bluuebunny/crossref_metadata_2025_split huggingface dataset:
Group I metabotropic glutamate receptors regulate the frequency–response function of hippocampal CA1 synapses for the induction of LTP and LTD
Authors: Van Dam Els J. M. , Kamal Amer , Artola Alain , De Graan Pierre N. E. , Gispen Willem Hendrik , Ramakers Geert M. J. 
Published: December 2004

AbstractSynaptically released glutamate binds to ionotropic or metabotropic glutamate receptors. Metabotropic glutamate receptors (mGluRs) are G‐protein‐coupled receptors and can be divided into three subclasses (Group I–III) depending on their pharmacology and coupling to signal transduction cascades. Group I mGluRs are coupled to phospholipase C and are implicated in several important physiological processes, including activity‐dependent synaptic plasticity, but their exact role in synaptic plasticity remains unclear. Synaptic plasticity can manifest itself as an increase or decrease of synaptic efficacy, referred to as long‐term potentiation (LTP) and long‐term depression (LTD). The likelihood, degree and direction of the change in synaptic efficacy depends on the history of the synapse and is referred to as ‘metaplasticity’. We provide direct experimental evidence for an involvement of group I mGluRs in metaplasticity in CA1 hippocampal synapses. Bath application of a low concentration of the specific group I agonist 3,5‐dihydroxyphenylglycine (DHPG), which does not affect basal synaptic transmission, resulted in a leftward shift of the frequency–response function for the induction of LTD and LTP in naïve synapses. DHPG resulted in the induction of LTP at frequencies which induced LTD in control slices. These alterations in the induction of LTD and LTP resemble the metaplastic changes observed in previously depressed synapses. In addition, in the presence of DHPG additional potentiation could be induced after LTP had apparently been saturated. These findings provide strong evidence for an involvement of group I mGluRs in the regulation of metaplasticity in the CA1 field of the hippocampus.
Environmental enrichment affects striatal graft morphology and functional recovery
Authors: Döbrössy Máté D. , Dunnett Stephen B. 
Published: December 2004

AbstractEnvironmental conditions and behavioural experience can affect neuronal function and morphology. It is less well known whether such factors also influence the growth, integration and functional recovery provided by neural grafts placed within the damaged brain. Here we report on the effects of differential housing conditions on striatal graft morphology and functional recovery after striatal lesions. Rats were pretrained on a skilled bilateral forelimb task, the staircase test, and lesioned unilaterally in the lateral dorsal striatum with quinolinic acid. One group of lesioned animals was given suspension grafts of E15 whole ganglionic eminence implanted into the lesioned striatum. Following transplantation, the animals were housed either in standard cages (four per cage) or in enriched environment housing conditions (10 per cage) with tunnels, ladders and increased living space available for exploration, social interaction and play. The differentially housed animals were retested on the skilled staircase test at two separate time points. Repeated testing, environmental enrichment and transplantation positively influenced behavioural recovery. Partial recovery was observed bilaterally amongst the grafted animals in both housing conditions. Nevertheless, the grafted animals housed in the enriched environment performed significantly better in the final test compared with all of the other experimental groups. The grafts survived equally well under both housing conditions but the grafts of animals housed in the enriched environment contained larger projection neurons and were somewhat better reinnervated by dopaminergic afferents. An increased level of striatal brain‐derived neurotrophic factor was observed in the control animals housed under the enriched compared with the standard conditions. The results indicate that an enriched environment can affect both graft function and graft morphology through as yet unknown mechanisms.
Glycine receptors and GABAA receptor α1 and γ2 subunits during the development of mouse hypoglossal nucleus
Authors: Muller Emilie , Triller Antoine , Legendre Pascal 
Published: December 2004

