Power Efficiency Enhancement of Organic Light-Emitting Diodes Due to the Favorable Horizontal Orientation of a Naphthyridine-Based Thermally Activated Delayed Fluorescence Luminophore.

Four emitters based on the naphthyridine acceptor moiety and various donor units exhibiting thermally activated delayed fluorescence (TADF) were designed and synthesized. The emitters exhibited excellent TADF properties with a small ΔE ST and a high photoluminescence quantum yield. A green TADF organic light-emitting diode based on 10-(4-(1,8-naphthyridin-2-yl)phenyl)-10H-phenothiazine exhibited a maximum external quantum efficiency of 16.4% with Commission Internationale de L'éclairage coordinates of (0.368, 0.569) as well as a high current and power efficiency of 58.6 cd/A and 57.1 lm/W, respectively. The supreme power efficiency is a record-high value among the reported values of devices with naphthyridine-based emitters. This results from its high photoluminescence quantum yield, efficient TADF, and horizontal molecular orientation. The molecular orientations of the films of the host and the host doped with the naphthyridine emitter were explored by angle-dependent photoluminescence and grazing-incidence small-angle X-ray scattering (GIWAXS). The orientation order parameters (ΘADPL) were found to be 0.37, 0.45, 0.62, and 0.74 for the naphthyridine dopants with dimethylacridan, carbazole, phenoxazine, and phenothiazine donor moieties, respectively. These results were also proven by GIWAXS measurement. The derivative of naphthyridine and phenothiazine was shown to be more flexible to align with the host and to show the favorable horizontal molecular orientation and crystalline domain size, benefiting the outcoupling efficiency and contributing to the device efficiency.

Extensive Lepromatous Lymphadenitis Preceding Lesions on the Face and Earlobes: An Unusual Presentation of Leprosy in Singapore.

Leprosy is also known as Hansen disease, as in some countries the diagnosis of leprosy carries a negative stigma and patients fear being shunned as outcasts. Presently, leprosy is primarily limited to specific geographical regions in resource-poor countries. As a result, there is increased difficulty for the younger generation of physicians today to correctly identify leprosy due to a lack of exposure and a low-index of suspicion, particularly in developed countries. In this case, the indurated lesions over the face demonstrated a preference for the outer lateral aspects over the maxillary areas, the nose bridge, and the pinna of the ears consistent with the organism's preference for cooler regions of the body. This was also evident in the other skin lesions affecting the more acral regions of the limbs in the early stage of disease progression. There is a need to keep this infective condition as an alternate diagnosis to all unusual cutaneous lesions.

A Fatal Case of "Bullous Erysipelas-like" Pseudomonas Vasculitis.

Erysipelas is a generally benign superficial bacterial skin infection, and its bullous form constitutes a rare and more severe variant. We describe the first and fatal case of "bullous erysipelas-like" septic vasculitis due to Pseudomonas bacteremi. A 69-year-old Chinese man presenting with diarrhea and septic shock initially began to rapidly develop sharply defined erythematous plaques with non-hemorrhagic bullae over his lower limbs. Culture of the aspirate from the bullae was positive for Pseudomonas aeruginosa. This was also consistent with his blood cultures showing Pseudomonas bacteremia. Histology of the skin lesion showed microthrombi and neutrophilic infiltrates in blood vessels with Gram-negative bacilli extruding from the vessel walls, characteristic of septic vasculitis. The bullous erysipelas-like lesions seen in this patient represents a rare manifestation of both septic vasculitis and Pseudomonas infection.

[Preparation of human meniscus acellular matrix].

OBJECTIVE: To investigate development of a cell extraction process for preparing human meniscus acellular matrix, and morphology and biomechanical properties. METHODS: Human meniscus were subjected to modified eight-step detergent, then, the specimens were assessed by staining with haematoxylin-eosin, toluidine blue, sirius red, saffron O, alcain blue and hoechst-33258, et al. The ultrastructure of the specimens was observed with scanning electron microscope. Transient recovery rate of deformation, maximal recovery rate of deformation and maximal compressive strength were tested to determine the biomechanical properties of the scaffold. RESULTS: Every stain confirmed that the celluar constituents of the specimens were removed. The specimens stained positively by staining with sirius red. Lacuna were found irregularly not only on the surface of the meniscus,but also in the meniscus with scanning electron microscope. Pores in the specinmens were large, the diameter of pores was 80 to 760 microm, porosity was over 67%. The transient recovery rate of deformation was (89.62 +/- 1.04)%, the maximal recovery rate of deformation was 100% and the maximal compressive strength was (3.04 +/- 0.13)N, when the specimens were compressed 30%. CONCLUSION: The modified eight-step detergent can remove the immunogenic cell components from human meniscus, in addition, 3D extracellular matrix can be retained. The scaffold has good biomechanical properties. This scaffold stands a good chance to be an implant for future tissue engineering of the human meniscus.

