bluuebunny/crossref_metadata_2025 huggingface dataset:
‘Amsterdamned’? The Uncertain Future of a Financial Centre
Authors: Engelen Ewald
Published: May 2007

Much has been written about the spatial effects of the introduction of new information and communication technologies on the flows of finance. Some people conclude that place has become irrelevant, while others maintain that face-to-face relations will remain of the utmost importance. In a seminal paper, Clark and O'Connor have argued against the ‘end of geography’ thesis and have used information-related factors to hypothesize a complex division of financial labour over different spatial scales. In this paper, the case of Amsterdam during the 1990s is used to test the validity of the Clark-O'Connor framework. In the concluding section I suggest some amendments to make the framework more robust.
Land-Use Changes in a Pro-Smart-Growth State: Maryland, USA
Authors: Shen Qing , Zhang Feng
Published: May 2007

In this paper we present a study of the effectiveness of the smart-growth initiatives in Maryland, USA, for shaping the spatial pattern of urban growth in the state by channeling development into designated areas. By estimating binary logit models of land conversion for selected counties in Maryland for both pre-smart-growth and post-smart-growth time periods, we find that the governmental policy has generally been successful in achieving its objective. However, there are significant variations across local counties in terms of policy effectiveness. Planners must pay much closer attention to these interjurisdictional differences in the effectiveness of smart-growth programs, examine the likely causes and consequences, and formulate strategies for making improvement.
Comparison and Representation Failures Both Cause Real-World Change Blindness
Authors: Varakin D Alexander , Levin Daniel T , Collins Krista M
Published: May 2007

Change blindness (CB) occurs when people miss changes across views. Hypothetically, CB would occur if observers failed to represent information about the changing object, but CB would also occur if observers represented and failed to compare information across views, or represented only the pre- or post-change object. For a variety of reasons, previous studies have been unable to determine which of these alternatives contribute to CB in an incidental real-world setting. To address these ambiguities, we conducted two real-world experiments using stimuli that changed on only one feature and tested recognition memory for both the changing feature and a non-changing feature. Participants also provided confidence ratings on recognition responses, allowing us to test whether CB has multiple causes within a single task setting. The results suggest that, in a single real-world setting, CB can be caused by both a failure to represent and a failure to compare information across views.
Searching for a Perceived Stare in the Crowd
Authors: Doi Hirokazu , Ueda Kazuhiro
Published: May 2007

Gaze direction can be represented in terms not only of local-feature information (ie the location of the pupil in the eye socket), but also of an emergent property—whether the perceived gaze direction is straight or averted. To examine whether this emergent property is preferentially accessed when searching for an oddly directed gaze, we experimentally manipulated the local-feature information and the emergent property independently, in order to investigate the influences of both types of information on visual searches for an oddly directed gaze. We found that the primary determinant of search efficiency was not the local-feature information of eye region, but the emergent property—the perceived direction of the gaze. This finding is consistent with the idea that important social signals are recognised primarily by their emergent properties.
The Depth of Distractor Processing in Search with Clutter
Authors: Bravo Mary J , Farid Hany
Published: May 2007

Some search tasks involve looking for a category target in clutter. This is the task faced, for example, by a baggage screener looking for weapons in a suitcase. Such tasks presumably involve the segmentation and recognition of the target object, but it is unknown whether they also involve the segmentation and recognition of the distractor objects. To examine the depth of distractor processing in this task, we had observers search through cluttered displays composed of normal and chimerical distractors. The normal distractors were photographs of recognizable objects, while the chimerical distractors were created by interchanging parts between the normal objects. The obsever's task was to identify the display quadrant that contained an animal or a vehicle target. We varied the difficulty of the search task by varying target and distractor discriminability, target uncertainty, and target occlusion. Only when the target was partially occluded did we find an effect of distractor type. In this case, observers may have found the target through a process of mentally eliminating whole distractor objects. When the target was unoccluded, we found no evidence that observers selected and rejected whole distractors during search. This second result supports our previous claim that often the items for search in clutter are not whole objects.
The frequency and structure of recombinant products is determined by the cellular level of MutL
Authors: Elez Marina , Radman Miroslav , Matic Ivan
Published: May 2007

The presence of repeated DNA sequences is a genomic liability, because interrepeat recombination can result in chromosomal rearrangements. The mismatch repair system prevents recombination between nonidentical repeats, but the mechanism of antirecombination has not been established. Although the MutS protein binds to base pair mismatches in heteroduplex DNA, the role of the MutL protein in preventing recombination is unknown. In a screen designed to identify new cellular functions that suppress deletion formation involving nonidentical DNA repeats, we isolated a
mutL
mutant having a separation-of-function phenotype. The mutant showed an increased frequency of deletions but not of mutations. The split phenotype is due to a decreased MutL level, indicating that recombination, but not replication editing, is highly sensitive to MutL level. By altering the MutL level, we found that the frequency of deletion-generating recombination is inversely related to the amount of cellular MutL. DNA sequence analysis of the recombined repeats shows that the tolerance of base pair mismatches in heteroduplex DNA is also inversely correlated with MutL level. Unlike recombination, correction of misincorporation errors by mismatch repair is insensitive to fluctuations in MutL level. Overproduction of MutS does not affect either of these phenotypes, suggesting that, unlike MutL, MutS is not limiting for mismatch repair activities. These results indicate that MutL (
i
) determines effective DNA homology in recombination processes and (
ii
) fine tunes the process of deletion formation involving repeated, diverged DNA sequences.
Bacteria of the genus
Asaia
stably associate with
Anopheles stephensi
, an Asian malarial mosquito vector
Authors: Favia Guido , Ricci Irene , Damiani Claudia , Raddadi Noura , Crotti Elena , Marzorati Massimo , Rizzi Aurora , Urso Roberta , Brusetti Lorenzo , Borin Sara , Mora Diego , Scuppa Patrizia , Pasqualini Luciano , Clementi Emanuela , Genchi Marco , Corona Silvia , Negri Ilaria , Grandi Giulio , Alma Alberto , Kramer Laura , Esposito Fulvio , Bandi Claudio , Sacchi Luciano , Daffonchio Daniele
Published: May 2007

