bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Acute Anticonvulsant Effects of Deoxycorticosterone in Developing Rats: Role of Metabolites and Mineralocorticoid‐receptor Responses
Authors: Edwards Heather E. , Vimal Sutha , Burnham W. McIntyre 
Published: November 2005

Summary: Purpose:The mechanisms that mediate the acute anticonvulsant effects of deoxycorticosterone (DOC) were investigated in young rats.Methods:Fifteen‐day‐old rats were pretreated with a variety of compounds, including (a) agonists of the receptors that bind DOC (mineralocorticoid receptors); (b) the DOC 5α− and 5α‐3α–reduced metabolites, plus agonists that bind the receptors of the 5α−reduced metabolite of DOC (progesterone receptors); and (c) DOC itself in the presence and absence of metabolism and receptor blockers. Fifteen minutes later, pentylenetetrazol (PTZ) was administered, and maximal pentylenetetrazol (MMT) seizure responses were scored.Results:Agonists of mineralocorticoid receptors increased the latency to forelimb flexion in PTZ seizures and sometimes suppressed the seizures completely. At low, nonconvulsant doses, spironolactone (a mineralocorticoid‐receptor antagonist) blocked the anticonvulsant effects of a nonsedating, but not a sedating, dose of DOC. These data suggest the possible direct involvement of mineralocorticoid receptors in the anticonvulsant effects of DOC. At low, nonconvulsant doses, finasteride (which blocks the metabolism of DOC) partially blocked the protective effects of DOC, suggesting the contribution of metabolites to the anticonvulsant actions of DOC. Dihydrodeoxycorticosterone (DHDOC)—the first metabolite of DOC, an agonist at progesterone receptors, and an allosteric modulator of the γ‐aminobutyric acid (GABA)Areceptor—and tetrahydrodeoxycorticosterone, a secondary metabolite of DOC and an allosteric modulator of the GABAAreceptor, both blocked MMT seizures.Conclusions:These findings suggest that both DOC and its metabolites may contribute to the anticonvulsant effects seen in young rats, perhaps acting via interactions with several different receptors.
Status Epilepticus and Frequent Seizures: Incidence and Clinical Characteristics in Pediatric Epilepsy Surgery Patients
Authors: Koh Susan , Mathern Gary W. , Glasser Gabrielle , Wu Joyce Y. , Shields W. Donald , Jonas Rinat , Yudovin Sue , Cepeda Carlos , Salamon Noriko , Vinters Harry V. , Sankar Raman 
Published: November 2005

Summary: Purpose:The literature suggests that pediatric epilepsy surgery cases that present in status epilepticus (SE) are an unusual occurrence. However, this concept is based on case reports, and the incidence and clinical characteristics of these patients have not been systematically assessed.Methods:The cohort consisted of resective epilepsy surgery cases from 2000 to 2005 (n = 115), and they were classified as presenting with continuous SE requiring medical suppression therapy (n = 6) or intermittent SE (greater than 3 seizures/hour; n = 17). The SE categories were compared with extratemporal surgery patients without SE (non‐SE; n = 64) for differences in clinical variables abstracted from the medical record.Results:Continuous SE was noted in 5% and intermittent SE in 15% of resective surgery cases, and all had extratemporal cortical involvement. Compared with continuous SE and non‐SE cases, intermittent SE patients were younger at surgery with shorter duration of seizures, and had an increased incidence of active infantile spasms during video scalp EEG monitoring. Compared with non‐SE cases, the continuous and intermittent SE groups required a larger number of antiepileptic medications presurgery and 6‐months postsurgery, underwent hemispherectomy more frequently, and had an increased incidence of hemimegalencephaly and Rasmussen encephalitis and a lower occurrence of infarct/ischemia and infectious etiologies. Seizure control was over 71% up to 2 years postsurgery, and there were no differences between patient groups. Finally, seizure frequency per hour was greater in continuous SE cases compared with the intermittent SE group.Conclusions:Children presenting with continuous or intermittent SE are not rare in pediatric epilepsy surgery centers, and such cases are more commonly associated with infantile spasms, Rasmussen's syndrome, and hemimegalencephaly pathologies. Seizure outcome after surgery was not altered in pediatric patients because they had presented with continuous or intermittent SE.
Employers' Attitudes to Employment of People with Epilepsy: Still the Same Old Story?
Authors: Jacoby Ann , Gorry Joanne , Baker Gus A. 
Published: November 2005

