Stem cell factor contributes to tumorigenesis of mast cells via an autocrine/paracrine mechanism

Mastocytosis is a disease accompanied by the abnormal expansion and accumulation of mast cells. Although the D816V mutation is detected in most cases of systemic mastocytosis, the mutation is rarely observed in other forms of mastocytosis, such as cutaneous mastocytosis and mast cell leukemia/sarcoma, for which the mechanism of tumorigenesis remains unknown. In this study, we demonstrated a novel mechanism of mast cell tumorigenesis via SCF autocrine/paracrine release. SCF was highly expressed in a WT KIT-expressing HRMC line, contributing to the phosphorylation of KIT. Neutralization of external SCF using a neutralizing antibody or suppression of SCF production by RNA interference inhibited the growth of HRMC cells, indicating the essential role of SCF in cell proliferation. To the best of our knowledge, this is the first report to determine the significant contribution of SCF autoproduction to neoplastic proliferation of mast cells. These results indicate the possibility that targeting SCF production may become a novel treatment for mast cell malignancies.

Antitumor effect of a novel multifunctional antitumor nucleoside, 3'-ethynylcytidine, on human cancers

The antitumor activity of 1-(3-C-ethynyl-beta-D-ribopentofuranosyl) cytosine (ECyd), designed as a potential multifunctional antitumor nucleoside that could be expected to inhibit RNA and DNA syntheses, was examined. ECyd inhibited the growth of 47 kinds of cultured human cells in vitro, and also showed strong antitumor effects on 15 human solid cancers xenografted into nude mice at a dose of 0.25 mg/kg by intravenous administration for 10 consecutive days. The in vitro cytotoxic effect of ECyd was prevented dose dependently by cytidine and uridine, suggesting that ECyd may require phosphorylation by uridine/cytidine kinase for antitumor activity. ECyd strongly inhibited RNA synthesis and also slightly inhibited DNA synthesis. ECyd has shown potent antitumor activity against human experimental solid type tumors with minimal toxic effects in vivo, suggesting that ECyd will be a promising agent with a unique mechanism of action for the treatment of cancer.

The interaction between Lyn and FcεRIβ is indispensable for FcεRI-mediated human mast cell activation

BACKGROUND

FcεRIβ reportedly functions as an amplifier of the FcεRIγ-mediated activation signal using a reconstitution system. However, the amplification mechanisms in human mast cells (MCs) are poorly understood. We previously reported the hyperexpression of FcεRIβ of MCs in giant papillae from vernal keratoconjunctivitis patients, compared with that in conjunctivae from nonallergic conjunctivitis patients. Elucidation of the molecular mechanisms of the amplification induced by FcεRIβ should provide new targets for novel therapeutic interventions. The aim is to understand in greater details the function of FcεRIβ in human MC FcεRI expression and signaling.

METHODS

FcεRIβ and Lyn expression was reduced using a lentiviral shRNA silencing technique. Localization of Lyn and FcεRIβ in cultured MCs was examined by confocal microscopic analysis. Mediators were measured by ELISAs.

RESULTS

The diminution of FcεRIβ significantly downregulated cell surface FcεRI expression and FcεRI-mediated mediator release/production. The downregulation of FcεRI-mediated degranulation was not only due to the decrease in FcεRI expression. The diminution of FcεRIβ inhibited the redistribution of Lyn within the cell membrane following IgE sensitization. The diminution of Lyn in MCs significantly downregulated FcεRI-mediated degranulation. The recombinant cell-penetrating forms of phosphorylated FcεRIβ immunoreceptor tyrosine-based activation motif (ITAM) for intracellular delivery disturbed the interaction between Lyn and phosphorylated endogenous FcεRIβ ITAM, resulted in inhibiting IgE-dependent histamine release from MCs in vitro and from giant papillae specimens ex vivo.

CONCLUSION

The interaction between Lyn and FcεRIβ is indispensable for FcεRI-mediated human MC activation, and specific inhibition of the interaction may represent a new therapeutic strategy for the treatment of human allergic diseases.

Clinical outcomes of recipients with aplastic bone disease after renal transplantation

OBJECTIVES

We expect that if chronic renal failure (CRF) is improved after renal transplantation (RTx), dialysis osteopathy bone lesions would also recover to normal. Nevertheless, it is controversial whether bone lesions really improve after RTx. In this study, we evaluated whether pathological dialysis osteopathy improved after RTx.