Here, we show that an α-proteobacterium of the genus
Asaia
is stably associated with larvae and adults of
Anopheles stephensi
, an important mosquito vector of
Plasmodium vivax
, a main malaria agent in Asia.
Asaia
bacteria dominate mosquito-associated microbiota, as shown by
16S rRNA
gene abundance, quantitative PCR, transmission electron microscopy and
in situ
-hybridization of
16S rRNA
genes. In adult mosquitoes,
Asaia
sp. is present in high population density in the female gut and in the male reproductive tract.
Asaia
sp. from
An. stephensi
has been cultured in cell-free media and then transformed with foreign DNA. A green fluorescent protein-tagged
Asaia
sp. strain effectively lodged in the female gut and salivary glands, sites that are crucial for
Plasmodium
sp. development and transmission. The larval gut and the male reproductive system were also colonized by the transformed
Asaia
sp. strain. As an efficient inducible colonizer of mosquitoes that transmit
Plasmodium
sp.,
Asaia
sp. may be a candidate for malaria control.
β-Actin regulates platelet nitric oxide synthase 3 activity through interaction with heat shock protein 90
Authors: Ji Yong , Ferracci Géraldine , Warley Alice , Ward Malcolm , Leung Kit-Yi , Samsuddin Salma , Lévêque Christian , Queen Lindsay , Reebye Vikash , Pal Pallavi , Gkaliagkousi Eugenia , Seager Michael , Ferro Albert
Published: May 2007

Cytoskeletal proteins are crucial in maintaining cellular structure and, in certain cell types, also play an essential role in motility and shape change. Nitric oxide (NO) is an important paracrine mediator of vascular and platelet function and is produced in the vasculature by the enzyme NO synthase type 3 (NOS-3). Here, we demonstrate in human platelets that the polymerization state of β-actin crucially regulates the activation state of NOS-3, and hence NO formation, through altering its binding of heat shock protein 90 (Hsp90). We found that NOS-3 binds to the globular, but not the filamentous, form of β-actin, and the affinity of NOS-3 for globular β-actin is, in turn, increased by Hsp90. Formation of this ternary complex among NOS-3, globular β-actin, and Hsp90, in turn, results in an increase in both NOS activity and cyclic guanosine-3′,5′-monophosphate, an index of bioactive NO, as well as an increased rate of Hsp90 degradation, thus limiting the duration for which NOS-3 remains activated. These observations suggest that β-actin plays a critical role in regulating NO formation and signaling in platelets.
Retrograde nuclear accumulation of cytoplasmic tRNA in rat hepatoma cells in response to amino acid deprivation
Authors: Shaheen Hussam H. , Horetsky Rick L. , Kimball Scot R. , Murthi Athulaprabha , Jefferson Leonard S. , Hopper Anita K.
Published: May 2007

Until recently, transport of tRNA was presumed to be unidirectional, from the nucleus to the cytoplasm. Our published findings, however, revealed that cytoplasmic tRNAs move retrograde to the nucleus in
Saccharomyces cerevisiae
and that nuclear accumulation of cytoplasmic tRNAs occurs when cells are nutrient deprived. The findings led us to examine whether retrograde nuclear accumulation of cytoplasmic tRNAs occurs in higher eukaryotes. Using RNA FISH and Northern and Western analyses we show that tRNAs accumulate in nuclei of a hepatoma cell line in response to amino acid deprivation. To discern whether tRNA nuclear accumulation results from nuclear import of cytoplasmic tRNAs, transcription of new RNAs was inhibited, and the location of “old” tRNAs in response to nutrient stress was determined. Even in the absence of new RNA synthesis, there were significant tRNA nuclear pools after amino acid depletion, providing strong evidence that retrograde traffic is responsible for the tRNA nuclear pools. Further analyses showed that retrograde tRNA nuclear accumulation in hepatoma cells is a reversible and energy-dependent process. The data provide evidence for retrograde tRNA nuclear accumulation in intact mammalian cells and support the hypothesis that nuclear accumulation of cytoplasmic tRNA and tRNA re-export to the cytoplasm may constitute a universal mechanism for posttranscriptional regulation of global gene expression in response to nutrient availability.
Automated 2D IR spectroscopy using a mid-IR pulse shaper and application of this technology to the human islet amyloid polypeptide
Authors: Shim Sang-Hee , Strasfeld David B. , Ling Yun L. , Zanni Martin T.
Published: May 2007

