bluuebunny/crossref_metadata_2025 huggingface dataset:
Iroquois homeobox gene 3
establishes fast conduction in the cardiac His–Purkinje network
Authors: Zhang Shan-Shan , Kim Kyoung-Han , Rosen Anna , Smyth James W. , Sakuma Rui , Delgado-Olguín Paul , Davis Mark , Chi Neil C. , Puviindran Vijitha , Gaborit Nathalie , Sukonnik Tatyana , Wylie John N. , Brand-Arzamendi Koroboshka , Farman Gerrie P. , Kim Jieun , Rose Robert A. , Marsden Phillip A. , Zhu Yonghong , Zhou Yu-Qing , Miquerol Lucile , Henkelman R. Mark , Stainier Didier Y. R. , Shaw Robin M. , Hui Chi-chung , Bruneau Benoit G. , Backx Peter H.
Published: August 2011

Rapid electrical conduction in the His–Purkinje system tightly controls spatiotemporal activation of the ventricles. Although recent work has shed much light on the regulation of early specification and morphogenesis of the His–Purkinje system, less is known about how transcriptional regulation establishes impulse conduction properties of the constituent cells. Here we show that
Iroquois homeobox gene 3
(
Irx3
) is critical for efficient conduction in this specialized tissue by antithetically regulating two gap junction–forming connexins (Cxs). Loss of
Irx3
resulted in disruption of the rapid coordinated spread of ventricular excitation, reduced levels of Cx40, and ectopic Cx43 expression in the proximal bundle branches. Irx3 directly represses Cx43 transcription and indirectly activates Cx40 transcription. Our results reveal a critical role for Irx3 in the precise regulation of intercellular gap junction coupling and impulse propagation in the heart.
Dedicated
ent
-kaurene and
ent
-atiserene synthases for platensimycin and platencin biosynthesis
Authors: Smanski Michael J. , Yu Zhiguo , Casper Jeffrey , Lin Shuangjun , Peterson Ryan M. , Chen Yihua , Wendt-Pienkowski Evelyn , Rajski Scott R. , Shen Ben
Published: August 2011

Platensimycin (PTM) and platencin (PTN) are potent and selective inhibitors of bacterial and mammalian fatty acid synthases and have emerged as promising drug leads for both antibacterial and antidiabetic therapies. Comparative analysis of the PTM and PTN biosynthetic machineries in
Streptomyces platensis
MA7327 and MA7339 revealed that the divergence of PTM and PTN biosynthesis is controlled by dedicated
ent
-kaurene and
ent
-atiserene synthases, the latter of which represents a new pathway for diterpenoid biosynthesis. The PTM and PTN biosynthetic machineries provide a rare glimpse at how secondary metabolic pathway evolution increases natural product structural diversity and support the wisdom of applying combinatorial biosynthesis methods for the generation of novel PTM and/or PTN analogues, thereby facilitating drug development efforts based on these privileged natural product scaffolds.
Synthesis of unnatural alkaloid scaffolds by exploiting plant polyketide synthase
Authors: Morita Hiroyuki , Yamashita Makoto , Shi She-Po , Wakimoto Toshiyuki , Kondo Shin , Kato Ryohei , Sugio Shigetoshi , Kohno Toshiyuki , Abe Ikuro
Published: August 2011

HsPKS1 from
Huperzia serrata
is a type III polyketide synthase (PKS) with remarkable substrate tolerance and catalytic potential. Here we present the synthesis of unnatural unique polyketide–alkaloid hybrid molecules by exploiting the enzyme reaction using precursor-directed and structure-based approaches. HsPKS1 produced novel pyridoisoindole (or benzopyridoisoindole) with the 6.5.6-fused (or 6.6.5.6-fused) ring system by the condensation of 2-carbamoylbenzoyl-CoA (or 3-carbamoyl-2-naphthoyl-CoA), a synthetic nitrogen-containing nonphysiological starter substrate, with two molecules of malonyl-CoA. The structure-based S348G mutant not only extended the product chain length but also altered the cyclization mechanism to produce a biologically active, ring-expanded 6.7.6-fused dibenzoazepine, by the condensation of 2-carbamoylbenzoyl-CoA with three malonyl-CoAs. Thus, the basic nitrogen atom and the structure-based mutagenesis enabled additional C─C and C─N bond formation to generate the novel polyketide-alkaloid scaffold.
Nuclear membranes control symbiotic calcium signaling of legumes
Authors: Capoen Ward , Sun Jongho , Wysham Derin , Otegui Marisa S. , Venkateshwaran Muthusubramanian , Hirsch Sibylle , Miwa Hiroki , Downie J. Allan , Morris Richard J. , Ané Jean-Michel , Oldroyd Giles E. D.
Published: August 2011

Nuclear-associated oscillations in calcium act as a secondary messenger in the symbiotic signaling pathway of legumes. These are decoded by a nuclear-localized calcium and calmodulin-dependent protein kinase, the activation of which is sufficient to drive downstream responses. This implies that the calcium oscillations within the nucleus are the predominant signals for legume symbiosis. However, the mechanisms that allow targeted release of calcium in the nuclear region have not been defined. Here we show that symbiosis-induced calcium changes occur in both the nucleoplasm and the perinuclear cytoplasm and seem to originate from the nuclear membranes. Reaction diffusion simulations suggest that spike generation within the nucleoplasm is not possible through transmission of a calcium wave from the cytoplasm alone and that calcium is likely to be released across the inner nuclear membrane to allow nuclear calcium changes. In agreement with this, we found that the cation channel DMI1, which is essential for symbiotic calcium oscillations, is preferentially located on the inner nuclear membrane, implying an essential function for the inner nuclear membrane in symbiotic calcium signaling. Furthermore, a sarco/endoplasmic reticulum calcium ATPase (SERCA) essential for symbiotic calcium oscillations is targeted to the inner nuclear membrane, as well as the outer nuclear membrane and endoplasmic reticulum (ER). We propose that release of calcium across the inner nuclear membrane allows targeted release of the ER calcium store, and efficient reloading of this calcium store necessitates the capture of calcium from the nucleoplasm and nuclear-associated cytoplasm.
The aneurogenic limb identifies developmental cell interactions underlying vertebrate limb regeneration
Authors: Kumar Anoop , Delgado Jean-Paul , Gates Phillip B. , Neville Graham , Forge Andrew , Brockes Jeremy P.
Published: August 2011

