Mycobacterium kyorinense sp. nov., a novel, slow-growing species, related to Mycobacterium celatum, isolated from human clinical specimens

A novel, non-pigmented, slow-growing mycobacterium was identified on the basis of biochemical and nucleic acid analyses, as well as growth characteristics. Three isolates were cultured from clinical samples (two from sputum and one from pus in lymph nodes) obtained from three immunocompetent patients with infections. Bacterial growth occurred at 28-42 degrees C on Middlebrook 7H11-OADC agar. The isolates showed negative results for Tween hydrolysis, nitrate reductase, semiquantitative catalase, urease activity, 3 day arylsulfatase activity, pyrazinamidase, tellurite reduction and niacin accumulation tests, but positive results for 14 day arylsulfatase activity and heat-stable catalase tests. The isolates contained alpha-, keto-, and dicarboxymycolates in their cell walls. Sequence analysis revealed that all isolates had identical, unique 16S rRNA sequences. Phylogenetic analysis of the 16S rRNA, rpoB, hsp65 and sodA gene sequences confirmed that these isolates are unique but closely related to Mycobacterium celatum. DNA-DNA hybridization of the isolates demonstrated less than 50 % reassociation with M. celatum and Mycobacterium branderi. On the basis of these findings, a novel species designated Mycobacterium kyorinense sp. nov. is proposed. The type strain is KUM 060204(T) (=JCM 15038(T)=DSM 45166(T)).

Structural analysis and biosynthesis gene cluster of an antigenic glycopeptidolipid from Mycobacterium intracellulare

Mycobacterium avium-Mycobacterium intracellulare complex (MAC) is the most common isolate of nontuberculous mycobacteria and causes pulmonary and extrapulmonary diseases. MAC species can be grouped into 31 serotypes by the epitopic oligosaccharide structure of the species-specific glycopeptidolipid (GPL) antigen. The GPL consists of a serotype-common fatty acyl peptide core with 3,4-di-O-methyl-rhamnose at the terminal alaninol and a 6-deoxy-talose at the allo-threonine and serotype-specific oligosaccharides extending from the 6-deoxy-talose. Although the complete structures of 15 serotype-specific GPLs have been defined, the serotype 16-specific GPL structure has not yet been elucidated. In this study, the chemical structure of the serotype 16 GPL derived from M. intracellulare was determined by using chromatography, mass spectrometry, and nuclear magnetic resonance analyses. The result indicates that the terminal carbohydrate epitope of the oligosaccharide is a novel N-acyl-dideoxy-hexose. By the combined linkage analysis, the oligosaccharide structure of serotype 16 GPL was determined to be 3-2'-methyl-3'-hydroxy-4'-methoxy-pentanoyl-amido-3,6-dideoxy-beta-hexose-(1-->3)-4-O-methyl-alpha-L-rhamnose-(1-->3)-alpha-L-rhamnose-(1-->3)-alpha-L-rhamnose-(1-->2)-6-deoxy-alpha-L-talose. Next, the 22.9-kb serotype 16-specific gene cluster involved in the glycosylation of oligosaccharide was isolated and sequenced. The cluster contained 17 open reading frames (ORFs). Based on the similarity of the deduced amino acid sequences, it was assumed that the ORF functions include encoding three glycosyltransferases, an acyltransferase, an aminotransferase, and a methyltransferase. An M. avium serotype 1 strain was transformed with cosmid clone no. 253 containing gtfB-drrC of M. intracellulare serotype 16, and the transformant produced serotype 16 GPL. Together, the ORFs of this serotype 16-specific gene cluster are responsible for the biosynthesis of serotype 16 GPL.

Control of cell wall assembly by a histone-like protein in Mycobacteria

Bacteria coordinate assembly of the cell wall as well as synthesis of cellular components depending on the growth state. The mycobacterial cell wall is dominated by mycolic acids covalently linked to sugars, such as trehalose and arabinose, and is critical for pathogenesis of mycobacteria. Transfer of mycolic acids to sugars is necessary for cell wall biogenesis and is mediated by mycolyltransferases, which have been previously identified as three antigen 85 (Ag85) complex proteins. However, the regulation mechanism which links cell wall biogenesis and the growth state has not been elucidated. Here we found that a histone-like protein has a dual concentration-dependent regulatory effect on mycolyltransferase functions of the Ag85 complex through direct binding to both the Ag85 complex and the substrate, trehalose-6-monomycolate, in the cell wall. A histone-like protein-deficient Mycobacterium smegmatis strain has an unusual crenellated cell wall structure and exhibits impaired cessation of glycolipid biosynthesis in the growth-retarded phase. Furthermore, we found that artificial alteration of the amount of the extracellular histone-like protein and the Ag85 complex changes the growth rate of mycobacteria, perhaps due to impaired down-regulation of glycolipid biosynthesis. Our results demonstrate novel regulation of cell wall assembly which has an impact on bacterial growth.

Deletion of kasB in Mycobacterium tuberculosis causes loss of acid-fastness and subclinical latent tuberculosis in immunocompetent mice

Mycobacterium tuberculosis, the causative agent of tuberculosis, has two distinguishing characteristics: its ability to stain acid-fast and its ability to cause long-term latent infections in humans. Although this distinctive staining characteristic has often been attributed to its lipid-rich cell wall, the specific dye-retaining components were not known. Here we report that targeted deletion of kasB, one of two M. tuberculosis genes encoding distinct beta-ketoacyl- acyl carrier protein synthases involved in mycolic acid synthesis, results in loss of acid-fast staining. Biochemical and structural analyses revealed that the DeltakasB mutant strain synthesized mycolates with shorter chain lengths. An additional and unexpected outcome of kasB deletion was the loss of ketomycolic acid trans-cyclopropanation and a drastic reduction in methoxymycolic acid trans-cyclopropanation, activities usually associated with the trans-cyclopropane synthase CmaA2. Although deletion of kasB also markedly altered the colony morphology and abolished classic serpentine growth (cording), the most profound effect of kasB deletion was the ability of the mutant strain to persist in infected immunocompetent mice for up to 600 days without causing disease or mortality. This long-term persistence of DeltakasB represents a model for studying latent M. tuberculosis infections and suggests that this attenuated strain may represent a valuable vaccine candidate against tuberculosis.

Mycobacterium kumamotonense Sp. Nov. recovered from clinical specimen and the first isolation report of Mycobacterium arupense in Japan: Novel slowly growing, nonchromogenic clinical isolates related to Mycobacterium terrae complex

Three mycobacterium strains isolated from clinical specimens in Japan were provisionally assigned to the genus Mycobacterium based on their phenotypical characteristics. These isolates were further investigated to determine their specific taxonomic statuses. Mycolic acid analysis and 16S rRNA gene, rpoB, and hsp65 sequence data for the isolates showed that they are most similar to M. terrae complex. DNA-DNA hybridization studies indicated that the three strains were of two species and were distinguishable from M. terrae, M. nonchromogenicum, and M. hiberniae. Therefore, these strains represent two novel species within the genus Mycobacterium. However, one potential new species should have been considered as M. arupense with the 16S rRNA gene and hsp65 sequences similarities of 99.8% and 100% respectively; it was isolated from human specimens in the United States and was proposed in June 2006 as a new species. This report describes the first isolation of M. arupense in Japan, suggesting that the organism is clinically relevant. In addition, we propose the novel species designation Mycobacterium kumamotonense sp. nov. The type strain is CST 7247(T) (=GTC 2729(T), =JCM 13453(T), =CCUG 51961(T)).