Development of rabbit meniscus acellular matrix / 中国医学科学院学报

<p><b>OBJECTIVE</b>To prepare a rabbit meniscus acellular matrix scaffold and explore the histomorphological and biomechanical properties of the scaffold.</p><p><b>METHODS</b>Rabbit meniscuses were collected and acellularized using a modified eight-step detergent process with hydrogen peroxide, distilled water, Triton X-100, and sodium deoxycholate. Its color and texture were observed. Histomorphological assessment was performed using routine hematoxylin-eosin stain, toluidine blue stain, Saffron stain, Hoechst-33258 stain, and immunohistochemical staining of collagen I. The ultrastructure of the specimens was observed with inverted phase contrast microscopy. Transient recovery rate of deformation, maximal recovery rate of deformation, and maximal compressive strength were tested to determine the biomechanical properties of the scaffold.</p><p><b>RESULTS</b>The processed meniscus was milk-white in color with loose structure. It histologically appeared cell-free, stained positively for collagen I, and had abundant micropores according to phase-contrast microscopy. The transient recovery rate of deformation was (76.65∓4.61)%, the maximal recovery rate of deformation was 100%, and the maximal compressive strength was (4.51∓0.69) N when the specimens were compressed 40%.</p><p><b>CONCLUSIONS</b>The rabbit meniscus acellular matrix scaffold, with numerous micropores, is easy to be recovered from deformation and suitable for the adhesiveness and growth of breeding cells. This scaffold can be used as an ideal implant for future tissue engineering of the meniscus.</p>

[Mechanisms of autologous chondrocytes mass transplantation in the repair of cartilage defects of rabbits' knee].

OBJECTIVE: To trace the pathological changes of the cultured autologous chondrocytes mass after implanted in cartilage defects and investigate the pathophysiological mechanisms of the antologous chondrocytes mass transplantation in the repair of cartilage defects. METHODS: Twenty-four New Zealand white rabbits of 4 to 6 month-old and weighing more than 3.0 kg (female and male was unrestricted) were randomly divided into experiment group and the control group. For 12 rabbits of experiment group, the cartilage defects were repaired with the autologous chondrocytes mass and sealed with one piece of periosteum. Firstly, cartilage tissue of 10 to 30 mg was obtained from the shoulder of the rabbits after anaesthetized by 1 mg/kg 20% sumianxin. Then, chondrocytes were isolated from the cartilage tissue with 0.2% type II collagenase digestion and were cultured in DMEM/F-12 supplemented with 20% fetal bovine serum (FBS), 50 microg/ml ascorbic acid-2-phosphate, 0.4 mM proline, 5 microg/ml insulin and 1 mM non-essential amino acids (NEAA) in flasks in vitro. The cells were harvested until a thin film of the cells covered the bottom of the flask could be seen with naked eyes. Then the film was collected with a curled glass stick and formed a solid mass. On this time, the animal was anaesthetized again and the full-thickness cartilage square defect of 4.0 mm x 6.0 mm was fabricated in the patellar grove of distal femur, and then the cellular mass was transplanted into the defect covered by one piece of periosteum which obtained from the upper anterior of tibia and sealed with the femoral condyles. For 12 rabbits of the control group, the defects were sealed with one piece of periosteum only. The animals were sacrificed in the 1st, 3rd, 6th and 12th weeks after the operation respectively. The histologic sections were stained with safranin O-fast green, hematoxylin-eosin (H&E) and picric acid-Sirius red and immunostained for type II collagen and aggrecan. RESULTS: In the 1st week, the transplanted cells oriented to articular surface differentiated to matured hyaline chondrocytes and excrete large amount cartilage matrix. In the 3rd week, the trend was more obvious and the periosteum was union to the cell mass. In the 12th week, the defects were repaired with hyaline-like cartilage tissue, and in the 24th week, the repair tissue turned to matured hyaline cartilage. In the control group, the defects were repaired with fibrocartilage tissues. CONCLUSION: It was evidenced that the defects were repaired by the autologous chondrocytes mass transplantation. The procedure was gradual and initialed from up toward joint to down to the deep of the defect.

