Optical dynamics of energy-transfer from a CdZnO quantum well to a proximal Ag nanostructure.

We studied photoluminescence (PL) and energy-transfer dynamics in a hybrid structure comprising a Cd(0.08)Zn(0.92)O quantum well (QW) and an Ag nanostructure. The observed PL quenching was dependent on the electronic states in the QW. Quenching occurred at low temperature where excited carriers recombined radiatively because of excitonic localization, which disappeared with increasing temperature due to delocalization of excitons. Furthermore, nanostructured Ag surfaces produced local surface plasmon (LSP) absorption that was resonant with the PL peak energy of the QW emission. These results indicate that the recombination energy of excitons transfers nonradiatively to induce LSP excitation, which was revealed using time-resolved PL measurements.

Size control of sol-gel-synthesized ZnO quantum dots using photo-induced desorption.

We developed a sol-gel method using photo-induced desorption for size-controlled ZnO quantum dots (QDs). This method successfully controlled the size and size variance of ZnO QDs, and size fluctuations decreased from 23% to 18% depending on the illuminated light intensity. The sol-gel synthesis effectively reduced the number of defect levels that originated from oxygen defects.

Distinguishing between ultrafast optical harmonic generation and multi-photon-induced luminescence from ZnO thin films by frequency-resolved interferometric autocorrelation microscopy.

The nonlinear optical properties of thin ZnO film are studied using interferometric autocorrelation (IFRAC) microscopy. Ultrafast, below-bandgap excitation with 6-fs laser pulses at 800 nm focused to a spot size of 1 µm results in two emission bands in the blue and blue-green spectral region with distinctly different coherence properties. We show that an analysis of the wavelength-dependence of the interference fringes in the IFRAC signal allows for an unambiguous assignment of these bands as coherent second harmonic emission and incoherent, multiphoton-induced photoluminescence, respectively. More generally our analysis shows that IFRAC allows for a complete characterization of the coherence properties of the nonlinear optical emission from nanostructures in a single-beam experiment. Since this technique combines a very high temporal and spatial resolution we anticipate broad applications in nonlinear nano-optics.

In situ real-time monitoring of changes in the surface roughness during nonadiabatic optical near-field etching.

We performed in situ real-time monitoring of the change in surface roughness during self-organized optical near-field etching. During near-field etching of a silica substrate, we detected the scattered light intensity from a continuum wave (CW) laser (lambda = 633 nm) in addition to the etching CW laser (lambda = 532 nm) light source. We discovered that near-field etching not only decreases surface roughness, but also increases the number of scatterers, as was confirmed by analyzing the AFM image. These approaches provide optimization criteria for the etching parameter and hence for further decreases in surface roughness.

Generating small-scale structures from large-scale ones via optical near-field interactions.

Optical near-fields, which appear in the vicinity of structures when irradiated with light, exhibit a hierarchical nature, meaning that the degree of localization of optical near-fields at a given point is related to the scale of the structure involved in this process. Therefore, if we could make optically induced fabrication processes selectively localized in the near-field region, we could generate a smaller-scale structure even from a larger-scale one via optical near-field interactions. We demonstrate the theoretical basis of this with an angular spectrum analysis of optical near-fields. We also experimentally demonstrate such principles by using ZnO nanoneedles fabricated through metal-organic vapor phase epitaxy (MOVPE) followed by a photo-induced MOVPE procedure where smaller-scale generated structures were clearly observed with the help of light irradiation. We also observed that the generated fine structures followed a power-law distribution, indicating that fractal structures emerged via optical near-field interactions.

Selective cytotoxicity of phospholipids and diacylglycerols to rat 3Y1 fibroblasts transformed by adenovirus type 12 or its E1A gene.