Neutrophil-activating activity and platelet-activating factor synthesis in cytokine-stimulated endothelial cells: Reduced activity in growth-arrested cells

The reactivity of endothelial cells (ECs) to proinflammatory cytokines is critically important for the pathogenesis of vascular diseases. Here, we studied functional alterations of human ECs during culture under a confluent condition; i.e., the alterations of neutrophil-activating activity, platelet-activating factor (PAF) synthesis, and granulocyte-macrophage colony-stimulating factor (GM-CSF) production in cytokine-stimulated ECs. Human umbilical vein-derived ECs exhibited the increased activity in neutrophil activation, PAF synthesis, and GM-CSF production when stimulated by proinflammatory cytokines such as interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha). The activity of cytokine-stimulated ECs to stimulate superoxide release in human neutrophils and to produce PAF declined markedly in parallel as ECs became growth-arrested during culture under a confluent condition. By contrast, GM-CSF production induced by cytokine stimulation was modestly increased, and up-regulation of intercellular adhesion molecule-1 (ICAM-1) and activation of mitogen-activated protein kinases were not altered. The neutrophil-activating activity of cytokine-stimulated ECs was dependent on PAF synthesis and GM-CSF production from ECs. These findings indicate that the reduced neutrophil-activating activity in growth-arrested ECs may be, at least in part, ascribed to down-regulation of PAF synthesis.

Structural characterization of a specific glycopeptidolipid containing a novel N-acyl-deoxy sugar from mycobacterium intracellulare serotype 7 and genetic analysis of its glycosylation pathway

The nontuberculous Mycobacterium avium-Mycobacterium intracellulare complex (MAC) is distributed ubiquitously in the environment and is an important cause of respiratory and lymphatic disease in humans and animals. These species produce polar glycopeptidolipids (GPLs), and of particular interest is their serotype-specific antigenicity. Structurally, GPLs contain an N-acylated tetrapeptide-amino alcohol core that is glycosylated at the C terminal with 3,4-di-O-methyl rhamnose and at the d-allo-threonine with a 6-deoxy-talose. This serotype nonspecific GPL is found in all MAC species. The serotype-specific GPLs are further glycosylated with a variable haptenic oligosaccharide at 6-deoxy-talose. At present, 31 distinct serotype-specific GPLs have been identified on the basis of oligosaccharide composition, and the complete structures of 14 serotype-specific GPLs have been defined. It is considered that the modification of the GPL structure plays an important role in bacterial physiology, pathogenesis, and host immune responses. In this study, we defined the complete structure of a novel serotype 7 GPL that has a unique terminal amido sugar. The main molecular mass is 1,874, and attached to the tetrapeptide-amino alcohol core is the serotype 7-specific oligosaccharide unit of 4-2'-hydroxypropanoyl-amido-4,6-dideoxy-2-O-methyl-beta-hexose-(1-->3)-alpha-l-rhamnose-(1-->3)-alpha-l-rhamnose-(1-->3)-alpha-l-rhamnose-(1-->2)-alpha-l-6-deoxy-talose. Moreover, we isolated and characterized the serotype 7-specific gene cluster involved in glycosylation of the oligosaccharide. Nine open reading frames (ORFs) were observed in the cluster. Based on the sequence homology, the ORFs are thought to participate in the biosynthesis of the serotype 7 GPL.

Ligand-of-Numb protein X is an endocytic scaffold for junctional adhesion molecule 4

Junctional adhesion molecule 4 (JAM4) is a cell adhesion molecule that interacts with a tight junction protein, membrane-associated guanylate kinase inverted 1 (MAGI-1). Our previous studies suggest that JAM4 is implicated in the regulation of paracellular permeability and the signalings of hepatocyte growth factor. In this study, we performed yeast two-hybrid screening to search for an unidentified JAM4-binding protein and obtained one isoform of Ligand-of-Numb protein X1 (LNX1), LNXp70, that is an interactor of Numb. Ligand-of-Numb protein X1 is expressed in kidney glomeruli and intestinal epithelial cells, where JAM4 is also detected. Immunoprecipitation from kidney lysates supports the in vivo interaction of proteins. Biochemical studies reveal that JAM4 directly binds the second PDZ domain of LNX1 through its carboxyl terminus. Junctional adhesion molecule 4, LNX1 and Numb form a tripartite complex in vitro and are partially colocalized in heterologous cells. Ligand-of-Numb protein X1 facilitates endocytosis of JAM4 and is involved in transforming growth factor beta -induced redistribution of JAM4 in mammary epithelial cells. Experiments using dominant-negative constructs and RNA interference insure that Numb is necessary for the LNX1-mediated endocytosis of JAM4. All these findings indicate that LNX1 provides an endocytic scaffold for JAM4 that is implicated in the reorganization of cell junctions.

Macrophages in inflammation

The inflammatory process is usually tightly regulated, involving both signals that initiate and maintain inflammation and signals that shut the process down. An imbalance between the two signals leaves inflammation unchecked, resulting in cellular and tissue damage. Macrophages are a major component of the mononuclear phagocyte system that consists of closely related cells of bone marrow origin, including blood monocytes, and tissue macrophages. From the blood, monocytes migrate into various tissues and transform macrophages. In inflammation, macrophages have three major function; antigen presentation, phagocytosis, and immunomodulation through production of various cytokines and growth factors. Macrophages play a critical role in the initiation, maintenance, and resolution of inflammation. They are activated and deactivated in the inflammatory process. Activation signals include cytokines (interferon gamma, granulocyte-monocyte colony stimulating factor, and tumor necrosis factor alpha), bacterial lipopolysaccharide, extracellular matrix proteins, and other chemical mediators. Inhibition of inflammation by removal or deactivation of mediators and inflammatory effector cells permits the host to repair damages tissues. Activated macrophages are deactivated by anti-inflammatory cytokines (interleukin 10 and transforming growth factor beta) and cytokine antagonists that are mainly produced by macrophages. Macrophages participate in the autoregulatory loop in the inflammatory process. Because macrophages produce a wide range of biologically active molecules participated in both beneficial and detrimental outcomes in inflammation, therapeutic interventions targeted macrophages and their products may open new avenues for controlling inflammatory diseases.

Mycobacterial trehalose 6,6′-dimycolate preferentially induces type 1 helper T cell responses through signal transducer and activator of transcription 4 protein

Mycobacterium tuberculosis is an intracellular pathogen of tuberculosis and its pathogenicity is related to the ability to escape killing by ingested macrophages and induce delayed-type hypersensitivity (DTH). A major component of the cell wall of M. tuberculosis is trehalose 6,6'-dimycolate (TDM), which has been implicated as a pathogenetic factor. The expression of DTH and cell-mediated immunity is dependent on the macrophage-cytokine-type 1 helper T (Th1) lymphocyte axis. Cytokines, interleukin-12 (IL-12) and interferon-gamma (IFN-gamma), play a critical role in the process and IL-12-activated signal transducer and activator of transcription (STAT) 4 is required for the development of fully functional Th1 cells. To clarify host responses to mycobacterial TDM, we have analyzed footpad reaction, histopathology and cytokine profile of experimental granulomatous lesions using STAT4-deficient mice. In the present study, we have demonstrated that mycobacterial TDM selectively induces the Th1 response through the STAT4 signaling pathway, because mice lacking STAT4 protein significantly reduced to develop DTH, hypersensitivity granulomas, and Th1 cytokine responses, when compared to BALB/c mice. These results shed light on the molecular pathogenesis of mycobacterial disease. Taken together with previous studies, TDM is a pleiotropic molecule against the host and participates in the pathogenesis.