The capability of 2D IR spectroscopy to elucidate time-evolving structures is enhanced by a programmable mid-IR pulse shaper that greatly improves the ease, speed, and accuracy of data collection. Traditional ways of collecting 2D IR spectra are difficult to implement, cause distorted peak shapes, and result in poor time resolution and/or phase problems. We report on several methods for collecting 2D IR spectra by using a computer-controlled germanium acoustooptic modulator that overcomes the above problems. The accuracy and resolution of each method is evaluated by using model metal carbonyl compounds that have well defined lineshapes. Furthermore, phase cycling can now be employed to largely alleviate background scatter from heterogeneous samples. With these methods in hand, we apply 2D IR spectroscopy to study the structural diversity in amyloid fibers of aggregated human islet amyloid polypeptide (hIAPP), which is involved with type 2 diabetes. The 2D IR spectra reveal that the β-sheet fibers have a large structural distribution, as evidenced by an inhomogeneously broadened β-sheet peak and strong coupling to random coil conformations. Structural diversity is an important characteristic of hIAPP because it may be that partly folded peptides cause the disease. This experiment on hIAPP is an example of how computer generation of 2D IR pulse sequences is a key step toward automating 2D IR spectroscopy, so that new pulse sequences can be implemented quickly and a diverse range of systems can be studied more easily.
Single-molecule FRET reveals sugar-induced conformational dynamics in LacY
Authors: Majumdar Devdoot S. , Smirnova Irina , Kasho Vladimir , Nir Eyal , Kong Xiangxu , Weiss Shimon , Kaback H. Ronald
Published: May 2007

The N- and C-terminal six-helix bundles of lactose permease (LacY) form a large internal cavity open on the cytoplasmic side and closed on the periplasmic side with a single sugar-binding site at the apex of the cavity near the middle of the molecule. During sugar/H
+
symport, an outward-facing cavity is thought to open with closing of the inward-facing cavity so that the sugar-binding site is alternately accessible to either face of the membrane. In this communication, single-molecule fluorescence (Förster) resonance energy transfer is used to test this model with wild-type LacY and a conformationally restricted mutant. Pairs of Cys residues at the ends of two helices on the cytoplasmic or periplasmic sides of wild-type LacY and the mutant were labeled with appropriate donor and acceptor fluorophores, single-molecule fluorescence resonance energy transfer was determined in the absence and presence of sugar, and distance changes were calculated. With wild-type LacY, binding of a galactopyranoside, but not a glucopyranoside, results in a decrease in distance on the cytoplasmic side and an increase in distance on the periplasmic side. In contrast, with the mutant, a more pronounced decrease in distance and in distance distribution is observed on the cytoplasmic side, but there is no change on the periplasmic side. The results are consistent with the alternating access model and indicate that the defect in the mutant is due to impaired ligand-induced flexibility on the periplasmic side.
Functionally distinct genes regulated by hydrogen limitation and growth rate in methanogenic Archaea
Authors: Hendrickson Erik L. , Haydock Andrew K. , Moore Brian C. , Whitman William B. , Leigh John A.
Published: May 2007

The use of molecular hydrogen as electron donor for energy generation is a defining characteristic of the hydrogenotrophic methanogens, an ancient group that dominates the phylum Eury archaeota. We present here a global study of changes in mRNA abundance in response to hydrogen availability for a hydrogenotrophic methanogen. Cells of
Methanococcus maripaludis
were grown by using continuous culture to deconvolute the effects of hydrogen limitation and growth rate, and microarray analyses were conducted. Hydrogen limitation markedly increased mRNA levels for genes encoding enzymes of the methanogenic pathway that reduce or oxidize the electron-carrying deazaflavin, coenzyme F
420
. F
420
-dependent redox functions in energy-generating metabolism are characteristic of the methanogenic Archaea, and the results show that their regulation is distinct from other redox processes in the cell. Rapid growth increased mRNA levels of the gene for an unusual hydrogenase, the hydrogen-dependent methylenetetrahydromethanopterin dehydrogenase.
A role for exposed mannosylations in presentation of human therapeutic self-proteins to CD4+ T lymphocytes
Authors: Dasgupta Suryasarathi , Navarrete Ana-Maria , Bayry Jagadeesh , Delignat Sandrine , Wootla Bharath , André Sébastien , Christophe Olivier , Nascimbeni Michelina , Jacquemin Marc , Martinez-Pomares Luisa , Geijtenbeek Teunis B. H. , Moris Arnaud , Saint-Remy Jean-Marie , Kazatchkine Michel D. , Kaveri Srinivas V. , Lacroix-Desmazes Sébastien
Published: May 2007

Several therapeutic self-proteins elicit immune responses when administered to patients. Such adverse immune responses reduce drug efficacy. To induce an immune response, a protein must interact with different immune cells, including antigen-presenting cells, T cells, and B cells. Each cell type recognizes distinct immunogenic patterns on antigens. Mannose-terminating glycans have been identified as pathogen-associated molecular patterns that are essential for internalization of microbes by antigen-presenting cells, leading to presentation. Here, we have investigated the importance of exposed mannosylation on an immunogenic therapeutic self-protein, procoagulant human factor VIII (FVIII). Administration of therapeutic FVIII to hemophilia A patients induces inhibitory anti-FVIII antibodies in up to 30% of the cases. We demonstrate that entry of FVIII into human dendritic cells (DC) leading to T cell activation, is mediated by mannose-terminating glycans on FVIII. Further, we identified macrophage mannose receptor (CD206) as a candidate endocytic receptor for FVIII on DC. Saturation of mannose receptors on DC with mannan, and enzymatic removal of mannosylated glycans from FVIII lead to reduced T cell activation. The interaction between FVIII and CD206 was blocked by VWF, suggesting that, under physiological conditions, the intrinsic mannose-dependent immunogenicity of FVIII is quenched by endogenous immunochaperones. These data provide a link between the mannosylation of therapeutic self-proteins and their iatrogenic immunogenicity. Such a link would be of special relevance in the context of replacement therapy where mechanisms of central and peripheral tolerance have not been established during ontogeny because of the absence of the antigen.
trans-SNARE complex assembly and yeast vacuole membrane fusion
Authors: Collins Kevin M. , Wickner William T.
Published: May 2007