AbstractIn the hypoglossal nucleus, GABA and glycine mediate inhibition at separate or mixed synapses containing glycine receptors (GlyRs) and/or GABAA receptors (GABAARs). The functional development of mixed inhibitory synapses depends on the brain area studied, but their relative proportion to total synapses generally decreases with time. We have determined the sequential process of inhibitory synapse maturation in the hypoglossal nucleus in vivo. Immunocytochemistry and confocal microscopy were used for codetection of VIAAT, the common presynaptic vesicular transporter of glycine and GABA, GlyRs, GABAAR α1 and γ2 subunits, and gephyrin, the scaffold protein implicated in the synaptic localization of inhibitory receptors. In E17 embryos, GlyRs were already clustered while GABAAR α1 and γ2 subunit immunoreactivity (IR) displayed both diffuse and clustered patterns. Quantitative analysis at this stage revealed that the majority of GlyR clusters were apposed to VIAAT‐IR accumulation and that 30% of them colocalized with γ2GABAAR clusters. This proportion increased with age to 50% at P30. GlyR clusters that did not colocalize with γ2GABAAR clusters were associated with GABAAR γ2 diffuse IR. Interestingly, the percentage of GlyR clusters surrounded by GABAAR γ2 diffuse IR decreased with age, while GlyR clusters colocalized with γ2GABAAR clusters increased. The developmental coclustered pattern of gephyrin and GABAAR α1 and γ2 subunits paralleled the coclustered pattern of GlyRs and GABAAR α1 and γ2 subunits. Our results indicate that the proportion of GlyR‐GABAAR coclusters increases until adulthood. A developmental sequence of the postsynaptic events is proposed in which diffuse extrasynaptic GABAARs accumulate at inhibitory synapses to form postsynaptic clusters, most of them being colocalized with GlyR clusters in the adult.
Does a latitudinal gradient in seedling survival favour larger seeds in the tropics?
Authors: Moles Angela T. , Warton David I. , Stevens Richard D. , Westoby Mark 
Published: December 2004

AbstractThe mean size of seeds produced by plants at the equator is two to three orders of magnitude higher than the mean size of seeds produced by plants at 60°. We compiled data from the literature to assess the possibility that this latitudinal gradient in seed size allows species to cope with more difficult seedling establishment conditions in tropical environments. We found no relationship between latitude and seedling survival through 1 week (P = 0.27, n = 112 species). There was also no evidence that a larger seed mass is required to gain a given level of seedling survival in tropical environments (P = 0.37, n = 112 species), and no relationship between latitude and the duration of the juvenile period (P = 0.57, n = 132 species). Thus, our results are not compatible with the idea that seedling establishment is more difficult in the tropics.
Transgenerational phenotypic plasticity under future atmospheric conditions
Authors: Mondor Edward B. , Tremblay Michelle N. , Lindroth Richard L. 
Published: December 2004

AbstractOrganisms often exhibit transgenerational phenotypic changes in response to an increased risk of parasitism or predation. Shifts in global atmospheric composition could modify these phenotypic effects through changes in either nutrient quantity/quality or altered interactions with higher trophic levels. Here we show that future atmospheric conditions alter a natural enemy‐induced wing polyphenism in aphids. Winged offspring production by Uroleucon nigrotuberculatum aphids on goldenrod (Solidago canadensis var. scabra) does not differ in enriched CO2 and/or O3 atmospheres. However, proportionally more winged offspring are produced in response to search cues from both coccinellid predators (Coccinella septempunctata) and hymenopteran parasitoids (Aphidius polygonaphis) relative to plants not searched by natural enemies. Moreover, the magnitude of this response differs under enriched CO2 and O3 environments. Aphids produce more winged offspring in response to predators under elevated CO2, but produce more winged offspring in response to parasitoids under elevated O3. Thus, global atmospheric changes influence natural enemy‐mediated phenotypic expression, with potentially far‐reaching consequences for trophic dynamics.
The effect of cleaning and disinfecting the sampling well on the microbial communities of deep subsurface water samples
Authors: Basso Odile , Lascourrèges Jean‐François , Jarry Marc , Magot Michel 
Published: December 2004

SummaryOur knowledge of the microbial characteristics of deep subsurface waters is currently very limited, mainly because of the methods used to collect representative microbial samples from such environments. In order to improve this procedure, a protocol designed to remove the unspecific, contaminant biofilm present on the walls of an approximately 800 m deep well is proposed. This procedure included extensive purges of the well, a mechanical cleaning of its wall, and three successive chlorine injections to disinfect the whole line before sampling. Total bacterial counts in water samples decreased from 2.5 × 105 to 1.0 × 104 per millilitre during the cleaning procedure. Culture experiments showed that the first samples were dominated by sulfate‐reducers and heterotrophs, whereas the final sample was dominated by oligotrophic and hydrogenotrophic bacteria. Community structures established on the diversity of the 16S rRNA genes and data analysis revealed that the water sample collected, after a purge without removal of the biofilm, was characterized by numerous phyla which are not representative of the deep subsurface water. On the other hand, several bacterial phyla were only detected after the full cleaning of the well, and were considered as important components of the subsurface ecosystem which would have been missed in the absence of well cleaning.
Divergent transcriptional and translational signals in Archaea
Authors: Torarinsson Elfar , Klenk Hans‐Peter , Garrett Roger A. 
Published: December 2004

