bluuebunny/crossref_metadata_2025 huggingface dataset:
σ
28
-Dependent Transcription in
Salmonella enterica
Is Independent of Flagellar Shearing
Authors: Rosu Valentina , Hughes Kelly T.
Published: June 2006

The FlgM anti-σ
28
factor is secreted in response to flagellar hook-basal body completion to allow σ
28
-dependent transcription of genes needed late in flagellar assembly, such as the flagellin structural gene,
fliC
. A long-standing hypothesis was that one role of FlgM secretion was to allow rapid expression of flagellin in response to shearing. We tested this hypothesis by following FlgM secretion and
fliC
transcription in response to flagellar shearing. Experiments showed that the level of FlgM inside the cell was unchanged after shearing whereas the extracellular FlgM levels increased in the growth medium as time passed. Identical results were obtained with cells that were not exposed to shear forces: internal FlgM levels remained constant while external FlgM levels rose with time at rates similar to those for the sheared culture. Consistent with this find, FlgM/σ
28
-dependent class 3 gene expression was unaffected by flagellar shearing but was affected by the growth phase of the cell. Regardless of exposure to shear forces, flagellar class 3 transcription rose sharply and then declined. These results demonstrate that flagellar regrowth following shearing is independent of FlgM secretion.
DevA, a GntR-Like Transcriptional Regulator Required for Development in
Streptomyces coelicolor
Authors: Hoskisson Paul A. , Rigali Sebastien , Fowler Kay , Findlay Kim C. , Buttner Mark J.
Published: June 2006

The gram-positive filamentous bacterium
Streptomyces coelicolor
has a complex developmental cycle with three distinct phases: growth of the substrate mycelium, development of reproductive structures called aerial hyphae, and differentiation of these aerial filaments into long chains of exospores. During a transposon mutagenesis screen, we identified a novel gene (
devA
) required for proper development. The
devA
mutant produced only rare aerial hyphae, and those that were produced developed aberrant spore chains that were much shorter than wild-type chains and had misplaced septa.
devA
encodes a member of the GntR superfamily, a class of transcriptional regulators that typically respond to metabolite effector molecules.
devA
forms an operon with the downstream gene
devB
, which encodes a putative hydrolase that is also required for aerial mycelium formation on R5 medium. S1 nuclease protection analysis showed that transcription from the single
devA
promoter was temporally associated with vegetative growth, and enhanced green fluorescent protein transcriptional fusions showed that transcription was spatially confined to the substrate hyphae in the wild type. In contrast,
devAB
transcript levels were dramatically upregulated in a
devA
mutant and the
devA
promoter was also active in aerial hyphae and spores in this background, suggesting that DevA might negatively regulate its own production. This suggestion was confirmed by gel mobility shift assays that showed that DevA binds its own promoter region in vitro.
Regulation of the
Myxococcus xanthus
C-Signal-Dependent Ω4400 Promoter by the Essential Developmental Protein FruA
Authors: Yoder-Himes Deborah R. , Kroos Lee
Published: June 2006

The bacterium
Myxococcus xanthus
employs extracellular signals to coordinate aggregation and sporulation during multicellular development. Extracellular, contact-dependent signaling that involves the CsgA protein (called C-signaling) activates FruA, a putative response regulator that governs a branched signaling pathway inside cells. One branch regulates cell movement, leading to aggregation. The other branch regulates gene expression, leading to sporulation. C-signaling is required for full expression of most genes induced after 6 h into development, including the gene identified by Tn
5 lac
insertion Ω4400. To determine if FruA is a direct regulator of Ω4400 transcription, a combination of in vivo and in vitro experiments was performed. Ω4400 expression was abolished in a
fruA
mutant. The DNA-binding domain of FruA bound specifically to DNA upstream of the promoter −35 region in vitro. Mutations between bp −86 and −77 greatly reduced binding. One of these mutations had been shown previously to reduce Ω4400 expression in vivo and make it independent of C-signaling. For the first time, chromatin immunoprecipitation (ChIP) experiments were performed on
M. xanthus
. The ChIP experiments demonstrated that FruA is associated with the Ω4400 promoter region late in development, even in the absence of C-signaling. Based on these results, we propose that FruA directly activates Ω4400 transcription to a moderate level prior to C-signaling and, in response to C-signaling, binds near bp −80 and activates transcription to a higher level. Also, the highly localized effects of mutations between bp −86 and −77 on DNA binding in vitro, together with recently published footprints, allow us to predict a consensus binding site of GTCG/CGA/G for the FruA DNA-binding domain.
RNase E Maintenance of Proper FtsZ/FtsA Ratio Required for Nonfilamentous Growth of
Escherichia coli
Cells but Not for Colony-Forming Ability
Authors: Tamura Masaru , Lee Kangseok , Miller Christine A. , Moore Christopher J. , Shirako Yukio , Kobayashi Masahiko , Cohen Stanley N.
Published: June 2006