Use of glycopeptidolipid core antigen for serodiagnosis of mycobacterium avium complex pulmonary disease in immunocompetent patients

We report the development of a serodiagnostic method for Mycobacterium avium complex (MAC) disease with an enzyme immunoassay (EIA) with the MAC-specific glycopeptidolipid (GPL) core as the antigen. In this study, we confirmed by EIA that the GPL core antibody was in the sera of immunocompetent patients with MAC disease. The EIA for quantifying the GPL core antibody was evaluated as a clinical tool for serodiagnosis of pulmonary MAC disease. A significant increase in GPL core antibodies (immunoglobulins G, A, and M) was detected in sera of patients with MAC pulmonary diseases when they were compared to patients who were colonized with MAC, patients with Mycobacterium kansasii disease or tuberculosis, and healthy subjects. The sensitivities and specificities of the GPL core-based EIA for diagnosis of MAC pulmonary disease were 72.6% and 92.2%, respectively, for IgG, 92.5% and 95.1%, respectively, for IgA, and 78.3% and 91.0%, respectively, for IgM. The best sensitivity and specificity were obtained by measuring immunoglobulin A antibodies against GPL core antigen. The level of GPL core antibodies reflected disease activity, since it decreased in cured MAC patients who had responded to chemotherapy. Measurement of serum antibodies against GPL core is useful for both diagnosis and assessment of disease activity in MAC disease of the lung.

Modulation of CD1d-restricted NKT cell responses by using N-acyl variants of alpha-galactosylceramides

A form of alpha-galactosylceramide, KRN7000, activates CD1d-restricted Valpha14-invariant (Valpha14i) natural killer (NK) T cells and initiates multiple downstream immune reactions. We report that substituting the C26:0 N-acyl chain of KRN7000 with shorter, unsaturated fatty acids modifies the outcome of Valpha14i NKT cell activation. One analogue containing a diunsaturated C20 fatty acid (C20:2) potently induced a T helper type 2-biased cytokine response, with diminished IFN-gamma production and reduced Valpha14i NKT cell expansion. C20:2 also exhibited less stringent requirements for loading onto CD1d than KRN7000, suggesting a mechanism for the immunomodulatory properties of this lipid. The differential cellular response elicited by this class of Valpha14i NKT cell agonists may prove to be useful in immunotherapeutic applications.

Mycobacterium tuberculosis controls host innate immune activation through cyclopropane modification of a glycolipid effector molecule

Mycobacterium tuberculosis (Mtb) infection remains a global health crisis. Recent genetic evidence implicates specific cell envelope lipids in Mtb pathogenesis, but it is unclear whether these cell envelope compounds affect pathogenesis through a structural role in the cell wall or as pathogenesis effectors that interact directly with host cells. Here we show that cyclopropane modification of the Mtb cell envelope glycolipid trehalose dimycolate (TDM) is critical for Mtb growth during the first week of infection in mice. In addition, TDM modification by the cyclopropane synthase pcaA was both necessary and sufficient for proinflammatory activation of macrophages during early infection. Purified TDM isolated from a cyclopropane-deficient pcaA mutant was hypoinflammatory for macrophages and induced less severe granulomatous inflammation in mice, demonstrating that the fine structure of this glycolipid was critical to its proinflammatory activity. These results established the fine structure of lipids contained in the Mtb cell envelope as direct effectors of pathogenesis and identified temporal control of host immune activation through cyclopropane modification of TDM as a critical pathogenic strategy of Mtb.

Rothia aeria sp. nov., Rhodococcus baikonurensis sp. nov. and Arthrobacter russicus sp. nov., isolated from air in the Russian space laboratory Mir

Four Gram-positive bacteria, strains A1-17BT, A1-22T, A1-3T and A1-8, isolated from the air in the Russian space laboratory Mir, were subjected to a polyphasic taxonomic study. Phylogenetic analysis of the bacteria based on their 16S rDNA sequence showed that they belong to the genera Rothia (A1-17BT), Rhodococcus (A1-22T) and Arthrobacter (A1-3T and A1-8). Morphological, physiological, chemotaxonomic and genomic characteristics supported the assignments of these strains to these genera, but they could not be classified as any existing species within each respective genus. 16S rDNA similarity values between strain A1-17BT and its neighbours, Rothia dentocariosa genomovar II, Rothia dentocariosa, Rothia mucilaginosa and Rothia nasimurium, were respectively 99·8, 98·0, 96·4 and 95·4 %. Polyphasic taxonomic evidence indicated that strain A1-17BT should be categorized together with the unofficially named Rothia dentocariosa genomovar II, but clearly differentiated them from the established species of the genus Rothia. Strain A1-22T formed a coherent cluster with Rhodococcus erythropolis, Rhodococcus globerulus, Rhodococcus marinonascens and Rhodococcus percolatus in 16S rDNA sequence analysis, but DNA–DNA relatedness values were only 45·5, 35·3, 18·9 and 21·9 %. Strains A1-3T and A1-8 shared 99·9 % 16S rDNA sequence similarity, and strain A1-3T showed the highest level of 16S rDNA similarity, 96·6 %, to Arthrobacter polychromogenes. Contrasting biochemical characteristics were also identified. Finally, as a result of the polyphasic taxonomic study, three of the strains are proposed as type strains of novel species: Rothia aeria sp. nov. (A1-17BT=GTC 867T=JCM 11412T=DSM 14556T), Rhodococcus baikonurensis sp. nov. (A1-22T=GTC 1041T=JCM 11411T=DSM 44587T) and Arthrobacter russicus sp. nov. (A1-3T=GTC 863T=JCM 11414T=DSM 14555T).

Sphingomonas yabuuchiae sp. nov. and Brevundimonas nasdae sp. nov., isolated from the Russian space laboratory Mir

On the basis of phenotypic and genotypic characteristics and 16S rRNA gene sequence analysis, novel species belonging to the genera Sphingomonas and Brevundimonas were identified from samples taken from the Russian space laboratory Mir. Strain A1-18T was isolated from the air. 16S rDNA sequence analysis showed that strain A1-18T formed a coherent cluster with Sphingomonas sanguinis, Sphingomonas parapaucimobilis, Sphingomonas paucimobilis and Sphingomonas roseiflava with sequence similarity of 97·5–98·6 %. Similar to other Sphingomonas species, the G+C content was 66·1 mol%, but DNA–DNA hybridization rates at optimal temperatures among these related species were only 24·7–51·7 %. Strain A1-18T can be differentiated biochemically from related species. Strain W1-2BT was isolated from condensation water. It forms a distinct lineage within the genus Brevundimonas, forming a coherent cluster with Brevundimonas vesicularis, Brevundimonas aurantiaca and Brevundimonas intermedia. 16S rDNA sequence similarities were 98·6–99·5 % and the G+C content was 66·5 mol%, similar to other Brevundimonas species, but DNA–DNA relatedness was only 50·2–54·8 %. Strain W1-2BT also showed some differential biochemical properties from its related species. A series of polyphasic taxonomic studies led to the proposal of two novel species, Sphingomonas yabuuchiae sp. nov. (type strain A1-18T=GTC 868T=JCM 11416T=DSM 14562T) and Brevundimonas nasdae sp. nov. (type strain W1-2BT=GTC 1043T=JCM 11415T=DSM 14572T).