Summary: Purpose:One area of life quality known to be compromised by having epilepsy is employment, and one factor contributing to the employment problems of people with epilepsy (PWE) is employer attitudes. Much research on this topic is now outdated and given the changing legal, medical, and social contexts in which PWE live, we therefore reexamined employer attitudes in the united Kingdom.Method:A mail survey of a random sample of U.K. companies selected to be representative of the 14 U.K. economic regions and proportional to the number of employees.Findings:The overall response rate was 41% (n = 204). Twenty‐six percent of respondents reported having experience of employing PWE. Sixteen percent considered that there were no jobs in their company suitable for PWE; 21% thought employing PWE would be “a major issue.” Employers were uniformly of the view that PWE, even when in remission, should disclose their condition to a prospective employer. Seizure severity, frequency, and controllability were all considered important features of epilepsy in the context of employment. Epilepsy created high concern to around half of employers, including the likelihood of it being linked to a work‐related accident. Employers were willing to make accommodations for PWE, in particular job sharing, temporary reassignment of duties, and flexible working hours. Attitudes to employment of PWE were influenced by company size and type and previous experience of doing so.Conclusions:We conclude that it is still the same old story for employers' attitudes toward PWE, though happily for PWE, with some room for optimism.
Conformational Changes of Spo0F along the Phosphotransfer Pathway
Authors: Varughese Kottayil I. 
Published: December 2005

ABSTRACTSpo0F is a secondary messenger in the sporulation phosphorelay, and its structure has been characterized crystallographically in the apo-state, in the metal-bound state, and in an interacting state with a phosphotransferase. Additionally, the solution structure of the molecule has been characterized by nuclear magnetic resonance techniques in the unliganded state and in complex with beryllofluoride. Spo0F is a single-domain protein with a well-defined three-dimensional structure, but it is capable of adapting to specific conformations for catching and releasing the phosphoryl moiety. This commentary deals with the conformational fluctuations of the molecule as it moves from an apo-state to a metal-coordinated state, to a phosphorylated state, and then to a phosphoryl-transferring state.
Spatial Periodicity of
Escherichia coli
K-12 Biofilm Microstructure Initiates during a Reversible, Polar Attachment Phase of Development and Requires the Polysaccharide Adhesin PGA
Authors: Agladze Konstantin , Wang Xin , Romeo Tony 
Published: December 2005

ABSTRACT

Using fast Fourier transform (FFT) analysis, we previously observed that cells within
Escherichia coli
biofilm are organized in nonrandom or periodic spatial patterns (K. Agladze et al., J. Bacteriol. 185:5632-5638, 2003). Here, we developed a gravity displacement assay for examining cell adherence and used it to quantitatively monitor the formation of two distinct forms of cell attachment, temporary and permanent, during early biofilm development. Temporarily attached cells were mainly surface associated by a cell pole; permanent attachments were via the lateral cell surface. While temporary attachment precedes permanent attachment, both forms can coexist in a population. Exposure of attached cells to gravity liberated an unattached population capable of rapidly reassembling a new monolayer, composed of temporarily attached cells, and possessing periodicity. A
csrA
mutant, which forms biofilm more vigorously than its wild-type parent, exhibited an increased proportion of permanently attached cells and a form of attachment that was not apparent in the parent strain, permanent polar attachment. Nevertheless, it formed periodic attachment patterns. In contrast, biofilm mutants with altered lipopolysaccharide synthesis (
waaG
) exhibited increased cell-cell interactions, bypassed the polar attachment step, and produced FFT spectra characteristic of aperiodic cell distribution. Mutants lacking the polysaccharide adhesin β-1,6-
N
-acetyl-
d
-glucosamine (
ΔpgaC
) also exhibited aperiodic cell distribution, but without apparent cell-cell interactions, and were defective in forming permanent attachments. Thus, spatial periodicity of biofilm microstructure is genetically determined and evident during the formation of temporary cell surface attachments.
Distribution and Expression of the ZmpA Metalloprotease in the
Burkholderia cepacia
Complex
Authors: Gingues S. , Kooi C. , Visser M. B. , Subsin B. , Sokol P. A. 
Published: December 2005

