Polymer-free patterning of graphene at sub-10-nm scale by low-energy repetitive electron beam.

A polymer-free technique for generating nanopatterns on both synthesized and exfoliated graphene sheets is proposed and demonstrated. A low-energy (5-30 keV) scanning electron beam with variable repetition rates is used to etch suspended and unsuspended graphene sheets on designed locations. The patterning mechanisms involve a defect-induced knockout process in the initial etching stage and a heat-induced curling process in a later stage. Rough pattern edges appear due to inevitable stochastic knockout of carbon atoms or graphene structure imperfection and can be smoothed by thermal annealing. By using this technique, the minimum feature sizes achieved are about 5 nm for suspended and 7 nm for unsuspended graphene. This study demonstrates a polymer-free direct nanopatterning approach for graphene.

Comparison of therapeutic effects between patella replacement and patella osteotomy in total knee arthroplasty: a case-control study / 中国骨伤

<p><b>OBJECTIVE</b>To compare therapeutic effects between patella replacement and patella osteotomy in total knee arthroplasty.</p><p><b>METHODS</b>From April 2004 to April 2011, 52 patients (54 knees) were enrolled in the clinical trail of total knee arthroplasty, who received patella replacement (24 knees, including 13 males and 11 females,ranging in age from 53 to 78 years old or patella osteotomy (30 knees,including 16 males and 12 females,ranging in age from 55 to 79 years old. The average follow-up period was 56 months,ranging from 20 to 80 months. The American HSS Score for knee, the Feller score for patella, range of motion (ROM) for knee, patient satisfaction and complications related to the patella were used to evaluate therapeutic effects.</p><p><b>RESULTS</b>In the patella replacement group,the preoperative and final follow-up HSS scores of patients were 38.4 +/- 8.2 and 91.2 +/- 8.6 respectively; Feller scores were 13.6 +/- 6.2 and 25.2 +/- 4.2; scores of anterior knee pain were 3.9 +/- 3.2 and 11.2 +/- 3.7; ROM were (78 +/- 26) degrees and(108 +/- 18) degrees. In the patella osteotomy group,the preoperative and final follow-up HSS scores of patients were 39.5 +/- 8.4 and 91.0 +/- 8.5 respectively;Feller scores were 13.4 +/- 6.5 and 25.6 +/- 4.0; scores of anterior knee pain were 3.7 +/- 3.1 and 11.3 +/- 3.6; ROM were (76 +/- 27) degrees and (110 +/- 19) degrees. In the patella replacement group,patient's satisfaction was 91%, and complication related to the patella was 16.7%; in the patella osteotomy group, patient's satisfaction was 89%, and complications related to the patella was 10.0%. There were no statistically significant differeneces in final follow-up HSS scores, Feller scores, scores of anterior knee pain and ROM between the two groups. However,there was no significant difference of patient's satisfaction between them. There was statistically significant differenece of patella-related complications between the two groups, and the complication rate in the patella replacement group was higher than that in the patella osteotomy group.</p><p><b>CONCLUSION</b>Total knee arthroplasty with patella replacement or patella osteotomy dramatically relieves pain and improves the knee function. Patella-related complications are associated with its treatment methods, but post-operative anterior knee pain and patient's satisfaction are not related to treatment methods of the patella.</p>

ERK1/2 signaling pathway is involved in 15-hydroxyeicosatetraenoic acid-induced hypoxic pulmonary vasoconstriction / 生理学报

Hypoxia-induced 15-hydroxyeicosatetraenoic acid (15-HETE) is an essential mediator to constrict pulmonary arteries (PA). The signaling pathway involved in 15-HETE-induced PA vasoconstriction remains obscure. The aim of the present study was to test the hypothesis that hypoxic PA constriction induced by 15-HETE was possibly regulated by the extracellular signal-regulated kinase-1/2 (ERK1/2) pathway. PA ring tension measurement, Western blot and immunocytochemistry were used in the study to determine the possible role of ERK1/2 in 15-HETE-induced PA vasoconstriction. The organ bath for PA rings tension study was employed. Adult male Wistar rats were raised in hypoxic environment with fractional inspired oxygen (FIO2, 0.12) for 9 d. PA 1~1.5 mm in diameter were dissected and cut into 3 mm long rings for tension study. ERK1/2 up-stream kinase (MEK) inhibitor PD98059, which blocks the activation of ERK1/2, was used. The results showed that pretreatment of PD98059 significantly blunted 15-HETE-induced PA vasoconstrictions in the rings from hypoxic rat. Moreover, in endothelium-denuded rings, PD98059 also significantly attenuated 15-HETE-induced vasoconstriction. Phosphorylation of ERK1/2 in pulmonary arterial smooth muscle cells (PASMCs) of rat was enhanced evidently when stimulated by 15-HETE. Thus, the data suggest that ERK1/2 signaling pathway is involved in 15-HETE-induced hypoxic pulmonary vasoconstriction.

15-hydroxyeicosatetraenoic acid depressed endothelial nitric oxide synthase activity in pulmonary artery / 生理学报

15-hydroxyeicosatetraenoic acid (15-HETE) plays an important role in hypoxia-induced pulmonary vasoconstriction. Release of nitric oxide (NO) is apparently decreased and activity of endothelial nitric oxide synthase (eNOS) is impaired in chronic hypoxia. However, little is known whether 15-HETE contributes to eNOS/NO pathway in the constriction induced by 15-HETE. We examined the response of rat pulmonary artery (PA) rings to 15-HETE, the production of NO, total eNOS expression and the phosphorylation of eNOS in bovine pulmonary artery endothelial cells (BPAECs) stimulated by 15-HETE. Rat PA rings were divided into three groups: endothelium intact group, endothelium denuded group, and nitro-L-arginine methyl ester (L-NAME, 0.1 mmol/L, an inhibitor of eNOS) group. Constrictions to 15-HETE were significantly enhanced in endothelium denuded group and L-NAME group (both P< 0.05 vs endothelium intact group, n= 9); BPAECs were incubated in different conditions to test nitrite production by Greiss method. Nitrite production was significantly reduced by 1 mumol/L 15-HETE (P<0.05), and increased by the lipoxygenase inhibitors, 10 mumol/L cinnamyl 3,4- dihydroxy-[alpha] -cyanocinnamate (CDC, P< 0.05) and 0.1 mmol/L nordihydroguiairetic acid (NDGA, P< 0.01 ); Western blot analysis of extracts from BPAECs incubated with 15-HETE in different time was carried out to test total eNOS expression, and the expression was changed unobviously. Immunoprecipitation (IP) and Western blot analysis of cell extracts from BPAECs treated with 2 mumol/L 15-HETE in different length of time were accomplished, using phospo-eNOS-threonine 495 (Thr495, an inhibitory site) antibody for IP, and eNOS or 15-lipoxygenase (15-LO) antibodies for Western blot. 15-HETE depressed eNOS activity by increasing the levels of phospho-eNOS-Thr 495. The data suggest that eNOS/NO pathway is involved in PA constrictions induced by 15-HETE and that 15-HETE depresses eNOS activity by phosphorylation in Thr495 site. The protein interaction between phospho-eNOS (Thr495) and 15-LO is discovered for the first time.