An outbreak of neonatal toxic shock syndrome-like exanthematous disease (NTED) caused by methicillin-resistant Staphylococcus aureus (MRSA) in a neonatal intensive care unit

Neonatal toxic shock syndrome-like exanthematous disease (NTED) is a new entity of methicillin-resistant Staphylococcus aureus (MRSA) infection. Most of NTED cases reported previously in the literature were sporadic ones. In the present report, we describe an outbreak of NTED that occurred in a neonatal intensive care unit (NICU) between April, 1999 and April, 2000 in Japan. All MRSA strains isolated from 14 patients (6 NTED, 2 infections and 6 colonizations) in this outbreak belonged to the group of coagulase II and produced toxic shock syndrome toxin 1 (TSST-1). Of these, 14 strains produced staphylococcal enterotoxin C (SEC). No other superantigenic toxins were produced by these strains. The pulsed field gel electrophoresis (PFGE) patterns of genomic DNA digested with SmaI were indistinguishable each other due to no band shifting in all of the 13 strains except for strain O-21 and M56. Strain M56 was different from the dominant type in the positions of only 2 bands, whereas the pattern of strain O-21 had no similarity with the other pattern, suggesting that this outbreak was associated with the spread of a unique MRSA strain in the NICU. Two-dimensional electrophoresis (2-DE) analysis of exoproteins revealed that the patterns of these 14 strains were very indistinguishable to each other, and that these strains produced very large amounts of TSST-1 and SEC3 subtype superantigens, as measured with computer-assisted image analysis of the intensity of 2-DE spots. The 2-DE gel of O-21 showed the different pattern from the others. These results as well as the profiles of toxin production also supported the conclusion drawn from PFGE analysis. Based on these results, the involvement of TSST-1 and SEC3 in the pathogenesis of NTED is discussed.     

Synthesis of 1,2-oxygenated 6-arylfurofuran lignan: stereoselective synthesis of (1S,2S,5R,6S)-1-hydroxysamin

(1S,2S,5R,6S)-6-(3,4-Methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octan-1,2-diol ((+)-1-hydroxysamin 1) was synthesized, starting from olefin 8. Stereoselective alpha-hydroxylation was achieved after converting 8 to aldehyde 13. Resulting unstable alpha-hydroxy aldehyde 14 was then transformed to (+)-1-hydroxysamin (1). This is a new efficient synthetic route to 1,2-oxygenated 6-arylfurofuran lignans.     

Epitope analysis of antibodies in Japanese to human cytomegalovirus phosphoprotein 150 with synthetic peptides

Serological detection of antibodies specific to human cytomegalovirus (HCMV) is not reliable because the assay uses the whole HCMV protein fraction. Antigenic materials composed of well-characterized viral proteins are being tried for serodiagnosis in Europe. Epitopes of antibodies to HCMV phosphoprotein 150 (pp150) encoded by UL32 in Japanese individuals were investigated for comparison with the results in Europe. The major epitopes on amino acid residues 496 to 652 of HCMV pp150 were identified and the detection of antibodies with an enzyme-linked immunosorbent assay (ELISA) of synthetic peptides against the main epitopes was established. Fifteen seropositive and five seronegative serum samples for the epitope mapping and 131 seropositive and 50 seronegative samples for ELISA were investigated. Overlapping 15-mer peptides moving by two amino acids through V496-H652 were synthesized. The main epitope regions were V508-D530, L526-Q544, S536-D554, T616-G634, S624-P642, and L632-H652. When each peptide was conjugated with bovine serum albumin for ELISA, 80.9% of the seropositive samples were judged to be positive. The results of this study are the same as those for European sera, so the antigenic materials developed in Europe might be used to replace the whole HCMV protein fraction in Japanese.     

Spatial and temporal aspects of Ca2+ signaling mediated by P2Y receptors in cultured rat hippocampal astrocytes