ABSTRACT

The distribution of the metalloprotease gene
zmpA
was determined among strains of the
Burkholderia cepacia
complex (Bcc). The
zmpA
gene was present in
B. cepacia
,
B. cenocepacia
,
B. stabilis
,
B. ambifaria
and
B. pyrrocinia
but absent from
B. multivorans
,
B. vietnamiensis
,
B. dolosa
, and
B. anthina
. The presence of
zmpA
generally correlated with extracellular proteolytic activity with the exception of five strains, which had
zmpA
but had no detectable proteolytic activity when skim milk agar was used as a substrate (
zmpA
protease deficient). Western immunoblot experiments with anti-ZmpA antibodies suggest that the
zmpA
protease-deficient strains do not secrete or accumulate detectable ZmpA. Transcriptional
zmpA
::
lacZ
fusions were introduced in selected strains of the Bcc.
zmpA
::
lacZ
was expressed in all strains, but expression was generally lower in the
zmpA
protease-deficient strains than in the
zmpA
protease-proficient strains. Quantitative reverse transcriptase real-time PCR demonstrated that
zmpA
protease-deficient strains did express
zmpA
mRNA, although at various levels.
ZmpA
has previously been shown to be positively regulated by the CepIR quorum-sensing system. Addition of exogenous AHLs did not restore extracellular protease production to any of the
zmpA
protease-deficient strains; however, introduction of
cepR
in
trans
complemented protease activity in two of five strains. Extracellular proteolytic activity was restored by the presence of
zmpA
in
trans
in two of the five strains. These studies suggest that although some strains of the Bcc contain the
zmpA
gene, multiple factors may influence its expression.
F-Like Type IV Secretion Systems Encode Proteins with Thioredoxin Folds That Are Putative DsbC Homologues
Authors: Elton Trevor C. , Holland Samantha J. , Frost Laura S. , Hazes Bart 
Published: December 2005

ABSTRACTF and R27 are conjugative plasmids of enteric bacteria belonging to the IncF and IncHI1 plasmid incompatibility groups, respectively. Based on sequence analysis, two genes of the F transfer region,traFandtrbB, and three genes of the R27 transfer region,trhF,dsbC, andhtdT, are predicted to encode periplasmic proteins containing a C-terminal thioredoxin fold. The C-X-X-C active-site motif of thioredoxins is present in all of these proteins except TraFF.Escherichia colicarrying adsbAmutation, which is deficient in disulfide bond formation, cannot synthesize pili and exhibits hypersensitivity to dithiothreitol (DTT) as monitored by mating ability. Overproduction of theE. colidisulfide bond isomerase DsbC, TrbBF, DsbCR27, or HtdTR27, but not TraFFor TrhFR27, reverses this hypersensitivity to DTT. Site-directed mutagenesis established that the C-X-X-C motif was necessary for this activity. Secretion into the periplasm of the C-terminal regions of TrbBFand DsbCR27, containing putative thioredoxin folds, but not TrhFR27, partially complemented the hostdsbAmutation. AtrbBFdeletion mutant showed a 10-fold-lower mating efficiency in anE. coli dsbCnull strain but had no phenotype in wild-typeE. coli, suggesting redundancy in function between TrbBFandE. coliDsbC. Our results indicate that TrbBF, DsbCR27, and HtdTR27are putative disulfide bond isomerases for their respective transfer systems. TraFFis essential for conjugation but appears to have a function other than disulfide bond chemistry.
ExbBD-Dependent Transport of Maltodextrins through the Novel MalA Protein across the Outer Membrane ofCaulobacter crescentus
Authors: Neugebauer Heidi , Herrmann Christina , Kammer Winfried , Schwarz Gerold , Nordheim Alfred , Braun Volkmar 
Published: December 2005

