Fabrication of three-dimensional nano, micro and micro/nano scaffolds of porous poly(lactic acid) by electrospinning and comparison of cell infiltration by Z-stacking/three-dimensional projection technique

The use of electrospun extracellular matrix (ECM)-mimicking nanofibrous scaffolds for tissue engineering is limited by poor cellular infiltration. The authors hypothesised that cell penetration could be enhanced in scaffolds by using a hierarchical structure where nano fibres are combined with micron-scale fibres while preserving the overall scaffold architecture. To assess this, we fabricated electrospun porous poly(lactic acid) (PLA) scaffolds having nanoscale, microscale and combined micro/nano architecture and evaluated the structural characteristics and biological response in detail. Although the bioactivity was intermediate to that for nanofibre and microfibre scaffold, a unique result of this study was that the micro/nano combined fibrous scaffold showed improved cell infiltration and distribution than the nanofibrous scaffold. Although the cells were found to be lining the scaffold periphery in the case of nanofibrous scaffold, micro/nano scaffolds had cells dispersed throughout the scaffold. Further, as expected, the addition of nanoparticles of hydroxyapatite (nHAp) improved the bioactivity, although it did not play a significant role in cell penetration. Thus, this strategy of creating a three-dimensional (3D) micro/nano architecture that would increase the porosity of the fibrous scaffold and thereby improving the cell penetration, can be utilised for the generation of functional tissue engineered constructs in vitro.

Wavelet-based resolution recovery using an anatomical prior provides quantitative recovery for human population phantom PET [¹¹C]raclopride data

The objective of this study was to evaluate a resolution recovery (RR) method using a variety of simulated human brain [¹¹C]raclopride positron emission tomography (PET) images. Simulated datasets of 15 numerical human phantoms were processed by a wavelet-based RR method using an anatomical prior. The anatomical prior was in the form of a hybrid segmented atlas, which combined an atlas for anatomical labelling and a PET image for functional labelling of each anatomical structure. We applied RR to both 60 min static and dynamic PET images. Recovery was quantified in 84 regions, comparing the typical 'true' value for the simulation, as obtained in normal subjects, simulated and RR PET images. The radioactivity concentration in the white matter, striatum and other cortical regions was successfully recovered for the 60 min static image of all 15 human phantoms; the dependence of the solution on accurate anatomical information was demonstrated by the difficulty of the technique to retrieve the subthalamic nuclei due to mismatch between the two atlases used for data simulation and recovery. Structural and functional synergy for resolution recovery (SFS-RR) improved quantification in the caudate and putamen, the main regions of interest, from -30.1% and -26.2% to -17.6% and -15.1%, respectively, for the 60 min static image and from -51.4% and -38.3% to -27.6% and -20.3% for the binding potential (BP(ND)) image, respectively. The proposed methodology proved effective in the RR of small structures from brain [¹¹C]raclopride PET images. The improvement is consistent across the anatomical variability of a simulated population as long as accurate anatomical segmentations are provided.

Hierarchically designed electrospun tubular scaffolds for cardiovascular applications

Hierarchically designed tubular scaffolds with bi-layer and multi-layer structures are expected to mimic native vessels in its structural geometry. A new approach for the fabrication of hierarchically designed tubular scaffold with suitable morphology was introduced through electrospinning technique. Among these scaffolds, bi-layer scaffold had a single inner and outer layer whereas multilayer scaffold had more number of inner layers. The inner layer/layers of the scaffolds were made up of aligned poly (lactic acid) (PLA) fibers for EC adhesion where as outer layers were composed of random fibers of poly (caprolactone) (PCL) and PLA providing larger pores for SMC penetration. The fabricated scaffolds were characterized by FTIR spectroscopy and Differential Thermal Analysis (DTA) and examined by evaluating cellular interactions. Human Umbilical Vein Endothelial Cells (HUVECs) seeded on aligned PLA fibers showed enhanced cellular orientation and cytoskeletal organization. In addition, the PCL-PLA composite random fibers supported SMC adhesion and proliferation sufficiently. The functionality of the endothelial cells grown on the PLA-aligned scaffold was also found to be satisfactory. Lining the constructs with a luminal monolayer of well-organized ECs along with homogenously distributed SMCs surrounding them might result in vascular conduits suitable for in vivo applications. Since this hierarchically designed tubular scaffold closely mimics the morphology of native vessel, this could be a better candidate for vascular tissue engineering.

Near-field optical mapping of quantum Hall edge states

We report on the mapping of quantum-Hall edge states by quasiresonant photovoltage measurements using a near-field scanning optical microscope. We have observed fine structures near sample edges that shift inward with an increase in magnetic field in accordance with the shift of the positions of the quantum-Hall edge states. We have found a transition from the weak disorder regime where compressible-incompressble strips are visible to the strong disorder regime where fluctuations smear out incompressible strips.

