(1 nmol?L~(-1)～1 ?mol?L~(-1)) caused concentration dependent relaxation in SHR thoracic aorta with endothelium and without endothelium(P

Objective To observe the effect of sustained release type Ⅰ collagen-vascular endothelial growth factor (VEGF) on healing of bone-tendon junction injuries.Methods Partial patellectomy was conducted in 72 rabbits divided equally into control group,type Ⅰ collagen group,and collagen type Ⅰ-VEGF group.The scaffold was planted into the bone-tendon interface.Animals were sacrificed at 4,8 and 12 weeks.New bone formation into the patella-patella tendon surface was detected using X-ray films and histological observations.Quality of bone healing was assayed using biomechanical testing.Results At postoperative 4,8 and 12 weeks,X-ray films showed bone formation of type Ⅰ collagen group [(4.1 ± 0.4) mm2,(12.1 ± 0.5) mm2,(13.0 ± 1.2) mm2 respectively] and of collagen type Ⅰ-VEGF group [(3.8 ± 0.4) mm2,(11.0 ± 0.5) mm2,(13.1 ± 1.0) mm2 respectively] were more than that of control group [(2.1 ± 0.6) mm2,(4.1 ± 0.3) mm2,(6.6 ± 0.6) mm2 respectively] (P ＜ 0.05).Histology identified few new bone,massive fibrocyte accumulation and disrupted alignment of tendon fiber in control group,massive new bone formation,neat and orderly alignment of collagen fiber tissues and massive aggrecan expression at postoperative 4 and 8 weeks (fibrous cartage repair in largely) in collagen type Ⅰ-VEGF group,and massive new bone formation but worse alignment of tendon collagen fibers and less aggrecan expression (fibrous repair in largely) in type Ⅰ collagen group.Biomechanical test showed the ultimate tensile strength increased over time in all groups,with significantly higher value at 12 weeks than that at 4 and 8 weeks.At the same time point,ultimate tensile strength ranged in an order as follows:collagen type Ⅰ-VEGF group ＞ collagen type Ⅰ group ＞ control group (P ＜ 0.05).Conclusion Sustained release type Ⅰ collagen-VEGF can accelerate early healing of bone-tendon junction injury and improve the histological and mechanical properties.

Objective To observe the expression changes of inflammatory cytokines of human tendon-derived stem cells (TDSCs) under uniaxial stretching.Methods TDSCs were isolated from human gracilis tendon by collagenase digestion at very low density.Cells were detected for surface markers by flow cytometry,and tested for multi-differentiation potential in vitro.Repetitive uniaxial stretching was applied on the cells at 0％,4％,8％ or 10％ strain.Under the microscopy,cell alignment was observed after mechanical stretching.Expressions of inflammation factors COX-2 and MMP-1 were detected by qPCR and western blotting.Results TDSCs were successfully isolated from human gracilis tendon.Inflammatory cytokines CD29,CD44 and CD105 were positive,but CD45 and CD14 were negative.TDSCs could differentiate into osteocytes,adipocytes and chondrocytes in vitro.Cells were not realigned4 hours after mechanical stretching.MMP-1 mRNA expression was significantly down-regulated at 4％ strain (0.090 ± 0.007) compared to that at 0％ strain (0.247 ± 0.032,P ＜ 0.05).No significant difference was found in COX-2 mRNA expression at 4％ and 8％ strain (both was 0.005 ±0.001,P ＞0.05).MMP-1 and COX-2 mRNA expressions at 8％ strain (0.168 ± 0.040 and 0.007 ± 0.001)revealed no significant differences from those at 0％ strain (0.134 ±0.075 and 0.006 ±0.003) (P ＞0.05),whereas at 10％ strain MMP-1 and COX-2 mRNA expressions were significantly up-regulated (0.047 ± 0.003 and 0.496 ± 0.036) compared to those at 0％ strain (0.011 ± 0.003 and 0.005 ± 0.003)(P ＜ 0.05).Changes in MMP-1 and COX-2 protein expressions revealed similar trend as their mRNA expressions.In contrast to the setting of 0％ strain,4％ strain induced down-regulated MMP-1 and COX-2 proteins,8％ strain induced no significant changes in MMP-1 and COX-2 proteins,and 10％ strain induced up-regulated COX-2 protein despite minor increase in MMP-1 protein.Conclusions Mechanical stretching can affect the secretion of inflammatory cytokines.Low tensile stretch is associated with decreased expression of inflammatory cytokines while high tensile stretch promotes secretion of inflammatory cytokines.

Objective:To understand and analyze the levels of individual dose to medical radiation workers from occupational external exposure in Inner Mongolia autonomous region from 2015 to 2019, with a view to provide basic scientific data for workers′ health protection and radiation protection management.Methods:By using National Individual Dose Registry, the individual dose monitoring result and other related data for medical workers were collected and analyzed.Results:The average annual individual doses to medical radiation workers in a time order from 2015 to 2019 were 0.72, 0.87, 0.88, 0.71 and 0.64 mSv, respectively. There were significant differences in the annual effective dose distribution in diagnostic radiology, dental radiology, nuclear medicine, radiotherapy, interventional radiology and other applications ( H=466.56, P<0.05). The average annual effective doses to workers in interventional radiology and nuclear medicine had not shown significant difference ( P>0.05), but significantly higher than those in other occupational categories ( Z=19.95, 9.87, 10.10, 12.76, P<0.05). Conclusions:The average annual effective dose to medical radiation workers is in accordance with the relevant national standards. The dose values for the radiation workers involved in interventional radiology and nuclear medicine are relatively high, especially for interventional radiology workers and radioactive drug operators. The protection measures should be further improved in radiation protection workplace.

Objective To explore the value of abnormal imaging findings on susceptibility weighted imaging (SWI) in delayed graft function (DGF). Methods The conventional MRI and SWI images of 26 cases with DGF and 20 cases with normal renal function of transplanted kidneys were retrospectively analyzed. Patients with cysts and angiomyolipomas were excluded. Normal structures of transplanted kidney were identified. If lesions of abnormal signal intensity were found in the transplanted kidney, the location, border and signal intensity compared to renal cortex would be analyzed. The differences in signal intensity between the abnormal signal lesions and normal renal cortex in the same SWI layer of DGF were compared by using independent-sample t test. The differences in positive detection rate of discovering the abnormal signal lesions in DGF between conventional MRI and SWI were compared by using McNemar test. Results Of the 26 cases with DGF, one case was found to exhibit abnormally low signal lesions with fuzzy boundary located at junctional zone between cortex and medulla on both conventional MRI and SWI images. Ten cases were found to exhibit abnormally low signal lesions with fuzzy boundary located at junctional zone between cortex and medulla on SWI images only. Fifteen cases exhibited no abnormal signal lesions on both conventional MRI and SWI images. Twenty cases with normal renal function of transplanted kidney, no abnormal signal lesions were found on both conventional MRI and SWI images. The differences in signal intensity between the abnormally low signal lesions (130±20) and normal renal cortex (177±25) in the same SWI layer of 11 cases with DGF were statistically significant (t=-4.582,P<0.01). The differences in positive detection rate of discovering the abnormally low signal lesions in DGF between conventional MRI [3.8%(1/26)] and SWI [42.3% (11/26)] were statistically significant (χ2=8.100,P=0.002). Conclusions Abnormally low signal lesions with fuzzy boundary located at junctional zone between cortex and medulla on SWI images suggest the presence of DGF. Compared with conventional MRI, SWI appears to be superior in detecting the abnormally low signal lesions.