Structural analysis of sphingophospholipids derived from Sphingobacterium spiritivorum, the type species of genus Sphingobacterium

The unique feature of the genus Sphingobacterium is the presence of sphingophospholipids and ceramides, besides diacylglycerophospholipids. As major cellular lipid components, five kinds of sphingophospholipids were purified from Sphingobacterium spiritivorum ATCC 33861(T), the type species of genus Sphingobacterium. They were identified as ceramide phosphorylethanolamines (CerPE-1 and CerPE-2), ceramide phosphoryl-myo-inositols (CerPI-1 and CerPI-2), and ceramide phosphorylmannose (CerPM-1). The ceramide of CerPE-1, CerPI-1, and CerPM-1 was composed of 15-methylhexadecasphinganine (isoheptadeca sphinganine, iso-C17:0) and 13-methyltetradecanoic acid (isopentadecanoic acid, iso-C15:0), whereas that of CerPE-2 and CerPI-2 was composed of isoheptadeca sphinganine and 2-hydroxy-13-methyltetradecanoic acid (2-hydroxy isopentadecanoic acid, 2-OH iso-C15:0). These sphingophospholipids were also found in cellular lipids of Sphingobacterium multivorum ATCC 33613(T), Sphingobacterium mizutaii ATCC 33299(T), Sphingobacterium faecium IFO 15299(T), Sphingobacterium thalpophilum ATCC 43320(T), and Sphingobacterium antarcticum ATCC 51969(T). To our knowledge, the existence of CerPM-1 is a novel sphingophospholipid through eukaryotic and prokaryotic cells.

Chryseobacterium miricola sp. nov., a novel species isolated from condensation water of space station Mir

Classification of strain W3-B1, which was isolated from condensation water in the Russian space laboratory Mir, was investigated by a polyphasic taxonomic approach. Cells of strain W3-B1 were nonmotile, asporogenous, gram-negative slender rods with rounded ends. 16S rRNA gene sequence analysis indicated that organism should be placed in the genus Chryseobacterium. This organism contains menaquinone MK-6 as the predominent isoprenoid quinone and 3-OH iso 17:0 (40%), iso 15:0 (33%) as the major fatty acids. Phylogenetically, the nearest relative of strain W3-B1 is Chryseobacterium meningosepticum with sequence similarity of 98.4%, but DNA-DNA hybridization resulted in similarity values of only 52.3%. The G+C mol% is 34.6 mol%. Based upon results obtained by morphological, biochemical, chemotaxonomic, and molecular methods, strain W3-B1 was clearly distinguishable from other Chryseobacterium species. For these reasons, a novel species of family Flavobacteriaceae is proposed; strain W3-B1(T) (= GTC 862(T) = JCM 11413(T) = DSM 14571(T)) is the type strain.

Asymmetric transport due to spin injection into a Kondo alloy

Spin injection is found to have a significant effect on the transport properties of the Kondo alloy Cu(Fe). When a spin-polarized electron current flows from Co into Cu(Fe) wires through the Co/Cu(Fe) interface, the resistivity of the Cu(Fe) wire is suppressed near the interface, as distinct from the ordinary logarithmic increase in the resistivity at low temperatures. For the opposite current direction, no significant changes are observed. The asymmetry of the resistivity with respect to the current direction decays with a characteristic length of 1.5+/-0.4 microm at 2.5 K as the distance from the interface is increased. Possible mechanisms for the asymmetry are discussed.

Serodiagnosis of pulmonary disease due to Mycobacterium avium complex with an enzyme immunoassay that uses a mixture of glycopeptidolipid antigens

It is difficult to distinguish pulmonary disease due to Mycobacterium avium complex (MAC) from that due to other mycobacteria, such as Mycobacterium tuberculosis and Mycobacterium kansasii. We developed an enzyme immunoassay (EIA) for diagnosis of MAC pulmonary diseases that uses glycopeptidolipid (GPL) antigens specific for MAC, and we used it for diagnosis in immunocompetent patients. The mean optical densities (+/- standard deviation) of serum immunoglobulin G antibodies to GPLs in patients with MAC disease, MAC colonization, M. kansasii disease, and tuberculosis and in healthy subjects were 0.778+/-0.784, 0.042+/-0.035, 0.059+/-0.035, 0.071+/-0.035, and 0.030+/-0.027, respectively. A significant increase in the level of anti-GPL antibodies was detected in patients with MAC disease. The level of anti-GPL antibodies reflected disease activity, because the level was decreased in culture-negative patients who had conversion of culture results. When a cutoff level of seropositivity (0.119) was defined, the sensitivity of EIA for diagnosis of MAC disease was 92.3%, and the specificity was 96.7%. Measurement of serum anti-GPL antibodies is useful for both the diagnosis of and assessment of activity in MAC disease.

Sphingomonas melonis sp. nov., a novel pathogen that causes brown spots on yellow Spanish melon fruits

A polyphasic taxonomic study was performed on the phytopathogenic bacterial strains DAPP-PG 224(T) and DAPP-PG 228, which cause brown spot on yellow Spanish melon (Cucumis melo var. inodorus) fruits. Based on the presence of glucuronosyl ceramide (SGL-1) in cellular lipids, the results of fatty acid analysis and 16S rDNA sequence comparison, the strains had been identified as belonging to the genus Sphingomonas and as phylogenetically related to Sphingomonas mali, Sphingomonas pruni and Sphingomonas asaccharolytica. The levels of 16S rDNA sequence similarity of these three species to strain DAPP-PG 224(T) were respectively 98.0, 98.0 and 97.4%. DNA-DNA hybridization experiments between strains pathogenic on melon fruit and S. mali, S. pruni and S. asaccharolytica revealed < or = 16% relatedness. Based on these results, the two isolates studied are regarded as independent from the type strains of the three species mentioned above. Sphingomonas strains from melon fruits are recognized as forming a genetically and phenotypically discrete species and to be differentiated by phenotypic characteristics from all 29 named species of the genus. Thus, the name Sphingomonas melonis sp. nov. is proposed for the isolates from diseased melon fruits. The type strain is DAPP-PG 224(T) (= LMG 19484(T) = DSM 14444(T)). The G+C content of DNA of the type strain is 65.0 mol%.

Emendation of the genus Sphingomonas Yabuuchi et al. 1990 and junior objective synonymy of the species of three genera, Sphingobium, Novosphingobium and Sphingopyxis, in conjunction with Blastomonas ursincola

The 16S rDNA sequence similarities between the type strains of Sphingomonas paucimobilis and 32 other Sphingomonas species range from 90.2 to 99.6%. It might be possible to divide the genus into several new genera according to a dendrogram drawn from 16S rDNA sequence similarity. However, the phenotypic and biochemical information needed to define clusters of strains representing distinct genera within this group of organisms was not previously available. Although the cellular lipids of type strains of all 28 Sphingomonas species tested contained glucuronosyl-(1 --> 1)-ceramide together with 2-hydroxymyristic acid, other molecular species of sphingoglycolipids were distributed randomly. Sphingomonas natatoria and Sphingomonas ursincola, bacteriochlorophyll a-containing, gram-negative facultative phototrophs, belong to the cluster of the genus Sphingomonas. Other phototrophic Porphyrobacter and Erythrobacter species in the Sphingomonadaceae were classified into a cluster different from the genus Sphingomonas, as reported previously. None of the physiological and biochemical characteristics considered, including cellular lipids and fatty acid composition, provided evidence for the division of the current genus Sphingomonas. It is therefore concluded that the genus Sphingomonas should remain undivided at this time. The species of three recently proposed genera, Sphingobium, Novosphingobium and Sphingopyxis, in conjunction with Blastobacter ursincola, are junior objective synonyms of species of the genus Sphingomonas.

Maturational change of parallel auditory processing in school-aged children revealed by simultaneous recording of magnetic and electric cortical responses

OBJECTIVES

To elucidate the maturational change of cortical auditory processing, we analyzed simultaneously recorded auditory evoked potentials (AEPs) and magnetic fields (AEFs) in school-aged children.