[A case of locally advanced sigmoid colon cancer invading the bladder and seminal vesicle effectively treated with preoperative mFOLFOX6]

A 77-year-old male was admitted to our hospital complaining of dyschezia. Computed tomography (CT) and colonoscopy (CF) revealed a huge sigmoid colon cancer invading the bladder and seminal vesicle. Chemotherapy with mFOLFOX6 was initiated preoperatively, and the tumor shrunk markedly after seven courses of treatment. Pelvic exenteration with negative margins was carried out. The patient is still alive and disease-free 16 months after surgery. It was suggested that mFOLFOX6 may be useful for advanced colon cancer invading other organs when used as neoadjuvant chemotherapy.

Chemopreventive activity of sesquiterpene lactones (SLs) from yacon against TPA-induced Raji cells deformation

Yacon is a medicinal plant used as a traditional medicine by the natives in South America. In Japan, it becomes popular as a health food. Sesquiterpene Lactones (SLs) from yacon leaves were investigated and the active SLs such as enhydrin, uvedalin and sonchifolin, bearing alpha-methylene-gamma-lactone and epoxides as the active functional groups, were identified by 1H-6000 MHz-NMR. Chemopreventive and cytotoxic activities were determined using different primary screening methods. In this study, all tested SLs strongly inhibited TPA-induced deformed of Raji cells. The IC50 values of yacon SLs from anti-deforming assay were 0.04-0.4 microM. Interestingly, yacon SLs showed more potential of chemo preventive activity than both curcumin and parthenolide. However, the cytotoxicity on Raji cells was observed at high concentration of yacon SLs. The degree of anti-deformation was ranked in order: enhydrin >uvedalin >sonchifolin >parthenolide >curcumin. As according to structure-activity relationship, the high activities of enhydrin, uvedalin and sonchifolin may be due to the 2-methyl-2-butenoate and its epoxide moiety.

Fabrication of chitin-chitosan/nano ZrO(2) composite scaffolds for tissue engineering applications

The urge to repair and regenerate natural tissues can now be satisfactorily fulfilled by various tissue engineering approaches. Chitin and chitosan are the most widely accepted biodegradable and biocompatible materials subsequent to cellulose. The incorporation of nano ZrO(2) onto the chitin-chitosan scaffold is thought to enhance osteogenesis. Hence a nanocomposite scaffold was fabricated by lyophilization technique using chitin-chitosan with nano ZrO(2). The prepared nanocomposite scaffolds were characterized using SEM, FTIR, XRD and TGA. In addition, the swelling, degradation, biomineralization, cell viability and cell attachment of the composite scaffolds were also evaluated. The results demonstrated better swelling and controlled degradation in comparison to the control scaffold. Cell viability studies proved the non toxic nature of the nanocomposite scaffolds. Cells were found to be attached to the pore walls and spread uniformly throughout the scaffolds. All these results suggested that the developed nanocomposite scaffolds possess the prerequisites for tissue engineering scaffolds and could be used for various tissue engineering applications.

The R-Phase Transformation in the Ti-Ni Shape Memory Alloy and its Application

We discuss a comprehensive design approach of Ti-Ni alloy coil springs and introduce a new application of the R-phase transformation. In order to attain high cyclic performance, one must understand the two relationships between design parameters and material characteristics and between material characteristics and cyclic performance. Metallurgical parameters and coil spring dimensions play an important role as design parameters in the former relationship. High cyclic performance of an actuator is closely related to the suppression of the monoclinic martensite. Transformation temperatures and their stress dependence is of primary importance as material characteristics in the latter relationship. A thermostatic mixing valve, which is the latest application of the R-phase transformation in Japan is then discussed as a new type of a shape memory alloy actuator. The R-phase transformation is employed to achieve not only a long cycle life but a linear operation with the set temperature to continuously control the mixing ratio of hot and cold water. This is achieved by changing the total length of the two-way actuator in a linear manner with the set temperature. The linear characteristic is satisfied between 35–50°C by optimizing thermomechanical treatment and the dimensions of Ti-Ni and biasing coil springs.

Development of polypoidal lesions in age-related macular degeneration

PURPOSE

To investigate the development of polypoidal lesions using indocyanine green angiography (IA) in eyes with typical age-related macular degeneration (AMD).

METHODS

We retrospectively reviewed the medical records of 47 consecutive patients (47 eyes) with typical AMD who had been followed up with IA for at least 2 years.