cis-SNARE complexes (anchored in one membrane) are disassembled by Sec17p (α-SNAP) and Sec18p (NSF), permitting the unpaired SNAREs to assemble in trans. We now report a direct assay of trans-SNARE complex formation during yeast vacuole docking. SNARE complex assembly and fusion is promoted by high concentrations of the SNARE Vam7p or Nyv1p or by addition of HOPS (homotypic fusion and vacuole protein sorting), a Ypt7p (Rab)-effector complex with a Sec1/Munc18-family subunit. Inhibitors that target Ypt7p, HOPS, or key regulatory lipids prevent trans-SNARE complex assembly and ensuing fusion. Strikingly, the lipid ligand MED (myristoylated alanine-rich C kinase substrate effector domain) or elevated concentrations of Sec17p, which can displace HOPS from SNARE complexes, permit full trans-SNARE pairing but block fusion. These findings suggest that efficient fusion requires trans-SNARE complex associations with factors such as HOPS and subsequent regulated lipid rearrangements.
Entrainment of the human circadian pacemaker to longer-than-24-h days
Authors: Gronfier Claude , Wright Kenneth P. , Kronauer Richard E. , Czeisler Charles A.
Published: May 2007

Entrainment of the circadian pacemaker to the light:dark cycle is necessary for rhythmic physiological functions to be appropriately timed over the 24-h day. Nonentrainment results in sleep, endocrine, and neurobehavioral impairments. Exposures to intermittent bright light pulses have been reported to phase shift the circadian pacemaker with great efficacy. Therefore, we tested the hypothesis that a modulated light exposure (MLE) with bright light pulses in the evening would entrain subjects to a light:dark cycle 1 h longer than their own circadian period (τ). Twelve subjects underwent a 65-day inpatient study. Individual subject's circadian period was determined in a forced desynchrony protocol. Subsequently, subjects were released into 30 longer-than-24-h days (daylength of τ + 1 h) in one of three light:dark conditions: (
i
) ≈25 lux; (
ii
) ≈100 lux; and (
iii
) MLE: ≈25 lux followed by ≈100 lux, plus two 45-min bright light pulses of ≈9,500 lux near the end of scheduled wakefulness. We found that lighting levels of ≈25 lux were insufficient to entrain all subjects tested. Exposure to ≈100 lux was sufficient to entrain subjects, although at a significantly wider phase angle compared with baseline. Exposure to MLE was able to entrain the subjects to the imposed sleep–wake cycles but at a phase angle comparable to baseline. These results suggest that MLE can be used to entrain the circadian pacemaker to non-24-h days. The implications of these findings are important because they could be used to treat circadian misalignment associated with space flight and circadian rhythm sleep disorders such as shift-work disorder.
Double proton transfer dynamics of model DNA base pairs in the condensed phase
Authors: Kwon Oh-Hoon , Zewail Ahmed H.
Published: May 2007

The dynamics of excited-state double proton transfer of model DNA base pairs, 7-azaindole dimers, is reported using femtosecond fluorescence spectroscopy. To elucidate the nature of the transfer in the condensed phase, here we examine variation of solvent polarity and viscosity, solute concentration, and isotopic fractionation. The rate of proton transfer is found to be significantly dependent on polarity and on the isotopic composition in the pair. Consistent with a stepwise mechanism, the results support the presence of an ionic intermediate species which forms on the femtosecond time scale and decays to the final tautomeric form on the picosecond time scale. We discuss the results in relation to the molecular motions involved and comment on recent claims of concerted transfer in the condensed phase. The nonconcerted mechanism is in agreement with previous isolated-molecule femtosecond dynamics and is also consistent with the most-recent high-level theoretical study on the same pair.
A solution NMR study showing that active site ligands and nucleotides directly perturb the allosteric equilibrium in aspartate transcarbamoylase
Authors: Velyvis Algirdas , Yang Ying R. , Schachman Howard K. , Kay Lewis E.
Published: May 2007

The 306-kDa aspartate transcarbamoylase is a well studied regulatory enzyme, and it has emerged as a paradigm for understanding allostery and cooperative binding processes. Although there is a consensus that the cooperative binding of active site ligands follows the Monod–Wyman–Changeux (MWC) model of allostery, there is some debate about the binding of effectors such as ATP and CTP and how they influence the allosteric equilibrium between R and T states of the enzyme. In this article, the binding of substrates, substrate analogues, and nucleotides is studied, along with their effect on the R–T equilibrium by using highly deuterated,
1
H,
13
C-methyl-labeled protein in concert with methyl-transverse relaxation optimized spectroscopy (TROSY) NMR. Although only the T state of the enzyme can be observed in spectra of wild-type unliganded aspartate transcarbamoylase, binding of active-site substrates shift the equilibrium so that correlations from the R state become visible, allowing the equilibrium constant (L′) between ligand-saturated R and T forms of the enzyme to be measured quantitatively. The equilibrium constant between unliganded R and T forms (L) also is obtained, despite the fact that the R state is “invisible” in spectra, by means of an indirect process that makes use of relations that emerge from the fact that ligand binding and the R–T equilibrium are linked. Titrations with MgATP unequivocally establish that its binding directly perturbs the R–T equilibrium, consistent with the Monod–Wyman–Changeux model. This study emphasizes the utility of modern solution NMR spectroscopy in understanding protein function, even for systems with aggregate molecular masses in the hundreds of kilodaltons.
Ubiquitination of serine, threonine, or lysine residues on the cytoplasmic tail can induce ERAD of MHC-I by viral E3 ligase mK3
Authors: Wang Xiaoli , Herr Roger A. , Chua Wei-Jen , Lybarger Lonnie , Wiertz Emmanuel J.H.J. , Hansen Ted H.
Published: May 2007

