Infrared spectroscopic and electron microscopic characterization of gold nanogap structure fabricated by focused ion beam.

Using infrared spectroscopy of plasmonic resonances and mapping of elemental composition and structure, we investigated the correlation between optical and structural properties of nanometre-scale gaps in gold nanorod dimers fabricated by electron beam lithography (EBL) and focused ion beam (FIB) milling. In spite of their very similar scanning electron microscopy (SEM) images, a fully cut nanogap and a shallower cut with slight imperfection near the gap region were clearly distinguished by their strongly different infrared plasmonic resonance behaviour. The differences in the infrared spectra are related to different structural and chemical results from elaborated cross-sectional transmission electron micrographs and energy dispersive x-ray spectrometry (EDX) mapping of the gap region.

Correlative association between circadian expression of mousePer2 gene and the proliferation of the neural stem cells.

We examined the circadian expression of mousePeriod (mPer) genes (mPer1 and mPer2) and the proliferation of the neural stem cells in vitro. The neural stem cells from the ganglionic eminence of embryonic mice were expanded by the neurosphere method and then treated with epidermal growth factor (EGF) to stimulate their mitotic activity. The time courses of the proliferation were examined by WST-8 assay and bromodeoxyuridine (BrdU) incorporation assay and the expression of mPer1 and mPer2 genes was examined by RT-PCR and immunocytochemistry. We have found that EGF treatment elicited the circadian change in both the increase in viable cell number and DNA synthesis activity of the neural stem cells. Also, the gene expression of mPer2, but not mPer1, changed rhythmically with a period of 24 h and correlated negatively with the DNA synthesis activity rhythm. Furthermore, the treatment with an antisense oligonucleotide against mPer2 increased the DNA synthesis activity of the neural stem cells. These results suggest that mPer2 might periodically suppress the proliferation of neural stem cells.

Successful treatment of disseminated nasal NK/T-cell lymphoma using double autologous peripheral blood stem cell transplantation.

Nasal natural killer (NK)/T-cell lymphoma is a rare disease with an aggressive clinical course. Prognosis is generally poor and the disease is invariably fatal after systemic dissemination. We report a patient with aggressive nasal NK/T-cell lymphoma who was resistant to therapy and developed systemic dissemination involving the intestine, skin, and stomach. Epstein-Barr virus (EBV) was detected by Southern blotting with EBV-terminal repeat probe and by in situ EBV-encoded small nuclear early region-1 hybridization. The patient was treated using double high-dose chemotherapy and autologous peripheral blood stem cell transplantation (auto-PBSCT). Pretransplant conditioning for the first auto-PBSCT was MCVC (high-dose ranimustine, carboplatin, etoposide [VP16], and cyclophosphamide), and for the second auto-PBSCT, modified ICE (high-dose ifosfamide, VP16, and carboplatin). The patient obtained a complete remission and has been free of disease for 3.0 years since the second PBSCT. These observations suggest that double high-dose chemotherapy with PBSCT support may be effective in resistant nasal NK/T-cell lymphoma.

Methamphetamine stimulates the release of neuropeptide Y and noradrenaline from the paraventricular nucleus in rats.

Effects of methamphetamine (MAP) on the extracellular neuropeptide Y (NPY) and noradrenaline (NA) levels were examined in the vicinity of the paraventricular nucleus (PVN) of freely moving rats by means of push-pull perfusion. The NA and NPY levels increased significantly in 30-60 min and reached the maximum level in 90-120 min after intraperitoneal administration of MAP. The effects were dose-dependent. The maximum levels were 1.6-fold of the pretreatment level for NPY and 7-fold for NA, respectively, when 5.0 mg/kg b.w. of methamphetamine was administered. It is concluded that MAP stimulates the releases of paraventricular NPY and NA, but the effect is more strong for NA than for NPY.

Independence of feeding-associated circadian rhythm from light conditions and meal intervals in SCN lesioned rats.

Free-running period of the feeding-associated circadian rhythm was assessed in suprachiasmatic nucleus (SCN) lesioned rats under three different conditions using a feeding-fasting (FF) paradigm; restricted feeding (RF) with meal intervals of 24 h (T = 24 h) under 24 h light-dark cycle (LD), RF with T = 24 h under continuous dim light (dim LL), and RF with T = 25 h under dim LL. After the termination of RF, the rats were subjected to FF regimen five times repeatedly, in which food and water were available for 7 days, followed by total food deprivation for 3 days with free-access to water. Free-running period, which was measured with reference to the prefeeding activity peak during food deprivation, was very close to 24 h and was not different under three conditions. It is concluded that the feeding-associated circadian rhythm has a major period close to 24 h, which is not affected either by light conditions nor by meal intervals.

