Identification of succinate exporter in Corynebacterium glutamicum and its physiological roles under anaerobic conditions

Corynebacterium glutamicum produces succinate from glucose via the reductive tricarboxylic acid cycle under microaerobic and anaerobic conditions. We identified a NCgl2130 gene of C. glutamicum as a novel succinate exporter that functions in succinate production, and designated sucE1. sucE1 expression levels were higher under microaerobic conditions than aerobic conditions, and overexpression or disruption of sucE1 respectively increased or decreased succinate productivity during fermentation. Under microaerobic conditions, the sucE1 disruptant sucE1Δ showed 30% less succinate productivity and a lower sugar-consumption rate than the parental strain. Under anaerobic conditions, succinate production by sucE1Δ ceased. The intracellular succinate and fructose-1,6-bisphosphate levels of sucE1Δ under microaerobic conditions were respectively 1.7-fold and 1.6-fold higher than those of the parental strain, suggesting that loss of SucE1 function caused a failure of succinate removal from the cells, leading to intracellular accumulation that inhibited upstream sugar metabolism. Homology and transmembrane helix searches identified SucE1 as a membrane protein belonging to the aspartate:alanine exchanger (AAE) family. Partially purified 6x-histidine-tagged SucE1 (SucE1-[His](6)) reconstituted in succinate-loaded liposomes clearly demonstrated counterflow and self-exchange activities for succinate. Together, these findings suggest that sucE1 encodes a novel succinate exporter that is induced under microaerobic conditions, and is important for succinate production under both microaerobic and anaerobic conditions.

Percutaneous application of peptidoglycan from Staphylococcus aureus induces infiltration of CCR4+ cells into mouse skin

BACKGROUND

The lesional skin of patients with atopic dermatitis has an increased number of type 2 helper T (TH2) cells in the dermis and is superficially colonized by Staphylococcus aureus. The purpose of this study was to determine the effects of peptidoglycan (PEG) from S aureus on TH2 cell induction in murine skin.

METHODS

Mice were sensitized with house dust mite antigen (MA) by topical application to barrier-disrupted abdominal skin. Seven days after sensitization, PEG was applied to the barrier-disrupted dorsal skin. After a further 3 days, C-C chemokine receptor type 4-positive (CCR4+) cells were counted in the PEG-treated skin.The production of chemokine (C-C) motif ligand 17 (CCL17) (thymus- and activation-regulated chemokine) and CCL22 (macrophage-derived chemokine) in the skin was investigated using reverse transcriptase polymerase chain reaction and immunohistological analysis.

RESULTS

Application of PEG to the dorsal skin of MA-sensitized mice led to a significant increase in the number of cells expressing CCR4 in the dermis. The skin of PEG-treated mice showed an increased level of CCL17 mRNA expression, which coincided with TH2 cytokine mRNA expression. Immunohistological analysis demonstrated that levels of CCL17 transcripts corresponded to those of protein synthesis in the epidermis. CCL17 production was induced mainly by Langerhans cells stimulated with PEG. Furthermore, intraperitoneal injection of anti-CCL17 antibody abrogated the induction of CCR4+ cells in the skin.

CONCLUSION

These results suggest that PEG may induce TH2 cells in the skin through the production of CCL17 by Langerhans cells and would explain the role of colonization by S aureus in patients with atopic dermatitis.

Attitudes of medical professionals and transplantation facilities toward living-donor liver transplantation in Japan

The Japan Society for Transplantation (JST) revised their guidelines in 2003 to specify that a living donor must be "a relative by blood within the sixth degree or an in-law within the third degree." Although several criticisms have been raised on this issue, these criteria have persisted without any empirical data showing the opinions and attitudes of people who are affected by the revision. Therefore, we performed a questionnaire survey to determine what Japanese medical professionals involved with living-donor liver transplantation (LDLT) regarded as eligible relationships for donation, as well as the kind of relationship for which they would be willing to donate their liver, and what donor eligibility criteria was currently used by their institutions. Among the 71 representatives of the Japanese Liver Transplantation Society, >90% answered that liver donations to emotionally close parents, siblings, children, or spouses were acceptable. However, the numbers were considerably lower for donation to emotionally close blood relatives, in-laws, friends, and strangers (78.2%, 52.1%, 18.6%, and 5.9%, respectively). This gap was more prominent when participants were questioned about their own willingness to donate. More than two-thirds of facilities that perform LDLTs have independent regulations for donor eligibility that are more conservative than the JST guidelines. No facility accepted friends or strangers as donors. When introducing policies or guidelines, it is important to carefully investigate the views of the people who are affected. The data obtained in this study should serve as a resource for ongoing discussions about the JST revised guidelines.