MATERIALS AND METHODS

The 84 patients who had undergone living related RTx had also undergone a bone biopsy (Bx) since January 2004, including 13 (16.0%) with a diagnosis of aplastic osteopathy. They included 7 men and 6 women. The average hemodialysis (HD) period was 40.3 months. The immunosuppression was tacrolimus (FK); mycophenalate mofetil (MMF) and steroid. We examined Ca, P, intact-PTH (i-PTH), metabolic bone markers, and bone density (DXA) before and 1 year after RTx. In addition, a Bx was performed after having osteal labeling twice before Bx. In addition 2 cases (15.3%) also underwent a Bx after RTx.

RESULTS

All cases survive with well functioning renal grafts. The mean levels of Ca and P before RTx were 8.7 mg/mL and 6.6 mg/dL, respectively. The mean i-PTH level was 137.8 pg/mL before RTx and of alkaline phosphatase (ALP) was 202.1 U/L before RTx. The total density and % age match of DXA before RTx averaged 398.7 mg/ccm and 96.7%, respectively. The mean bone volume fraction (BV/TV: Bone Volume/Tissue Volume) before RTx was 17.2%. The mean osteoid volume (OV/TV) before RTx was 2.7%. The mean fibrosis volume (Fb.V/TV) before RTx was 0%. The mean bone formation rate (BFR/BV) before RTx was 2.1 %/y. Two cases were also pathologically diagnosed as renal osteodystrophy at 1 year after RTx: 1 case was mixed type, and another was osteomalacia, which was accompanied by a lumbar compression fracture (Fx) during the clinical course.

CONCLUSIONS

Bone metabolism in patients with aplastic ROD histologically improved at 1 year after RTx, presumably due to good renal transplant function. However, it is unknown whether both hypophosphatemia and decrease of FGF-23 improved bone However, patients with aplastic ROD were not completely normalized histologically at 1 year after RTx.

Enhanced nonlinear double excitation of He in intense extreme ultraviolet laser fields

Nonlinear, three-photon double excitation of He in intense extreme ultraviolet free-electron laser fields (∼24.1  eV, ∼5  TW/cm2) is presented. Resonances to the doubly excited states converging to the He+ N=3 level are revealed by the shot-by-shot photoelectron spectroscopy and identified by theoretical calculations based on the time-dependent Schrödinger equation for the two-electron atom under a laser field. It is shown that the three-photon double excitation is enhanced by intermediate Rydberg states below the first ionization threshold, giving a greater contribution to the photoionization yields than the two-photon process by more than 1 order of magnitude.

High rate growth of device grade silicon thin films for solar cells

We have developed a plasma enhanced chemical vapor deposition (PECVD) technique for high-rate growth of µc-Si:H at low temperatures using hydrogen diluted monosilane source gas under high-pressure depletion conditions. It was found that material qualities deteriorate, e.g. crystallinity decreases and defect density increases with increasing growth rate mainly due to ion damage from the plasma. We have found that deuterium dilution improves not only the crystallinity but also defect density as compared to hydrogen dilution and that deuterium to hydrogen ratio incorporated in the film has a good correlation with crystallinity. The advantages of the deuterium dilution are ascribed to lower ion bombardment due to slower ambipolar diffusion of deuterium ion from the plasma. Further improvement of material quality has been achieved using a triode technique where a mesh electrode inserted between cathode and anode electrodes prevents from ion bombardment. In combination with a shower head cathode, the triode technique remarkably improves the crystallinity as well as defect density at a high growth rate. As a consequence, we have succeeded to obtain much better crystallinity and uniformity at 5.8 nm/s with a defect density of 2.6×1016cm−3. We also discuss the limiting factors of growth rate and material quality for µc-Si solar cells.