Inactivation or deletion of the RNase E-encoding
rne
gene of
Escherichia coli
results in the growth of bacterial cells as filamentous chains in liquid culture (K. Goldblum and D. Apirion, J. Bacteriol.
146:
128-132, 1981) and the loss of colony-forming ability (CFA) on solid media. RNase E dysfunction is also associated with abnormal processing of
ftsQAZ
transcripts (K. Cam, G. Rome, H. M. Krisch, and J.-P. Bouché, Nucleic Acids Res.
24:
3065-3070, 1996), which encode proteins having a central role in septum formation during cell division. We show here that RNase E regulates the relative abundances of FtsZ and FtsA proteins and that RNase E depletion results in decreased FtsZ, increased FtsA, and consequently an altered FtsZ/FtsA ratio. However, while restoration of the level of FtsZ to normal in
rne
null mutant bacteria reverses the filamentation phenotype, it does not restore CFA. Conversely, overexpression of a related RNase, RNase G, in
rne
-deleted bacteria restores CFA, as previously reported, without affecting FtsZ abundance. Our results demonstrate that RNase E activity is required to maintain a proper cellular ratio of the FtsZ and FtsA proteins in
E. coli
but that FtsZ deficiency does not account for the nonviability of cells lacking RNase E.
Mutations of the Membrane-Bound Disulfide Reductase DsbD That Block Electron Transfer Steps from Cytoplasm to Periplasm in
Escherichia coli
Authors: Cho Seung-Hyun , Beckwith Jon
Published: June 2006

The cytoplasmic membrane protein DsbD keeps the periplasmic disulfide isomerase DsbC reduced, using the cytoplasmic reducing power of thioredoxin. DsbD contains three domains, each containing two reactive cysteines. One membrane-embedded domain, DsbDβ, transfers electrons from thioredoxin to the carboxy-terminal thioredoxin-like periplasmic domain DsbDγ. To evaluate the role of conserved amino acid residues in DsbDβ in the electron transfer process, we substituted alanines for each of 19 conserved amino acid residues and assessed the in vivo redox states of DsbC and DsbD. The mutant DsbDs of 11 mutants which caused defects in DsbC reduction showed relatively oxidized redox states. To analyze the redox state of each DsbD domain, we constructed a thrombin-cleavable DsbD (DsbD
TH
) from which we could generate all three domains as separate polypeptide chains by thrombin treatment in vitro. We divided the mutants with strong defects into two classes. The first mutant class consists of mutant DsbDβ proteins that cannot receive electrons from cytoplasmic thioredoxin, resulting in a DsbD that has all six of its cysteines disulfide bonded. The second mutant class represents proteins in which the transfer of electrons from DsbDβ to DsbDγ appears to be blocked. This class includes the mutant with the most clear-cut defect, P284A. We relate the properties of the mutants to the positions of the amino acids in the structure of DsbD and discuss mechanisms that would interfere with the electron transfer process.
Interplay of the Wzx Translocase and the Corresponding Polymerase and Chain LengthRegulator Proteins in the Translocation and Periplasmic Assembly of Lipopolysaccharide O Antigen
Authors: Marolda Cristina L. , Tatar Laura D. , Alaimo Cristina , Aebi Markus , Valvano Miguel A.
Published: June 2006

Genetic evidence suggests that a family of bacterial and eukaryotic integral
membrane proteins (referred to as Wzx and Rft1, respectively) mediates
the transbilayer movement of isoprenoid lipid-linked glycans. Recent
work in our laboratory has shown that Wzx proteins involved in
O-antigen lipopolysaccharide (LPS) assembly have relaxed specificity
for the carbohydrate structure of the O-antigen subunit. Furthermore,
the proximal sugar bound to the isoprenoid lipid carrier,
undecaprenyl-phosphate (Und-P), is the minimal structure required for
translocation. In
Escherichia coli
K-12,
N
-acetylglucosamine (GlcNAc) is the proximal sugar of
the O16 and enterobacterial common antigen (ECA) subunits. Both O16 and
ECA systems have their respective translocases, Wzx
O16
and
Wzx
E
, and also corresponding polymerases (Wzy
O16
and Wzy
E
) and O-antigen chain-length regulators
(Wzz
O16
and Wzz
E
), respectively. In
this study, we show that the
E. coli wzx
E
gene can
fully complement a
wzx
O16
translocase deletion
mutant only if the majority of the ECA gene cluster is deleted. In
addition, we demonstrate that introduction of plasmids expressing
either the Wzy
E
polymerase or the Wzz
E
chain-length regulator proteins drastically reduces the O16
LPS-complementing activity of Wzx
E
. We also show that this
property is not unique to Wzx
E
, since Wzx
O16
and
Wzx
O7
can cross-complement translocase defects in the O16
and O7 antigen clusters only in the absence of their corresponding Wzz
and Wzy proteins. These genetic data are consistent with the notion
that the translocation of O-antigen and ECA subunits across the plasma
membrane and the subsequent assembly of periplasmic O-antigen and ECA
Und-PP-linked polymers depend on interactions among Wzx, Wzz, and Wzy,
which presumably form a multiprotein
complex.
Global Transcriptome Analysis ofTropheryma whippleiin Response to Temperature Stresses
Authors: Crapoulet Nicolas , Barbry Pascal , Raoult Didier , Renesto Patricia
Published: June 2006

