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Notes: The effects of hydrogen annealing on capacitance–voltage (C–V) characteristics and interface-state density (Dit) of 4H–SiC metal–oxide–semiconductor (MOS) structures have been investigated. The Dit was reduced to as low as 1×1011 eV−1 cm−2 at Ec−E=0.6 eV using hydrogen annealing above 800 °C, where Ec−E is the energy level from the conduction-band edge. Secondary ion mass spectroscopy and Dit analysis revealed that Dit decreased with the increase of hydrogen concentration accumulated at the SiO2/4H–SiC interface. The interface states at SiO2/4H–SiC are thought to be originated from the dangling bonds of C atoms as well as Si atoms, because Dit decreases as the hydrogen annealing temperature increases and saturates around 800 °C. This high-temperature hydrogen annealing is useful for accumulation-type SiC metal–oxide–semiconductor field-effect transistors, which have n-type MOS structures to reduce the Dit. © 2000 American Institute of Physics.

Notes: A phylogenetic tree of aquabirnaviruses, including marine birnaviruses (MABV) and infectious pancreatic necrosis virus (IPNV), was developed based on the nucleotide sequences and deduced amino acid sequences of the polyprotein and VP5 genes of genomic segment A. In the polyprotein of MABV strains, the amino acid sequences were very similar, with identities of 98.3–99.7%. Twenty-one unique amino acid residues were found in the deduced amino acid sequences of the polyprotein gene of MABV strains. The phylogenetic tree based on the nucleotide sequence of genomic segment A and polyprotein sequences showed that 31 aquabirnavirus strains were clustered into seven genogroups. All MABV strains isolated in Japan and Korea were clustered into one genogroup which was distinct from other aquabirnaviruses. The seventh genogroup containing all MABV strains showed amino acid sequence similarities of 80.7–90.6% with other genogroups. In VP5, four unique residues were found in MABV strains when compared with IPNV strains. The MABV strains exhibited amino acid sequence similarities of 63.9–86.4% with IPNV strains. The amino acid sequences of VP5 were conserved among MABV strains, but differed from those of IPNV strains. The MABV strains isolated from different host species and different geographical areas were very similar to each other, suggesting that the MABV are distinct from the other genogroups.

Notes: summary  Of the cytochrome P450 (CYP) family of carcinogen-activating enzymes, CYP3A is the major form found in human livers. The purpose of this study was to investigate the cytotoxic effects of dental resin monomers after being metabolized by CYP3A4 and CYP3A7, using a colony formation assay and a neutral red assay. Specimen wells were plated with transfected cells derived from the Chinese hamster lung at 100 cells well−1. The experimental group consisted of CYP-producing 3A4-10 and 3A7-40 cells, while the control group consisted of non-CYP-producing CR-119 cells. Bisphenol A (BPA) and bisphenol A glycidyl methacrylate (Bis-GMA) and a positive control (Aflatoxine Bl) were added separately to each well and cultured for 7 days. After cultivation, the number of the colonies was counted and IC50 values were determined. The data were statistically analysed by a Student's t-test. The resultant of IC50 values indicated that the monomers were not metabolically activated by CYP3A4 or CYP3A7 as compared with the control (P 〈 0·05). We also confirmed that these monomers act neither as activators nor as inhibitors of CYP3A4 and CYP3A7.

Notes: Background:  Formaldehyde (FA) is well documented as a cause of occupational asthma. Recently, attention has been paid to FA as an allergen and a pollutant that enhances allergic sensitization. We have investigated the prevalence of FA-specific IgE in asthmatic children and the correlation between IgE sensitization to FA and the severity of asthma.Methods:  One hundred and fifty-five children were investigated, 122 of them asthmatic and 33 nonallergic. Specific IgE against FA was measured by CAP RAST. In addition, the patients answered a questionnaire, containing questions on clinical features of their asthma, their living conditions, and symptoms of mucosal irritation.Results:  Of all the subjects assessed, FA-specific IgE was detected in only two asthmatics, and their IgE levels of FA were low (0.42 and 0.46 UA/ml). One of the two patients with FA-specific IgE had severe asthma and frequent symptoms of mucosal irritation, but the other had mild asthma and only rare symptoms of mucosal irritation.Conclusions:  The prevalence of IgE sensitization to FA appears very low in Japanese children, whether or not they have asthma. Therefore, it appears likely that FA is not one of the major allergens causing childhood asthma.

Notes: IgA nephropathy (IgAN) is characterized by the presence of IgA deposits, predominantly in the glomerular mesangium, and by mesangial proliferative glomerulonephritis (GN). Concerning its pathogenesis, several investigators have suggested that the glomerular IgA deposits in IgAN are antibodies (Ab) to viral, bacterial or dietary antigens. Thus, the Ab are probably produced as part of the specific host immune response to various environmental antigens. Such reports strengthen the possibility of a relationship between mucosal immunity and the pathogenesis of IgAN. Nevertheless, attempts to isolate a specific IgA circulating immune complex-associated antigen in patients with IgAN have been unsuccessful.We have shown that mucosal infections such as pharyngitis are often associated with the acute onset of IgAN.1 IgAN is, then, an immune complex disease that is caused by a poor mucosal immune response to environmental antigens to which the patient has been chronically exposed. We have observed previously that Haemophilus parainfluenzae (HP) is more commonly isolated from the pharynx of patients with IgAN than from those with other glomerular diseases.2 We have also identified the glomerular deposition of outer membranes of HP antigens (OMHP) and an increased serum concentration of IgA-Ab against OMHP in patients with IgAN.2 Furthermore, we have shown that patients with IgAN have a specific increase in the production of IgA-Ab against OMHP via polyclonal activation against these, with switching of production from one isotype to another (e.g. from IgM to IgA3), and that a significant relationship between IgA-Ab against OMHP and renal lesions exists in patients with IgAN,4 and that OMHP stimulate tonsillar B-lymphocytes to produce specific IgA1-Ab against OMHP and tonsillar T-lymphocytes in patients with IgAN.5,6Our objective was to investigate the production of IgA and several cytokines by tonsillar lymphocytes from patients with IgAN induced by stimulation with OMHP. We used tonsillar lymphocytes from the palatine tonsils of 18 patients with IgAN and 25 patients with chronic tonsillitis but without renal diseases as controls. There were no significant differences in the backgrounds of the two groups. Haemophilus parainfluenzae was detected in the tonsils of all 43 patients before tonsillectomy. We examined production of total IgA, IgA-Ab against OMHP, IL-4, IL-6, IL-10, and TGF-β in the culture supernatants after lymphocyte incubation with OMHP. The spontaneous production of total IgA and TGF-β by tonsillar lymphocytes from patients with IgAN was higher than that by tonsillar lymphocytes from controls (P 〈 0.05). Stimulation with OMHP in vitro enhanced the production of HP-specific IgA by tonsillar lymphocytes from patients with IgAN (P 〈 0.01), but not by tonsillar lymphocytes from controls. Outer membranes of HP stimulation also enhanced the production of TGF-β and IL-10 by tonsillar lymphocytes from patients with IgAN (P 〈 0.001).Our results suggest that the infection of HP in the tonsil may be involved in the aetiology of IgAN.