The colony-forming ability of rat 3Y1 fibroblasts transformed by adenovirus type 12 (Ad12) was drastically reduced when the cells were cultivated for 18 h in medium augmented with 300 micrograms/ml of liposomes composed of either phosphatidylcholine (PC) or phosphatidylinositol. In contrast, those of untransformed 3Y1 cells and simian virus 40-transformed and polyomavirus-transformed 3Y1 cells were not. The cytotoxicity of PC liposomes was also observed in 3Y1 cells transformed by plasmid DNA containing Ad12-E1A gene but not in those transformed by adenovirus type 2, Rous avian sarcoma virus, or plasmid DNA carrying v-Ha-ras oncogene. The extensive killing of Ad12-transformed and E1A-transformed 3Y1 cells occurred in liposomes of dioleoyl-PC and of dilinoleoyl PC but not those of dipalmitoyl PC, distearoyl-PC, or diarachidonyl PC, suggesting that the acyl groups of phospholipids play an important role in cytotoxicity. Dilinoleoylglycerol, 60 micrograms/ml, was also cytotoxic selectively to Ad12-transformed and E1A-transformed 3Y1 cells, although the toxicity of lysophosphatidylcholine or linoleic acid was not specific to these transformants. These results suggest that cell transformation by Ad12 is characterized by a high sensitivity to exogenously administered phospholipids and diacylglycerol that contain oleoyl or linoleoyl acyl groups and that the sensitivity is attributable to the expression of E1A gene of Ad12.

Mechanism of selective killing by dilinoleoylglycerol of cells transformed by the E1A gene of adenovirus type 12.

Rat 3Y1 fibroblasts transformed by the E1A gene of adenovirus type 12 (E1A-3Y1 cells) are highly sensitive to the cell-killing effect of 1,3-dilinoleoylglycerol (DLG) administered in a culture medium, whereas the parental 3Y1 cells are less sensitive (H. Shimura et al., Cancer Res., 48: 578-583, 1988). The selective cytotoxicity of DLG to E1A-3Y1 cells was markedly reduced by the simultaneous administration of nonspecific antioxidants such as vitamin E, butylated hydroxytoluene, and ascorbic acid. Specific scavengers for oxygen radicals had no effect. Lipoxygenase inhibitors (nordihydroguaiaretic acid, esculetin, and baicalein) reduced the DLG-mediated selective cytotoxicity, whereas cyclooxygenase inhibitors (acetylsalicylic acid and indomethacin) showed no effect. The intracellular and extracellular contents of the products from lipid peroxidation as measured by the thiobarbituric acid test were significantly greater in E1A-3Y1 cells than in the parental 3Y1 cells. In comparison with DLG, linoleic acid and monolinoleoylglycerol were equally toxic to E1A-3Y1 and parental 3Y1, and trilinoleoylglycerol was weakly toxic to both types of cells. Scanning electron microscopy revealed that numerous holes about 0.2 micron in diameter were scattered all over the surface of the E1A-3Y1 cells after treating the cultures with DLG. These results suggest that; (a) the DLG-mediated cytotoxicity to the E1A-transformed cells is attributable to lipid peroxidation; (b) the structural property of DLG is essential to the E1A specificity of cytotoxicity; and finally (c) the destruction of the cell membrane is the basis of cytotoxicity of DLG.

Elevation of serum IgE level and peripheral eosinophil count during T lymphocyte-directed gene therapy for ADA deficiency: implication of Tc2-like cells after gene transduction procedure.

We have successfully carried out T-cell-directed gene therapy for a boy with severe combined immunodeficiency due to adenosine deaminase deficiency (ADA SCID) and unexpectedly found an elevation of serum IgE level and peripheral eosinophil count during the course. More than 90% of transduced cells cultured for 7-11 days before infusion into the patient were positive for CD8 and expressed Th2-type cytokine genes such as IL-4, IL-5 and IL-13. Furthermore, CD4(+) T-depleted PBMC (peripheral blood mononuclear cells) from the patient synthesized IgE in vitro by stimulation with IL-4. Collectively, these results suggested that Tc2-like cells in the transduced cells have distinct immunological functions to help IgE synthesis and activate eosinophils.

The high sensitivity of cells transformed by E1A gene of adenovirus type 12 to diacylglycerol-mediated cell killing.

Viability of rat 3Y1 fibroblasts transformed by adenovirus type 12 (Ad12) was markedly impaired by the administration of dilinoleoylglycerol (DLG) to the culture medium. To identify the gene(s) of Ad12 responsible for the high sensitivity to DLG, we established several transformed sublines of 3Y1 induced by the viral E1A gene or by the mutants of Ad12 which have mutations in the E1A region. All of the transformed sublines of 3Y1 expressing either the 12S or the 13S message from the E1A region were highly sensitive to the cytotoxicity of DLG. We propose that the high sensitivity of Ad12-transformed cells to the DLG mediated cytotoxicity is attributable to the common function of E1A-12S and E1A-13S mRNA products.