The removal of the neural tube in salamander embryos allows the development of nerve-free aneurogenic limbs. Limb regeneration is normally nerve-dependent, but the aneurogenic limb regenerates without nerves and becomes nerve-dependent after innervation. The molecular basis for these tissue interactions is unclear. Anterior Gradient (AG) protein, previously shown to rescue regeneration of denervated limbs and to act as a growth factor for cultured limb blastemal cells, is expressed throughout the larval limb epidermis and is down-regulated by innervation. In an aneurogenic limb, the level of AG protein remains high in the epidermis throughout development and regeneration, but decreases after innervation following transplantation to a normal host. Aneurogenic epidermis also shows a fivefold difference in secretory gland cells, which express AG protein. The persistently high expression of AG in the epithelial cells of an aneurogenic limb ensures that regeneration is independent of the nerve. These findings provide an explanation for this classical problem, and identify regulation of the epidermal niche by innervation as a distinctive developmental mechanism that initiates the nerve dependence of limb regeneration. The absence of this regulation during anuran limb development might suggest that it evolved in relation to limb regeneration.
Iduna is a poly(ADP-ribose) (PAR)-dependent E3 ubiquitin ligase that regulates DNA damage
Authors: Kang Ho Chul , Lee Yun-Il , Shin Joo-Ho , Andrabi Shaida A. , Chi Zhikai , Gagné Jean-Philippe , Lee Yunjong , Ko Han Seok , Lee Byoung Dae , Poirier Guy G. , Dawson Valina L. , Dawson Ted M.
Published: August 2011

Ubiquitin mediated protein degradation is crucial for regulation of cell signaling and protein quality control. Poly(ADP-ribose) (PAR) is a cell-signaling molecule that mediates changes in protein function through binding at PAR binding sites. Here we characterize the PAR binding protein, Iduna, and show that it is a PAR-dependent ubiquitin E3 ligase. Iduna’s E3 ligase activity requires PAR binding because point mutations at Y156A and R157A eliminate Iduna’s PAR binding and Iduna’s E3 ligase activity. Iduna’s E3 ligase activity also requires an intact really interesting new gene (RING) domain because Iduna possessing point mutations at either H54A or C60A is devoid of ubiquitination activity. Tandem affinity purification reveals that Iduna binds to a number of proteins that are either PARsylated or bind PAR including PAR polymerase-1, 2 (PARP1, 2), nucleolin, DNA ligase III, KU70, KU86, XRCC1, and histones. PAR binding to Iduna activates its E3 ligase function, and PAR binding is required for Iduna ubiquitination of PARP1, XRCC1, DNA ligase III, and KU70. Iduna’s PAR-dependent ubiquitination of PARP1 targets it for proteasomal degradation. Via PAR binding and ubiquitin E3 ligase activity, Iduna protects against cell death induced by the DNA damaging agent N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and rescues cells from G1 arrest and promotes cell survival after γ-irradiation. Moreover, Iduna facilitates DNA repair by reducing apurinic/apyrimidinic (AP) sites after MNNG exposure and facilitates DNA repair following γ-irradiation as assessed by the comet assay. These results define Iduna as a PAR-dependent E3 ligase that regulates cell survival and DNA repair.
Snapshots of the maltose transporter during ATP hydrolysis
Authors: Oldham Michael L. , Chen Jue
Published: August 2011

ATP-binding cassette transporters are powered by ATP, but the mechanism by which these transporters hydrolyze ATP is unclear. In this study, four crystal structures of the full-length wild-type maltose transporter, stabilized by adenosine 5′-(β,γ-imido)triphosphate or ADP in conjunction with phosphate analogs

,

, or

, were determined to 2.2- to 2.4-Å resolution. These structures led to the assignment of two enzymatic states during ATP hydrolysis and demonstrate specific functional roles of highly conserved residues in the nucleotide-binding domain, suggesting that ATP-binding cassette transporters catalyze ATP hydrolysis via a general base mechanism.
Exome sequencing and analysis of induced pluripotent stem cells identify the cilia-related gene
male germ cell-associated kinase
(
MAK
) as a cause of retinitis pigmentosa
Authors: Tucker Budd A. , Scheetz Todd E. , Mullins Robert F. , DeLuca Adam P. , Hoffmann Jeremy M. , Johnston Rebecca M. , Jacobson Samuel G. , Sheffield Val C. , Stone Edwin M.
Published: August 2011