SummaryMany Archaea, in contrast to bacteria, produce a high proportion of leaderless transcripts, show a wide variation in their consensus Shine–Dalgarno (S‐D) sequences and frequently use GUG and UUG start codons. In order to understand the basis for these differences, 18 complete archaeal genomes were examined for sequence signals that are positionally conserved upstream from genes. These functional motifs include box A promoter sequences for leaderless transcripts and S‐D sequences for transcripts with leaders. Most of the box A sequences were preceded by a BRE‐like motif and followed by a previously undetected A/T peak centred on position −10. Moreover, the sequence of the predominant S‐D motifs in an archaeon is shown to depend on the precise number of nucleotides between the conserved anti‐S‐D CCUCC sequence and the 3′‐terminal nucleotide of 16S RNA. Correlations with phylogenetic trees, constructed for the 18 Archaea, reveal that usage of high levels of both S‐D motifs, and GUG and UUG start codons occurs exclusively in the shorter branched Archaea. High levels of leaderless transcripts are found in the longer branched Archaea.
Clonal Relatedness and Conserved Integron Structures in Epidemiologically Unrelated
Pseudomonas aeruginosa
Strains Producing the VIM-1 Metallo-β-Lactamase from Different Italian Hospitals
Authors: Riccio Maria Letizia , Pallecchi Lucia , Docquier Jean-Denis , Cresti Stefania , Catania Maria Rosaria , Pagani Laura , Lagatolla Cristina , Cornaglia Giuseppe , Fontana Roberta , Rossolini Gian Maria 
Published: December 2004

ABSTRACT

Three epidemiologically independent
Pseudomonas aeruginosa
isolates, representative of the first VIM-1 metallo-β-lactamase producers detected at three different hospitals in northern Italy, were investigated to determine their genomic relatedness and to compare the structures of the genetic supports for the VIM-1 determinants. The three isolates, all of serotype O11, appeared to be clonally related according to the results of genotyping by macrorestriction analysis of genomic DNA by pulsed-field gel electrophoresis and random amplification of polymorphic DNA. Investigation of the genetic support for the
bla
VIM-1
determinant revealed that it was carried on identical or almost identical integrons (named In70.2 and In70.3) located within a conserved genomic context. The integrons were structurally related to In70 and In110, two plasmid-borne
bla
VIM-1
-containing integrons from
Achromobacter xylosoxidans
and
Pseudomonas putida
isolates, respectively, from the same geographic area (northern Italy) and were found to be inserted close to the
res
site of a Tn
5051
-like transposon, different from any of those described previously, that was apparently carried on the bacterial chromosome. The present findings suggest that the three VIM-1-producing isolates are members of the same clonal complex which have been spreading in hospitals in northern Italy since the late 1990s and point to a common ancestry of their
bla
VIM-1
-containing integrons.
Antibacterial Activity and Specificity of the Six Human α-Defensins
Authors: Ericksen Bryan , Wu Zhibin , Lu Wuyuan , Lehrer Robert I. 
Published: December 2004

ABSTRACT

We developed a kinetic, 96-well turbidimetric procedure that is capable of testing the antimicrobial properties of six human α-defensins concurrently on a single microplate. The defensins were prepared by solid-phase peptide synthesis and tested against gram-positive bacteria (
Staphylococcus aureus
and
Bacillus cereus
) and gram-negative bacteria (
Enterobacter aerogenes
and
Escherichia coli
). Analysis of the growth curves provided virtual lethal doses (vLDs) equivalent to conventional 50% lethal doses (LD
50
s), LD
90
s, LD
99
s, and LD
99.9
s obtained from colony counts. On the basis of their respective vLD
90
s and vLD
99
s, the relative potencies of human myeloid α-defensins against
S. aureus
were HNP2 > HNP1 > HNP3 > HNP4. In contrast, their relative potencies against
E. coli
and
E. aerogenes
were HNP4 > HNP2 > HNP1 = HNP3. HD5 was as effective as HNP2 against
S. aureus
and as effective as HNP4 against the gram-negative bacteria in our panel. HD6 showed little or no activity against any of the bacteria in our panel, including
B. cereus
, which was highly susceptible to the other five α-defensins. The assay described provides a quantitative, precise, and economical way to study the antimicrobial activities of host-defense peptides. Its use has clarified the relative potencies of human α-defensins and raised intriguing questions about the in vivo function(s) of HD6.
Serine-to-Asparagine Substitution in the GyrA Gene Leads to Quinolone Resistance in Moxifloxacin-Exposed
Chlamydia pneumoniae
Authors: Rupp Jan , Gebert Andreas , Solbach Werner , Maass Matthias 
Published: December 2004