Bone regeneration by octacalcium phosphate collagen composites in a dog alveolar cleft model

Octacalcium phosphate (OCP) and porcine atelocollagen sponge composites (OCP/Col) markedly enhanced bone regeneration in a rat cranial defect model. To assess clinical application, the authors examined whether OCP/Col would enhance bone regeneration in an alveolar cleft model in an adult dog, which was assumed to reflect patients with alveolar cleft. Disks of OCP/Col or collagen were implanted into the defect and bone regeneration by OCP/Col or collagen was investigated 4 months after implantation. Macroscopically, the OCP/Col-treated alveolus was obviously augmented and occupied by radio-opacity, and the border between the original bone and the defect was indistinguishable. Histological analysis revealed it was filled and bridged with newly formed bone; a small quantity of the remaining implanted OCP was observed. X-ray diffraction patterns of the area of implanted OCP/Col indicated no difference from those of dog bone. In the collagen-treated alveolus, the hollowed alveolus was mainly filled with fibrous connective tissue, and a small amount of new bone was observed at the defect margin. These results suggest that bone was obviously repaired when OCP/Col was implanted into the alveolar cleft model in a dog, and OCP/Col would be a significant bone regenerative material to substitute for autogeneous bone.

Inhibitory effects of Schefflera leucantha extract on production of allergic mediators by Langerhans cells and mast cells

BACKGROUND

Schefflera leucantha Viguier is used as a traditional medicine in Thailand and China to relieve chronic cough and asthma. However, little is known about its anti-allergic effects.

OBJECTIVE

This study was designed to investigate the effects of S leucantha ethanol extract (SLEE) on chemokine production by epidermal Langerhans cells (LCs) stimulated with peptidoglycan (PEG) from Staphylococcus aureus and histamine release from mast cells.

METHODS

LCs were purified from murine epidermal cells using the panning method with anti-IA(d) monoclonal antibody. Chemokine production by LCs was investigated by reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). Mast cells for histamine release assay were induced by long-term culture of mouse spleen cells. Histamine release from these mast cells was measured by a competitive ELISA.

RESULTS

Production of the eosinophil chemoattractant CCL5 and the type 2 T helper (TH2)-associated chemokine CCL17 from PEG-stimulated LCs was significantly inhibited by SLEE. Furthermore, SLEE significantly decreased the release of histamine from mast cells by IgE-mediated degranulation.

CONCLUSION

These results suggest that S leucantha may offer a new therapeutic approach for the control of atopic dermatitis associated with S aureus colonization through inhibition of the production of allergic mediators.

Distribution of the introduced cyprinid herpesvirus 3 in a wild population of common carp, Cyprinus carpio L

Cyprinid herpesvirus 3 (CyHV-3), which causes a lethal disease in common carp, Cyprinus carpio L., and koi, C. carpio koi, first occurred in Lake Biwa, Japan in 2004. To elucidate distribution of CyHV-3 in a wild common carp population, we conducted a PCR survey of CyHV-3 among such fish in Lake Biwa in 2006. Only 6% (1/18) of the common carp smaller than 300 mm were positive with PCR, whereas 31% (18/58) of fish larger than 300 mm were positive. To evaluate their past exposure to CyHV-3 infection based on the presence of antibodies, we also measured the levels of serum anti-CyHV-3 antibodies in the carp, using an enzyme-linked immunosorbent assay. None (0/26) of the fish smaller than 300 mm was positive for the antibodies, whereas 54% (33/61) of fish larger than 300 mm were positive. Of the antibody-positive individuals, 44% (14/32) were also positive by PCR strongly suggesting that wild common carp that survived infection become CyHV-3 carriers. Five individuals were positive by PCR but negative for antibodies indicating that their infection with CyHV-3 had occurred recently. These results suggest that transmission of CyHV-3 from carriers to naïve common carp is still occurring in Lake Biwa.

