bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colorimetric Assay to Determine In Vitro Antibacterial Activity Against Clinical Isolates: Enhanced Activity in Damaged Chinese Masson Pine Needles
Authors: Dong Guijun , Pan Weidong , Zheng Tao , Liu Xianghui , Liu Gongshe 
Published: October 2006

AbstractA colorimetric assay for antibacterial susceptibility testing of clinical isolates (Escherichia coli, Pseudomonas aeruginosa, Shigella dysenteriae, Staphylococcus aureus, Bacillus cereus, and Streptococcus pneumoniae) is described based on the reduction of a novel tetrazolium salt, 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium (MTS), in the presence of phenazine methosulfate (PMS) as an electron‐coupling agent. The combination of 200 μg/mL MTS with 25 μmol/L PMS resulted in production of large amounts of formazan within 1 h of exposure. In this setting, fractions extracted from Chinese Masson pine (Pinus massoniana Lamb.) needles damaged by the pine caterpillar Dendrolimus punctatus Walker were found to have enhanced levels of antibacterial activity. These fractions, which were designated “Master”, “Technique”, and “Strength”, were isolated and identified by reverse‐phase C18 cartridge concentration, gel filtration, and affinity chromatography. Two fractions purified from healthy and undamaged needles were designated H1 and H2, respectively. For all test bacteria species. Technique produced the lowest minimal inhibitory concentrations (MICs), ranging from 2 to 32 μg/mL, and H2 produced the highest values, with four of the six MICs being higher than 128 μg/mL We found that the Rmax model fitted the data well in that the r2 ranged between 0.87 and 0.96 (median, 0.92) and no statistically significant deviations from the model were found (P= 0.23). The median coefficient of variation of the log RC50 values and the slope m of the fitted model for all six strains among the replicates were 38 and 41%, respectively. In the course of the investigation, the physiological and functional factors involved in pest damage to plants were also explored. In summary, the MTS‐PMS colorimetric assay has advantages over existing methods for the examination of antibacterial activity, and could be developed further such that it would be suitable for screening new antibiotic molecules.(Managing editor: Ping He)
How we do it: Chemo‐electroporation in the head and neck for otherwise untreatable patients
Authors: Tijink B.M. , De Bree R. , Van Dongen G.A.M.S. , Leemans C.R. 
Published: October 2006

Keypoints• Chemo‐electroporation therapy with bleomycin is a locoregional treatment modality for head and neck and skin cancer, with the potential to preserve function.• In our institution, chemo‐electroporation therapy is used for patients that can no longer be treated by surgery or radiotherapy, or for whom surgical treatment would be very extensive and thus declined by the patient.• This paper describes in detail the technique of bleomycin‐electroporation therapy. The literature is reviewed and preliminary results of the clinical trial are presented.• The main focus of the trial is to determine the safety, effectiveness, and burden of bleomycin‐electroporation therapy for the patient.• All 17 tumours responded to therapy. Local tumour control was reached in 14 of the 17 (82.4 %) tumours.• Based on the outcome of the clinical trial, bleomycin‐electroporation therapy has the potential to become a valuable addition to the late‐stage treatment options for patients with head and neck or skin tumours.
How we do it: Dispensing with drains in hemithyroidectomy – a feasibility study
Authors: Hopkins C. , Mansuri S. , Terry R.M. 
Published: October 2006

Keypoints• The NHS plan states that 75% of all elective surgery should be carried out as day cases, but reports confirm that we are falling well below such targets.• The use of the harmonic scalpel in thyroidectomy in our department has facilitated faster surgery, minimal intra‐operative haemorrhage, and reduced postoperative blood loss into the drain.• We propose that patients with small solitary nodules (<25 cm3 on preoperative ultrasound) undergoing hemithyroidectomy for diagnostic purposes are candidates for selective use of drains, or where used, early removal of the drain and same day discharge.
Is admission for epistaxis more common in Caucasian than in Asian people? A preliminary study
Authors: Daniel M. , Jaberoo M.C. , Stead R.E. , Reddy V.M. , Moir A.A. 
Published: October 2006