The mechanism by which substrates for endoplasmic reticulum–associated degradation are retrotranslocated to the cytosol remains largely unknown, although ubiquitination is known to play a key role. The mouse γ-herpesvirus protein mK3 is a viral RING-CH–type E3 ligase that specifically targets nascent major histocompatibility complex I heavy chain (HC) for degradation, thus blocking the immune detection of virus-infected cells. To address the question of how HC is retrotranslocated and what role mK3 ligase plays in this action, we investigated ubiquitin conjugation sites on HC using mutagenesis and biochemistry approaches. In total, our data demonstrate that mK3-mediated ubiquitination can occur via serine, threonine, or lysine residues on the HC tail, each of which is sufficient to induce the rapid degradation of HC. Given that mK3 has numerous cellular and viral homologues, it will be of considerable interest to determine the pervasiveness of this novel mechanism of ubiquitination.
Zinc is a novel intracellular second messenger
Authors: Yamasaki Satoru , Sakata-Sogawa Kumiko , Hasegawa Aiko , Suzuki Tomoyuki , Kabu Koki , Sato Emi , Kurosaki Tomohiro , Yamashita Susumu , Tokunaga Makio , Nishida Keigo , Hirano Toshio
Published: May 2007

Zinc is an essential trace element required for enzymatic activity and for maintaining the conformation of many transcription factors; thus, zinc homeostasis is tightly regulated. Although zinc affects several signaling molecules and may act as a neurotransmitter, it remains unknown whether zinc acts as an intracellular second messenger capable of transducing extracellular stimuli into intracellular signaling events. In this study, we report that the cross-linking of the high affinity immunoglobin E receptor (Fcε receptor I [FcεRI]) induced a release of free zinc from the perinuclear area, including the endoplasmic reticulum in mast cells, a phenomenon we call the zinc wave. The zinc wave was dependent on calcium influx and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase activation. The results suggest that the zinc wave is involved in intracellular signaling events, at least in part by modulating the duration and strength of FcεRI-mediated signaling. Collectively, our findings indicate that zinc is a novel intracellular second messenger.
Defects in coding joint formation in vivo in developing ATM-deficient B and T lymphocytes
Authors: Huang Ching-Yu , Sharma Girdhar G. , Walker Laura M. , Bassing Craig H. , Pandita Tej K. , Sleckman Barry P.
Published: May 2007

Ataxia-telangiectasia mutated (ATM)–deficient lymphocytes exhibit defects in coding joint formation during V(D)J recombination in vitro. Similar defects in vivo should affect both T and B cell development, yet the lymphoid phenotypes of ATM deficiency are more pronounced in the T cell compartment. In this regard, ATM-deficient mice exhibit a preferential T lymphopenia and have an increased incidence of nontransformed and transformed T cells with T cell receptor α/δ locus translocations. We demonstrate that there is an increase in the accumulation of unrepaired coding ends during different steps of antigen receptor gene assembly at both the immunoglobulin and T cell receptor loci in developing ATM-deficient B and T lymphocytes. Furthermore, we show that the frequency of ATM-deficient αβ T cells with translocations involving the T cell receptor α/δ locus is directly related to the number of T cell receptor α rearrangements that these cells can make during development. Collectively, these findings demonstrate that ATM deficiency leads to broad defects in coding joint formation in developing B and T lymphocytes in vivo, and they provide a potential molecular explanation as to why the developmental impact of these defects could be more pronounced in the T cell compartment.
Type I interferons produced by hematopoietic cells protect mice against lethal infection by mammalian reovirus
Authors: Johansson Cecilia , Wetzel J. Denise , He JianPing , Mikacenic Carmen , Dermody Terence S. , Kelsall Brian L.
Published: May 2007

We defined the function of type I interferons (IFNs) in defense against reovirus strain type 1 Lang (T1L), which is a double-stranded RNA virus that infects Peyer's patches (PPs) after peroral inoculation of mice. T1L induced expression of mRNA for IFN-α, IFN-β, and Mx-1 in PPs and caused localized intestinal infection that was cleared in 10 d. In contrast, T1L produced fatal systemic infection in IFNαR1 knockout (KO) mice with extensive cell loss in lymphoid tissues and necrosis of the intestinal mucosa. Studies of bone-marrow chimeric mice indicated an essential role for hematopoietic cells in IFN-dependent viral clearance. Dendritic cells (DCs), including conventional DCs (cDCs), were the major source of type I IFNs in PPs of reovirus-infected mice, whereas all cell types expressed the antiviral protein Mx-1. Neither NK cells nor signaling via Toll-like receptor 3 or MyD88 were essential for viral clearance. These data demonstrate a requirement for type I IFNs in the control of an intestinal viral infection and indicate that cDCs are a significant source of type I IFN production in vivo. Therefore, innate immunity in PPs is an essential component of host defense that limits systemic spread of pathogens that infect the intestinal mucosa.
Cyclic adenosine monophosphate is a key component of regulatory T cell–mediated suppression
Authors: Bopp Tobias , Becker Christian , Klein Matthias , Klein-Heßling Stefan , Palmetshofer Alois , Serfling Edgar , Heib Valeska , Becker Marc , Kubach Jan , Schmitt Steffen , Stoll Sabine , Schild Hansjörg , Staege Martin S. , Stassen Michael , Jonuleit Helmut , Schmitt Edgar
Published: May 2007