Retinitis pigmentosa (RP) is a genetically heterogeneous heritable disease characterized by apoptotic death of photoreceptor cells. We used exome sequencing to identify a homozygous Alu insertion in exon 9 of
male germ cell-associated kinase
(
MAK
) as the cause of disease in an isolated individual with RP. Screening of 1,798 unrelated RP patients identified 20 additional probands homozygous for this insertion (1.2%). All 21 affected probands are of Jewish ancestry.
MAK
encodes a kinase involved in the regulation of photoreceptor-connecting cilium length. Immunohistochemistry of human donor tissue revealed that
MAK
is expressed in the inner segments, cell bodies, and axons of rod and cone photoreceptors. Several isoforms of MAK that result from alternative splicing were identified. Induced pluripotent stem cells were derived from the skin of the proband and a patient with non-
MAK
–associated RP (RP control). In the RP control individual, we found that a transcript lacking exon 9 was predominant in undifferentiated cells, whereas a transcript bearing exon 9 and a previously unrecognized exon 12 predominated in cells that were differentiated into retinal precursors. However, in the proband with the Alu insertion, the developmental switch to the
MAK
transcript bearing exons 9 and 12 did not occur. In addition to showing the use of induced pluripotent stem cells to efficiently evaluate the pathogenicity of specific mutations in relatively inaccessible tissues like retina, this study reveals algorithmic and molecular obstacles to the discovery of pathogenic insertions and suggests specific changes in strategy that can be implemented to more fully harness the power of sequencing technologies.
Multiple enhancers ensure precision of gap gene-expression patterns in the
Drosophila
embryo
Authors: Perry Michael W. , Boettiger Alistair N. , Levine Michael
Published: August 2011

Segmentation of the
Drosophila
embryo begins with the establishment of spatially restricted gap gene-expression patterns in response to broad gradients of maternal transcription factors, such as Bicoid. Numerous studies have documented the fidelity of these expression patterns, even when embryos are subjected to genetic or environmental stress, but the underlying mechanisms for this transcriptional precision are uncertain. Here we present evidence that every gap gene contains multiple enhancers with overlapping activities to produce authentic patterns of gene expression. For example, a recently identified
hunchback
(
hb
) enhancer (located 5-kb upstream of the classic enhancer) ensures repression at the anterior pole. The combination of intronic and 5′
knirps
(
kni
) enhancers produces a faithful expression pattern, even though the intronic enhancer alone directs an abnormally broad expression pattern. We present different models for “enhancer synergy,” whereby two enhancers with overlapping activities produce authentic patterns of gene expression.
Modulation of pancreatic islets-stress axis by hypothalamic releasing hormones and 11β-hydroxysteroid dehydrogenase
Authors: Schmid Janine , Ludwig Barbara , Schally Andrew V. , Steffen Anja , Ziegler Christian G. , Block Norman L. , Koutmani Yassemi , Brendel Mathias D. , Karalis Katia P. , Simeonovic Charmaine J. , Licinio Julio , Ehrhart-Bornstein Monika , Bornstein Stefan R.
Published: August 2011

Corticotropin-releasing hormone (CRH) and growth hormone-releasing hormone (GHRH), primarily characterized as neuroregulators of the hypothalamic-pituitary-adrenal axis, directly influence tissue-specific receptor-systems for CRH and GHRH in the endocrine pancreas. Here, we demonstrate the expression of mRNA for CRH and CRH-receptor type 1 (CRHR1) and of protein for CRHR1 in rat and human pancreatic islets and rat insulinoma cells. Activation of CRHR1 and GHRH-receptor significantly increased cell proliferation and reduced cell apoptosis. CRH stimulated both cellular content and release of insulin in rat islet and insulinoma cells. At the ultrastructural level, CRHR1 stimulation revealed a more active metabolic state with enlarged mitochondria. Moreover, glucocorticoids that promote glucose production are balanced by both 11b-hydroxysteroid dehydrogenase (11β-HSD) isoforms; 11β-HSD–type-1 and 11β-HSD–type-2. We demonstrated expression of mRNA for 11β-HSD-1 and 11β-HSD-2 and protein for 11β-HSD-1 in rat and human pancreatic islets and insulinoma cells. Quantitative real-time PCR revealed that stimulation of CRHR1 and GHRH-receptor affects the metabolism of insulinoma cells by down-regulating 11β-HSD-1 and up-regulating 11β-HSD-2. The 11β-HSD enzyme activity was analyzed by measuring the production of cortisol from cortisone. Similarly, activation of CRHR1 resulted in reduced cortisol levels, indicating either decreased 11β-HSD-1 enzyme activity or increased 11β-HSD-2 enzyme activity; thus, activation of CRHR1 alters the glucocorticoid balance toward the inactive form. These data indicate that functional receptor systems for hypothalamic-releasing hormone agonists exist within the endocrine pancreas and influence synthesis of insulin and the pancreatic glucocorticoid shuttle. Agonists of CRHR1 and GHRH-receptor, therefore, may play an important role as novel therapeutic tools in the treatment of diabetes mellitus.
Structural and functional characterization of a single-chain peptide–MHC molecule that modulates both naive and activated CD8+T cells
Authors: Samanta Dibyendu , Mukherjee Gayatri , Ramagopal Udupi A. , Chaparro Rodolfo J. , Nathenson Stanley G. , DiLorenzo Teresa P. , Almo Steven C.
Published: August 2011

Peptide–MHC (pMHC) multimers, in addition to being tools for tracking and quantifying antigen-specific T cells, can mediate downstream signaling after T-cell receptor engagement. In the absence of costimulation, this can lead to anergy or apoptosis of cognate T cells, a property that could be exploited in the setting of autoimmune disease. Most studies with class I pMHC multimers used noncovalently linked peptides, which can allow unwanted CD8+T-cell activation as a result of peptide transfer to cellular MHC molecules. To circumvent this problem, and given the role of self-reactive CD8+T cells in the development of type 1 diabetes, we designed a single-chain pMHC complex (scKd.IGRP) by using the class I MHC molecule H-2Kdand a covalently linked peptide derived from islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP206–214), a well established autoantigen in NOD mice. X-ray diffraction studies revealed that the peptide is presented in the groove of the MHC molecule in canonical fashion, and it was also demonstrated that scKd.IGRP tetramers bound specifically to cognate CD8+T cells. Tetramer binding induced death of naive T cells and in vitro- and in vivo-differentiated cytotoxic T lymphocytes, and tetramer-treated cytotoxic T lymphocytes showed a diminished IFN-γ response to antigen stimulation. Tetramer accessibility to disease-relevant T cells in vivo was also demonstrated. Our study suggests the potential of single-chain pMHC tetramers as possible therapeutic agents in autoimmune disease. Their ability to affect the fate of naive and activated CD8+T cells makes them a potential intervention strategy in early and late stages of disease.
Protease phenotype of constitutive connective tissue and of induced mucosal mast cells in mice is regulated by the tissue
Authors: Xing Wei , Austen K. Frank , Gurish Michael F. , Jones Tatiana G.
Published: August 2011