RESULTS

At the initial visit, although all eyes showed classic and/or occult choroidal neovascularization (CNV) associated with AMD, no eyes showed polypoidal lesions by IA. However, during follow-up, 13 (27.7%) of the 47 eyes did show polypoidal lesions. All polypoidal lesions developed at the edge of persistent CNV or, more often, at the terminus of recently progressed CNV. Of 12 eyes with a final lesion area >8 disc area, 7 (58.3%) showed newly developed polypoidal lesions. In the eyes with these newly developed polypoidal lesions, the mean area of the vascular lesion had extended significantly from 10.50 ± 7.88 mm² to 20.87 ± 10.21 mm² during follow-up (P=0.0018).

CONCLUSION

The current observation suggests that IA of active AMD sometimes reveals polypoidal lesions if there is progression of the CNV in the subretinal pigment epithelium space.

Fabrication of chitin-chitosan/nano TiO2-composite scaffolds for tissue engineering applications

In this study, we prepared chitin-chitosan/nano TiO(2) composite scaffolds using lyophilization technique for bone tissue engineering. The prepared composite scaffold was characterized using SEM, XRD, FTIR and TGA. In addition, swelling, degradation and biomineralization capability of the composite scaffolds were evaluated. The developed composite scaffold showed controlled swelling and degradation when compared to the control scaffold. Cytocompatibility of the scaffold was assessed by MTT assay and cell attachment studies using osteoblast-like cells (MG-63), fibroblast cells (L929) and human mesenchymal stem cells (hMSCs). Results indicated no sign of toxicity and cells were found attached to the pore walls within the scaffolds. These results suggested that the developed composite scaffold possess the prerequisites for tissue engineering scaffolds and it can be used for tissue engineering applications.

Development of novel chitin/nanosilver composite scaffolds for wound dressing applications

Antibiotic resistance of microorganisms is one of the major problems faced in the field of wound care and management resulting in complications like infection and delayed wound healing. Currently a lot of research is focused on developing newer antimicrobials to treat wounds infected with antibiotic resistant microorganisms. Silver has been used as an antimicrobial agent for a long time in the form of metallic silver and silver sulfadiazine ointments. Recently silver nanoparticles have come up as a potent antimicrobial agent and are finding diverse medical applications ranging from silver based dressings to silver coated medical devices. Chitin is a natural biopolymer with properties like biocompatibility and biodegradability. It is widely used as a scaffold for tissue engineering applications. In this work, we developed and characterized novel chitin/nanosilver composite scaffolds for wound healing applications. The antibacterial, blood clotting and cytotoxicity of the prepared composite scaffolds were also studied. These chitin/nanosilver composite scaffolds were found to be bactericidal against S. aureus and E. coli and good blood clotting ability. These results suggested that these chitin/nanosilver composite scaffolds could be used for wound healing applications.

Fano-Kondo interplay in a side-coupled double quantum dot

We investigate low-temperature transport characteristics of a side-coupled double quantum dot where only one of the dots is directly connected to the leads. We observe Fano resonances, which arise from interference between discrete levels in one dot and the Kondo effect, or cotunneling in general, in the other dot, playing the role of a continuum. The Kondo resonance is partially suppressed by destructive Fano interference, reflecting novel Fano-Kondo competition. We also present a theoretical calculation based on the tight-binding model with the slave boson mean field approximation, which qualitatively reproduces the experimental findings.

Nanopattern transfer from high-density self-assembled nanosphere arrays on prepatterned substrates

We have fabricated nanoimprint moulds with high-density well-defined nanopatterns by pattern transfer from self-assembled nanosphere arrays on prepatterned substrates. Silica nanospheres of 100 and 25 nm diameter were regularly arranged over large areas in a self-assembling manner by capillary force via a dip-coating technique on topographically patterned substrates having 220 nm pitch line/space patterns. The nanosphere arrays were used as etching masks, and nanodot arrays with the same arrangements were created on the silica substrate surfaces by reactive ion etching (RIE). By developing a combined pattern transfer process using Ru and SiO(x) mask layers and CF4 and O2 RIE, the aspect ratio between the height and diameter of the nanodots made from the 25 nm nanospheres is improved to about two. It is demonstrated that the nanopatterns of the moulds can be inversely transferred into polymer surfaces reproducibly by UV nanoimprint process.

Three-body nonmesonic weak decay of the (Lambda)12C hypernucleus

We have measured the branching ratio of the three-body process in the nonmesonic weak decay of Lambda12C to be 0.29+/-0.13. This result was obtained by reproducing the nucleon and the nucleon pair yields introducing a measured final state interaction. At the same time, we have determined the absolute decay widths, Gamma(n) and Gamma(p), along with Gamma2N, whose relative ratio has been a long-standing puzzle. Including the three-body process, we have successfully reproduced the nucleon energy distribution, the coincidence two-nucleon angular correlation, and the momentum sum distribution simultaneously.