[Blood supply of liver metastasis].

OBJECTIVE: To probe the blood supply of liver metastasis by celiac arteriography, proper hepatic arteriogaphy, pure portal vein perfusion CT. METHODS: Fifty patients with liver metastasis were examined prospectively by plain CT scan, multiphase enhanced CT scan, celiac arteriography and proper hepatic arteriography, of whom, 23 were examined by pure portal vein perfusion CT during superior mesenteric arterial portography. The imaging manifestations were observed, and the time attenuation curves (TDC)of tumor center, tumor edge, portal vein and normal liver parenchyma were used to calculate liver perfusion with a software of PhotoShop(used in DSA image analysis)and a deconvolution model (CT perfusion software) designed for the dual blood supply. RESULTS: DSA findings: hypervascular 12 cases, hypovascular 38 cases, and ring tumor stain 36 cases. TDC of proper hepatic arteriography showed: the mean peak concentration (K value) in tumor center (67.48+/-11.56)%, the mean peak concentration (K value) on tumor edge (76.23 +/-14.89)%, the mean peak concentration (K value) in normal liver parenchyma (51.42+/-10.26)%; the mean time to peak concentration in tumor center(9.00+/- 1.03) s, and the mean time to peak concentration on tumor edge (10.69+/-2.82) s; TDC of celiac arteriogaphy showed: the concentration of tumor center and tumor edge increased fastly in early stage, then maintained an increasing plateau slowly, in the meanwhile, the concentration of normal liver parenchyma increased slowly and steadily, after 14 s of acquisition, the concentration of tumor center was lower than that of tumor edge and normal liver parenchyma. Mean time to peak concentration of portal vein was(11.84+/-1.81) s. Multiphase enhanced CT scan findings: ring enhancement in artery phase 11 cases; mild ring enhancement in artery phase,continued thick ring enhancement in portal phase 5 cases; no enhancement in artery phase,ring enhancement in portal phase 25 cases; ring enhancement in equilibrium phase 8 cases; no enhancement in artery phase, portal phase and equilibrium phase 1 case. The mean time to peak enhancement of portal vein was(14.33+/-2.23) s, and the mean enhancement peak value (320.00+/-28.78) HU; the densily of normal liver parenchyma increased slowly after contrast medium administration, the mean time to peak enhancement was (22.25+/-3.44) s, and the mean enhancement peak value (110.75+/-16.31) HU. CONCLUSION: The blood supply of liver metastasis only comes from hepatic artery, and portal vein does not join in the blood supply of liver metastasis.

[The interactions of stromal-epithelial in a model of co-culture in the rabbit cornea].

OBJECTIVE: The purpose of the study is to produce a reconstructed cornea including epithelia and stroma by tissue engineering. The reconstructed tissue may provide a physiologic model for the investigations of interaction between corneal epithelial cells and keratocytes. METHODS: Epithelial cells and keratocytes were isolated from rabbit corneas and cultured on plastic substrates in vitro. The co-culture model was established using a special transwell in which two different cells were separated but were able to interact each other. Histological and immunohistological studies were performed to identify the cell types. Intercellular communication of both the cultured epithelial cells in pure and in co-culture with the keratocytes was studied by laser confocal scanning microscopy. RESULTS: Population doubling time (PDT) was 3.45, 3.30, 2.11 and 2.32 d in pure corneal epithelial cells, co-culture epithelial cells, pure keratocytes and co-culture keratocytes respectively. The epithelial cells in co-culture grew quicker than those in pure (P < 0.01) and the stromal cells in co-culture grew slower than those in pure (P < 0.01). Intercellular communication of the cultured epithelial cells in co-culture were more than that in pure (U = 2.691, P < 0.05). CONCLUSIONS: The co-culture model of epithelial cell and keratocyte is feasible. Under the co-culture system the responses of cell proliferation and intercellular communication are different between epithelial cells and keratocytes.