Circadian rhythm of nitric oxide production in the dorsal region of the suprachiasmatic nucleus in rats.

Extracellular concentration of nitrite (NO2-), an oxidized product of nitric oxide (NO), was measured consecutively in the dorsal region of the rat suprachiasmatic nucleus (SCN) by means of in vivo microdialysis. The NO2- concentrations in the dialysates showed robust circadian rhythm under a 12:12 h light/dark cycle and were higher during the dark phase than during the light phase. When the rats were transferred to constant darkness, the 24 h rhythm of NO2- persisted without damping the amplitude. The NO2- level was significantly lowered by an injection of NO synthase inhibitor (NG-monomethyl-L-arginine, 10 mg/kg i.p.). These findings indicate that the daily fluctuation of NO2- in the dorsal region of the SCN, which represents endogenous rhythm of NO, is regulated independently of photic inputs into the SCN and may be related to the circadian clock functions.

Optimum condition of convergent beam illumination for observation of local structure by high resolution transmission electron microscopy.

We propose the convergent beam illumination as a technique for the local structural analysis by high resolution transmission electron microscopy. The image contrast is lower in the convergent beam illumination than in the parallel beam illumination because of the lower coherency. However the intensity oscillation around an atom image, which appears due to interference effect, is much reduced with the convergent beam illumination, and pseudo-images do not appear at termination of crystal periodicity. The convergent beam illumination, rather than parallel beam illumination, precisely reveals non-periodic local structures, such as interfaces, surfaces and fine particles, which are even embedded in a crystal. From theoretical analysis the optimum condition is derived as divergence of q(s )* = 0.44 and focus of delta(z)* = 1.35 in generalized coordinates. Using the convergent beam illumination the point resolution is improved by 20% compared to conventional parallel beam illumination.

Human periodontal ligament cells derived from deciduous teeth induce osteoclastogenesis in vitro.

The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), are the important proteins involved in osteoclastogenesis. In this study, we investigated the expressions of RANKL and OPG in cultured human periodontal ligament cells derived from deciduous teeth (DPDL cells) and their roles in osteoclastogenesis. Northern blotting revealed that the OPG mRNA was down-regulated by application of 10(-8) M 1 alpha, 25(OH)2 vitamin D3 [1,25-(OH)2D3] and 10(-7) M dexamethasone (Dex). In contrast, RANKL mRNA was up-regulated by the same treatment. Western blotting demonstrated a decrease in OPG following application of 1, 25-(OH)2D3 and Dex. Tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells (MNCs) were induced when DPDL cells were co-cultured with mouse bone marrow cells in the presence of 1,25-(OH)2D3 and Dex. TRAP-positive MNCs increased significantly when the DPDL cells were co-cultured with bone marrow cells in the presence of anti-human OPG antibody together with 1, 25-(OH)2D3 and Dex. These results indicate that PDL cells derived from deciduous teeth synthesize both RANKL and OPG and could regulate the differentiation of osteoclasts.

Salivary catecholamine assay for assessing anxiety in pediatric dental patients.

For the behavioral management of pediatric dental patients, it is important to estimate the degree of anxiety during dental treatment. The purpose of this study was to investigate salivary catecholamine levels in children undergoing dental treatment and to assess the degree of anxiety at each dental procedure. The salivary norepinephrine (NE) level was not influenced by a subcutaneous injection of 50 micrograms of NE in 6 adult volunteers, suggesting a poor diffusive effect of plasma NE into the salivary gland. The salivary NE and epinephrine (E) were measured in 8 children between the ages of 3 and 7 years who underwent restorative dental procedures. Salivary NE significantly increased when the children lay on a dental chair and subsequently received infiltration anesthesia. The salivary E level did not show a significant change throughout the study. After the treatment, salivary NE returned to the pretreatment level. These findings suggest that the increase in salivary NE before infiltration anesthesia reflects enhanced peripheral NE release as a result of stress-induced sympathetic responses and that salivary NE assay is useful for the assessment of dental anxiety in children.

[Development of cerebellar astrocytoma in a patient with acute myeloid leukemia 8 years after his second bone marrow transplant].

