Differential expression of MHC class II antigens and cathepsin L by subtypes of cortical epithelial cells in the rat thymus: an immunoelectron microscopic study

To better comprehend the thymic microenvironment, it is necessary to identify the antigenic profile of cortical thymic epithelial cells (cTECs) that are involved in the development of major histocompatibility complex (MHC)-restricted T cells. Ultrastructurally, cTECs can be classified into four morphologically distinct subtypes: subcapsular/perivascular (EC1), pale (EC2), intermediate (EC3) and dark (EC4) cells. Several immunohistochemical studies were done on cTECs at the light and electron microscopic levels, but not with reference to the above subtypes. In the present paper, we analysed the expression of MHC class II antigen and cathepsin L by individual cTEC subtypes at the electron microscopic level. We show that (1) MHC class II antigens are expressed on the cell surfaces except on the basal surface of EC1, both on the cell surface and in intracytoplasmic vacuoles of EC2, and only in the intracytoplasmic vacuoles of EC3 and EC4, and (2) that cathepsin L is expressed strongly and uniformly throughout the cytoplasm of EC2, but weakly and non-uniformly in the cytoplasm of EC1, EC3 and EC4. These results show that MHC class II antigen expression and cathepsin L expression is heterogeneous in cTEC subtypes and suggest that EC2 might play a significant role in the development of CD4+ T cells.     

A sulphur matrix complex,elastic fibril composed of a fine core of amorphous elastin and microfibrils was largely accumulated in the aortic intima of aged rats

We examined elastic fibrils in the aortic intima of aged rats with elastin staining, elastase digestion and X-ray microanalysis. The innermost elastic lamina, heavily stained by a brief treatment with azure II-toluidine blue without heating, was thin and fragmented, and an amorphous substance that stained weakly to moderately was accumulated in the thick subendothelial space of 26-28-month-old rat aortas. The substance was always present in the intimas; to a large extent in the aged rats but rarely in 5-month-old rats, and disappeared after digestion with elastase. The amorphous substance was identified as elastic fibrils approximately 0.1-0.2 microm in diameter under an electron microscope with tannic acid-uranyl acetate/lead citrate staining. Elastase digestion revealed that elastic fibrils were composed of a number of microfibrils, which were 10-12 nm in diameter, in and around a fine core of amorphous elastin. X-ray microanalysis revealed a clear peak of sulphur in the elastic fibrils.     

Bacterial cellulose membrane as separation medium

A thin membrane of bacterial cellulose (BC) obtained from Acetobacter culture was tested for its performance as a dialysis membrane in aqueous systems. The BC membrane showed superior mechanical strength to that of a dialysis-grade regenerated cellulose membrane, allowing the use of a thinner membrane than the latter. As a result, the BC membrane gave higher permeation rates for poly(ethylene glycols) as probe solutes. The cutoff molecular weight of the original BC membrane, significantly greater than that of regenerated cellulose, could be modified by concentrated alkali treatments of the membrane. The nature of the change at the ultrastructural level caused by the alkali treatments was studied by X-ray diffraction and scanning electron microscopy. © 1993 John Wiley & Sons, Inc.     

Immunohistochemical localization of HLA-DR-positive cells in unerupted and erupted normal and carious human teeth

Class II major histocompatibility complex (MHC) antigen-expressing cells are generally associated with the early phase of the immune response. We have studied the distribution of class II-expressing cells in developing, normal, and carious human teeth to clarify when human pulp acquires an immunologic defense potential and how this reacts to dental caries. Antigen-expressing cells were identified immunohistochemically by means of HLA-DR monoclonal antibody. In the pulp of unerupted developing teeth, numerous HLA-DR-positive cells were distributed mainly in and around the odontoblast layer. In erupted teeth, HLA-DR-positive cells were located, for the most part, just beneath the odontoblast layer, with slender cytoplasmic processes extending into the layer. Superficial caries lesions caused an aggregation of HLA-DR-positive cells in dental pulp corresponding to the lesion. In teeth with deeper caries lesions, this aggregation of cells expanded to include the odontoblast layer. Also noted were HLA-DR-positive cells lying along the pulp-dentin border, with cytoplasmic processes projecting deep into the dentinal tubules, where they co-localized with odontoblast processes. These findings suggest that: (1) human dental pulp is equipped with immunologic defense potential prior to eruption; (2) in the initial stage of caries infection, an immunoresponse mediated by class-II-expressing cells is initiated in human dental pulp; and (3) HLA-DR-positive cells trespass deep into dentinal tubules as the caries lesion advances.     

Research,technology and development evaluation; developments in Japan

The reseach, technology and development (RTD) evaluation in terms of science and technology policy has come to be important in stimulating research activities and in continuously keeping the vitality and the higher quality of research in RTD institutions. There are two criteria on the RTD evaluation, i.e, in-house evaluation from the stand point of RTD management and independent macroscopic evaluation for the decision making of companies and/or policy making for science and technology policy.The most important point for RTD evaluation in the former criteria is in the mission itself. RTD in universities, public research institutes, and enterprises have different objectives and characteristics. Therefore, the mission and methodology of RTD evaluations should be different, by categorized type and objectives of research institutions, and be developed inhouse. Results of RTD evaluations should be fed back to researchers or engineers and disclosed principally if the mission was to stimulate knowledge creation through RTD activities.The in-house RTD evaluation can be classified in general into three categories: prior evaluation, mid-term review, and ex-post facto review. The methodologies to evaluate RTD in each phase of the RTD process are different, even among those institutes categorized into the same type such as national and regional research institutes. In this paper, two cases of RTD evaluation a) in Riken, which was founded in 1917 as a private research foundation and later reorganized as a semi-public research corporation of the Science and Technology-Agency, b) in regional public research institutes.RTD evaluation from the view point of policy assessment of governmental science and technology policy is discussed through analysis of data obtained by the survey of research activities in regional public research institutes. It can be concluded that developments and introduction of RTD evaluation as a new management system in these institutes is improving the research environment and advancing the quality of research. The differences of RTD evaluation between a Center of Excellence (COE) such as Riken and local technology centers, will be compared and the policy implication of RTD evaluation will also be discussed in terms of promotion of science and technology.     