Objectives:  Epistaxis is a common ENT complaint. Although casual observation suggested that it is more common in Caucasian, compared with Asian people, a literature search failed to find any studies investigating ethnicity and epistaxis. The aim of this study was to identify any differences in emergency admission rates for epistaxis between Asian and Caucasian people.Design:  Retrospective observational study using hospital computerised data (HISS).Setting:  Large University Hospital accepting ENT emergencies.Participants:  All Asian and Caucasian patients admitted under ENT care as an emergency (1 January 2000 to 30 November 2005), split into two groups: one composed of epistaxis patients, the other of all other ENT emergency admissions.Main outcomes measures:  The proportions of Asian and Caucasian patients among the two patient groups, either epistaxis admissions or other ENT emergency admissions.Results:  The proportions of Asian and Caucasian patients in the group admitted with emergency epistaxis were 7.1% (100/1410) and 92.9% (1310/1410) respectively. However, the proportions of Asian and Caucasian patients in the group composed of any other ENT emergency were 13.2% (729/5515) and 86.8% (4786/5515), respectively (chi‐squared P < 0.01).Conclusions:  Caucasian people form an unexpectedly large, and Asians a smaller proportion of emergency epistaxis admissions. The possibility of an ethnic risk factor for epistaxis warrants further investigation.
Exploring the relationship between severity of dysphonia and voice‐related quality of life
Authors: Jones S.M. , Carding P.N. , Drinnan M.J. 
Published: October 2006

Objectives:  To explore whether severity and/or consistency of dysphonia are linked to voice‐related quality of life.Design:  Cross‐sectional study.Setting:  Specialist voice clinics, University Teaching Hospital.Participants:  Sixty adult patients attending with a primary complaint of dysphonia. Exclusion criteria were those below 16 years of age, transexual patients and those with a persistent dysphonia of >2 years.Main outcome measures:  Voice‐related quality of life as assessed by VoiSS.Explanatory factors:  Severity of dysphonia as judged by perceptual ratings of voice (GRBAS); a visual analogue scale to judge best, worst and today's voice.Results:  There was a highly significant correlation between perceptual dysphonia severity as assessed by GRBAS and the total, impairment and emotional subsets of the VoiSS questionnaire (r from 0.48 to 0.64).There was a similar and highly significant correlation between best, worst and today's self‐rated voice and the total, impairment and emotional subsets of the VoiSS questionnaire (r from −0.40 to −0.60). However, none of the self‐rated parameters was demonstrably better at explaining the effect on quality of life.Conclusions:  An increasingly negative effect on quality of life appears to be associated with an increase in the severity of dysphonia. Further research on the role of quality of life measures in the assessment and treatment of dysphonia would be of value.
The Three-Dimensional Structure of the Flagellar Rotor from a Clockwise-Locked Mutant of
Salmonella enterica
Serovar Typhimurium
Authors: Thomas Dennis R. , Francis Noreen R. , Xu Chen , DeRosier David J. 
Published: October 2006

ABSTRACT
Three-dimensional reconstructions from electron cryomicrographs of the rotor of the flagellar motor reveal that the symmetry of individual M rings varies from 24-fold to 26-fold while that of the C rings, containing the two motor/switch proteins FliM and FliN, varies from 32-fold to 36-fold, with no apparent correlation between the symmetries of the two rings. Results from other studies provided evidence that, in addition to the transmembrane protein FliF, at least some part of the third motor/switch protein, FliG, contributes to a thickening on the face of the M ring, but there was no evidence as to whether or not any portion of FliG also contributes to the C ring. Of the four morphological features in the cross section of the C ring, the feature closest to the M ring is not present with the rotational symmetry of the rest of the C ring, but instead it has the symmetry of the M ring. We suggest that this inner feature arises from a domain of FliG. We present a hypothetical docking in which the C-terminal motor domain of FliG lies in the C ring, where it can interact intimately with FliM.
Regulation of Mercury Resistance in the Crenarchaeote
Sulfolobus solfataricus
Authors: Schelert James , Drozda Melissa , Dixit Vidula , Dillman Amanda , Blum Paul 
Published: October 2006