Tropheryma whipplei, the agent responsible for Whipple disease, is a poorly known pathogen suspected to have an environmental origin. The availability of the sequence of the 0.92-Mb genome of this organism made a global gene expression analysis in response to thermal stresses feasible, which resulted in unique transcription profiles. A few genes were differentially transcribed after 15 min of exposure at 43°C. The effects observed included up-regulation of thednaKregulon, which is composed of six genes and is likely to be under control of two HspR-associated inverted repeats (HAIR motifs) found in the 5′ region. Putative virulence factors, like the RibC and IspDF proteins, were also overexpressed. While it was not affected much by heat shock, theT. whippleitranscriptome was strongly modified following cold shock at 4°C. For the 149 genes that were differentially transcribed, eight regulons were identified, and one of them was composed of five genes exhibiting similarity with genes encoding ABC transporters. Up-regulation of these genes suggested that there was an increase in nutrient uptake when the bacterium was exposed to cold stress. As observed for other bacterial species, the major classes of differentially transcribed genes encode membrane proteins and enzymes involved in fatty acid biosynthesis, indicating that membrane modifications are critical. Paradoxically, the heat shock proteins GroEL2 and ClpP1 were up-regulated. Altogether, the data show that despite the lack of classical regulation pathways,T. whippleiexhibits an adaptive response to thermal stresses which is consistent with its specific environmental origin and could allow survival under cold conditions.
Role of DNA Replication and Repair in Thymineless Death in
Escherichia coli
Authors: Morganroth Pamela A. , Hanawalt Philip C.
Published: June 2006

Inhibition of DNA replication with hydroxyurea during thymine starvation of
Escherichia coli
shows that active DNA synthesis is not required for thymineless death (TLD). Hydroxyurea experiments and thymine starvation of
lexA3
and
uvrA
DNA repair mutants rule out unbalanced growth, the SOS response, and nucleotide excision repair as explanations for TLD.
H-NS RepressesinvTranscription inYersinia enterocoliticathrough Competition with RovA and Interaction with YmoA
Authors: Ellison Damon W. , Miller Virginia L.
Published: June 2006

Yersinia enterocoliticais able to efficiently invade Peyer's patches with the aid of invasin, an outer member protein involved in the attachment and invasion of M cells. Invasin is encoded byinv, which is positively regulated by RovA in bothY. enterocoliticaandYersinia pseudotuberculosiswhile negatively regulated by YmoA inY. enterocoliticaand H-NS inY. pseudotuberculosis. In this study we present data indicating H-NS and RovA bind directly and specifically to theinvpromoter ofY. enterocolitica. We also show that RovA and H-NS fromY. enterocoliticabind to a similar region of theinvpromoter and suggest they compete for binding sites. This is similar to recently published data fromY. pseudotuberculosis, revealing a potentially conserved mechanism ofinvregulation betweenY. enterocoliticaandY. pseudotuberculosis. Furthermore, we present data suggesting H-NS and YmoA form a repression complex on theinvpromoter, with H-NS providing the binding specificity and YmoA interacting with H-NS to form a repression complex. We also demonstrate that deletion of the predicted H-NS binding region relieves the requirement for RovA-dependent transcription of theinvpromoter, consistent with RovA acting as a derepressor of H-NS-mediated repression. Levels of H-NS and YmoA are similar between 26°C and 37°C, suggesting that the H-NS/YmoA repression complex is present at both temperatures, while the levels ofrovAtranscript are low at 37°C and high at 26°C, leading to expression ofinvat 26°C. Expression of RovA at 37°C results in transcription ofinvand production of invasin. Data presented here support a model ofinvregulation where the level of RovA within the cell governsinvexpression. As RovA levels increase, RovA can successfully compete for binding to theinvpromoter with the H-NS/YmoA complex, resulting in derepression ofinvtranscription.
Phylogenomic and Biochemical Characterization of ThreeLegionella pneumophilaPolypeptide Deformylases
Authors: Huang Jianzhong , Van Aller Glenn S. , Taylor Amy N. , Kerrigan John J. , Liu Wu-Schyong , Trulli Janice M. , Lai Zhihong , Holmes David , Aubart Kelly M. , Brown James R. , Zalacain Magdalena
Published: June 2006

Legionella pneumophilais a gram-negative facultative intracellular human pathogen that can cause fatal Legionnaires' disease. Polypeptide deformylase (PDF) is a novel broad-spectrum antibacterial target, and reports of inhibitors of PDF with potent activities againstL. pneumophilahave been published previously. Here, we report the identification of not one but three putativepdfgenes,pdfA,pdfB, andpdfC, in the complete genome sequences of three strains ofL. pneumophila. Phylogenetic analysis showed thatL. pneumophilaPdfA is most closely related to the commonly known γ-proteobacterial PDFs encoded by the genedef.PdfB and PdfC are more divergent and do not cluster with any specific bacterial or eukaryotic PDF. All three putativepdfgenes fromL. pneumophilastrain Philadelphia 1 have been cloned, and their encoded products have been overexpressed inEscherichia coliand purified. Enzymatic characterization shows that the purified PDFs with Ni2+substituted are catalytically active and able to remove the N-formyl group from several synthetic polypeptides, although they appear to have different substrate specificities. Surprisingly, while PdfA and PdfB with Zn2+substituted are much less active than the Ni2+forms of each enzyme, PdfC with Zn2+substituted was as active as the Ni2+form for the fMA substrate and exhibited substrate specificity different from that of Ni2+PdfC. Furthermore, the catalytic activities of these enzymes are potently inhibited by a known small-molecule PDF inhibitor, BB-3497, which also inhibits the extracellular growth ofL. pneumophila. These results indicate that even thoughL. pneumophilahas three PDFs, they can be effectively inhibited by PDF inhibitors which can, therefore, have potent anti-L. pneumophilaactivity.
Population Structure of
Francisella tularensis
Authors: Nübel Ulrich , Reissbrodt Rolf , Weller Annette , Grunow Roland , Porsch-Özcürümez Mustafa , Tomaso Herbert , Hofer Erwin , Splettstoesser Wolf , Finke Ernst-Jürgen , Tschäpe Helmut , Witte Wolfgang
Published: June 2006