High-temperature oxidation and hot corrosion behavior of two kinds of thermal barrier coating systems for advanced gas turbines

High-temperature oxidation and hot corrosion tests were conducted at 800 to 1100 °C under isothermal and thermal-cycle conditions for two kinds of thermal barrier coating (TBC) systems with different compositions of ceramic top coat: Y₂O₃-stabiIized zirconia (YSZ) and CaO-SiO₂-ZrO₂ (C₂S-CZ). Qualitative and quantitative failure analyses were carried out to clarify the failure mechanisms of TBC systems. In high-temperature oxidation up to 1100 °C, the YSZ-TBC system was subjected more easily to spalling of the ceramic top coat. This is attributed to the localized oxidation along the ceramic top coat/metallic (NiCrAlY) bond coat interface, as compared with the case of the C₂S-CZ-TBC system. Thus, the most significant oxidation damage resulted in the YSZ system under the thermal-cycle condition. On the other hand, for hot corrosion by Na₂SO₄-NaCI molten salt up to 1000 °C, the C₂S-CZ system was more reactive with the molten salt to form a new phase layer composed of both the metallic bond coat constituents, such as aluminum and chromium, and corrosive species such as oxygen at the inner region of the ceramic top coat. Furthermore, effects of both the heat treatment, in particular the atmosphere after plasma spraying, and the chromium content of the bond coat were investigated for each coating system.     

Stabilizing Atomically Dispersed Catalytic Sites on Tellurium Nanosheets with Strong Metal–Support Interaction Boosts Photocatalysis

The utilization of appropriate supports for constructing single‐atom‐catalysts is of vital importance to achieve high catalytic performances, as the strong mutual interactions between the atomically dispersed metal atoms and supports significantly influence their electronic properties. Herein, it is reported that atomic cobalt species (ACS) anchored 2D tellurium nanosheets (Te NS) can act as a highly active single‐atom cocatalyst for boosting photocatalytic H₂ production and CO₂ reduction reactions under visible light irradiation, wherein Te NS serves as the ideal support material to bridge the light absorbers and ACS catalytic sites for efficient electron transfer. X‐ray absorption near‐edge structure spectroscopy reveals that the ACS are built by a Co center coordinated with five Co? O bonding, which are anchored on Te NS through one Co? Te bonding. The strong mutual interaction between the Te NS and ACS alters the electronic structure of Te NS, inducing the introduction of intermediate energy states, which act as trap sites to accommodate the photogenerated electrons for promoting photocatalytic reactions. This work may inspire further capability in designing other Te‐based single‐atom‐catalysts for highly efficient solar energy conversion.     

Adaptively controlled supercontinuum pulse from a microstructure fiber for two-photon excited fluorescence microscopy

Selective fluorescence excitation of specific molecular species is demonstrated by using coherent control of two-photon excitation with supercontinuum pulses generated with a microstructure fiber. Pulse shaping prior to pulse propagation through the fiber is controlled by a self-learning optimization loop so that the highest fluorescence signal contrast between two fluorescent proteins is obtainable. The self-learning optimization loop successfully controls both the optical nonlinarity of the microstructure fiber and the two-photon excitation of the fluorescent proteins.     

Effects of H2O2 under low- and high-aeration-level conditions on growth and catalase activity in Exiguobacterium oxidotolerans T-2-2T

The effects of H2O2 under low- and high-aeration-level conditions on growth and catalase activity in Exiguobacterium oxidotolerans T-2-2T were investigated. Continuous addition of 5-200 mM H2O2 to the culture medium from the mid-exponential growth phase enhanced the growth of the strain under the low-aeration-level condition, whereas the addition of 5-50 mM H2O2 decreased intracellular specific catalase activity and extracellular total catalases activity. The detection of extracellular catalase by the cells and the decrease in intracellular specific catalase activity and extracellular total catalase activity under the high-aeration-level condition account for the stimulation of growth by the introduced H2O2 and the decrease in catalase activities induced by O(2) from H2O2 in the medium. On the other hand, the addition of H2O2 to the medium prior to the initiation of growth inhibited the growth but increased the specific activity of intracellular catalase in the stationary growth phase. Strain T-2-2T grew when 10 mM H2O2 was added to the medium prior to growth. However, the growth was completely inhibited by the catalase inhibitor 3-amino-1,2,4-triazole (3-AT). The continuous addition of H2O2 at an appropriate concentration from prior to the initiation of growth to the stationary growth phase under the low-aeration-level condition resulted in higher intracellular specific catalase activity and cell growth rate than single H2O2 addition prior to growth.     

2000年以来日本行政管理与规划体系修正的评述

区域规划与管理是每一个国家所面临的普遍问题,特别是那些拥有巨大城镇群的新兴工业国家。随着经济的不断发展,日本在东京、近畿等地区出现了若干个大城市的急速扩张——已经超出了地方政府的行政辖区,这给协调不同辖区之间的规划带来了一定的困难。首先讨论首都圈与近畿圈等发展过程中所存在的问题及其内在原因,并评述日本试图通过旨在"增效分权"的平成大合并、部分修正国家和区域规划体系以及"道州制"设想来应对这些问题的经验,最后也论及对中国区域规划与管理的启示。