ATP produces a variety of Ca2+ responses in astrocytes. To address the complex spatio-temporal Ca2+ signals, we analyzed the ATP-evoked increase in intracellular Ca2+ concentration ([Ca2+]i) in cultured rat hippocampal astrocytes using fura-2 or fluo-3 based Ca2+ imaging techniques. ATP at less than 10 nM produced elementary Ca2+ release event "puffs" in a manner independent of extracellular Ca2+. Stimulation with higher ATP concentrations (3 or 10 micro M) resulted in global Ca2+ responses such as intercellular Ca2+ wave. These Ca2+ responses were mainly mediated by metabotropic P2Y receptors. ATP acting on both P2Y1 and P2Y2 receptors produced a transient Ca2+ release by inositol 1,4,5-trisphosphate (InsP3). When cells were stimulated with ATP much longer, the transient [Ca2+]i elevation was followed by sustained Ca2+ entry from the extracellular space. This sustained rise in [Ca2+]i was inhibited by Zn2+ (<10 micro M), an inhibitor of capacitative Ca2+ entry (CCE). CCE induced by cyclopiazonic acid or thapsigargin and Ca2+ entry evoked by ATP share the same pharmacological profile in astrocytes. Taken together, the hierarchical Ca2+ responses to ATP were observed in hippocampal astrocytes, i.e., puffs, global Ca2+ release by InsP3, and CCE in response to depletion of InsP3-sensitive Ca2+ stores. It should be noted that these Ca2+ signals and their modulation by Zn2+ could occur in the hippocampus in situ since both ATP and Zn2+ are rich in the hippocampus and could be released by excitatory stimulation.     

Age-related decline of serotonin transporters in living human brain of healthy males

There is growing interest in serotonin transporter (5-HTT) function in the human brain, since alteration in 5-HTT has been suggested in a variety of neurophychiatric disorders. Age-related decline in postsynaptic 5-HT receptors has been demonstrated in postmortem human studies and in vivo imaging studies, and has been assumed to be related to changes in mental function in the normal aging process. However, few studies have investigated the aging effect on 5-HTT in human brain in vivo, since the availability of suitable ligands has been limited. To investigate the aging effect on 5-HTT in living human brain, we performed positron emission tomography (PET) scans with a selective ligand for 5-HTT, [11C](+)McN5652. We examined 28 healthy male volunteers aged between 20 and 79 years. The uptake was quantified in the thalamus and midbrain by graphical analysis with the cerebellum as a reference tissue, and binding potential (BP) was used for the index of 5-HTT binding. There was a significant age-related decline in BP in the thalamus and midbrain. The decline in [11C](+)McN5652 binding was 9.6% per decade in the thalamus and 10.5% per decade in the midbrain.     

Effects of phenytoin and/or vitamin K2 (menatetrenone) on bone mineral density in the tibiae of growing rats

In this study, we investigated 1) whether the administration of phenytoin induced bone loss; and 2) whether menatetrenone could prevent bone loss induced by phenytoin. For this purpose, we previously developed a procedure to measure the bone mineral density using a conventional X-ray absorptiometry method. A long-termed administration of phenytoin (20 mg/kg per day for 5 weeks) produced bone loss in the tibiae of growing rats. The values of bone mineral density (BMD) were significantly decreased in the tibial diaphysis and metaphysis in the phenytoin-treated group. In this period, we measured the serum level of vitamin K-dependent protein, osteocalcin, a marker of bone formation. The serum level of osteocalcin showed a decrease in the phenytoin-treated group compared with the vehicle-treated group. Combined administration of menatetrenone (30 mg/kg in diet per day) with phenytoin for 5 weeks prevented the reduction of BMD, and the level of osteocalcin was slightly increased. Thus, it is suggested that long-termed phenytoin exposure may inhibit bone formation concomitantly with insufficient vitamin K, which, at least in part, contributed to bone loss in rats. Finally, these findings implicated the therapeutic usefulness of menatetrenone on a moderate degree of bone abnormality such as drug-induced osteopenia.     

Brain-specific expression of the nuclear actin-related protein ArpNalpha and its involvement in mammalian SWI/SNF chromatin remodeling complex

Actin-related proteins share significant homology with conventional actins and are classified into subfamilies based on the similarity of their sequences and functions. The Arp4 subfamily of Arps is localized in the nucleus, and a mammalian isoform, ArpNbeta (also known as BAF53), is a component of the chromatin remodeling and histone acetyltransferase complexes. Another isoform identified in humans, ArpNalpha has scarcely been characterized yet. We identified mouse ArpNalpha, and showed that ArpNalpha is more similar between humans and mice than ArpNbeta. No difference was observed between ArpNalpha and beta in subcellular localization and interaction with BRM, which is an ATPase subunit of mammalian SWI/SNF chromatin remodeling complex. However, ArpNalpha was expressed exclusively in the brain and its expression was induced during neural differentiation of P19 mouse embryonic carcinoma cells. ArpNalpha is the first brain-specific component of a chromatin remodeling complex to be identified, suggesting that ArpNalpha has conserved and important roles in the differentiation of neural cells through regulation of chromatin structure.