METHODS

Simultaneous recording of AEP and AEF were performed in 32 healthy children of age ranging from 6 to 14 years and 10 adults. Tone bursts of 1 kHz were presented to the left and right ears alternately with 3 different within-ear stimulus onset asynchronies (SOAs) (1.6, 3.0 and 5.0 s for each ear) under attention-distracted condition.

RESULTS

All subjects showed clear N100 and N100m peaks under the longest SOA condition (5.0 s). Under the shortest SOA condition (1.6 s), 4 out of 19 subjects under 12 years (21%) failed to show the N100m component. By contrast, N250 and N250m were observed in the majority of children (29/32: 91%) while those were detected in only 4 out of 10 adults (40%). The spatial distribution of N100 in children under 9 years differed from that in older subjects, whereas the dipole orientation of N100m was constant among age groups, suggesting that radially oriented sources might make additional contribution to the generation of N100 in early childhood. N250 was significantly larger in children than in adults. The strength of N250 was suppressed with longer SOAs, whereas that of N100 was enhanced. The dipole of N250m was located around Heschl's gyrus on the superior temporal plane which was significantly medial, anterior and inferior to that of N100m.

CONCLUSIONS

Dissociation of maturational change between the tangential and radial components of N100 suggests that auditory processing at around 100 ms consists of multiple parallel pathways which mature independently. Furthermore, a negative peak at around 250 ms specifically seen in children has different generators from N100 and might represent a special auditory processing which takes an active part until acquisition of the efficient cortical networks of the adult brain.

A mechanism for mercury oxidation in coat-derived exhausts

This paper evaluates an elementary reaction mechanism for Hg0 oxidation in coal-derived exhausts consisting of a previously formulated homogeneous mechanism with 102 steps and a new three-step heterogeneous mechanism for unburned carbon (UBC) particles. Model predictions were evaluated with the extents of Hg oxidation monitored in the exhausts from a pilot-scale coal flame fired with five different coals. Exhaust conditions in the tests were very similar to those in full-scale systems. The predictions were quantitatively consistent with the reported coal-quality impacts over the full range of residence times. The role of Cl atoms in the homogeneous mechanism is hereby supplanted with carbon sites that have been chlorinated by HCl. The large storage capacity of carbon for Cl provided a source of Cl for Hg oxidation over a broad temperature range, so initiation was not problematic. Super-equilibrium levels of Cl atoms were not required, so Hg was predicted to oxidize in systems with realistic quench rates. Whereas many fundamental aspects of the heterogeneous chemistry remain uncertain, the information needed to characterize Hg oxidation in coal-derived exhausts is now evident: complete gas compositions (CO, hydrocarbons, H2O, O2 NOx, SOx), UBC properties (size, total surface area), and the ash partitioning throughout the exhaust system are required.

Discrepancies in dietary intakes and plasma concentrations of fatty acids according to age among Japanese female dietitians

OBJECTIVE

To clarify the influences of age on dietary intakes and plasma concentrations of fatty acids (FAs) in Japanese female dietitians.

SUBJECTS AND METHODS

In autumn 1996, we estimated dietary FA intakes based on 7 day weighed diet records and analyzed plasma FA concentrations in 79 healthy Japanese female dietitians, and investigated their relationships with age, dividing into three age groups (young (32-42 y), middle-aged (43-50 y) and elderly (51-66 y)).

RESULTS

Dietary intakes of total FA, saturated FAs, monounsaturated FAs, n-3 polyunsaturated FAs (PUFAs) and alpha-linolenic acid (18:3n-3) were significantly highest in the middle-aged group, and lowest in the elderly. Similar trends were observed for dietary intakes of n-6 PUFAs and linoleic acid (18:2n-6), but there were no differences with regard to eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3) and n-3 highly unsaturated FAs (HUFAs=EPA+22:5n-3+DHA). On the other hand, plasma concentrations of all FAs except for arachidonic acid (20:4n-6) demonstrated positive correlations with age. Moreover, plasma concentrations of EPA in all age groups, DHA in the elderly and n-3 HUFAs in the middle-aged and the elderly were all positively correlated with dietary intakes.

CONCLUSIONS

We should take into account the influence of age on dietary habit and lipid metabolism when interpreting associations between dietary FA intakes and plasma FA concentrations.

Enzymatic reaction of hydrogen peroxide-dependent peroxygenase cytochrome P450s: kinetic deuterium isotope effects and analyses by resonance Raman spectroscopy

Cytochromes P450SP(alpha) (CYP152B1) and P450BS(beta) (CYP152A1), which are isolated from Sphingomonas paucimobilis and Bacillus subtilis, respectively, belong to the P450 superfamily, but catalyze hydroxylation reactions, in which an oxygen atom from H2O2 is efficiently introduced into fatty acids (e.g., myristic acid). P450SP(alpha) produces the alpha-hydroxylated (alpha-OH) products at 100%, while P450BS(beta) produces alpha- and beta-hydroxylated (beta-OH) products at 33 and 67%, respectively. Using deuterium-substituted fatty acids ([2,2-d2]-myristic acid and d27-myristic acid) as a substrate, the peroxygenase reactions of the two bacterial P450s were investigated. In the P450SP(alpha) reaction, we observed an intermolecular noncompetitive kinetic isotope effect on Vmax (DV = 4.1) when [2,2-d2]-myristic acid was used, suggesting that an isotopically sensitive step involving the alpha-hydrogen of the fatty acid is present in the catalytic cycle. On the other hand, D(V/K) was masked, in sharp contrast to the features of usual monooxygenases P450. The characteristic kinetic features can be interpreted in terms of the faster product formation than the substrate dissociation. A similar kinetic isotope effect was observed [DV = 4.9, D(V/K) approximately 1] for the P450BS(beta) reaction, when d27-myristic acid was used as a substrate, indicating that the reaction mechanism is the same for both peroxygenases. The resonance Raman spectral data of P450BS(beta) in the ferric and ferrous-CO forms in the presence and absence of myristic acid demonstrated that the catalytic pocket of the enzyme is polar, so that the location of the carboxylate of the substrate close to the sixth ligand of the heme could be allowed. On the basis of these results on the kinetic isotope effects and spectroscopy, we discuss the possible mechanisms of the alpha- and beta-hydroxylation of fatty acids catalyzed by peroxygenases P450SP(alpha) and P450BS(beta).

Optical imaging of excitation propagation evoked by stimulation to the trigeminal caudalis

The present study reports on a characteristic spatio-temporal propagation of differential fluorescent images in the rat brain stem slice by a high-speed optical imaging technique. Coronal or sagittal slices were stained with a voltage-sensitive dye RH-414, and the superficial layer of the trigeminal caudalis (Vc) was then electrically stimulated. The marginal layer and substantia gelatinosa showed larger rostrocaudal excitation than coronal, despite a lack of tract stimulation expansion in either direction. A perfusion of 0.5 micromol/l TTX, not 10 micromol/l CNQX suppressed these propagations. These findings suggest that the superficial layer of Vc has spatial differences in neuronal excitation propagation, as evidenced by morphological observations that dendrites in the superficial layers extend in the rostrocaudal direction.

Vasospastic total occlusion at the left main tract in a single coronary artery

A 64-year-old man was admitted to hospital under the suspicion of unstable angina pectoris. Coronary angiography showed that he has a single coronary artery originating from the right coronary artery (RCA) without significant fixed stenosis. Acetylcholine was superselectively infused into the left main coronary artery (LMCA), and confirmed the coronary vasospastic occlusion associated with chest pain and elevation of the ST-segment in the precordial leads. This is the first report of the induction of a totally occlusive spasm of the LMCA of a patient with a RCA type single coronary artery, and this case suggests that spasm of the aberrant coronary artery is a potential mechanism for sudden death in patients with a single coronary artery.

