Nanolight sources, which are based on resonant excitation of plasmons near a sharp metallic nanostructure, have attracted tremendous interest in the vast research fields of optical nanoimaging. However, being a resonant phenomenon, this ideally works only for one wavelength that resonates with the plasmons. Multiple wavelengths of light in a broad range confined to one spot within a nanometric volume would be an interesting form of light, useful in numerous applications. Plasmon nanofocusing can generate a nanolight source through the propagation and adiabatic compressions of plasmons on a tapered metallic nanostructure, which is independent of wavelength, as it is based on the propagation, rather than resonance, of plasmons. Here, we report the generation of a white nanolight source spanning over the entire visible range through plasmon nanofocusing and demonstrate spectral bandgap nanoimaging of carbon nanotubes. Our experimental demonstration of the white nanolight source would stimulate diverse research fields toward next-generation nanophotonic technologies.

A mitogen for growth-arrested cultured bovine aortic smooth muscle cells was purified to homogeneity from the supernatant of cultured human umbilical vein endothelial cells by heparin affinity chromatography and reverse-phase high performance liquid chromatography. This mitogen was revealed to be tissue factor pathway inhibitor-2 (TFPI-2), which is a Kunitz-type serine protease inhibitor. TFPI-2 was expressed in baby hamster kidney cells using a mammalian expression vector. Recombinant TFPI-2 (rTFPI-2) stimulated DNA synthesis and cell proliferation in a dose-dependent manner (1-500 nM). rTFPI-2 activated mitogen-activated protein kinase (MAPK) activity and stimulated early proto-oncogene c-fos mRNA expression in smooth muscle cells. MAPK, c-fos expression and the mitogenic activity were inhibited by a specific inhibitor of MAPK kinase, PD098059. Thus, the mitogenic function of rTFPI-2 is considered to be mediated through MAPK pathway. TFPI has been reported to exhibit antiproliferative action after vascular smooth muscle injury in addition to the ability to inhibit activation of the extrinsic coagulation cascade. However, structurally similar TFPI-2 was found to have a mitogenic activity for the smooth muscle cell.

We have developed a novel method to predict the success of PCR amplification for a specific primer set and DNA template based on the relationship between the primer sequence and the template. To perform the prediction using a recurrent neural network, the usual double-stranded formation between the primer and template nucleotide sequences was herein expressed as a five-lettered word. The set of words (pseudo-sentences) was placed to indicate the success or failure of PCR targeted to learn recurrent neural network (RNN). After learning pseudo-sentences, RNN predicted PCR results from pseudo-sentences which were created by primer and template sequences with 70% accuracy. These results suggest that PCR results could be predicted using learned RNN and the trained RNN could be used as a replacement for preliminary PCR experimentation. This is the first report which utilized the application of neural network for primer design and prediction of PCR results.

We established abnormal isoform of prion protein (PrP Sc )-specific double immunostaining using mAb 132, which recognizes aa 119-127 of the PrP molecule, and novel PrP Sc -specific mAb 8D5, which recognizes the N-terminal region of the PrP molecule. Using the PrP Sc -specific double immunostaining, we analysed PrP Sc in immortalized neuronal cell lines and primary cerebralneuronal cultures infected with prions. The PrP Sc -specific double immunostaining showed the existence of PrP Sc positive for both mAbs 132 and 8D5, as well as those positive only for either mAb 132 or mAb 8D5. This indicated that double immunostaining detects a greater number of PrP Sc species than single immunostaining. Double immunostaining revealed cell-type-dependent differences in PrP Sc staining patterns. In the 22 L prion strain-infected Neuro2a (N2a)-3 cells, a subclone of N2a neuroblastoma cell line, or GT1-7, a subclone of the GT1 hypothalamic neuronal cell line, granular PrP Sc stains were observed at the perinuclear regions and cytoplasm, whereas unique string-like PrP Sc stains were predominantly observed on the surface of the 22 L straininfected primary cerebral neurons. Only 14 % of PrP Sc in the 22 L strain-infected N2a-3 cells were positive for mAb 8D5, indicating that most of the PrP Sc in N2a-3 lack the N-terminal portion. In contrast, nearly half PrP Sc detected in the 22 L strain-infected primary cerebral neurons were positive for mAb 8D5, suggesting the abundance of full-length PrP Sc that possesses the Nterminal portion of PrP. Further analysis of prion-infected primary neurons using PrP Sc -specific immunostaining will reveal the neuron-specific mechanism for prion propagation.

Conversion of cellular prion protein (PrP C ) into the pathogenic isoform of prion protein (PrP Sc ) in neurons is one of the key pathophysiological events in prion diseases. However, the molecular mechanism of neurodegeneration in prion diseases has yet to be fully elucidated because of a lack of suitable experimental models for analyzing neuron-autonomous responses to prion infection. In the present study, we used neuron-enriched primary cultures of cortical and thalamic mouse neurons to analyze autonomous neuronal responses to prion infection. PrP Sc levels in neurons increased over the time after prion infection; however, no obvious neuronal losses or neurite alterations were observed. Interestingly, a finer analysis of individual neurons co-stained with PrP Sc and phosphorylated protein kinase RNA-activated-like endoplasmic reticulum (ER) kinase (p-PERK), the early cellular response of the PERK-eukaryotic initiation factor 2 (eIF2α) pathway, demonstrated a positive correlation between the number of PrP Sc granular stains and p-PERK granular stains, in cortical neurons at 21 dpi. Although the phosphorylation of PERK was enhanced in prion-infected cortical neurons, there was no sign of subsequent translational repression of synaptic protein synthesis or activations of downstream unfolded protein response (UPR) in the PERK-eIF2α pathway. These results suggest that PrP Sc production in neurons induces ER stress in a neuron-autonomous manner; however, it does not fully activate UPR in prion-infected neurons. Our findings provide insights into the autonomous neuronal responses to prion propagation and the involvement of neuron-non-autonomous factor(s) in the mechanisms of neurodegeneration in prion diseases.