ABSTRACTAnalysis of the genome sequence ofCaulobacter crescentuspredicts 67 TonB-dependent outer membrane proteins. To demonstrate that among them are proteins that transport nutrients other than chelated Fe3+and vitamin B12—the substrates hitherto known to be transported by TonB-dependent transporters—the outer membrane protein profile of cells grown on different substrates was determined by two-dimensional electrophoresis. Maltose induced the synthesis of a hitherto unknown 99.5-kDa protein, designated here as MalA, encoded by the cc2287 genomic locus. MalA mediated growth on maltodextrins and transported [14C]maltodextrins from [14C]maltose to [14C]maltopentaose. [14C]maltose transport showed biphasic kinetics, with a fast initial rate and a slower second rate. The initial transport had aKdof 0.2 μM, while the second transport had aKdof 5 μM. It is proposed that the fast rate reflects binding to MalA and the second rate reflects transport into the cells. Energy depletion of cells by 100 μM carbonyl cyanide 3-chlorophenylhydrazone abolished maltose binding and transport. Deletion of themalAgene diminished maltose transport to 1% of the wild-typemalAstrain and impaired transport of the larger maltodextrins. ThemalAmutant was unable to grow on maltodextrins larger than maltotetraose. Deletion of twoC. crescentusgenes homologous to theexbB exbDgenes ofEscherichia coliabolished [14C]maltodextrin binding and transport and growth on maltodextrins larger than maltotetraose. These mutants also showed impaired growth on Fe3+-rhodotorulate as the sole iron source, which provided evidence of energy-coupled transport. Unexpectedly, a deletion mutant of atonBhomolog transported maltose at the wild-type rate and grew on all maltodextrins tested. Since Fe3+-rhodotorulate served as an iron source for thetonBmutant, an additional gene encoding a protein with a TonB function is postulated. Permeation of maltose and maltotriose through the outer membrane of theC. crescentus malAmutant was slower than permeation through the outer membrane of anE. coli lamBmutant, which suggests a low porin activity inC. crescentus. The pores of theC. crescentusporins are slightly larger than those ofE. coliK-12, since maltotetraose supported growth of theC. crescentus malAmutant but failed to support growth of theE. coli lamBmutant. The data are consistent with the proposal that binding of maltodextrins to MalA requires energy and MalA actively transports maltodextrins withKdvalues 1,000-fold smaller than those for the LamB porin and 100-fold larger than those for the vitamin B12and ferric siderophore outer membrane transporters. MalA is the first example of an outer membrane protein for which an ExbB/ExbD-dependent transport of a nutrient other than iron and vitamin B12has been demonstrated.
The Maltodextrin System ofEscherichia coli: Metabolism and Transport
Authors: Dippel Renate , Boos Winfried 
Published: December 2005

ABSTRACTThe maltose/maltodextrin regulon ofEscherichia coliconsists of 10 genes which encode a binding protein-dependent ABC transporter and four enzymes acting on maltodextrins. Allmalgenes are controlled by MalT, a transcriptional activator that is exclusively activated by maltotriose. By the action of amylomaltase, we prepared uniformly labeled [14C]maltodextrins from maltose up to maltoheptaose with identical specific radioactivities with respect to their glucosyl residues, which made it possible to quantitatively follow the rate of transport for each maltodextrin. IsogenicmalQmutants lacking maltodextrin phosphorylase (MalP) or maltodextrin glucosidase (MalZ) or both were constructed. The resulting in vivo pattern of maltodextrin metabolism was determined by analyzing accumulated [14C]maltodextrins. MalP−MalZ+strains degraded all dextrins to maltose, whereas MalP+MalZ−strains degraded them to maltotriose. The labeled dextrins were used to measure the rate of transport in the absence of cytoplasmic metabolism. Irrespective of the length of the dextrin, the rates of transport at a submicromolar concentration were similar for the maltodextrins when the rate was calculated per glucosyl residue, suggesting a novel mode for substrate translocation. Strains lacking MalQ and maltose transacetylase were tested for their ability to accumulate maltose. At 1.8 nM external maltose, the ratio of internal to external maltose concentration under equilibrium conditions reached 106to 1 but declined at higher external maltose concentrations. The maximal internal level of maltose at increasing external maltose concentrations was around 100 mM. A strain lackingmalQ,malP, andmalZas well as glycogen synthesis and in which maltodextrins are not chemically altered could be induced by external maltose as well as by all other maltodextrins, demonstrating the role of transport per se for induction.
Catabolite Control Protein A (CcpA) Contributes to Virulence and Regulation of Sugar Metabolism in
Streptococcus pneumoniae
Authors: Iyer Ramkumar , Baliga Nitin S. , Camilli Andrew 
Published: December 2005