ABSTRACT

Quinolone resistance of
Chlamydia pneumoniae
has not been described previously. Serial subcultures of
C. pneumoniae
under increasing moxifloxacin concentrations (0.0125 to 6.4 mg/liter) resulted in a 256-fold MIC increase compared to moxifloxacin-naive strains. GyrA gene sequencing revealed a novel point mutation with a Ser→Asn substitution. Subcultures under rifalazil and macrolides did not alter the respective MICs.
Effect of Parenteral Antibiotic Administration on Establishment of Intestinal Colonization by
Candida glabrata
in Adult Mice
Authors: Pultz Nicole J. , Stiefel Usha , Ghannoum Mahmoud , Helfand Marion S. , Donskey Curtis J. 
Published: December 2004

ABSTRACT

We examined the effect of antibiotic treatment on establishment of intestinal colonization by
Candida glabrata
in adult mice. Subcutaneous ceftriaxone, piperacillin-tazobactam, clindamycin, and metronidazole promoted increased density of stool colonization, whereas cefepime, levofloxacin, and aztreonam did not. These findings suggest that antibiotics that inhibit intestinal anaerobes promote
C. glabrata
colonization.
Characterization of
pncA
Mutations in Pyrazinamide-Resistant
Mycobacterium tuberculosis
in Brazil
Authors: Rodrigues Vívian de F. Sumnienski , Telles Maria Alice , Ribeiro Marta Osório , Cafrune Patrícia Izquierdo , Rossetti Maria Lucia Rosa , Zaha Arnaldo 
Published: December 2004

ABSTRACT

In this study the nucleotide sequence of the
pncA
gene from 59
Mycobacterium tuberculosis
clinical isolates was analyzed. Mutations in the
pncA
gene were identified in 29 of 40 pyrazinamide-resistant isolates, and no pyrazinamidase activity was detected in 39 of them. Twelve mutations found in this work have not been described previously.
Anaplasma phagocytophilumModulates gp91phoxGene Expression through Altered Interferon Regulatory Factor 1 and PU.1 Levels and Binding of CCAAT Displacement Protein
Authors: Thomas Venetta , Samanta Swapna , Wu Caiyun , Berliner Nancy , Fikrig Erol 
Published: December 2004

ABSTRACTInfection of neutrophil precursors withAnaplasma phagocytophilum, the causative agent of human granulocytic ehrlichiosis, results in downregulation of the gp91phoxgene, a key component of NADPH oxidase. We now show that repression of gp91phoxgene transcription is associated with reduced expression of interferon regulatory factor 1 (IRF-1) and PU.1 in nuclear extracts ofA. phagocytophilum-infected cells. Loss of PU.1 and IRF-1 correlated with increased binding of the repressor, CCAAT displacement protein (CDP), to the promoter of the gp91phoxgene. Reduced protein expression of IRF-1 was observed with or without gamma interferon (IFN-γ) stimulation, and the defect in IFN-γ signaling was associated with diminished binding of phosphorylated Stat1 to the Stat1 binding element of the IRF-1 promoter. The diminished levels of activator proteins and enhanced binding of CDP account for the transcriptional inhibition of the gp91phoxgene duringA. phagocytophiluminfection, providing evidence of the first molecular mechanism that a pathogen uses to alter the regulation of genes that contribute to an effective respiratory burst.
Gamma Interferon and Monophosphoryl Lipid A-Trehalose Dicorynomycolate Are Efficient Adjuvants forMycobacterium tuberculosisMultivalent Acellular Vaccine
Authors: Hovav Avi-Hai , Fishman Yolanta , Bercovier Herve 
Published: December 2004