Dioxin and fly ash free incineration by ash pelletization and reburning

Dioxins (DXNs) in municipal waste incinerator fly ash were effectively reduced by pelletizing the mixture of ash, cement, and sodium phosphate and reburning the pellets in a laboratory scale bubbling fluidized bed (BFB) furnace. Three types of pellets--A, B and C, of various sizes and compositions were used in the experiments. The efficiency of DXN reduction in the pellet matrix was proportional to the incineration time, temperature, and degree of pellet incineration. At 700 degrees C and incineration time sufficient for a complete burnout, the efficiency of DXN reduction in the pellets of type A and C was found to be 99.9% and 99.7%, respectively. Correspondingly, the DXN concentration in the pellets decreased from 862 ng TEQ/kg to 0.9 ng TEQ/kg for pellets A and 2.2 ng TEQ/kg for pellets C. The residual concentration of coplanar polychlorinated biphenyls (coplanar PCBs) was below 0.2 ng TEQ/kg and 0.4 ng TEQ/kg, respectively. Assuming a tortuosity factor of tau = 3 and the reaction rate constants of 0.013 m/s (at 700 degrees C) and 0.025 m/s (at 800 degrees C), the experimental pellet incineration times were reasonably predicted by using the shrinking core model. Possible DXN evaporation from the pellets was also studied. The amount of DXNs in the flue gas captured by an impinger trap was less than 3% when the reactor was operated at 700 and 800 degrees C. The described method of fly ash pelletization and reburning seems to be a relatively easy and inexpensive way to reduce both the emission of DXNs and the amount of fly ash.

Kinetic modeling of homogeneous mercury oxidation: the importance of NO and H2O in predicting oxidation in coal-derived systems

This paper develops and evaluates an elementary reaction mechanism for homogeneous Hg0 oxidation that accounts for major interactions among Cl-species and other pollutants in coal-derived exhausts. Most importantly, interactions among NO and Cl-species were found to exert a strong and previously unrecognized impact on homogeneous Hg0 oxidation under some but not all conditions. The proposed oxidation mechanism is subjected to quantitative evaluations against all the available laboratory datasets that characterize homogeneous Hg0 oxidation when HCl is the primary chlorinated species. The simulations depict the reported extents of oxidation for broad ranges of HCl and temperature within useful quantitative tolerances without any heuristic parameter adjustments. The predicted pool of Cl-atoms was found to be governed by the chemistries of moist CO oxidation, Cl-species transformations, and NO production. However, an artificial initiation scheme was needed to depict the temperature dependence observed in one set of literature data. This indicates that either the kinetic mechanisms are incomplete or that heterogeneous initiation came into play under these test conditions. The evaluations further show that Hg oxidation is primarily through a Cl atom recycle process, with Cl and Cl2 concentrations both playing an important role. Oxygen weakly promotes homogeneous Hg oxidation, whereas moisture is a stronger inhibitor. NO can promote or inhibit homogeneous Hg oxidation, depending on its concentration. In the presence of NO, extents of Hg oxidation increased for progressively faster quenching. Conversely, without NO, extents of oxidation diminished for faster quenching.

Relative validity of a semi-quantitative food frequency questionnaire versus 28 day weighed diet records in Japanese female dietitians

OBJECTIVE

To assess the relative validity of a semi-quantitative food frequency questionnaire (SQFFQ) against 28 day weighed diet records (WDRs).

SUBJECTS AND METHODS

The SQFFQ was administered to 106 (21 male and 85 female) Japanese dietitians in Aichi Prefecture in autumn, 1996 and four-season consecutive 7 day WDRs were carried out during 1996-1997. We evaluated validity of intakes of 15 foods and 31 macro- and micro-nutrients based on the SQFFQ against those according to 28 day WDRs among 79 Japanese female dietitians.

RESULTS

Mean daily intakes of selected foods and nutrients determined by the SQFFQ were generally equivalent to those measured by 28 day WDRs. Pearson's de-attenuated correlation coefficients (CCs) with log-transformation and energy-adjustment between intakes of selected foods and nutrients quantified by the SQFFQ and 28 day WDRs (minimum-median-maximum) ranged from 0.17 (beverages)-0.52 to 0.74 (rice), and Spearman's rank CCs with energy-adjustment ranged from 0.28 (confectionery)-0.42 to 0.68 (rice). Respective Pearson's CCs for intakes of nutrients were 0.28 (PUFAs)-0.51 to 0.73 (magnesium), and Spearman's rank CCs ranged from 0.23 (n-3 PUFAs)-0.45 to 0.71 (magnesium). Favorably higher agreement for intakes of foods/nutrients was achieved along with lower disagreement.

CONCLUSIONS

Satisfactorily higher relative validity was attained in Japanese female dietitians with the SQFFQ. This calibrated questionnaire seems therefore appropriate for administration to Japanese dietitians to clarify associations between diet and health/disease.

SPONSORSHIP

A grant-in-aid from the Ministry of Education, Science, Sports and Culture (06454242).

Mycobacterial cord factor, but not sulfolipid, causes depletion of NKT cells and upregulation of CD1d1 on murine macrophages

Trehalose 6,6'-dimycolate (TDM, cord factor) has frequently been used as an adjuvant to stimulate antibody production. Although it also induces cellular immunity, detailed studies about the underlying events do not exist. To determine the kinetics of TDM-specific changes promoting a T helper 1 (Th1) response, we injected mice with TDM or 2,3,6,6'-tetraacyl trehalose 2'-sulfate (SL, sulfolipid), another mycobacterial trehalose-containing glycolipid without mycolic acid. TDM, but not SL, caused a strong increase in serum interferon-gamma (IFN-gamma) levels 2 days later, accompanied by expansion of natural killer (NK) cells. Subsequent TDM effects included depletion of normal-density CD4(+) NK1.1(+) TCRalpha/beta(intermediate) cells from day 7 on, upregulation of MHC class II and CD1d1 on macrophages (peaking on day 21), and an increased proportion of Th1 cells evident after 3 weeks. TDM, but not a similar glycolipid without mycolic acid, can therefore initiate a cascade of events starting with strong release of IFN-gamma and NK cell expansion, resulting in the appearance of macrophages activated for antigen presentation. Our data therefore provide the basis for optimized immunization schedules with TDM as the adjuvant component of a Th1 vaccine.

Roles of N-terminal active cysteines and C-terminal cysteine-selenocysteine in the catalytic mechanism of mammalian thioredoxin reductase

Mammalian thioredoxin reductase [EC 1.6.4.5], a homodimeric flavoprotein, has a marked similarity to glutathione reductase. The two cysteines in the N-terminal FAD domain (-Cys59-x-x-x-x-Cys64-) and histidine (His472) are conserved between them at corresponding positions, but the mammalian thioredoxin reductase contains a C-terminal extension of selenocysteine (Sec or U) at the penultimate position and a preceding cysteine (-Gly-Cys497-Sec498-Gly). Introduction of mutations into the cloned rat thioredoxin reductase gene revealed that residues Cys59, Cys64, His472, Cys497, and Sec498, as well as the sequence of Cys497 and Sec498 were essential for thioredoxin-reducing activity. To analyze the catalytic mechanism of the mammalian thioredoxin reductase, the wild-type, U498C, U498S, C59S, and C64S were overproduced in a baculovirus/insect cell system and purified. The wild-type thioredoxin reductase produced in this system, designated as WT, was found to lack the Sec residue and to terminate at Cys497. A Sec-containing thioredoxin reductase, which was purified from COS-1 cells transfected with the wild-type cDNA, was designated as SecWT and was used as an authentic enzyme. Among mutant enzymes, only U498C retained a slight thioredoxin-reducing activity at about three orders magnitude lower than SecWT. WT, U498C, and U498S showed some 5,5'-dithiobis(2-nitrobenzoic acid)-reducing activity and transhydrogenase activity, and C59S and C64S had substantially no such activities. These data and spectral analyses of these enzymes suggest that Cys59 and Cys64 at the N-terminus, in conjunction with His472, function as primary acceptors for electrons from NADPH via FAD, and that the electrons are then transferred to Cys497-Sec498 at the C-terminus for the reduction of oxidized thioredoxin in the mammalian thioredoxin reductase.