We have sequenced fragments of five metabolic housekeeping genes and two genes encoding outer membrane proteins from 81 isolates of
Francisella tularensis
, representing all four subspecies. Phylogenetic clustering of gene sequences from
F. tularensis
subsp.
tularensis
and
F. tularensis
subsp.
holarctica
aligned well with subspecies affiliations. In contrast,
F. tularensis
subsp.
novicida
and
F. tularensis
subsp.
mediasiatica
were indicated to be phylogenetically incoherent taxa. Incongruent gene trees and mosaic structures of housekeeping genes provided evidence for genetic recombination in
F. tularensis
.
Holdfast Formation in Motile Swarmer Cells Optimizes Surface Attachment duringCaulobacter crescentusDevelopment
Authors: Levi Assaf , Jenal Urs
Published: June 2006

The adhesive holdfast is required for irreversible surface anchoring ofCaulobacter crescentuscells. The holdfast is synthesized early during swarmer cell development and, together with pili and a functional flagellum, contributes to optimal attachment during cell differentiation. We present evidence that the timing of holdfast formation in swarmer cells is regulated posttranslationally and is dependent on the diguanylate cyclase PleD.
Occurrence of Two 5-Aminolevulinate Biosynthetic Pathways in
Streptomyces nodosus
subsp.
asukaensis
Is Linked with the Production of Asukamycin
Authors: Petříček Miroslav , Petříčková Kateřina , Havlíček Libor , Felsberg Jürgen
Published: June 2006

We report the results of cloning genes for two key biosynthetic enzymes of different 5-aminolevulinic acid (ALA) biosynthetic routes from
Streptomyces
. The genes encode the glutamyl-tRNA
Glu
reductase (GluTR) of the C
5
pathway and the ALA synthase (ALAS) of the Shemin pathway. While
Streptomyces coelicolor
A3(2) synthesizes ALA via the C
5
route, both pathways are operational in
Streptomyces nodosus
subsp.
asukaensis
, a producer of asukamycin. In this strain, the C
5
route produces ALA for tetrapyrrole biosynthesis; the ALA formed by the Shemin pathway serves as a precursor of the 2-amino-3-hydroxycyclopent-2-enone moiety (C
5
N unit), an antibiotic component. The growth of
S. nodosus
and
S. coelicolor
strains deficient in the GluTR genes (
gtr
) is strictly dependent on ALA or heme supplementation, whereas the defect in the ALAS-encoding gene (
hemA-asuA
) abolishes the asukamycin production in
S. nodosus
. The recombinant
hemA-asuA
gene was expressed in
Escherichia coli
and in
Streptomyces
, and the encoded enzyme activity was demonstrated both in vivo and in vitro. The
hemA-asuA
gene is situated within a putative cluster of asukamycin biosynthetic genes. This is the first report about the cloning of genes for two different ALA biosynthetic routes from a single bacterium.
RecA and RadA Proteins ofBrucella abortusDo Not Perform Overlapping Protective DNA Repair Functions following Oxidative Burst
Authors: Roux Christelle M. , Booth Natha J. , Bellaire Bryan H. , Gee Jason M. , Roop R. Martin , Kovach Michael E. , Tsolis Renée M. , Elzer Philip H. , Ennis Don G.
Published: June 2006

Very little is known about the role of DNA repair networks inBrucella abortusand its role in pathogenesis. We investigated the roles of RecA protein, DNA repair, and SOS regulation inB. abortus. WhilerecAmutants in most bacterial species are hypersensitive to UV damage, surprisingly aB. abortus recAnull mutant conferred only modest sensitivity. We considered the presence of a second RecA protein to account for this modest UV sensitivity. Analyses of theBrucellaspp. genomes and our molecular studies documented the presence of only onerecAgene, suggesting a RecA-independent repair process. Searches of the availableBrucellagenomes revealed some homology between RecA and RadA, a protein implicated inE. coliDNA repair. We considered the possibility thatB. abortusRadA might be compensating for the loss of RecA by promoting similar repair activities. We present functional analyses that demonstrated thatB. abortusRadA complements aradAdefect inE. colibut could not act in place of theB. abortusRecA. We show that RecA but not RadA was required for survival in macrophages. We also discovered thatrecAwas expressed at high constitutive levels, due to constitutive LexA cleavage by RecA, with little induction following DNA damage. Higher basal levels of RecA and its SOS-regulated gene products might protect against DNA damage experienced following the oxidative burst within macrophages.
Clinical ethical dilemmas: convergent and divergent views of two scholarly communities
Authors: Stiggelbout A M , Elstein A S , Molewijk B , Otten W , Kievit J
Published: June 2006

Objective:To survey members of the American Society for Bioethics and Humanities (ASBH; n = 327) and of the Society for Medical Decision Making (SMDM; n = 77) to elicit the similarities and differences in their reasoning about two clinical cases that involved ethical dilemmas.

Cases:Case 1 was that of a patient refusing treatment that a surgeon thought would be beneficial. Case 2 dealt with end-of-life care. The argument was whether intensive treatment should be continued of an unconscious patient with multiorgan failure.

Method:Four questions, with structured multiple alternatives, were asked about each case: identified core problems, needed additional information, appropriate next steps and who the decision maker should be.