Naturally occurring regulatory T cells (T reg cells) are a thymus-derived subset of T cells, which are crucial for the maintenance of peripheral tolerance by controlling potentially autoreactive T cells. However, the underlying molecular mechanisms of this strictly cell contact–dependent process are still elusive. Here we show that naturally occurring T reg cells harbor high levels of cyclic adenosine monophosphate (cAMP). This second messenger is known to be a potent inhibitor of proliferation and interleukin 2 synthesis in T cells. Upon coactivation with naturally occurring T reg cells the cAMP content of responder T cells is also strongly increased. Furthermore, we demonstrate that naturally occurring T reg cells and conventional T cells communicate via cell contact–dependent gap junction formation. The suppressive activity of naturally occurring T reg cells is abolished by a cAMP antagonist as well as by a gap junction inhibitor, which blocks the cell contact–dependent transfer of cAMP to responder T cells. Accordingly, our results suggest that cAMP is crucial for naturally occurring T reg cell–mediated suppression and traverses membranes via gap junctions. Hence, naturally occurring T reg cells unexpectedly may control the immune regulatory network by a well-known mechanism based on the intercellular transport of cAMP via gap junctions.
Transoral Laser Marsupialization of Epiglottic Cysts
Authors: Su Chih‐Ying , Hsu Jui‐Lin
Published: May 2007

Objective: The objective of this study is to investigate the safety and effectiveness of laser marsupialization of epiglottic cysts via a transoral route.

Study Design: A prospective clinical series.

Methods: Twenty‐eight consecutive patients with epiglottic cyst underwent laser marsupialization of an epiglottic cyst via a transoral approach. Pre‐ and postoperative laryngoscopic examinations were carried out.

Results: A total of 28 patients were enrolled, including 19 males and 9 females, ranging in age from 38 to 69 years, with a mean age of 54 years. Among these patients, 23 had a lumpy throat, and the remaining 5 had a voice alternation. The diameters of the cysts ranged from 1 to 3 cm. No perioperative bleeding or airway swelling was noted in any patient. The postoperative follow‐up period ranged from 4 to 41 (mean, 16) months. No recurrence was found during the follow‐up examinations.

Conclusion: Transoral laser marsupialization is a simple, safe, and effective method for treatment of epiglottic cysts. This procedure has the potential to serve as the treatment of choice in the management of this condition.
Limited Parotidectomy: The Role of Extracapsular Dissection in Parotid Gland Neoplasms
Authors: Smith Sarah L. , Komisar Arnold
Published: May 2007

Objective: Surgical techniques for parotid gland neoplasm removal have been shaped over the years by the importance of the gland's relationship with the facial nerve, histologic behavior of parotid tumors, and recurrence rates from specific techniques. Parotidectomy with facial nerve dissection has become the procedure of choice in removal of parotid gland neoplasms because of the resulting low recurrence rate. However, these more comprehensive dissections can cause significant postoperative complications, some cosmetically devastating. We propose that a more limited dissection yields a similar low recurrence rate but with less risk of complications.

Study Design: Retrospective case series.

Methods: A retrospective review of the clinical outcomes and pathology of 27 patients who underwent extracapsular dissection for parotid gland neoplasms.

Results: All tumors were located in the superficial lobe of the parotid gland and size of the masses ranged from 4.0 to 1.0 cm (mean 2.4 cm) in diameter. Pathology of the parotid tumors consisted of 11 pleomorphic adenomas, six Warthin's tumors, six benign epithelial cysts, one sarcoid lesion, two lymphoid hyperplasia, and one Kaposi's sarcoma. There were no cases of capsular rupture. There was no temporary or permanent facial paralysis and no incidence of Frey's syndrome. One patient developed a sialocele, which was aspirated and resolved after 3 months. There were no recurrences with follow‐up times between 5 months and 6 years (mean 41 mo).

Conclusion: We advocate extracapsular dissection for benign parotid neoplasms because of the acceptable recurrence rates with limited complications as compared to superficial parotidectomy.
Yin Yang 1 is a critical regulator of B-cell development
Authors: Liu Huifei , Schmidt-Supprian Marc , Shi Yujiang , Hobeika Elias , Barteneva Natasha , Jumaa Hassan , Pelanda Roberta , Reth Michael , Skok Jane , Rajewsky Klaus , Shi Yang
Published: May 2007

The role of the transcription factor Yin Yang 1 (YY1) in development is largely unknown. Here we show that specific ablation of YY1 in mouse B cells caused a defect in somatic rearrangement in the immunoglobulin heavy-chain (IgH) locus and a block in the progenitor-B-to-precursor-B-cell transition, which was partially rescued by a prerearranged IgH transgene. Three-dimensional DNA fluorescence in situ hybridization analysis revealed an important function for YY1 in IgH locus contraction, a process indispensable for distal VH to DHJH recombination. We provide evidence that YY1 binds the intronic Eiμ enhancer within the IgH locus, consistent with a direct role for YY1 in VHDHJH recombination. These findings identified YY1 as a critical regulator of early B-cell development.
Ipl1p-dependent phosphorylation of Mad3p is required for the spindle checkpoint response to lack of tension at kinetochores
Authors: King Emma M.J. , Rachidi Najma , Morrice Nick , Hardwick Kevin G. , Stark Michael J.R.
Published: May 2007