Proposal of Sphingomonas wittichii sp. nov. for strain RW1T, known as a dibenzo-p-dioxin metabolizer

A polyphasic taxonomic study was performed on Sphingomonas sp. strain RW1T. The organism was isolated from water of the River Elbe and has been known as a potent metabolizer of dibenzo-p-dioxin and its relatives. TLC of a mild alkaline hydrolysate of extractable cellular lipids of strain RW1T and type strains of 21 Sphingomonas species gave a spot of sphingoglycolipid (SGL)-1 (glucuronosyl ceramide), which is characteristic of sphingomonads. In addition, strain RW1T and type strains of three Sphingomonas species (Sphingomonas yanoikuyae, Sphingomonas terrae and Sphingomonas macrogoltabidus) showed a second spot of SGL (SGL-1') identified as galacturonosyl ceramide. The presence of SGL-1 in cellular lipids suggested that strain RW1T is a member of the genus Sphingomonas. DNA-DNA reassociation rates between strain RW1T and each type strain of 14 Sphingomonas species including Sphingomonas paucimobilis, type species for the genus, revealed that strain RW1T is independent from these species. Results of phylogenetic analysis of 16S rDNA sequences of strain RW1T and type strains of 21 named Sphingomonas species verified that strain RW1T belongs to the genus Sphingomonas. Strain RW1T could be differentiated from named species of the genus by phenotypic characteristics and has been assigned to a new species, Sphingomonas wittichii sp. nov. The type strain is DSM 6014T (= JCM 10273T = EY 4224T). DNA G+C content is 67 mol %.

Effects of lifestyle factors on ultrasonographically determined bone health in Japanese women

The objective of this study was to determine by ultrasonographic measurements, an inexpensive and radiation-free technique, the association between bone health and lifestyle factors among a large population of Japanese women. Two hundred and fifty-six pre-menopausal women and 585 post-menopausal women who underwent a voluntary medical check-up for osteoporosis in 1996-1997 were analyzed. There were significant positive correlations between the bone density (designated as the stiffness value) vs the weight, the height and the body mass index of the subjects only in the post-menopausal group. Negative correlations were also found between the bone density vs the age and the years since menopause. Our data using ultrasonographic technique agree well with previous studies using other devices. In both groups, subjects with current or past exercise habits had higher stiffness values. Dietary habits had no effects on the stiffness value. Smoking habits had a trend towards negative effects and alcohol consumption seemed to have a trend towards positive effects on the stiffness value in post-menopausal women, but these effects did not reach statistical significance. Positive effects of current exercise on bone density were maintained after adjustment for past exercise habits. These results support the effectiveness of exercise begun in adulthood. Having a good exercise habit is one of the most effective ways of maintaining good bone health.

Proposal of Sphingomonadaceae fam. nov., consisting of Sphingomonas Yabuuchi et al. 1990, Erythrobacter Shiba and Shimidu 1982, Erythromicrobium Yurkov et al. 1994, Porphyrobacter Fuerst et al. 1993, Zymomonas Kluyver and van Niel 1936, and Sandaracinobacter Yurkov et al. 1997, with the type genus Sphingomonas Yabuuchi et al. 1990

Based on the results of phylogenetic analysis of the 16S rDNA sequences and the presence of N-2'-hydroxymyristoyl dihydrosphingosine 1-glucuronic acid (SGL-1) and 2-hydroxymyristic acid (non-hydroxymyristic acid in Zymomonas) in cellular lipids, a new family, Sphingomonadaceae, for Group 4 of the alpha-subclass of the class Proteobacteria is herein proposed and a description of the family is given. The family consists of six genera, Sphingomonas, Erythrobacter, Erythromicrobium, Porphyrobacter, Sandaracinobacter and Zymomonas. Thus, all the validly published and currently known genera in Group 4 of the alpha-subclass of Proteobacteria belong to Sphingomonadaceae fam. nov. Among them, type strains of two species, Porphyrobacter and Erythrobacter, Sandaracinobacter sibiricus and Sphingomonas ursincola, respectively, are facultatively photosynthetic due to bacteriochlorophyll (Bchl)-a. The type strains of two subspecies of Zymomonas mobilis are facultative anaerobes. The presence of SGL-1 together with the results of a phylogenetic analysis of the 16S rDNA sequences recommends a new criteria by which to define the new family Sphingomonadaceae. The type genus is Sphingomonas Yabuuchi et al. 1990.

Estrogen induces the Akt-dependent activation of endothelial nitric-oxide synthase in vascular endothelial cells

Although estrogen is known to activate endothelial nitric oxide synthase (eNOS) in the vascular endothelium, the molecular mechanism responsible for this effect remains to be elucidated. In studies of both human umbilical vein endothelial cells (HUVECs) and simian virus 40-transformed rat lung vascular endothelial cells (TRLECs), 17beta-estradiol (E2), but not 17alpha-E2, caused acute activation of eNOS that was unaffected by actinomycin D and was specifically blocked by the pure estrogen receptor antagonist ICI-182,780. Treatment of both TRLECs and HUVECs with 17beta-E2 stimulated the activation of Akt, and the PI3K inhibitor wortmannin blocked the 17beta-E2-induced activation of Akt. 17beta-E2-induced Akt activation was also inhibited by ICI-182,780, but not by actinomycin D. Either treatment with wortmannin or exogenous expression of a dominant negative Akt in TRLECs decreased the 17beta-E2-induced eNOS activation. Moreover, 17beta-E2-induced Akt activation actually enhances the phosphorylation of eNOS. 17beta-E2-induced Akt activation was dependent on both extracellular and intracellular Ca(2+). We further examined the 17beta-E2-induced Akt activity in Chinese hamster ovary (CHO) cells transiently transfected with cDNAs for estrogen receptor alpha (ERalpha) or estrogen receptor beta (ERbeta). 17beta-E2 stimulated the activation of Akt in CHO cells expressing ERalpha but not in CHO cells expressing ERbeta. Our findings suggest that 17beta-E2 induced eNOS activation through an Akt-dependent mechanism, which is mediated by ERalpha via a nongenomic mechanism.

Structure-activity relationship of mycoloyl glycolipids derived from Rhodococcus sp. 4306

Novel mycoloyl glycolipids with short carbon chains were isolated and purified from Rhodococcus sp. 4306, a soil origin of Actinomycetales. Their chemical structures were identified as trehalose 6,6'-dimycolate (TDM), trehalose 6-monomycolate, glucose 6-monomycolate, mannose 6-monomycolate and fructose 6-monomycolate. The length of carbon chains and number of double bonds of mycolic acids were C(34), C(36)and C(38)saturated, monoenoic and dienoic molecular species, which were much shorter than those of Mycobacterium tuberculosis (C(78-88)monoenoic and dienoic). Among them, only TDM could induce prominent granulomatous inflammation of the lung and spleen in mice. By contrast, other mycoloyl glycolipids induced mild lesions. The small-sized TDM of Rhodococcus possessed granulomatogenic activity, however, the toxicity was much lower than that of M. tuberculosis. Rhodococcal TDM was composed of mycolic acid with the shortest carbon chains, when compared to granulomatogenic TDM of Mycobacterium, Nocardia and Rhodococcus reported previously. Our results imply that rhodococcal TDM is a pathogenetic factor similar to that of M. tuberculosis, although rhodococcal TDM exhibits low toxicity.