Observations and results:Substantial similarities were noticed between the two groups in identifying the core problems, the information needed and the appropriate next steps. SMDM members gave more weight to outcomes and trade-offs and ASBH members had patient autonomy trump other considerations more strongly. In case 1, more than 60% of ASBH respondents identified the patient alone as the decision maker, whereas members of SMDM were almost evenly divided between having the patient as the solo decision maker or preferring a group of some sort as the decision maker, a significant difference (p<0.02). In case 2, both groups agreed that the question of discontinuing treatment should be discussed with the family and that the family alone should not be the decision maker.

Conclusion:Despite distinctively different methods of case analysis and little communication between the two professional communities, many similarities were observed in the actual decisions they reached on the two clinical dilemmas.
Distinguishing treatment from research: a functional approach
Authors: Lewens T
Published: June 2006

The best way to distinguish treatment from research is by their functions. This mode of distinction fits well with the basic ethical work that needs to be carried out. The distinction needs to serve as an ethical flag, highlighting areas in which the goals of doctors and patients are more likely than usual to diverge. The distinction also allows us to illuminate and understand some otherwise puzzling elements of debates on research ethics: it shows the peculiarity of exclusive conceptions of the distinction between research and treatment; it allows us to frame questions about therapeutic obligations in the research context, and it allows us to consider whether there may be research obligations in the therapeutic context.
Ethical issues in psychopharmacology
Authors: McHenry L
Published: June 2006

The marketing of selective serotonin reuptake inhibitors in the psychopharmacological industry presents a serious moral problem for the corporate model of medicine. In this paper I examine ethical issues relating to the efficacy and safety of these drugs. Pharmaceutical companies have a moral obligation to disclose all information in their possession bearing on the true risks and benefits of their drugs. Only then can patients make fully informed decisions about their treatment.
Who is willing to take the risk? Assessing the readiness for living liver donation in the general German population
Authors: Popp F C , Eggert N , Hoy L , Lang S A , Obed A , Piso P , Schlitt H J , Dahlke M H
Published: June 2006

Background:Shortage of donor organs is one of the major problems for liver transplant programmes. Living liver donation is a possible alternative, which could increase the amount of donor organs available in the short term.

Objective:To assess the attitude towards living organ donation in the general population to have an overview of the overall attitude within Germany.

Methods:A representative quota of people was evaluated by a mail questionnaire (n = 250). This questionnaire had 24 questions assessing the willingness to be a living liver donor for different potential recipients. Factors for and against living liver donation were assessed.

Results:Donating a part of the liver was almost as accepted as donating a kidney. The readiness to donate was highest when participants were asked to donate for children. In an urgent life-threatening situation the will to donate was especially high, whereas it was lower in the case of recipient substance misuse. More women than men expressed a higher disposition to donate for their children. Sex, religion, state of health and age of the donor, however, did not influence other questions on the readiness to consider living organ donation. The will for postmortem organ donation positively correlated with the will to be a living organ donor.

Conclusions:The motivation in different demographic subgroups to participate in living liver transplantation is described. Differences in donation readiness resulting from the situation of every donor and recipient are thoroughly outlined. The acceptance for a living liver donation was found to be high – and comparable to that of living kidney donation.
Can patients be sure they are fully informed when representatives of surgical equipment manufacturers attend their operations?: Table 1
Authors: Sillender M
Published: June 2006

Objective:To determine the practice in UK hospitals regarding the level of patient involvement and consent when representatives of commercial surgical device manufacturers attend and advise during operations.

Methods:An anonymous postal questionnaire was sent to the senior nurse in charge in all 236 UK gynaecology theatres in 2004. 79/236 (33%) replies were received.

Results:Operating departments were visited every 2 weeks on average by a representative of the surgical device manufacturer. Actual operations were attended every 10 weeks, although there was much variation. 33/79 (42%) units consistently obtained patient consent for visits, usually orally, whereas 40/79 (51%) units did not. 65/79 (82%) units had no guidelines for surgical device representative visits. 91% of nurses in charge believed that there should be guidelines to protect both patients and staff. 6/79 (8%) units were preparing local guidelines at the time of the survey.

Conclusions:Currently, patient safety, confidentiality and autonomy are being protected by a minority of NHS operating theatres when surgical device representatives attend surgery. National guidelines would hopefully ensure that fully informed patient consent is obtained and that representatives are fully trained and supervised.
Wickedness or folly? The ethics of NICE’s decisions
Authors: Claxton K , Culyer A J
Published: June 2006

A rebuttal is provided to each of the arguments adduced by John Harris, an Editor-in-Chief of theJournal of Medical Ethics, in two editorials in the journal in support of the view that National Institute for Health and Clinical Excellence’s procedures and methods for making recommendations about healthcare procedures for use in the National Health Service in England and Wales are the product of “wickedness or folly or more likely both”, “ethically illiterate as well as socially divisive”, responsible for the “perversion of science as well as of morality” and are “contrary to basic morality and contrary to human rights”.
Taste Receptors in the Gastrointestinal Tract III. Salty and sour taste: sensing of sodium and protons by the tongue
Authors: DeSimone John A. , Lyall Vijay
Published: June 2006