Mouse mast cells (MCs) express a large number of serine proteases including tryptases, mouse mast cell protease (mMCP)-6 and -7; chymases, mMCP-1, -2, and -4; and an elastase, mMCP-5; along with carboxypeptidase-A3 (CPA3). In helminth-infected mouse intestine, distinct protease phenotypes are observed for connective tissue MCs (CTMCs) (mMCP-4+–7+, and CPA3+) and mucosal MCs (MMCs) (mMCP-1+and 2+). To determine whether the protease phenotype was regulated by the tissue, we compared the phenotype of constitutive CTMCs and induced MMCs in trachea and large airways in antigen-sensitized unchallenged and challenged mice to MCs in skin and helminthic-infected intestine. We found that in the trachea, unlike in skin and intestine, CTMCs and MMCs both express all six serine proteases and CPA3 (mMCP-1+, -2+, 4+–7+, CPA3+). This phenotype also holds for the lung CTMCs in the proximal bronchi, whereas the induced MMCs express only four proteases, mMCP-1, -2, -6, and -7. Thus, the T-cell–dependent induction of MMCs in trachea, large bronchi, and small intestine provides numbers but does not determine the protease phenotype. Furthermore, the CTMCs, which are constitutive, also show striking differences at these tissue sites, supporting the view that the differences in expression are tissue directed and not dependent on inflammation.
A fitness trade-off between local competition and dispersal in
Vibrio cholerae
biofilms
Authors: Nadell Carey D. , Bassler Bonnie L.
Published: August 2011

Bacteria commonly grow in densely populated surface-bound communities, termed biofilms, where they gain benefits including superior access to nutrients and resistance to environmental insults. The secretion of extracellular polymeric substances (EPS), which bind bacterial collectives together, is ubiquitously associated with biofilm formation. It is generally assumed that EPS secretion is a cooperative phenotype that benefits all neighboring cells, but in fact little is known about the competitive and evolutionary dynamics of EPS production. By studying
Vibrio cholerae
biofilms in microfluidic devices, we show that EPS-producing cells selectively benefit their clonemates and gain a dramatic advantage in competition against an isogenic EPS-deficient strain. However, this advantage carries an ecological cost beyond the energetic requirement for EPS production: EPS-producing cells are impaired for dispersal to new locations. Our study establishes that a fundamental tradeoff between local competition and dispersal exists among bacteria. Furthermore, this tradeoff can be governed by a single phenotype.
Fungal recognition is mediated by the association of dectin-1 and galectin-3 in macrophages
Authors: Esteban Alexandre , Popp Maximilian W. , Vyas Valmik K. , Strijbis Karin , Ploegh Hidde L. , Fink Gerald R.
Published: August 2011

Dectin-1, the major β-glucan receptor in leukocytes, triggers an effective immune response upon fungal recognition. Here we use sortase-mediated transpeptidation, a technique that allows placement of a variety of probes on a polypeptide backbone, to monitor the behavior of labeled functional dectin-1 in live cells with and without fungal challenge. Installation of probes on dectin-1 by sortagging permitted highly specific visualization of functional protein on the cell surface and its subsequent internalization upon ligand presentation. Retrieval of sortagged dectin-1 expressed in macrophages uncovered a unique interaction between dectin-1 and galectin-3 that functions in the proinflammatory response of macrophages to pathogenic fungi. When macrophages expressing dectin-1 are exposed to
Candida albicans
mutants with increased exposure of β-glucan, the loss of galectin-3 dramatically accentuates the failure to trigger an appropriate TNF-α response.
Aryl hydrocarbon receptor deficiency in T cells suppresses the development of collagen-induced arthritis
Authors: Nakahama Taisuke , Kimura Akihiro , Nguyen Nam Trung , Chinen Ichino , Hanieh Hamza , Nohara Keiko , Fujii-Kuriyama Yoshiaki , Kishimoto Tadamitsu
Published: August 2011

The contributions of aryl hydrocarbon receptor (Ahr) to the pathogenesis of rheumatoid arthritis have not been elucidated. Here, we show that Ahr deficiency ameliorated collagen-induced arthritis, a mouse model of RA. Collagen-immunized Ahr KO mice showed decreased serum levels of such proinflammatory cytokines as IL-1β and IL-6. The Th17 and Th1 cell populations in lymph nodes from these mice decreased and increased, respectively, whereas the percentage of regulatory T cells was unchanged. Interestingly, a lack of Ahr specifically in T cells significantly suppressed collagen-induced arthritis development, whereas Ahr deficiency in macrophages had no effect. These finding indicate that the development of experimental autoimmune arthritis depends on the presence of Ahr in T cells, and that Th1/Th17 balance may be particularly important for this process.
Constitutive intestinal NF-κB does not trigger destructive inflammation unless accompanied by MAPK activation
Authors: Guma Monica , Stepniak Dariusz , Shaked Helena , Spehlmann Martina E. , Shenouda Steve , Cheroutre Hilde , Vicente-Suarez Ildelfonso , Eckmann Lars , Kagnoff Martin F. , Karin Michael
Published: August 2011