[Tracheostenosis caused by blunt thoracic trauma]

Blunt thoracic trauma rarely implicate retropharyngeal hematoma obstructing trachea. 85-year-old woman being struck on her cheek and anterior chest, visited our emergency room. She was nearly suffocated following stridor and dyspnea. Tracheal intubation relieved her dyspnea Chest computed tomography (CT) showed retropharyngeal hematoma obstructing trachea. 5 days conservative management reduced the hematoma and tracheal tube was extubated through an uneventful course.

Disruption of the EGFR E884-R958 ion pair conserved in the human kinome differentially alters signaling and inhibitor sensitivity

Targeted therapy against epidermal growth factor receptor (EGFR) represents a major therapeutic advance in lung cancer treatment. Somatic mutations of the EGFR gene, most commonly L858R (exon 21) and short in-frame exon 19 deletions, have been found to confer enhanced sensitivity towards the inhibitors gefitinib and erlotinib. We have recently identified an EGFR mutation E884K, in combination with L858R, in a patient with advanced lung cancer who progressed on erlotinib maintenance therapy, and subsequently had leptomeningeal metastases that responded to gefitinib. The somatic E884K substitution appears to be relatively infrequent, and resulted in a mutant lysine residue that disrupts an ion pair with residue R958 in the EGFR kinase domain C-lobe, an interaction that is highly conserved within the human kinome as demonstrated by our sequence analysis and structure analysis. Our studies here, using COS-7 transfection model system, show that E884K works in concert with L858R in-cis, in a dominant fashion, to change downstream signaling, differentially induce MAPK-ERK1/2 signaling and associated cell proliferation, and differentially alter sensitivity of EGFR phosphorylation inhibition by ERBB family inhibitors in an inhibitor-specific fashion. Mutations of the conserved ion pair E884-R958 may result in conformational changes that alter kinase substrate recognition. The analogous E1271K-MET mutation conferred differential sensitivity towards preclinical MET inhibitors SU11274 (unchanged), and PHA665752 (more sensitive). Systematic bioinformatics analysis of the mutation catalog in the human kinome (COSMIC) revealed the presence of cancer-associated mutations involving the conserved E884 homologous residue, and adjacent residues at the ion pair, in known proto-oncogenes (KIT, RET, MET, FAK) and tumor suppressor gene (LKB1). Targeted therapy using small molecule inhibitors should take into account potential cooperative effects of multiple kinase mutations, and their specific effects on downstream signaling and inhibitor sensitivity. Improved efficacy of targeted kinase inhibitors may be achieved by targeting the dominant activating mutations present.

Randomised phase II trial of irinotecan plus cisplatin vs irinotecan, cisplatin plus etoposide repeated every 3 weeks in patients with extensive-disease small-cell lung cancer

Patients with previously untreated extensive-disease small-cell lung cancer were treated with irinotecan 60 mg m(-2) on days 1 and 8 and cisplatin 60 mg m(-2) on day 1 with (n=55) or without (n=54) etoposide 50 mg m(-2) on days 1-3 with granulocyte colony-stimulating factor support repeated every 3 weeks for four cycles. The triplet regimen was too toxic to be considered for further studies.

Computer-aided rational design of the phosphotransferase system for enhanced glucose uptake in Escherichia coli

The phosphotransferase system (PTS) is the sugar transportation machinery that is widely distributed in prokaryotes and is critical for enhanced production of useful metabolites. To increase the glucose uptake rate, we propose a rational strategy for designing the molecular architecture of the Escherichia coli glucose PTS by using a computer-aided design (CAD) system and verified the simulated results with biological experiments. CAD supports construction of a biochemical map, mathematical modeling, simulation, and system analysis. Assuming that the PTS aims at controlling the glucose uptake rate, the PTS was decomposed into hierarchical modules, functional and flux modules, and the effect of changes in gene expression on the glucose uptake rate was simulated to make a rational strategy of how the gene regulatory network is engineered. Such design and analysis predicted that the mlc knockout mutant with ptsI gene overexpression would greatly increase the specific glucose uptake rate. By using biological experiments, we validated the prediction and the presented strategy, thereby enhancing the specific glucose uptake rate.