ABSTRACT

We characterized the role of catabolite control protein A (
ccpA
) in the physiology and virulence of
Streptococcus pneumoniae. S. pneumoniae
has a large percentage of its genome devoted to sugar uptake and metabolism, and therefore, regulation of these processes is likely to be crucial for fitness in the nasopharynx and may play a role during invasive disease. In many bacteria, carbon catabolite repression (CCR) is central to such regulation, influencing hierarchical sugar utilization and growth rates. CcpA is the major transcriptional regulator in CCR in several gram-positive bacteria. We show that CcpA functions in CCR of lactose-inducible β-galactosidase activity in
S. pneumoniae
. CCR of maltose-inducible α-glucosidase, raffinose-inducible α-galactosidase, and cellobiose-inducible β-glucosidase is unaffected in the
ccpA
strain, suggesting that other regulators, possibly redundant with CcpA, control these systems. The
ccpA
strain is severely attenuated for nasopharyngeal colonization and lung infection in the mouse, establishing its role in fitness on these mucosal surfaces. Comparison of the cell wall fraction of the
ccpA
and wild-type strains shows that CcpA regulates many proteins in this compartment that are involved in central and intermediary metabolism, a subset of which are required for survival and multiplication in vivo. Both in vitro and in vivo defects were complemented by providing
ccpA
in
trans
. Our results demonstrate that CcpA, though not a global regulator of CCR in
S. pneumoniae
, is required for colonization of the nasopharynx and survival and multiplication in the lung.
Heme A Synthase Enzyme Functions Dissected by Mutagenesis ofBacillus subtilisCtaA
Authors: Hederstedt Lars , Lewin Anna , Throne-Holst Mimmi 
Published: December 2005

ABSTRACTHeme A, as a prosthetic group, is found exclusively in respiratory oxidases of mitochondria and aerobic bacteria.Bacillus subtilisCtaA and other heme A synthases catalyze the conversion of a methyl side group on heme O into a formyl group. The catalytic mechanism of heme A synthase is not understood, and little is known about the composition and structure of the enzyme. In this work, we have: (i) constructed actaAdeletion mutant and a system for overproduction of mutant variants of the CtaA protein inB. subtilis, (ii) developed anaffinity purification procedure for isolation of preparative amounts of CtaA, and (iii) investigated the functional roles of four invariant histidine residues in heme A synthase by in vivo and in vitro analyses of the properties of mutant variants of CtaA. Our results show an important function of three histidine residues for heme A synthase activity. Several of the purified mutant enzyme proteins contained tightly bound heme O. One variant also contained trapped hydroxylated heme O, which is a postulated enzyme reaction intermediate. The findings indicate functional roles for the invariant histidine residues and provide strong evidence that the heme A synthase enzyme reaction includes two consecutive monooxygenations.
Identification of a Twin-Arginine Translocation System in
Pseudomonas syringae
pv. tomato DC3000 and Its Contribution to Pathogenicity and Fitness
Authors: Bronstein Philip A. , Marrichi Matthew , Cartinhour Sam , Schneider David J. , DeLisa Matthew P. 
Published: December 2005

ABSTRACT

The bacterial plant pathogen
Pseudomonas syringae
pv. tomato DC3000 (DC3000) causes disease in
Arabidopsis thaliana
and tomato plants, and it elicits the hypersensitive response in nonhost plants such as
Nicotiana tabacum
and
Nicotiana benthamiana
. While these events chiefly depend upon the type III protein secretion system and the effector proteins that this system translocates into plant cells, additional factors have been shown to contribute to DC3000 virulence and still many others are likely to exist. Therefore, we explored the contribution of the twin-arginine translocation (Tat) system to the physiology of DC3000. We found that a
tatC
mutant strain of DC3000 displayed a number of phenotypes, including loss of motility on soft agar plates, deficiency in siderophore synthesis and iron acquisition, sensitivity to copper, loss of extracellular phospholipase activity, and attenuated virulence in host plant leaves. In the latter case, we provide evidence that decreased virulence of
tatC
mutants likely arises from a synergistic combination of (i) compromised fitness of bacteria in planta; (ii) decreased efficiency of type III translocation; and (iii) cytoplasmically retained virulence factors. Finally, we demonstrate a novel broad-host-range genetic reporter based on the green fluorescent protein for the identification of Tat-targeted secreted virulence factors that should be generally applicable to any gram-negative bacterium. Collectively, our evidence supports the notion that virulence of DC3000 is a multifactorial process and that the Tat system is an important virulence determinant of this phytopathogenic bacterium.