Combined immunodeficiency, chromosomal instability, and postnatal growth deficiency in a Japanese girl.

We report on an 11-year-old Japanese girl with combined immunodeficiency and chromosomal instability. She had postnatal growth deficiency and microcephaly, preaxial polydactyly of the left hand, and susceptibility to infections. Immunological studies showed marked lymphocytopenia (around 500/ll), reduced lymphocyte response to various mitogens, and reduced or absent serum IgA, IgG, and IgM. Cell biological studies of her primary skin fibroblasts demonstrated spontaneous chromosome aberrations and radiation hypersensitivity. The combination of immunodeficiency, chromosomal instability, and radiation hypersensitivity as seen in the girl is present in both ataxia-telangiectasia and Nijmegen breakage syndrome. Ataxia-telangiectasia was excluded because of differences in clinical features and laboratory data. Likewise, Nijmegen breakage syndrome is unlikely to be the case because the characteristic face, hyperpigmented spots, and mental retardation present in the syndrome were missing in the girl. Sequence analysis of a Nijmegen breakage syndrome responsible gene, NBS1, revealed no mutations. A normal NBS1 product was also demonstrated by immunoblot analysis using an anti-NBS1 antibody. We propose that the disorder in the girl represents a new combination of combined immunodeficiency and chromosomal instability.

Fabrication of a pencil-shaped fiber probe with a nanometric protrusion from a metal film for near-field optical microscopy.

We propose a method to fabricate a probe with a nanometric protrusion for near-field optical microscopy. The method involves tapering process based on selective etching of an GeO2 doped fiber in buffered hydrogen fluoride solution and metallizing process by vacuum evaporation and chemical polishing. We obtained the tapered probe having a protrusion emerged from a metal film. The protrusion has an apex diameter less than 10nm and a foot diameter less than 20nm. Employing the probe, we succeeded in obtaining a highly spatially resolved image of 20nm sized gold particles.

Dependency of the efficiency of transformation by simian-virus-40 on the proliferative state of cultured fibroblasts at the time of virus inoculation.

We previously demonstrated that the efficiency of cell transformation by simian virus 40 (SV40) is reduced when proliferating rat 3Y1 cells are inoculated with SV40 as compared with when density-arrested cells are inoculated. In this study, we characterized in more detail the cellular state at the time of virus inoculation that affects the susceptibility to SV40 transformation. When density-arrested 3Y1 cells were stimulated to progress one round of cell cycle by refeeding with medium containing high serum, they began to reduce the susceptibility to SV40 transformation before entering S phase. After re-entry into the non-proliferative state, prolonged maintenance of cells in the non-proliferative state was necessary for restoration of the susceptibility to SV40 transformation. Such dependency of the transformation efficiency on the cellular state at the time of SV40 inoculation paralleled with that of the expression of T antigen in nuclei, while virus adsorption and degradation of the DNA of the adsorbed virus was not dependent on the cellular state. We conclude that after inoculation of proliferating cells with SV40, an unidentified event between the virus adsorption and the accumulation of T antigen protein in nuclei is blocked and that this blockage causes the inhibition of the initiation of transformation.

Clinical and pedigree study on familial cases of West syndrome in Japan.