Nuclear factor (NF)-κB, activated by IκB kinase (IKK), is a key regulator of inflammation, innate immunity, and tissue integrity. NF-κB and one of its main activators and transcriptional targets, tumor necrosis factor (TNF), are up-regulated in many inflammatory diseases that are accompanied by tissue destruction. The etiology of many inflammatory diseases is poorly understood, but often depends on genetic factors and environmental triggers that affect NF-κB and related pathways. It is unknown, however, whether persistent NF-κB activation is sufficient for driving symptomatic chronic inflammation and tissue damage. To address this question, we generated IKKβ(EE)IEC mice, which express a constitutively active form of IKKβ in intestinal epithelial cell (IECs). IKKβ(EE)IEC mice exhibit NF-κB activation in IECs and express copious amounts of inflammatory chemokines, but only small amounts of TNF. Although IKKβ(EE)IEC mice exhibit inflammatory cell infiltration in the lamina propria (LP) of their small intestine, they do not manifest tissue damage. Yet, upon challenge with relatively mild immune and microbial stimuli, IKKβ(EE)IEC mice succumb to destructive acute inflammation accompanied by enterocyte apoptosis, intestinal barrier disruption, and bacterial translocation. Inflammation is driven by massive TNF production, which requires additional activation of p38 and extracellular-signal–regulated kinase mitogen-activated protein kinases (MAPKs).
Coordinate regulation of tissue macrophage and dendritic cell population dynamics by CSF-1
Authors: Tagliani Elisa , Shi Chao , Nancy Patrice , Tay Chin-Siean , Pamer Eric G. , Erlebacher Adrian
Published: August 2011

Tissue macrophages (Mϕs) and dendritic cells (DCs) play essential roles in tissue homeostasis and immunity. How these cells are maintained at their characteristic densities in different tissues has remained unclear. Aided by a novel flow cytometric technique for assessing relative rates of blood-borne precursor recruitment, we examined Mϕ and DC population dynamics in the pregnant mouse uterus, where rapid tissue growth facilitated a dissection of underlying regulatory mechanisms. We demonstrate how Mϕ dynamics, and thus Mϕ tissue densities, are locally controlled by CSF-1, a pleiotropic growth factor whose in situ level of activity varied widely between uterine tissue layers. CSF-1 acted in part by inducing Mϕ proliferation and in part by stimulating the extravasation of Ly6Chi monocytes (Mos) that served as Mϕ precursors. Mo recruitment was dependent on the production of CCR2 chemokine receptor ligands by uterine Mϕs in response to CSF-1. Unexpectedly, a parallel CSF-1–regulated, but CCR2-independent pathway influenced uterine DC tissue densities by controlling local pre-DC extravasation rates. Together, these data provide cellular and molecular insight into the regulation of Mϕ tissue densities under noninflammatory conditions and reveal a central role for CSF-1 in the coordination of Mϕ and DC homeostasis.
Implementing the MRSA Bundle in ICUs: One Citywide Collaborative's Key Lessons Learned
Authors: Welsh Catherine Amber , Flanagan Mindy E. , Kiess Chris , Doebbeling Bradley N.
Published: August 2011

Because bundle implementation in intensive care units to reduce methicillin-resistant Staphylococcus aureus is challenging, we conducted in-depth interviews with implementation teams at 5 participating hospitals. Key lessons learned across hospitals included the following: maintain management support, engage frontline staff, build the right multidisciplinary team, conduct process mapping, and commit to data collection and feedback.
Carbapenem-Resistant Klebsiella pneumoniae in Post-Acute-Care Facilities in Israel
Authors: Ben-David Debby , Masarwa Samira , Navon-Venezia Shiri , Mishali Hagit , Fridental Ilan , Rubinovitch Bina , Smollan Gill , Carmeli Yehuda , Schwaber Mitchell J. ,   Israel PACF CRKP (Post-Acute-Care Facility Carbapenem-Resistant Klebsiella pneumoniae) Working Group
Published: August 2011

Objective.

To assess the prevalence of and risk factors for carbapenem-resistant Klebsiella pneumoniae (CRKP) carriage among patients in post-acute-care facilities (PACFs) in Israel.

Design, Setting, and Patients.

A cross-sectional prevalence survey was conducted in 12 PACFs. Rectal swab samples were obtained from 1,144 patients in 33 wards. Risk factors for CRKP carriage were assessed among the cohort. Next, a nested, matched case-control study was conducted to define individual risk factors for colonization. Finally, the cohort of patients with a history of CRKP carriage was characterized to determine risk factors for continuous carriage.

Results.

The prevalence of rectal carriage of CRKP among 1,004 patients without a history of CRKP carriage was 12.0%. Independent risk factors for CRKP carriage were prolonged length of stay (odds ratio [OR], 1.001; P < .001), sharing a room with a known carrier (OR, 3.09; P = .02), and increased prevalence of known carriers on the ward (OR, 1.02; P = .013). A policy of screening for carriage on admission was protective (OR, 0.41; P = .03). Risk factors identified in the nested case-control study were antibiotic exposure during the prior 3 months (OR, 1.66; P = .03) and colonization with other resistant pathogens (OR, 1.64; P = .03). Among 140 patients with a history of CRKP carriage, 47% were colonized. Independent risk factors for continued CRKP carriage were antibiotic exposure during the prior 3 months (OR, 3.05; P = .04), receipt of amoxicillin-clavulanate (OR, 4.18; P = .007), and screening within 90 days of the first culture growing CRKP (OR, 2.9; P = .012).

Conclusions.

We found a large reservoir of CRKP in PACFs. Infection-control polices and antibiotic exposure were associated with patient colonization.
A Retrospective Cohort Study into Acquisition of MRSA and Associated Risk Factors after Implementation of Universal Screening in Scottish Hospitals
Authors: van Velzen E. V. H. , Reilly J. S. , Kavanagh K. , Leanord A. , Edwards G. F. S. , Girvan E. K. , Gould I. M. , MacKenzie F. M. , Masterton R.
Published: August 2011

Objective.