The spindle checkpoint delays anaphase onset until all chromosomes are correctly attached to microtubules. Ipl1 protein kinase (Aurora B) is required to correct inappropriate kinetochore–microtubule attachments and for the response to lack of tension between sister kinetochores. Here we identify residues in the checkpoint protein Mad3p that are phosphorylated by Ipl1p. When phosphorylation of Mad3p at two sites is prevented, the cell’s response to reduced kinetochore tension is dramatically curtailed. Our data provide strong evidence for a distinct checkpoint pathway responding to lack of sister kinetochore tension, in which Ipl1p-dependent phosphorylation of Mad3p is a key step.
1H NMR‐based metabolite profiling as a potential selection tool for breeding passive resistance against Fusarium head blight (FHB) in wheat
Authors: BROWNE ROY A. , BRINDLE KEVIN M.
Published: May 2007

1H NMR measurements on protein‐free extracts from wheat leaf and stem tissue were used to investigate the biochemical correlates of partial resistance to fungal species implicated in the Fusarium head blight (FHB) disease complex. The wheat genotypes included five commercial wheat cultivars and 116 wheat genotypes, from the CIMMYT international FHB breeding programme in Mexico, that had been bred for FHB disease resistance, utilizing exotic, typically Chinese, resistance sources. Principal component analysis of the nuclear magentic resonance (NMR)‐derived metabolite profiles revealed distinct separation of the commercial wheat cultivars from the majority of the CIMMYT wheat genotypes with the commercial cultivars exhibiting markedly higher carbohydrate concentrations. A cross‐validated partial least squares (PLS) regression model of the metabolite profile against the partial disease resistance component latent period (delay in sporulation of the fungus on the plant tissue) predicted latent periods that were significantly correlated with the experimentally determined values (R2 = 0.34, P < 0.001). Identified metabolites that were found in plants with shorter latent periods (higher disease susceptibility) included choline, the single most influential metabolite in the PLS model, betaine, the amino acids glutamine, glutamate and alanine, trans‐aconitate and sucrose. Metabolites related to increased disease resistance included glucose and unassigned resonances in the carbohydrate and aromatic regions of the NMR spectra. The current study has demonstrated the potential of metabolite profiling as a tool for marker‐assisted selection in commercial breeding for resistance to FHB in wheat.
The siderophore biosynthetic gene SID1, but not the ferroxidase gene FET3, is required for full Fusarium graminearum virulence
Authors: GREENSHIELDS DAVID L. , LIU GUOSHENG , FENG JIE , SELVARAJ GOPALAN , WEI YANGDOU
Published: May 2007

To acquire iron from plant hosts, fungal pathogens have evolved at least two pathways for iron uptake. One system is hinged on the secretion and subsequent uptake of low‐molecular‐weight iron chelators termed siderophores, while the other uses cell‐surface reductases to solubilize ferric iron by reducing it to ferrous iron for uptake. We identified five iron uptake‐related genes from the head blight pathogen Fusarium graminearum and showed that they were transcribed in response to iron limitation. To examine the relative contribution of the reductive and siderophore pathways of iron uptake, we created mutants disrupted at the ferroxidase gene FET3 (Δfet3) or the siderophore biosynthetic gene SID1 (Δsid1). The Δfet3 mutants produced wild‐type amounts of siderophores and grew at the same rate as the wild‐type under iron limitation, but accumulated high levels of free intracellular iron. The Δsid1 mutants did not produce siderophores and grew slowly under low iron conditions. Transcription of the iron uptake‐related genes was induced in the Δsid1 mutant regardless of the growth medium iron content, whereas these genes were transcribed normally in the Δfet3 mutant. Finally, the Δsid1 mutants could infect single, inoculated spikelets, but were unable to spread from spikelet‐to‐spikelet through the rachises of wheat spikes, while the Δfet3 mutants behaved as wild‐type throughout infection. Together, our data suggest that siderophore‐mediated iron uptake is the major pathway of cellular iron uptake and is required for full virulence in F. graminearum.
Ergotamine treatment during pregnancy and a higher rate of low birthweight and preterm birth
Authors: Bánhidy Ferenc , Ács Nándor , Puhó Erzsébet , Czeizel Andrew E.
Published: May 2007

What is already known about this subject

• Previously the association between oral ergotamine treatment during pregnancy and gestational age, birthweight, the frequency of preterm birth and low birthweight has not been studied.

• Ergotamine is a drug that is not used frequently nowadays.

What this study adds

• The association between low birthweight and/or preterm birth and ergotamine treatment may be connected with ergotamine‐induced vasoconstriction in the placenta of pregnant women.

• The pharmacological model used in this study could be used to evaluate the placental effects of other drugs.

Aims

Previously the association between oral ergotamine treatment during pregnancy and gestational age at delivery, birthweight, the rate of preterm birth and low birthweight has not been studied.

Methods

Newborn infants without congenital abnormalities born to mothers with or without ergotamine treatment during pregnancy were evaluated in the population‐based data set of the Hungarian Case‐Control Surveillance of Congenital Abnormalities between 1980 and 1996.