Microcrystalline Silicon Thin-Film Solar Cells Prepared at Low Temperature

Hydrogenated microcrystalline silicon (µc-Si:H) p-i-n solar cells have been prepared using a conventional RF plasma-enhanced chemical vapor deposition (PECVD) method at a low process temperature of 140 °C. The low temperature deposition of µc-Si:H has been found to be effective to suppress the formation of oxygen-related donors that cause a reduction in open circuit voltage (Voc) due to shunt leakage. We demonstrate the improvement of Voc by lowering the deposition temperature down to 140, while suppressing the reduction in high short circuit current density (Jsc) and fill factor (FF). A high efficiency of 8.9% was obtained using an Aasahi-U substrate. Furthermore, by optimizing textured structures on ZnO transparent conductive oxide (TCO) substrates, an efficiency of 9.4% (Voc=0.526V, Jsc=25.3mA/cm2, FF=0.710) was obtained. In addition, relatively high efficiency of 8.1% was achieved using VHF (60MHz) plasma at a deposition rate of 12 Å/s. Thus, this low temperature deposition technique for µc-Si:H is promising for both high efficiency and high rate deposition of µc-Si:H solar cells.

Role of Surface and Growth-Zone Reactions in the Formation Process of µc-Si:H

The role of the surface reaction is discussed in the formation process of µc-Si:H in comparison to that of a-Si:H. It is suggested that the responsible radicals for the formation of µc-Si:H are SiH3 as same in the case of a-Si:H depositions. On the top film-growing surface, a lot of H atoms reach the surface during the course of the μc-Si:H growth giving rise to the change in the surface condition, i. e. the loss probability of SiH3 radicals is increased. At the same time, a full H-coverage of the surface is expected which enhances the surface diffusion of SiH3 radicals, leading to the appearance of a gc nucleus. Moreover, it is speculated that the reaction in the growth zone is not necessary for the nucleation process in µc-Si:H.

Novel Plasma Control Method in PECVD for Preparing Microcrystalline Silicon

A novel plasma enhanced vapor deposition (PECVD) technique employing biased wall (BW) method has been developed for the enhanced growth rate of the hydrogenated microcrystalline silicon (μc-Si:H) films. Using this method, we have achieved a growth rate of more than 6Å/sec for the formation of μc-Si-H having an average grain size of 200Å; at 350°C.

High-Rate Growth of Stable a-Si:H

Correlation between the gas phase species in silane plasma measured by mass spectrometry and the properties of hydrogenated amorphous silicon (a-Si:H) films deposited by plasma enhanced chemical vapour deposition (PECVD) has been investigated. We have especially been interested in the higher-order silane related species in the plasma, whose contribution to the film growth is considered to be the cause of light-induced degradation in the film quality, especially at high growth rate. In this study, we varied excitation frequency, gas pressure and power density to vary the growth rates of a-Si:H films ranging from 2 Å/s to 20 Å/s.

Molecular density ratio of trisilane, representative of higher silane related radicals, to monosilane has shown a clear correspondence to the fill factor after light soaking of Schottky cells fabricated on the resulting films.

Modified Triode Plasma Configuration Allowing Precise Control of Ion-Energy for Preparing High Mobility a-Si:H

We have previously shown that the carrier drift mobility in amorphous silicon can be enhanced by optimizing the ion-bombardment energy during growth on conducting substrates. However, there exists a lack of reproducibility of samples exhibiting high mobility which we attribute to the rf field induced fluctuation of the plasma potential in a conventional (Te ≈ 2eV) silane plasma. Here we introduce an enclosed plasma configuration that allows us to confine the effect of the rf field and therefore obtain a low-electron-temperature (Te ≈ 0.1 eV) silane plasma as determined from Langmuir probe measurements. The measured ion-energy distributions correlate with those for electrons and the mean ion-energy can be controlled by biasing the substrate which allows us to reproducibly fabricate high drift mobility amorphous silicon.

STM Observation on the Initial growth of Amorphous and Microcrystalline Silicon Films

Direct nanoscale observation on the nucleation and growth of hydrogenated amorphous and microcrystalline silicon on graphite substrates was made using scanning tunneling microscopy, atomic force microscopy, and Raman scattering spectroscopy. Nucleation of hydrogenated silicon clusters is initiated through the nucleation sites created by reactive hydrogen species coming from the source gas plasma. The difference in spatial distribution of nucleated clusters at the initial stage of deposition between a-Si:H and μc-Si:H is ascribed to the difference in the number density of nucleation sites which results in difference in the diffusion length of a SiH3 radical at the initial stage of deposition on the graphite substrate. The RMS roughness of μc-Si:H films is larger than that of a-Si:H when the film thickness is larger than 10 Å, which is opposite to the behavior at the initial nucleation stage on the graphite substrate.