To estimate the proportion of patients who acquire methicillin-resistant Staphylococcus aureus (MRSA) while in hospital and to identify risk factors associated with acquisition of MRSA.

Design.

Retrospective cohort study.

Patients.

Adult patients discharged from 36 general specialty wards of 2 Scottish hospitals that had implemented universal screening for MRSA on admission.

Methods.

Patients were screened for MRSA on discharge from hospital by using multisite body swabs that were tested by culture. Discharge screening results were linked to admission screening results. Genotyping was undertaken to identify newly acquired MRSA in MRSA-positive patients on admission.

Results.

Of the 5,155 patients screened for MRSA on discharge, 2.9% (95% confidence interval [CI], 2.43–3.34) were found to be positive. In the subcohort screened on both admission and discharge (n = 2,724), 1.3% of all patients acquired MRSA while in hospital (incidence rate, 2.1/1,000 hospital bed-days in this cohort [95% CI, 1.5–2.9]), while 1.3% remained MRSA positive throughout hospital stay. Three risk factors for acquisition of MRSA were identified: age above 64 years, self-reported renal failure, and self-reported presence of open wounds. On a population level, the prevalence of MRSA colonization did not differ between admission and discharge.

Conclusions.

Cross-transmission of MRSA takes place in Scottish hospitals that have implemented universal screening for MRSA. This study reinforces the importance of infection prevention and control measures to prevent MRSA cross-transmission in hospitals; universal screening for MRSA on admission will in itself not be sufficient to reduce the number of MRSA colonizations and subsequent MRSA infections.
Evaluating a Decade of Exposures to Blood and Body Fluids in an Inner-City Teaching Hospital
Authors: Treakle Amy M. , Schultz Maureen , Giannakos George P. , Joyce Patrick C. , Gordin Fred M.
Published: August 2011

Objective.

To analyze a decade of hospital staff and student exposures to blood and body fluids (BBF) and to identify risk factors relevant to prevention strategies.

Design.

Retrospective review of a 1999–2008 data set of BBF exposures. The data, maintained by occupational health staff, detailed the type of exposure, the setting in which the exposure occurred, and the occupational group of the BBF-exposed personnel.

Setting.

Washington DC Veterans Affairs Medical Center (VA-DC), an inner-city tertiary care hospital.

Participants.

All healthcare workers and staff at the VA-DC.

Methods.

Review of database.

Results.

A review of 10 years of data revealed 564 occupational exposures to BBF, of which 66% were caused by needlesticks and 20% were caused by sharp objects. Exposures occurred most often in the acute care setting (which accounted for 39% of exposures) and the operating room (which accounted for 22%). There was a mean of 4.9 exposures per 10,000 acute care patient-days, 0.5 exposures per 10,000 long-term care patient-days, and 0.35 exposures per 10,000 outpatient visits. Housestaff accounted for the highest number of all exposures (196 [35%]). There were, on average, 15.2 exposures per 100 housestaff full-time equivalents. An average of only 1 exposure per year occurred in the hemodialysis center.

Conclusions.

Occupational exposures to BBF remain common, but rates vary widely by setting and occupational group. Overall rates are steady across a decade, despite the use of various antiexposure devices and provider education programs. Targeting occupational groups and hospital settings that have been shown to have the highest risk rates should become foundational to future preventative strategies.
Point-of-Use Membrane Filtration and Hyperchlorination to Prevent Patient Exposure to Rapidly Growing Mycobacteria in the Potable Water Supply of a Skilled Nursing Facility
Authors: Williams Margaret M. , Chen Tai-Ho , Keane Tim , Toney Nadege , Toney Sean , Armbruster Catherine R. , Butler W. Ray , Arduino Matthew J.
Published: August 2011

Background.

Healthcare-associated outbreaks and pseudo-outbreaks of rapidly growing mycobacteria (RGM) are frequently associated with contaminated tap water. A pseudo-outbreak of Mycobacterium chelonae–M. abscessus in patients undergoing bronchoscopy was identified by 2 acute care hospitals. RGM was identified in bronchoscopy specimens of 28 patients, 25 of whom resided in the same skilled nursing facility (SNF). An investigation ruled out bronchoscopy procedures, specimen collection, and scope reprocessing at the hospitals as sources of transmission.

Objective.

To identify the reservoir for RGM within the SNF and evaluate 2 water system treatments, hyperchlorination and point-of-use (POU) membrane filters, to reduce RGM.

Design.

A comparative in situ study of 2 water system treatments to prevent RGM transmission.

Setting.

An SNF specializing in care of patients requiring ventilator support.

Methods.

RGM and heterotrophic plate count (HPC) bacteria were examined in facility water before and after hyperchlorination and in a subsequent 24-week assessment of filtered water by colony enumeration on Middlebrook and R2A media.

Results.

Mycobacterium chelonae was consistently isolated from the SNF water supply. Hyperchlorination reduced RGM by 1.5 log10 initially, but the population returned to original levels within 90 days. Concentration of HPC bacteria also decreased temporarily. RGM were reduced below detection level in filtered water, a 3-log10 reduction. HPC bacteria were not recovered from newly installed filters, although low quantities were found in water from 2-week-old filters.

Conclusion.

POU membrane filters may be a feasible prevention measure for healthcare facilities to limit exposure of sensitive individuals to RGM in potable water systems.
Clostridium difficile Outbreak Strain BI Is Highly Endemic in Chicago Area Hospitals
Authors: Black Stephanie R. , Weaver Kingsley N. , Jones Roderick C. , Ritger Kathleen A. , Petrella Laurica A. , Sambol Susan P. , Vernon Michael , Burton Stephanie , Garcia-Houchins Sylvia , Weber Stephen G. , Lavin Mary Alice , Gerding Dale , Johnson Stuart , Gerber Susan I.
Published: August 2011

Objective.