Results

Of 38 151 newborn infants with medically recorded gestational age and birth weight, 77 were born to mothers who had received ergotamine treatment during pregnancy. A statistically significant decrease was found in the mean gestational age (0.7 weeks) and birth weight (196 g) among exposed relative to unexposed infants, though these differences were not obstetrically significant. However, there was a significant increase in the proportion of low birthweight newborns (16.4% vs. 5.7%) and preterm births (16.4% vs. 9.2%) after the use of ergotamine during pregnancy. The effect of ergotamine was more obvious in male newborn infants, particularly after treatment in the third trimester.

Conclusions

The association between low birthweight and/or preterm birth and ergotamine treatment may be connected with the effect of ergotamine on the placenta of pregnant women.
Effects of Schisandra sphenanthera extract on the pharmacokinetics of tacrolimus in healthy volunteers
Authors: Xin Hua‐Wen , Wu Xiao‐Chun , Li Qing , Yu Ai‐Rong , Zhu Min , Shen Yang , Su Dan , Xiong Lei
Published: May 2007

What is already known about this subject

• Schisandra sphenanthera extract (SchE) and tacrolimus are often co‐administrated in treating renal and liver transplant recipients in China.

• We discovered occasionally that blood tacrolimus concentrations are markedly increased in some patients who receive tacrolimus and concomitant SchE.

• This is the first study to investigate the effects of SchE on the pharmacokinetics of tacrolimus.

What this study adds

• Following administration of SchE in healthy volunteers, the mean AUC, AUMC and Cmax of tacrolimus substantially increases, whereas its CL/F and V/F decreases significantly.

• Blood tacrolimus concentrations need to be closely monitored and dose adjustments of tacrolimus have to be made accordingly in the presence of SchE.

Aim

To assess the effect of Schisandra sphenanthera extract (SchE) on the pharmacokinetics of tacrolimus in healthy volunteers.

Methods

Twelve healthy male volunteers were orally treated with SchE, three capsules twice daily for 13 days. Pharmacokinetic investigations of oral tacrolimus administration at 2 mg were performed both before and at the end of the SchE treatment period. Whole blood tacrolimus concentrations were determined by enzyme‐linked immunosorbent assay. Estimated pharmacokinetic parameters before and with SchE were calculated with noncompartmental techniques.

Results

Following administration of SchE, the average percentage increases of individual increases in AUC, AUMC and Cmax of tacrolimus were 164.2% [95% confidence interval (CI) 70.1, 258.4], 133.1% (95% CI 49.5, 261.3) and 227.1% (95% CI 155.8, 298.4), respectively (P < 0.01 or 0.05). On average, there was a 36.8% (95% CI 13.4, 60.2) increase in tacrolimus tmax (P < 0.01). The average percentage decreases in CL/F and V/F were 49.0% (95% CI 31.1, 66.9) and 53.7% (95% CI 40.1, 67.4), respectively (P < 0.01).

Conclusions

SchE can increase the oral bioavailability of tacrolimus. The results of this study will add important information to the interaction area between drugs and herbal products.
Foundation year 1 doctors and clinical pharmacology and therapeutics teaching. A retrospective view in light of experience
Authors: Tobaiqy Mansour , McLay James , Ross Sarah
Published: May 2007

What is already known about this subject

• In the UK prescribing‐related errors are common.

• Poor prescribing and prescribing errors result in significant patient morbidity and mortality.

• In hospital, junior doctors are responsible for a significant number of prescribing errors.

What this study adds

• Only 8% of foundation year (FY) 1 doctors rate their knowledge of clinical pharmacology as good and 30% as poor or worse.

• The majority of FY1 doctors reported themselves confident to prescribe medicines associated with high levels of patient morbidity and mortality.

• Potentially avoidable adverse drug reactions and drug interactions were reported by 60–75% of FY1 doctors, many of which were reported to have been avoidable with more extensive undergraduate training.

• FY1 doctors would like more focused undergraduate teaching on the avoidance of adverse drug reactions and drug–drug interactions, together with increased clinical pharmacology and therapeutics in their postgraduate training programme.

Aims

To determine whether, in retrospect, first year foundation (FY1) programme doctors believe that their undergraduate education in Clinical Pharmacology and Therapeutics (CPT) has prepared them to prescribe safely and rationally.

Methods

This was a prospective questionnaire survey. Ninety FY1 doctors, employed in the Aberdeen Teaching Hospitals, participated.

Results

Seventy‐one percent of FY1 doctors completed the survey. Thirty percent of respondents rated their knowledge of CPT as poor or worse and only 8% as good; 74% reported having witnessed an adverse drug reaction (ADR) and 55% a drug–drug interaction, a number of which had resulted in patient morbidity or mortality. Many of these events were reported to have been avoidable or predictable with more extensive undergraduate and postgraduate training. Forty‐two percent of respondents stated that they had not been taught enough about avoiding ADRs and 60% about avoiding drug–drug interactions during their undergraduate years. Over 75% of respondents reported high levels of confidence for the unsupervised use of warfarin, nonsteroidal analgesics and opiate analgesics. In retrospect, FY1 doctors would like more undergraduate teaching in prescribing for special patient groups, ADRs, drug interactions, together with CPT in their postgraduate teaching programme.

Conclusions

FY1 doctors believe that their undergraduate and postgraduate training in CPT is insufficient to prescribe safely and rationally. This study adds further weight to the call for an increase in the training of junior doctors in the rational and safe use of medicines.