Taste plays an essential role in food selection and consequently overall nutrition. Because salt taste is appetitive, humans ingest more salt than they need. Acids are the source of intrinsically aversive sour taste, but in mixtures with sweeteners they are consumed in large quantities. Recent results have provided fresh insights into transduction and sensory adaptation for the salty and sour taste modalities. The sodium-specific salt taste receptor is the epithelial sodium channel whereas a nonspecific salt taste receptor is a taste variant of the vanilloid receptor-1 nonselective cation channel, TRPV1. The proximate stimulus for sour taste is a decrease in the intracellular pH of a subset of acid-sensing taste cells, which serves as the input to separate transduction pathways for the phasic and tonic parts of the sour neural response. Adaptation to sour arises from the activation of the basolateral sodium-hydrogen exchanger isoform-1 by an increase in intracellular calcium that sustains the tonic phase of the sour taste response.
Luminal amino acid sensing in the rat gastric mucosa
Authors: Uneyama Hisayuki , Niijima Akira , San Gabriel Ana , Torii Kunio
Published: June 2006

Recent advancements in molecular biology in the field of taste perception in the oral cavity have raised the possibility for ingested nutrients to be “tasted” in the upper gastrointestinal tract. The purpose of this study was to identify the existence of a nutrient-sensing system by the vagus in the rat stomach. Afferent fibers of the gastric branch increased their firing rate solely with the intragastric application of the amino acid glutamate. Other amino acids failed to have the same effect. This response to glutamate was blocked by the depletion of serotonin (5-HT) and inhibition of serotonin receptor3 (5-HT3) or nitric oxide (NO) synthase enzyme. Luminal perfusion with the local anesthesia lidocaine abolished the glutamate-evoked afferent activation. The afferent response was also mimicked by luminal perfusion with a NO donor, sodium nitroprusside. In addition, the NO donor-induced afferent activation was abolished by 5-HT3 blockade as well. Altogether, these results strongly suggest the existence of a sensing system for glutamate in the rat gastric mucosa. Thus luminal glutamate would enhance the electrophysiological firing rate of afferent fibers from the vagus nerve of the stomach through the production of mucosal bioactive substances such as NO and 5-HT. Assuming there is a universal coexistence of free glutamate with dietary protein, a glutamate-sensing system in the stomach could contribute to the gastric phase of protein digestion.
Hyperglycemia and loss of ovarian hormones mediate atheroma formation through endothelial layer disruption and increased permeability
Authors: Benton Jeana , Powers Andrew , Eiselein Larissa , Fitch Richard , Wilson Dennis , Villablanca Amparo C. , Rutledge John C.
Published: June 2006

The overall goal of this project was to examine the interactions of hyperglycemia and loss of ovarian hormones on the artery wall in a type I diabetic mouse model. Intact or ovariectomized (OVX) female BALB/C mice were fed a high-cholesterol diet. Half the animals were treated with steptozotocin to induce insulin-deficient diabetes mellitus, generating four treatment groups: control, intact; control, ovariectomized; diabetic, intact; diabetic, ovariectomized (DOVX). We examined arterial structure and function and found that 1) diabetes and ovariectomy additively increased endothelial layer permeability, 2) arterial stiffening was increased in DOVX, 3) DOVX synergistically increased atheroma formation, and 4) ultrastructural evaluation revealed that the basal lamina was often multilayered and formed convoluted aggregates separating endothelium from the internal elastic lamina in diabetic, but not control arteries or arteries from OVX mice. Endothelium overlying these regions formed thin cytoplasmic extensions between these aggregates and was often separated from the basal lamina by electron lucent spaces. Our studies showed that diabetes and loss of ovarian function have additive and synergistic effects to worsen arterial pathophysiology by disrupting the arterial endothelial layer with increased permeability and increased atheroma formation.
Prolactin and the expression of suppressor of cytokine signaling-3 in the sheep adrenal gland before birth
Authors: Gentili S. , Schwartz J. S. , Waters M. J. , McMillen I. C.
Published: June 2006

The fetal pituitary-adrenal axis plays a key role in the fetal response to intrauterine stress and in the timing of parturition. The fetal sheep adrenal gland is relatively refractory to stimulation in midgestation (90–120 days) before the prepartum activation, which occurs around 135 days gestation (term = 147 ± 3 days). The mechanisms underlying the switch from adrenal quiescence to activation are unclear. Therefore, we have investigated the expression of suppressor of cytokine signaling-3 (SOCS-3), a putative inhibitor of tissue growth in the fetal sheep adrenal between 50 and 145 days gestation and in the adrenal of the growth-restricted fetal sheep in late gestation. SOCS-3 is activated by a range of cytokines, including prolactin (PRL), and we have, therefore, determined whether PRL administered in vivo or in vitro stimulates SOCS-3 mRNA expression in the fetal adrenal in late gestation. There was a decrease ( P < 0.005) in SOCS-3 expression in the fetal adrenal between 54 and 133 days and between 141 and 144 days gestation. Infusion of the dopaminergic agonist, bromocriptine, which suppressed fetal PRL concentrations but did not decrease adrenal SOCS-3 mRNA expression. PRL administration, however, significantly increased adrenal SOCS-3 mRNA expression ( P < 0.05). Similarly, there was an increase ( P < 0.05) in SOCS-3 mRNA expression in adrenocortical cells in vitro after exposure to PRL (50 ng/ml). Placental and fetal growth restriction had no effect on SOCS-3 expression in the adrenal during late gestation. In summary, the decrease in the expression of the inhibitor SOCS-3 after 133 days gestation may be permissive for a subsequent increase in fetal adrenal growth before birth. We conclude that factors other than PRL act to maintain adrenal SOCS-3 mRNA expression before 133 days gestation but that acute elevations of PRL can act to upregulate adrenal SOCS-3 expression in the sheep fetus during late gestation.
Circulating interleukin-6 induces fever through a STAT3-linked activation of COX-2 in the brain
Authors: Rummel Christoph , Sachot Christelle , Poole Stephen , Luheshi Giamal N.
Published: June 2006