Describe the clinical and molecular epidemiology of incident Clostridium difficile infection (CDI) cases in Chicago area acute healthcare facilities (HCFs).

Design and Setting.

Laboratory, clinical, and epidemiologic information was collected for patients with incident CDI who were admitted to acute HCFs in February 2009. Stool cultures and restriction endonuclease analysis typing of the recovered C. difficile isolates was performed.

Patients.

Two hundred sixty-three patients from 25 acute HCFs.

Results.

Acute HCF rates ranged from 2 to 7 patients with CDI per 10,000 patient-days. The crude mortality rate was 8%, with 20 deaths occurring in patients with CDI. Forty-two (16%) patients had complications from CDI, including 4 patients who required partial, subtotal, or total colectomy, 3 of whom died. C. difficile was isolated and typed from 129 of 178 available stool specimens. The BI strain was identified in 79 (61%) isolates. Of patients discharged to long-term care who had their isolate typed, 36 (67%) had BI-associated CDI.

Conclusions.

Severe disease was common and crude mortality was substantial among patients with CDI in Chicago area acute HCFs in February 2009. The outbreak-associated BI strain was the predominant endemic strain identified, accounting for nearly two-thirds of cases. Focal HCF outbreaks were not reported, despite the presence of the BI strain. Transfer of patients between acute and long-term HCFs may have contributed to the high incidence of BI cases in this investigation.
High Incidence of Multidrug-Resistant Gram-Negative Bacteria Recovered from Afghan Patients at a Deployed US Military Hospital
Authors: Sutter Deena E. , Bradshaw Linda U. , Simkins Lucas H. , Summers Amy M. , Atha Michael , Elwood Robert L. , Robertson Janelle L. , Murray Clinton K. , Wortmann Glenn W. , Hospenthal Duane R.
Published: August 2011

Objective.

To investigate potential sources and risks associated with multidrug-resistant (MDR) bacteria in a deployed US military hospital.

Design.

Retrospective analysis of factors associated with recovery of MDR bacteria, supplemented by environmental sampling.

Setting.

The largest US military hospital in Afghanistan.

Patients.

US and Afghan patients with positive bacterial culture results, from September 2007 through August 2008.

Methods.

Microbiologic, demographic, and clinical data were analyzed. Potential risk factors included admission diagnosis or mechanism of injury, length of stay, gender, age, and nationality (US or Afghan). Environmental sampling of selected hospital high-touch surfaces and equipment was performed to help elucidate whether environmental MDR bacteria were contributing to nosocomial spread.

Results.

A total of 266 patients had 411 bacterial isolates that were identified during the study period, including 211 MDR bacteria (51%). Gram-negative bacteria were common among Afghan patients (241 [76%] of 319), and 70% of these were classified as MDR. This included 58% of bacteria recovered from Afghan patients within 48 hours of hospital admission. The most common gram-negative bacteria were Escherichia coli (53% were MDR), Acinetobacter (90% were MDR), and Klebsiella (63% were MDR). Almost one-half of potential extended-spectrum β-lactamase (ESBL) producers were community acquired. Of 100 environmental swab samples, 18 yielded MDR bacteria, including 10 that were Acinetobacter, but no potential ESBL-producing bacteria.

Conclusions.

Gram-negative bacteria from Afghan patients had high rates of antimicrobial resistance. Patients experiencing Complex trauma and prolonged hospital stays likely contribute to the presence of MDR bacteria in this facility. However, many of these patients had community-acquired cases, which implies high rates of colonization prior to hospital admission.
Effectiveness of Measures to Eradicate Staphylococcus aureus Carriage in Patients with Community-Associated Skin and Soft-Tissue Infections: A Randomized Trial
Authors: Fritz Stephanie A. , Camins Bernard C. , Eisenstein Kimberly A. , Fritz Joseph M. , Epplin Emma K. , Burnham Carey-Ann , Dukes Jonathan , Storch Gregory A.
Published: August 2011

Background.

Despite a paucity of evidence, decolonization measures are prescribed for outpatients with recurrent Staphylococcus aureus skin and soft-tissue infection (SSTI).

Objective.

Compare the effectiveness of 4 regimens for eradicating S. aureus carriage.

Design.

Open-label, randomized controlled trial. Colonization status and recurrent SSTI were ascertained at 1 and 4 months.

Setting.

Barnes-Jewish and St. Louis Children's Hospitals, St. Louis, Missouri, 2007–2009.

Participants.

Three hundred patients with community-onset SSTI and S. aureus colonization in the nares, axilla, or inguinal folds.

Interventions.

Participants were randomized to receive no therapeutic intervention (control subjects) or one of three 5-day regimens: 2% mupirocin ointment applied to the nares twice daily, intranasal mupirocin plus daily 4% chlorhexidine body washes, or intranasal mupirocin plus daily dilute bleach water baths.

Results.

Among 244 participants with 1-month colonization data, modified intention-to-treat analysis revealed S. aureus eradication in 38% of participants in the education only (control) group, 56% of those in the mupirocin group (P = .03 vs controls), 55% of those in the mupirocin and chlorhexidine group (P = .05), and 63% off those in the mupirocin and bleach group (P = .006). Of 229 participants with 4-month colonization data, eradication rates were 48% in the control group, 56% in the mupirocin only group (P = .40 vs controls), 54% in the mupirocin and chlorhexidine group (P = .51), and 71% in the mupirocin and bleach group (P = .02). At 1 and 4 months, recurrent SSTIs were reported by 20% and 36% of participants, respectively.

Conclusions.

An inexpensive regimen of dilute bleach baths, intranasal mupirocin, and hygiene education effectively eradicated S. aureus over a 4-month period. High rates of recurrent SSTI suggest that factors other than endogenous colonization are important determinants of infection.

Trial Registration.