We report a case of cerebellar astrocytoma occurring 8 years after the second bone marrow transplantation (BMT) in 32-year-old man. The patient was admitted to our hospital in December 1997 because of dysarthria and gait disturbance. He had been treated earlier for acute myeloid leukemia (AML M2) with chemotherapy and cranial irradiation followed by allogeneic BMT from a sibling in december 1988. Three months after the first BMT, testicular relapse was observed and followed by systemic relapse. The patient received reinduction therapy and a second successful BMT. He had been well until about 1 month before admission to our hospital. Neurological examination revealed left cerebellar ataxia, and brain magnetic resonance imaging disclosed a left cerebellar tumor. The tumor was surgically resected and a histological diagnosis of cerebellar astrocytoma was made. The patient was further treated by irradiation for residual tumor and discharged without progression of the disease.

[The central mechanism of feeding-associated circadian corticosterone rhythm in rats: analyses of paraventricular noradrenaline by in vivo microdialysis].

A prefeeding peak of plasma corticosterone level in rats under a periodic feeding schedule is controlled by a food-entrainable circadian rhythm, an oscillatory mechanism of which is located outside of the suprachiasmatic nucleus. A stimulatory role of the catecholaminergic neurons innervating the paraventricular nucleus (PVN), where the corticotropin releasing hormone (CRH) producing neurons are located, have been suggested in the expression of the hormone peak. A periodic feeding schedule with free-access to meal from 10 to 12 (14) hour was imposed on male Wistar rats for 2-3 weeks under the light-dark cycle. Prefeeding peaks of plasma corticosterone and wheel running activity that appear during a 3 day food deprivation after the periodic feeding schedule were suppressed by the intraventricular injection of 6-OHDA, a catecholamine deprivator. The release of endogenous noradrenaline in the vicinity of PVN was measured by means of in vivo microdialysis. A 24 hour variation of noradrenaline release was observed in rats under ad libitum feeding with a peak in the dark period. On the other hand, under periodic feeding noradrenaline release was significantly increased prior to daily meal, and decreased after meal intake. And the noradrenaline release was also enhanced during the time of previous meal feeding when food was deprived for 3 days after the periodic feeding schedule. The finding indicates that the central noradrenergic neurons innervating the PVN mediates the food-entrainable circadian oscillation to the hypothalamus-pituitary-adrenocortical axis as well as the locomotor activity.

Prefeeding increase in paraventricular NE release is regulated by a feeding-associated rhythm in rats.

Extracellular norepinephrine (NE) in the vicinity of the paraventricular nucleus was continuously measured over 24 h by means of in vivo microdialysis in rats under restricted daily feeding and ad libitum feeding. A 24-h rhythm in plasma corticosterone was monitored in separate rats under identical conditions. Under ad libitum feeding, the paraventricular NE showed a 24-h rhythm with lower levels in the light period and higher levels in the dark period. The temporal pattern was not affected by food deprivation for 3 days. The circadian peak of paraventricular NE lagged slightly behind that of plasma corticosterone under ad libitum feeding. On the other hand, when rats were fed for 2 h at a fixed time of day for 3 wk, the NE rhythm was changed and showed a major peak just before daily meals. To examine the nature of the prefeeding NE peak, a 24-hour variation of paraventricular NE was measured in rats under food deprivation that had been subjected to restricted daily feeding for 3 wk and subsequently to ad libitum feeding for 7 days. The paraventricular NE was high around the time when meal had been supplied under restricted daily feeding and low in the dark period. Similar changes were observed in plasma corticosterone. The findings indicate that the prefeeding increase in the paraventricular NE release is regulated by a feeding-associated circadian rhythm manifest in rats under restricted daily feeding.

Temperature dependency of radiation damage in inorganic materials by 300 keV electrons.

Temperature dependency of radiation damage in albite and natrolite was studied quantitatively by measuring the diffraction intensity with imaging plates. Radiation damage was reduced at low temperature in albite but was enhanced in natrolite. A damage process model, in which creation and annihilation of localized defects were considered, was proposed. According to this model, Boltzmann factor in temperature dependency is dominated by a difference between energy for diffusion of the localized defects and energy for breakdown of a crystal framework. When the diffusion energy is larger than breakdown energy, the activation energy in Boltzmann factor seems to be effectively negative.

Towards the reconstruction of central nervous system white matter using neural precursor cells.

Epidermal growth factor-responsive neural precursor cells were used as donor cells for transplantation into wild-type and myelin-deficient shiverer (shi) mice. The cells engrafted robustly within the CNS following intracerebroventricular and cisternal transplantation in neonatal mice. The cells adopted glial phenotypes, and some functioned as oligodendrocytes, producing myelin basic protein and morphologically normal internodal myelin sheaths. When individual shi mice received two transplants (on post-natal days 1 and 3), donor-derived cells disseminated widely and expressed myelin basic protein in central white matter tracts throughout the brain.