[Biological characterization of rabbit's articular chondrocytes by confluent culture in vitro].

OBJECTIVE: To obtain large amount of differentiated chondrocytes in vitro, examine and compare the biological characterization of rabbits' articular chondrocyte cultured in different density in vitvo. METHODS: From November 2001 to June 2004, articulate tissues were obtained from the joints of the adult rabbits. Chondrocytes were isolated from the cartilage tissue with type II collagenase digestion and cultured in DMEM/F-12 supplemented with 20% fetal bovine serum (FBS). The chondrocytes were cultured with low density of monolayer culture and high density of confluent culture respectively. The differentiated phenotype was evaluated by histochemistry or immunohistochemistry. RESULTS: When chondrocytes cultured in monolayer and in low density, it proliferated rapidly during the three generations, but with the same time, dedifferentiation was also rapid. After the third passage, most of the passage cells lost the phenotype, and the proliferation also stagnated. While chondrocytes cultured in high density, dedifferentiation slowed down. And even the phenotypes of the dedifferentiated chondrocyte which were cultured in low density could reduced partly by followed high density culture. CONCLUSIONS: Culture chondrocytes by high density in vitro can effectively maintain the differentiated phenotype of chondrocyte. It also keeps the proliferation character as monolayer culture. The dedifferentiated chondrocyte caused by many passages could redifferentiate partly. So it is indicated that confluent culture of original or expanded chondrocytes in high density is a better culture methods than culture in low density.

[The preparation, structure evaluation and preliminary application of biomimetic biphasic calcium phosphate scaffold].

OBJECTIVE: To fabricate biomimetic biphasic calcium phosphate BCP ceramic scaffolds using three-dimensional (3D) gel-lamination technology and evaluated their structure with 3D parameters and related method. METHODS: Series two-dimensional images of femoral head's specimen of dogs were obtained by micro-computed tomography (Micro-CT). According to these images, porous biomimetic biphasic calcium phosphate (BCP) ceramic scaffolds with oriented trabecular structure were fabricated by three-dimensional (3D) gel-lamination technology. And then, the three-dimensional structure of the scaffolds were reconstructed by computer according to Micro-CT images of these scaffolds and evaluated by three-dimensional parameters. These parameters included bone volume fraction (BVF, BV/TV), bone surface/bone volume (BS/BV) ratio, trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp) and structure model index (SMI). The biomechanical properties and biocompatibility of these scaffolds were also evaluated in the study. Six scaffolds, which were combined with BMCs (bone mesenchymal cells, BMCs), were planted into the bone defect of six dogs' femoral head respectively. RESULTS: There was no significant difference between trabecular samples and BCP scaffolds in BV/TV, Tb.Th, Tb.N, and Tb.Pf (P > 0.05). The trabecular system of the scaffold, which had some orientation, represented plate-like model. With a micro-porous porosity of 62%, the average compressive modulus and ultimate strength along the axis of the scaffolds reached (464.0 +/- 36.0) MPa and (5.6 +/- 0.8) MPa respectively. The results of animal test indicated that the trabeculae of these scaffolds were covered by a layer of new bone after 10 weeks of operation. CONCLUSION: Porous BCP scaffolds have been produced with oriented microarchitectural features designed to facilitate vascular invasion and cellular attachment and with initial mechanical properties comparable to those of trabecular bone.

[Comparative study on the main biological characteristics of marrow-derived stromal cells and chondrocytes in vitro culture in rabbits].