ClinicalTrials.gov identifier: NCT00513799.
Low Frequency of Endemic Patient-to-Patient Transmission of Antibiotic-Resistant Gram-Negative Bacilli in a Pediatric Intensive Care Unit
Authors: Zoltanski Joan , Dul Michael , O’Riordan Mary Ann , Blumer Jeffrey , Toltzis Philip
Published: August 2011

We sought to determine the frequency of horizontal transmission of antibiotic-resistant gram-negative bacilli (ARGNB) in a pediatric intensive care unit during a nonoutbreak period. Among 5,300 admissions over 39 consecutive months, 13 ARGNB clusters involving 35 children were identified by pulsed-filed gel electrophoresis analysis, which suggests that person-to-person transmission was uncommon.
Student Immunity Requirements of Health Professional Schools: Vaccination and Other Means of Fulfillment—United States, 2008
Authors: Miller Brady L. , Lindley Megan C. , Ahmed Faruque , Wortley Pascale M.
Published: August 2011

US health professional schools with student immunity requirements for recommended vaccines frequently accept evidence of immunity other than vaccination but vary widely on the types of evidence that are accepted. Exemptions for nonmedical reasons and, to a lesser extent, medical reasons are often obtainable by a student-written document.
A survey of electron Bernstein wave heating and current drive potential for spherical tokamaks
Authors: Urban Jakub , Decker Joan , Peysson Yves , Preinhaelter Josef , Shevchenko Vladimir , Taylor Gary , Vahala Linda , Vahala George
Published: August 2011

The electron Bernstein wave (EBW) is typically the only wave in the electron cyclotron (EC) range that can be applied in spherical tokamaks for heating and current drive (H&CD). Spherical tokamaks (STs) operate generally in high-β regimes, in which the usual EC O- and X-modes are cut off. In this case, EBWs seem to be the only option that can provide features similar to the EC waves—controllable localized H&CD that can be used for core plasma heating as well as for accurate plasma stabilization.

The EBW is a quasi-electrostatic wave that can be excited by mode conversion from a suitably launched O- or X-mode; its propagation further inside the plasma is strongly influenced by the plasma parameters. These rather awkward properties make its application somewhat more difficult. In this paper we perform an extensive numerical study of EBW H&CD performance in four typical ST plasmas (NSTX L- and H-mode, MAST Upgrade, NHTX). Coupled ray-tracing (AMR) and Fokker–Planck (LUKE) codes are employed to simulate EBWs of varying frequencies and launch conditions, which are the fundamental EBW parameters that can be chosen and controlled. Our results indicate that an efficient and universal EBW H&CD system is indeed viable. In particular, power can be deposited and current reasonably efficiently driven across the whole plasma radius. Such a system could be controlled by a suitably chosen launching antenna vertical position and would also be sufficiently robust.
Some eigenvalue problems for vectorial Sturm-Liouville equations with eigenparameter dependent boundary conditions
Authors: Chan Chi-Hua
Published: August 2011

We investigate the

n
n

-dimensional vectorial Sturm-Liouville equation
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="ModifyingAbove y With right-arrow left-parenthesis x right-parenthesis plus left-bracket lamda squared upper I Subscript n Baseline minus upper Q left-parenthesis x right-parenthesis right-bracket ModifyingAbove y With right-arrow left-parenthesis x right-parenthesis equals ModifyingAbove 0 With right-arrow">

y
→

 
(
x
)
+
[

λ
2

I
n

−
Q
(
x
)
]

y
→

(
x
)
=

0
→

\vec {y}\ (x)+[\lambda ^2 I_n -Q(x)]\vec {y}(x)=\vec {0}

\]
with eigenparameter dependent boundary conditions
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="ModifyingAbove y With right-arrow left-parenthesis 0 right-parenthesis equals ModifyingAbove 0 With right-arrow comma upper A ModifyingAbove y With right-arrow prime left-parenthesis pi right-parenthesis plus lamda ModifyingAbove y With right-arrow left-parenthesis pi right-parenthesis equals ModifyingAbove 0 With right-arrow period">

y
→

(
0
)
=

0
→

,
A

y
→

 
′

(
π
)
+
λ

y
→

(
π
)
=

0
→

.

\vec {y}(0)=\vec {0}, A\vec {y}\ ’(\pi )+\lambda \vec {y}(\pi )=\vec {0}.

\]
Under the assumption that

Q
(
x
)

Q(x)

is nonnegative definite in [0,

π
\pi

], we prove that the eigenvalues of the

n
n

-dimensional vectorial Sturm-Liouville equation are real.

For the case

n
=
2

n=2

, we show that the algebraic multiplicity of an eigenvalue of the problem as a zero of the characteristic function
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="omega Subscript upper A Baseline left-parenthesis lamda semicolon upper Q right-parenthesis equals det left-bracket upper A upper Y prime left-parenthesis pi semicolon lamda squared semicolon upper Q right-parenthesis plus lamda upper Y left-parenthesis pi semicolon lamda squared semicolon upper Q right-parenthesis right-bracket">

ω
A

(
λ
;
Q
)
=
det
[
A

Y
′

(
π
;

λ
2

;
Q
)
+
λ
Y
(
π
;

λ
2

;
Q
)
]

\omega _A(\lambda ;Q)=\det [AY’(\pi ;\lambda ^2;Q)+\lambda Y(\pi ;\lambda ^2;Q)]

\]
is equal to its geometric multiplicity. By the theory of Hadamard’s factorization, we also prove that the characteristic function

ω
A

(
λ
;
Q
)

\omega _A(\lambda ;Q)

is uniquely determined by the spectral set of the equation. Moreover, we consider the inverse problem for the equation, i.e., how many spectral sets can determine the potential function

Q
(
x
)

Q(x)

uniquely, and we find that three spectral sets are necessary for us to determine the potential function

Q
(
x
)

Q(x)

uniquely.