Interleukin (IL)-6 is an important humoral mediator of fever following infection and inflammation and satisfies a number of criteria for a circulating pyrogen. However, evidence supporting such a role is diminished by the moderate or even absent ability of the recombinant protein to induce fever and activate the cyclooxygenase-2 (COX-2) pathway in the brain, a prerequisite step in the initiation and maintenance of fever. In the present study, we investigated the role of endogenous circulating IL-6 in a rodent model of localized inflammation, by neutralizing its action using a specific antiserum (IL-6AS). Rats were injected with LPS (100 μg/kg) or saline into a preformed air pouch in combination with an intraperitoneal injection of either normal sheep serum or IL-6AS (1.8 ml/rat). LPS induced a febrile response, which was accompanied by a significant rise in plasma IL-6 and nuclear STAT3 translocation in endothelial cells throughout the brain 2 h after treatment, including areas surrounding the sensory circumventricular organs and the median preoptic area (MnPO), important regions in mediating fever. These responses were abolished in the presence of the IL-6AS, which also significantly inhibited the LPS-induced upregulation of mRNA expression or immunoreactivity (IR) of the inducible form of COX, the rate-limiting enzyme for PGE2-synthesis. Interestingly, nuclear signal transducer and activator of transcription (STAT)3-positive cells colocalized with COX-2-IR, signifying that IL-6-activated cells are directly involved in PGE2 production. These observations suggest that IL-6 is an important circulating pyrogen that activates the COX-2-pathway in cerebral microvasculature, most likely through a STAT3-dependent pathway.
Hypothermia modulates circadian clock gene expression in lizard peripheral tissues
Authors: Vallone Daniela , Frigato Elena , Vernesi Cristiano , Foà Augusto , Foulkes Nicholas S. , Bertolucci Cristiano
Published: June 2006

The molecular mechanisms whereby the circadian clock responds to temperature changes are poorly understood. The ruin lizard Podarcis sicula has historically proven to be a valuable vertebrate model for exploring the influence of temperature on circadian physiology. It is an ectotherm that naturally experiences an impressive range of temperatures during the course of the year. However, no tools have been available to dissect the molecular basis of the clock in this organism. Here, we report the cloning of three lizard clock gene homologs ( Period2, Cryptochrome1, and Clock) that have a close phylogenetic relationship with avian clock genes. These genes are expressed in many tissues and show a rhythmic expression profile at 29°C in light-dark and constant darkness lighting conditions, with phases comparable to their mammalian and avian counterparts. Interestingly, we show that at low temperatures (6°C), cycling clock gene expression is attenuated in peripheral clocks with a characteristic increase in basal expression levels. We speculate that this represents a conserved vertebrate clock gene response to low temperatures. Furthermore, these results bring new insight into the issue of whether circadian clock function is compatible with hypothermia.
Contractile properties and myosin heavy chain composition of rat tongue retrusor musculature show changes in early adulthood after 19 days of artificial rearing
Authors: Smith J. Chadwick , Moore W. Allen , Goldberg Stephen J. , Shall Mary S.
Published: June 2006

Previously, we showed that artificial rearing using the “pup in a cup” model results in decreased tongue activity and caused some minor alterations in the tongue retrusor musculature. However, the artificial rearing time frame previously chosen was brief (11 days). The purpose of the present investigation was to extend the artificial rearing period from postnatal days 3 to 21 (P21) to determine whether significant alterations occur as a result of this reduced tongue use. Several changes in contractile properties due to the artificial rearing process were observed, which fully recovered by postnatal days 41 to 42 (P41–2). These changes included a shorter twitch contraction time, shorter twitch half-relaxation time, and decreased fatigue resistance. Styloglossus muscle exhibited more neonatal myosin heavy chain (MHC) isoform at P21 for the artificially reared (AR) group. Changes that were persistent at P41–2 were also observed. Maximum tetanic tension was lower for the AR group at P21 and P41–2 compared with their dam-reared counterparts. Twitch tension was also lower by P41–2 in the AR group. At P41–2, the AR group exhibited an increase in MHC IIa and a decrease in MHC IIb for the styloglossus muscle. In addition, the AR group exhibited a decreased MHC IIb for the long head of the biceps brachii at P41–2. Our results are similar to other models of hindlimb immobilization and suspension. By extending our artificial rearing period, this reduced tongue activity induced acute changes and alterations in the tongue retrusor musculature that persisted into early adulthood.
Feedback-controlled stimulation enhances human paralyzed muscle performance
Authors: Shields Richard K. , Dudley-Javoroski Shauna , Cole Keith R.
Published: June 2006