Nationwide survey on familial cases of West syndrome (WS) in first- and second-degree relatives was conducted by mailing a questionnaire to 64 major university hospitals, children's hospitals, and epilepsy centers in Japan, and by review of the Japanese cases in the literatures. Thirty-four familial cases, 20 males and 14 females, were obtained in 15 families including one with five affected members in two generations and another with three affected male siblings including a half brother by a different father (X-linked WS). A mother and the child or children were involved in three families. Nine families had 21 cryptogenic cases and six families had 13 symptomatic cases, and the etiologies were same among the affected members in each family. Familial cases of WS have characteristic clinical features and genetic mechanisms. Age of onset, seizure types, electroencephalographic abnormalities, early seizure outcome, effective treatment, long-term seizure prognosis, and long-term developmental prognosis were concordant among the affected members in each family. Long-term seizure and developmental prognoses were far better than those in WS in general, with seizure-free rate of 82% and normal mental development rate of 44%. Poor prognosis was limited to specific symptomatic cases. Adrenocorticotropic hormone (ACTH) was a treatment of choice, and even in relapse of WS after ACTH therapy, the patients well responded to antiepileptic drugs. Specific inheritance pattern was difficult to imagine in the majority of the present cases, except for one family with X-linked WS and another family with five patients of maternal inheritance. These results are helpful for the treatment choice and prognostication of clinical course for familial cases of WS.

[Clinical study on epileptic aura in children with temporal lobe epilepsy].

We studied the clinical characteristics of epileptic aura with temporal lobe epilepsy (TLE) in children, by retrospectively reviewing medical records of 33 patients whose first seizures developed under 15 years of age. The diagnosis of TLE was made by interictal EEG and head MRI/SPECT, both of which demonstrated a temporal lesion. The patients were classified into 24 with mesial TLE syndrome, 3 with a temporal lobe tumor, 3 with temporal lobe dysplasia and 3 with other causes. The epileptic aura was not recognized in 5 patients (15%). The age at onset of aura ranged from 4 to 10 years with a median age at 7. In patients older than 10, it was always followed by impairment of consciousness. It was manifested with nausea in 14 patients (42%), vertigo, a sense of fear, palpitation and heating sensation on the back in three patients (9%) each. Thus, clinical manifestations of epileptic aura in children with TLE were largely identical to those of adult patients. Detailed history taking about the aura may provide a clue to the diagnosis of TLE even in children.

Fabrication of vertically aligned ultrafine ZnO nanorods using metal-organic vapor phase epitaxy with a two-temperature growth method.

We report the fabrication of vertically aligned ultrafine ZnO nanorods using metal-organic vapor phase epitaxy and applying a two-temperature growth method. First, thick nanorods were grown vertically on the substrate at a lower temperature. Then, ultrafine ZnO nanorods with an average diameter of 17.7 nm were grown from the tips of the thick nanorods at a higher temperature. The direction of the ultrafine ZnO nanorods followed that of the preformed vertically aligned thick nanorods. Electron microscopy revealed that the ultrafine nanorods were single crystals and the growth direction was along the c axis. Excellent photoluminescence characteristics of the nanorods were confirmed.

Early-onset form of benign childhood epilepsy with centro-temporal EEG foci--a different nosological perspective from Panayiotopoulos syndrome.

PURPOSE: We have studied the clinical differences between early-onset benign epilepsy with centro-temporal spikes (early-onset BECT) and Panayiotopoulos syndrome (PS) to investigate the hypothesis that BECT and PS nosologically constitute age-dependent benign childhood seizure susceptibility syndromes based on a common etiopathogenesis. SUBJECTS AND METHODS: The subjects were 24 patients with BECT and 62 patients with PS, who satisfied the following definitions: 1) onset of epilepsy before 5 years of age; 2) the BECT and PS seizures started mainly with orofacial focal motor attacks and emetic symptoms followed by focal seizures, respectively; 3) follow-up examinations for longer than 2 years. We compared the various clinical features between these two groups. RESULTS: In children with early-onset BECT, the seizures at times manifested with hypersalivation, vomiting, and focal motor seizures, but the vomiting that developed in the middle of seizures was different from the initial vomiting observed in patients with PS. Although the seizures recurred more frequently in patients with early-onset BECT, the incidence of status epilepticus as well as prolonged seizures was higher in those with PS. The patients demonstrating below borderline IQ scores and mild developmental behavioral disorders were more frequently seen in early-onset BECT than PS, accounting for 37.5 and 14.6% (P<0.05), and for 8% and 21%, respectively (P<0.05). DISCUSSION: Early-onset BECT and PS have heterogeneous clinical characteristics, except for the same onset age, and appear to be nosologically different epileptic syndromes. The former seems to develop in combination with other acquired disturbances based on a BECT predisposition, while the latter develops based on a PS predisposition and involves a better prognosis.