ABSTRACTIn this study, we examined the immunogenicity and protective efficacy of six immunodominantMycobacterium tuberculosisrecombinant antigens (85B, 38kDa, ESAT-6, CFP21, Mtb8.4, and 16kDa) in a multivalent vaccine preparation (6Ag). Gamma interferon (IFN-γ) and monophosphoryl lipid A-trehalose dicorynomycolate (Ribi) adjuvant systems were used separately or in combination for immunization with the recombinant antigens. Our results demonstrate that immunization of mice with Ribi emulsified antigens in the presence of IFN-γ (Ribi+6Ag+IFN-γ) resulted after challenge with a virulentM. tuberculosisstrain in a significant reduction in the CFU counts that was comparable to that achieved with the BCG vaccine (∼0.9-log protection). Antigen-specific immunoglobulin G (IgG) titers in the Ribi+6Ag+IFN-γ-immunized mice were lower than in mice immunized with Ribi+6Ag and were oriented toward a Th1-type response, as confirmed by elevated IgG2a levels. In addition, splenocyte proliferation, IFN-γ secretion, and NO production were significantly higher in splenocytes derived from Ribi+6Ag+IFN-γ-immunized mice, whereas IL-10 secretion was decreased. These findings confirm the induction of a strong cellular immunity in the vaccinated mice that correlates well with their enhanced resistance toM. tuberculosis. The adjuvant effect of IFN-γ was dose dependent. A dose of 5 μg of IFN-γ per mouse per immunization gave optimal protection, whereas lower or higher amounts (0.5 or 50 μg/ mouse) of IFN-γ failed to enhance protection.
Upregulation of Intercellular Adhesion Molecule 1 and Proinflammatory Cytokines by the Major Surface Proteins of
Treponema maltophilum
and
Treponema lecithinolyticum
, the Phylogenetic Group IV Oral Spirochetes Associated with Periodontitis and Endodontic Infections
Authors: Lee Sung-Hoon , Kim Kack-Kyun , Choi Bong-Kyu 
Published: December 2004

ABSTRACT

Treponema maltophilum
and
Treponema lecithinolyticum
belong to the group IV oral spirochetes and are associated with endodontic infections, as well as periodontitis. Recently, the genes encoding the major surface proteins (Msps) of these bacteria (MspA and MspTL, respectively) were cloned and sequenced. The amino acid sequences of these proteins showed significant similarity. In this study we analyzed the functional role of these homologous proteins in human monocytic THP-1 cells and primary cultured periodontal ligament (PDL) cells using recombinant proteins. The complete genes encoding MspA and MspTL without the signal sequence were cloned into
Escherichia coli
by using the expression vector pQE-30. Fusion proteins tagged with N-terminal hexahistidine (recombinant MspA [rMspA] and rMspTL) were obtained, and any possible contamination of the recombinant proteins with
E. coli
endotoxin was removed by using polymyxin B-agarose. Flow cytometry showed that rMspA and rMspTL upregulated the expression of intercellular adhesion molecule 1 (ICAM-1) in both THP-1 and PDL cells. Expression of proinflammatory cytokines, such as interleukin-6 (IL-6) and IL-8, was also induced significantly in both cell types by the Msps, as determined by reverse transcription-PCR and an enzyme-linked immunosorbent assay, whereas IL-1β synthesis could be detected only in the THP-1 cells. The upregulation of ICAM-1, IL-6, and IL-8 was completely inhibited by pretreating the cells with an NF-κB activation inhibitor,
l
-1-tosylamido-2-phenylethyl chloromethyl ketone. This suggests involvement of NF-κB activation. The increased ICAM-1 and IL-8 expression in the THP-1 cells obtained with rMsps was not inhibited in the presence of the IL-1 receptor antagonist (IL-1ra), a natural inhibitor of IL-1. Our results show that the Msps of the group IV oral spirochetes may play an important role in amplifying the local immune response by continuous inflammatory cell recruitment and retention at an infection site by stimulation of expression of ICAM-1 and proinflammatory cytokines.
Pasteurella multocidaToxin Activates Human Monocyte-Derived and Murine Bone Marrow-Derived Dendritic Cells In Vitro but Suppresses Antibody Production In Vivo
Authors: Bagley Kenneth C. , Abdelwahab Sayed F. , Tuskan Robert G. , Lewis George K. 
Published: December 2004

ABSTRACTPasteurella multocidatoxin (PMT) is a potent mitogen for fibroblasts and osteoblastic cells. PMT activates phospholipase C-β through Gqα, and the activation of this pathway is responsible for its mitogenic activity. Here, we investigated the effects of PMT on human monocyte-derived dendritic cells (MDDC) in vitro and show a novel activity for PMT. In this regard, PMT activates MDDC to mature in a dose-dependent manner through the activation of phospholipase C and subsequent mobilization of calcium. This activation was accompanied by enhanced stimulation of naïve alloreactive T cells and dominant inhibition of interleukin-12 production in the presence of saturating concentrations of lipopolysaccharide. Surprisingly, although PMT mimics the activating effects of cholera toxin on human MDDC and mouse bone marrow-derived dendritic cells, we found that PMT is not a mucosal adjuvant and that it suppresses the adjuvant effects of cholera toxin in mice. Together, these results indicate discordant effects for PMT in vitro compared to those in vivo.