OBJECTIVE: To observe the main biological characteristics and chondrogenesis potency of bone marrow-derived stromal cells (MSCs) after cytokines induction or gene modification in vitro. METHODS: MSCs from an adult New Zealand white rabbit were isolated and cultivated, and then MSCs were divided into the common medium group (Group A, 15% FBS in DMEM), the induced group by cytokines (Group B), the transfected group (Group C) with adenovirus-hepatocyte growth factor transgene (adHGF). The medium of group B consisted of transforming growth factor-beta 1 (TGF-beta 1, 10 ng/ml), basic fibroblast growth factor (bFGF, 25 ng/ml) and dexamethasone (DEX, 10(-7) mol/L) with 15%FBS in DMEM. Cartilage slices were obtained from femoral condyles and patellar grove in the same rabbit. The minced cartilage was digested in II collagenase (3 mg/ml) to obtain chondrocytes(Group D). The change of cell appearance, proliferation capacity, glycosaminoglycans (GAG), immunohistochemical staining for type I, II collagen were observed during the 5th passage MSCs and MSCs after induction or gene modification. Expression of mRNA for type I and II collagen was detected by RT-PCR. RESULTS: Primary MSCs proliferated as short-spindle shape, while the 5th MSCs showed long-spindle shape. Positive stain of type I collagen could be found in groups A, B and C, while positive stain of type II collagen was shown in groups B and D. The content of GAG in group B was higher than that in group A, but there was no significant difference between them (P > 0.05), and there was significant difference between groups A and D(P < 0.05). No significant difference was noted in groups A, B and C on proliferation by MTT(P > 0.05), except that of at the fourth day after transfection between groups A and C(P < 0.05). RT-PCR demonstrated that MSCs always had higher levels of mRNA type I collagen in groups A, B and C. The expression of mRNA type II collagen was identified in groups B and D, and only low levels of mRNA type II collagen in group C. CONCLUSION: The above results indicate MSCs have a natural tendency of osteogenic differentiation in vitro culture, and also demonstrate the chondrogenic potency with the technique of cytokines induction or gene modification after passage. MSCs can be transfected efficiently being seed cells in tissue engineered bone or cartilage to accept target genes such as adHGF, and have a higher levels of expression in vitro, which lasted 4 weeks at least.

[An experimental study of demineralized bone matrix to repair bone defects as a scaffold of tissue engineering].

OBJECTIVE: To evaluate application of the sponge of demineralized bone matrix (SDBM) in tissue engineering of bone. METHODS: SDBM was prepared from long bone of rabbits. Bone marrow cells were flushed from the bone shaft of femurs of a two-month-old New Zealand white rabbit. After the cells were cultured for 9 days, the flasks were added into dexamethasone (10(-8) mol/L), beta-glycerophosphate sodium (10 mmol/L) and L-ascorbic acid (50 micrograms/ml). After 5 weeks, the cultured cells were collected and marked by 5-Bromo-2'-dexyouridine (BrdU). The grand sum of cells seeded on a piece of SDBM was about (4-6) x 10(6). The composites of cells and SDBM (tissue engineered chip, TEC) were implanted into muscles and bone defects of radius in rabbits. A standard procedure was applied to make a 10 mm long defect bilaterally in the radius of nine skeletally mature male New Zealand white rabbits. All of the 18 defects were randomly divided into three groups: group I, six defects were grafted by TEC; group II, six defects were grafted with SDBM alone; group III, six defects were empty. RESULTS: The results of radiographic and histological evaluation showed that all of the defects were repaired in group I and group II at 6 weeks, none of the defects was repaired in group III. The results of BrdU staining showed that the staining was positive in group I, but negative in group II. Biomechanical test showed that the compressive ultimate strength (CUS) of new bone in TEC implanted group was comparable with normal radius (P = 0.623) and in SDBM implanted group was significant lower than normal radius (P = 0.038). CONCLUSIONS: The TEC can form cartilage and bone tissue in muscles and repair segmental bone defects. SDBM is a kind of effective natural scaffold in tissue engineering of bone.

[Experimental study on repair of articular cartilage defect in large area with chondrocytes cultured on fascia].

OBJECTIVE: To study the biological characteristic and potential of chondrocytes grafting cultured on fascia in repairing large defect of articular cartilage in rabbits. METHODS: Chondrocytes of young rabbits were isolated and sub-cultured on fascia. The large defect of articular cartilage was repaired by grafts of freeze-preserved and fresh chondrocytes cultured on fascia, and free chondrocytes respectively; the biological characteristic and metabolism were evaluated by macroscopic, histological and immunohistochemical observations, autoradiography method and the measurement of nitric oxide content 6, 12, 24 weeks after grafting. RESULTS: The chondrocytes cultured on fascia maintained normal growth feature and metabolism, and there was no damage to chondrocytes after cryopreservation; the repaired cartilage was similar to the normal cartilage in cellular morphology and biological characteristics. CONCLUSION: Chondrocytes could be cultured normally on fascia, which could be used as an ideal carrier of chondrocytes.