Large‐Deformation Behavior of Honeycomb‐Structured Polymer Sheets as a Function of Polar Angle

To construct the structure/property relationships of patterned polymer architectures depending on symmetry, the large‐deformation behavior of 2D HSPS with respect to the polar angle was studied. Holes aligned along the HSPS apex were more effective in decreasing tensile force and reducing stress concentration than those located along the plane. On varying the polar angle from 0 to 30°, the tensile force fluctuated up and down like an undamped negative sinusoidal wave with a wavelength of 15°. Additionally, molecular orientations of HSPS were monitored in situ. By comparing experimental measurements with computer simulations, it was concluded that the tensile force depends on the number of holes as well as the orientation of the axes of the honeycomb structure.

     

Effects of protopanaxatriol-ginsenoside metabolites on rat N-methyl-d-aspartic Acid receptor-mediated ion currents

Ginsenosides are low molecular weight glycosides found in ginseng that exhibit neuroprotective effects through inhibition of N-methyl-D-aspartic acid (NMDA) receptor channel activity. Ginsenosides, like other natural compounds, are metabolized by gastric juices and intestinal microorganisms to produce ginsenoside metabolites. However, little is known about how ginsenoside metabolites regulate NMDA receptor channel activity. In the present study, we investigated the effects of ginsenoside metabolites, such as compound K (CK), protopanaxadiol (PPD), and protopanaxatriol (PPT), on oocytes that heterologously express the rat NMDA receptor. NMDA receptor-mediated ion current (I(NMDA)) was measured using the 2-electrode voltage clamp technique. In oocytes injected with cRNAs encoding NMDA receptor subunits, PPT, but not CK or PPD, reversibly inhibited I(NMDA) in a concentration-dependent manner. The IC(50) for PPT on I(NMDA) was 48.1±4.6 μM, was non-competitive with NMDA, and was independent of the membrane holding potential. These results demonstrate the possibility that PPT interacts with the NMDA receptor, although not at the NMDA binding site, and that the inhibitory effects of PPT on I(NMDA) could be related to ginseng-mediated neuroprotection.     

Selective argon laser suturelysis versus needle suturelysis to treat induced corneal astigmatism after cataract surgery

PURPOSE: To compare the complications and subjective experience of patients having argon laser suturelysis (LS) with those of patients having needle suturelysis (NS) for corneal astigmatism after extracapsular cataract extraction (ECCE). SETTING: Department of Ophthalmology, Tan Tock Seng Hospital, Singapore. METHODS: This prospective study comprised 30 patients (30 eyes) with more than 3.00 diopters of with-the-rule astigmatism after ECCE. A minimum of 5 weeks after surgery, 2 sutures along the steepest meridian were lysed by the same surgeon, 1 by a needle and the other by laser using a Hoskins lens. Patients were randomized to receive NS first followed by LS or LS followed by NS. The complications were recorded. The patients subjectively graded their fear and discomfort/pain during suturelysis using a scale from 0 to 10. Patient preference for either procedure was also recorded. RESULTS: The complications of NS were conjunctival epithelial defect (17/30), subconjunctival hemorrhage (13/30), and corneal abrasion (4/30) and of LS, minor conjunctival burn (1/30) and conjunctival epithelial defect (1/30). The mean subjective fear and discomfort/pain scores in the NS group were significantly higher than in the LS group (P =.0010 and P =.0014, respectively). Nineteen patients preferred LS, 3 preferred NS, and 8 had no preference for either procedure. CONCLUSION: Argon laser suturelysis was associated with fewer complications than NS and was preferred by patients.     

Respiratory Motional Effect on Cone-Beam CT in Lung Radiation Surgery

The cone-beam CT (CBCT), which is acquired using an on-board imager (OBI) attached to a linear accelerator, is used effectively in the verification of setup accuracy for lung radiation surgery. In this study, the respiratory organ motional effect on the CBCT was evaluated with a properly devised phantom system, and the level of possible error in conditions of a real clinical process was assessed. In a comparison study between the CBCT in static status and CBCT images acquired in 20 different motional cases, we confirmed that the image quality and information of CBCT were degraded, with an increase of motional ranges in the region of inhomogeneous structures. The 4D-CT MIP (50～55%) for the planning of lung radiation surgery and the 4D-CT MIP (full phase) were compared with CBCT in the various motional cases for the evaluation of the influence of the motional effect on CBCT in the process of the setup error correction. The average ratio of relative difference between plan CT: 4D-CT MIP (50%～55%) and CBCT was 5.79% and between plan CT: 4D-CT MIP (50%～55%) and 4D-CT MIP (full phase) was 42.95% in the phantom study. In the analysis of clinical cases of lung radiation surgery, the gross tumor volumes were compared in each CT image. The average ratio of relative difference between plan CT: 4D-CT MIP (50～55%) and CBCT was 10.72% and between plan CT: 4D-CT MIP (50～55%) and 4D-CT MIP (full phase) was 28.19%. These results showed that, although a respiratory organ motional effect on CBCT introduced variation in image quality, the error as a result of this variation could be estimated relatively low in the setup error correction for a gated-lung radiation surgery when the planning was performed in 4D-CT MIP (50～55%), which already included a related signal of motional effect.     

Activation of annexin II and V expression, terminal differentiation, mineralization and apoptosis in human osteoarthritic cartilage

OBJECTIVE: To test the hypothesis that terminal differentiation of chondrocytes in human osteoarthritic cartilage might lead to the failure of repair mechanisms and might cause progressive loss of structure and function of articular cartilage. DESIGN: Markers for terminally differentiated chondrocytes, such as alkaline phosphatase, annexin II, annexin V and type X collagen, were detected by immunohistochemical analysis of human normal and osteoarthritic knee cartilage from medial and lateral femoral condyles. Apoptosis in these specimens was detected using the TUNEL labeling. Mineralization and matrix vesicles were detected by alizarin red S staining and electron microscopic analysis. RESULTS: Alkaline phosphatase, annexin II, annexin V and type X collagen were expressed by chondrocytes in the upper zone of early stage and late stage human osteoarthritic cartilage. However, these proteins, which are typically expressed in hypertrophic and calcifying growth plate cartilage, were not detectable in the upper, middle and deep zones of healthy human articular cartilage. TUNEL labeling of normal and osteoarthritic human cartilage sections provided evidence that chondrocytes in the upper zone of late stage osteoarthritic cartilage undergo apoptotic changes. In addition, mineral deposits were detected in the upper zone of late stage osteoarthritic cartilage. Needle-like mineral crystals were often associated with matrix vesicles in these areas, as seen in calcifying growth plate cartilage. CONCLUSION: Human osteoarthritic chondrocytes adjacent to the joint space undergo terminal differentiation, release alkaline phosphatase-, annexin II- and annexin V-containing matrix vesicles, which initiate mineral formation, and eventually die by apoptosis. Thus, these cells resume phenotypic changes similar to terminal differentiation of chondrocytes in growth plate cartilage culminating in the destruction of articular cartilage in osteoarthritis.