Chronically paralyzed muscle requires extensive training before it can deliver a therapeutic dose of repetitive stress to the musculoskeletal system. Neuromuscular electrical stimulation, under feedback control, may subvert the effects of fatigue, yielding more rapid and extensive adaptations to training. The purposes of this investigation were to 1) compare the effectiveness of torque feedback-controlled (FDBCK) electrical stimulation with classic open-loop constant-frequency (CONST) stimulation, and 2) ascertain which of three stimulation strategies best maintains soleus torque during repetitive stimulation. When torque declined by 10%, the FDBCK protocol modulated the base stimulation frequency in three ways: by a fixed increase, by a paired pulse (doublet) at the beginning of the stimulation train, and by a fixed decrease. The stimulation strategy that most effectively restored torque continued for successive contractions. This process repeated each time torque declined by 10%. In fresh muscle, FDBCK stimulation offered minimal advantage in maintaining peak torque or mean torque over CONST stimulation. As long-duration fatigue developed in subsequent bouts, FDBCK stimulation became most effective (∼40% higher final normalized torque than CONST). The high-frequency strategy was selected ∼90% of the time, supporting that excitation-contraction coupling compromise and not neuromuscular transmission failure contributed to fatigue of paralyzed muscle. Ideal stimulation strategies may vary according to the site of fatigue; this stimulation approach offered the advantage of online modulation of stimulation strategies in response to fatigue conditions. Based on stress-adaptation principles, FDBCK-controlled stimulation may enhance training effects in chronically paralyzed muscle.
Increased submaximal insulin-stimulated glucose uptake in mouse skeletal muscle after treadmill exercise
Authors: Hamada Taku , Arias Edward B. , Cartee Gregory D.
Published: June 2006

The primary purpose of this study was to determine the effect of prior exercise on insulin-stimulated glucose uptake with physiological insulin in isolated muscles of mice. Male C57BL/6 mice completed a 60-min treadmill exercise protocol or were sedentary. Paired epitrochlearis, soleus, and extensor digitorum longus (EDL) muscles were incubated with [3H]-2-deoxyglucose without or with insulin (60 μU/ml) to measure glucose uptake. Insulin-stimulated glucose uptake for paired muscles was calculated by subtracting glucose uptake without insulin from glucose uptake with insulin. Muscles from other mice were assessed for glycogen and AMPK Thr172phosphorylation. Exercised vs. sedentary mice had decreased glycogen in epitrochlearis (48%, P < 0.001), soleus (51%, P < 0.001), and EDL (41%, P < 0.01) and increased AMPK Thr172phosphorylation ( P < 0.05) in epitrochlearis (1.7-fold), soleus (2.0-fold), and EDL (1.4-fold). Insulin-independent glucose uptake was increased 30 min postexercise vs. sedentary in the epitrochlearis (1.2-fold, P < 0.001), soleus (1.4-fold, P < 0.05), and EDL (1.3-fold, P < 0.01). Insulin-stimulated glucose uptake was increased ( P < 0.05) ∼85 min after exercise in the epitrochlearis (sedentary: 0.266 ± 0.045 μmol·g−1·15 min−1; exercised: 0.414 ± 0.051) and soleus (sedentary: 0.102 ± 0.049; exercised: 0.347 ± 0.098) but not in the EDL. Akt Ser473and Akt Thr308phosphorylation for insulin-stimulated muscles did not differ in exercised vs. sedentary. These results demonstrate enhanced submaximal insulin-stimulated glucose uptake in the epitrochlearis and soleus of mice 85 min postexercise and suggest that it will be feasible to probe the mechanism of enhanced postexercise insulin sensitivity by using genetically modified mice.
Systemic hypoxia and vasoconstrictor responsiveness in exercising human muscle
Authors: Wilkins Brad W. , Schrage William G. , Liu Zhong , Hancock Kellie C. , Joyner Michael J.
Published: June 2006

Exercise blunts sympathetic α-adrenergic vasoconstriction (functional sympatholysis). We hypothesized that sympatholysis would be augmented during hypoxic exercise compared with exercise alone. Fourteen subjects were monitored with ECG and pulse oximetry. Brachial artery and antecubital vein catheters were placed in the nondominant (exercising) arm. Subjects breathed hypoxic gas to titrate arterial O2 saturation to 80% while remaining normocapnic via a rebreath system. Baseline and two 8-min bouts of rhythmic forearm exercise (10 and 20% of maximum) were performed during normoxia and hypoxia. Forearm blood flow, blood pressure, heart rate, minute ventilation, and end-tidal CO2 were measured at rest and during exercise. Vasoconstrictor responsiveness was determined by responses to intra-arterial tyramine during the final 3 min of rest and each exercise bout. Heart rate was higher during hypoxia ( P < 0.01), whereas blood pressure was similar ( P = 0.84). Hypoxic exercise potentiated minute ventilation compared with normoxic exercise ( P < 0.01). Forearm blood flow was higher during hypoxia compared with normoxia at rest (85 ± 9 vs. 66 ± 7 ml/min), at 10% exercise (276 ± 33 vs. 217 ± 27 ml/min), and at 20% exercise (464 ± 32 vs. 386 ± 28 ml/min; P < 0.01). Arterial epinephrine was higher during hypoxia ( P < 0.01); however, venoarterial norepinephrine difference was similar between hypoxia and normoxia before ( P = 0.47) and during tyramine administration ( P = 0.14). Vasoconstriction to tyramine (%decrease from pretyramine values) was blunted in a dose-dependent manner with increasing exercise intensity ( P < 0.01). Interestingly, vasoconstrictor responsiveness tended to be greater ( P = 0.06) at rest (−37 ± 6% vs. −33 ± 6%), at 10% exercise (−27 ± 5 vs. −22 ± 4%), and at 20% exercise (−22 ± 5 vs. −14 ± 4%) between hypoxia and normoxia, respectively. Thus sympatholysis is not augmented by moderate hypoxia nor does it contribute to the increased blood flow during hypoxic exercise.