Trehalose 6,6'-dimycolate (cord factor) of Mycobacterium tuberculosis induces foreign-body- and hypersensitivity-type granulomas in mice

Granulomatous inflammation is characterized morphologically by a compact organized collection of macrophages and their derivatives. It is classified as either a hypersensitivity type or a foreign-body type. Lipid components of the Mycobacterium tuberculosis cell wall participate in the pathogenesis of infection. Strains of M. tuberculosis have cord factor (trehalose 6,6'-dimycolate [TDM]) on their surface. To clarify host responses to TDM, including immunogenicity and pathogenicity, we have analyzed the footpad reaction, histopathology, and cytokine profiles of experimental granulomatous lesions in immunized and unimmunized mice challenged with TDM. In the present study, we have demonstrated for the first time that TDM can induce both foreign-body-type (nonimmune) and hypersensitivity-type (immune) granulomas by acting as a nonspecific irritant and T-cell-dependent antigen. Immunized mice challenged with TDM developed more severe lesions than unimmunized mice. At the active lesion, we found monocyte chemotactic, proinflammatory, and immunoregulatory cytokines. The level was enhanced in immunized mice challenged with TDM. This result implies that both nonimmune and immune mechanisms participate in granulomatous inflammation induced by mycobacterial infection. Taken together with a previous report, this study shows that TDM is a pleiotropic molecule against the host and plays an important role in the pathogenesis of tuberculosis.

Differential effects of inhaled nitric oxide and hyperoxia on pulmonary dysfunction in newborn guinea pigs

This study tested the hypothesis that inhaled nitric oxide (NO) and combined NO and hyperoxia will result in less pulmonary dysfunction and delay onset of respiratory signs compared with hyperoxia-exposed newborn guinea pigs (GPs). GPs were exposed to room air (n = 14), 95% O(2) (n = 36), 20 parts per million (ppm) NO (n = 14), or combined 20 ppm NO and 95% O(2) (NO/O(2), n = 13) for up to 5 days. Data evaluated included latency interval for onset of respiratory distress, pressure volume curves, lung histology, and bronchoalveolar lavage (BAL) polymorphonuclear cells (PMNs), proteolytic activity, and total protein. NO-exposed GPs did not develop respiratory distress and had no evidence of pulmonary dysfunction. O(2)-exposed GPs developed respiratory distress after 1-5 days (median 4.0) vs. 3-5 days (median 5.0) for NO/O(2) exposure (P < 0.05). BAL from O(2)-exposed GPs showed increased PMNs compared with NO/O(2)-exposed GPs. O(2)- and NO/O(2)-exposed GPs had comparable reduced lung volumes, lung histology, and increased BAL proteinase activity and total protein. In summary 1) O(2) exposure resulted in multiple measures of pulmonary dysfunction in newborn GPs, 2) 5-day exposure to NO produced no noticeable respiratory effects and pulmonary dysfunction, and 3) short-term exposure (</=5 days) to NO/O(2) delayed onset of respiratory distress and neither exacerbated nor attenuated pulmonary dysfunction compared with O(2) exposure alone.

Postnatal differentiation of Merkel cells in the rat palatine mucosa, with special reference to the timing of peripheral nerve development and the potency of cell mitosis

The origin and mechanism of the differentiation and proliferation of Merkel cells are enigmatic. A preliminary study in our laboratory showed that Merkel cells in the rat palatine mucosa emerge after birth. This is in contrast to the case of similar cells in the skin that differentiate during the embryonic period prior to the establishment of peripheral nerve innervation. We studied immunohistochemically the developmental timings of Merkel cells and peripheral nerves in the rat palatine mucosa using antibodies to cytokeratins 18 and 20, PGP 9.5, and CGRP using developing palates of prenatal and postnatal rats. We also studied the potency of mitosis in Merkel cells by immunohistochemistry using antibodies for a cell proliferation marker Ki67 and cyclin D-kinase inhibitors p16, p21 and p27. It was shown that Merkel cells in the rat palatine mucosa differentiate postnatally, after the development of peripheral nerve fiber terminals was almost established. The emergence and increase in number of Merkel cells progressed in an anterior-to-posterior wave. Newly appearing Merkel cells were usually negative for anti-cytokeratin 20 antibody but gained affinity for the antibody with progress of maturation. All Merkel cells in the palatine mucosa were negative for anti-Ki67 antibody but positive for anti-p27 antibody. These results indicate that Merkel cells in the rat palatine mucosa are not responsible for the development of peripheral nerve fiber terminals and that these cells differentiate in situ from intraepithelial stem cells.

Trehalose 6,6'-dimycolate (cord factor) of Mycobacterium tuberculosis induces corneal angiogenesis in rats

Neovascularization or angiogenesis is required for the progression of chronic inflammation. The mechanism of inflammatory neovascularization in tuberculosis remains unknown. Trehalose 6, 6'-dimycolate (TDM) purified from Mycobacterium tuberculosis was injected into rat corneas. TDM challenge provoked a local granulomatous response in association with neovascularization. Neovascularization was seen within a few days after the challenge, with the extent of neovascularization being dose dependent, although granulomatous lesions developed 14 days after the challenge. Cytokines, including tumor necrosis factor alpha (TNF-alpha), interleukin-8 (IL-8), IL-1beta, and vascular endothelial growth factor (VEGF), were found in lesions at the early stage (within a few days after the challenge) and were detectable until day 21. Neovascularization was inhibited substantially by neutralizing antibodies to VEGF and IL-8 but not IL-1beta. Treatment with anti-TNF-alpha antibodies resulted in partial inhibition. TDM possesses pleiotropic activities, and the cytokine network plays an important role in the process of neovascularization.

Ischemic tolerance preserves propagation of membrane depolarization

The functional integrity of the synaptic connections within the hippocampus in gerbils that had acquired ischemic tolerance was investigated. The propagation of membrane depolarization across the hippocampus in response to electrical stimulation of CA1 was monitored with the use of a high speed optical recording technique. In comparison to control slices, propagation was significantly depressed and depolarization was shortened in slices from gerbils subjected to 5 min of ischemia. Hippocampal slices from gerbils who were preconditioned with prior sublethal ischemia demonstrated only a slight reduction in propagation. The duration of depolarization was longer than that of ischemia group. These findings suggest that ischemia induces a functional disturbance of synaptic transmission and membrane depolarization. Ischemic preconditioning significantly reduced the extent of this functional disturbance.

Burkholderia uboniae sp. nov., L-arabinose-assimilating but different from Burkholderia thailandensis and Burkholderia vietnamiensis

A polar multitrichous gram-negative motile rod, EY 3383, originally identified as Burkholderia thailandensis, revealed a DNA-DNA reassociation rate of 36.7%, under stringent conditions, with the type strain of B. thailandensis, despite the 16S rDNA homology value between two type strains being as high as 97.9%. The strain was clearly differentiated from the type strain of B. thailandensis by physiological, bio-chemical, and nutritional characteristics, without significant difference in cellular fatty acid and lipid composition. Based on the results of 16S rDNA sequence analysis, DNA-DNA hybridization and phenotypic characterization, Burkholderia uboniae sp. nov. is herein proposed. The type strain is NCTC 13147=EY 3383, isolated on 8 December 1989 from surface soil along the roadside in Ubon Ratchathani, Thailand. Major respiratory quinone is ubiquinone-8(Q8). G+C content of DNA is 69.71%.