ABSTRACT

Mercuric ion, Hg(II), inactivates generalized transcription in the crenarchaeote
Sulfolobus solfataricus
. Metal challenge simultaneously derepresses transcription of mercuric reductase (
merA
) by interacting with the archaeal transcription factor aMerR. Northern blot and primer extension analyses identified two additional Hg(II)-inducible
S. solfataricus
genes,
merH
and
merI
(SSO2690), located on either side of
merA
. Transcription initiating upstream of
merH
at promoter
merHp
was metal inducible and extended through
merA
and
merI
, producing a
merHAI
transcript. Northern analysis of a
merRA
double mutant produced by linear DNA recombination demonstrated
merHp
promoter activity was dependent on aMerR to overcome Hg(II) transcriptional inhibition. Unexpectedly, in a
merA
disruption mutant, the
merH
transcript was transiently induced after an initial period of Hg(II)-mediated transcription inhibition, indicating continued Hg(II) detoxification. Metal challenge experiments using mutants created by markerless exchange verified the identity of the MerR binding site as an inverted repeat (IR) sequence overlapping the transcription factor B binding recognition element of
merHp
. The interaction of recombinant aMerR with
merHp
DNA, studied using electrophoretic mobility shift analysis, demonstrated that complex formation was template specific and dependent on the presence of the IR sequence but insensitive to Hg(II) addition and site-specific IR mutations that relieved in vivo
merHp
repression. Despite containing a motif resembling a distant ArsR homolog, these results indicate aMerR remains continuously DNA bound to protect and coordinate Hg(II)-responsive control over
merHAI
transcription. The new genetic methods developed in this work will promote experimental studies on
S. solfataricus
and other
Crenarchaeota
.
Altered Ca2+Regulation of Yop Secretion inYersinia enterocoliticaafter DNA Adenine Methyltransferase Overproduction Is Mediated by Clp-Dependent Degradation of LcrG
Authors: Fälker Stefan , Schmidt M. Alexander , Heusipp Gerhard 
Published: October 2006

ABSTRACTDNA methylation by the DNA adenine methyltransferase (Dam) interferes with the coordinated expression of virulence functions in an increasing number of pathogens. While analyzing the effect of Dam on the virulence of the human pathogenYersinia enterocolitica, we observed type III secretion of Yop effector proteins under nonpermissive conditions. Dam alters the Ca2+regulation of Yop secretion but does not affect the temperature regulation of Yop/Ysc expression. The phenotype is different from that of classical “Ca2+-blind” mutants ofYersinia, as Dam-overproducing (DamOP) strains still translocate Yops polarly into eukaryotic cells. Although transcription of thelcrGVandyopN-tyeAoperons is slightly upregulated, LcrG is absent from lysates of DamOPbacteria, while the amounts of YopN and TyeA are not changed. We present evidence thatclpXPexpression increases after Dam overproduction and that the ClpP protease then degrades LcrG, thereby releasing a block in type III secretion. This is the first example of posttranslational regulation of type III secretion by the Clp protease and adds a new flavor to the complex regulatory mechanisms underlying the controlled release of effector proteins from bacterial cells.
Regulatory Loop between Redox Sensing of the NADH/NAD
+
Ratio by Rex (YdiH) and Oxidation of NADH by NADH Dehydrogenase Ndh in
Bacillus subtilis
Authors: Gyan Smita , Shiohira Yoshihiko , Sato Ichiro , Takeuchi Michio , Sato Tsutomu 
Published: October 2006

ABSTRACT

NADH dehydrogenase is a key component of the respiratory chain. It catalyzes the oxidation of NADH by transferring electrons to ubiquinone and establishes a proton motive force across the cell membrane. The
yjlD
(renamed
ndh
) gene of
Bacillus subtilis
is predicted to encode an enzyme similar to the NADH dehydrogenase II of
Escherichia coli
, encoded by the
ndh
gene. We have shown that the
yjlC-ndh
operon is negatively regulated by YdiH (renamed Rex), a homolog of Rex in
Streptomyces coelicolor
, and a redox-sensing transcriptional regulator that responds to the NADH/NAD
+
ratio. The
ndh
gene regulates expression of the
yjlC-ndh
operon, as indicated by the fact that mutation in
ndh
causes a higher NADH/NAD
+
ratio. An in vitro study showed that Rex binds to the downstream region of the
yjlC-ndh
promoter and that NAD
+
enhances the binding of Rex to the putative Rex-binding sites in the
yjlC-ndh
operon as well as in the
cydABCD
operon. These results indicated that Rex and Ndh together form a regulatory loop which functions to prevent a large fluctuation in the NADH/NAD
+
ratio in
B. subtilis
.
A Plasmid-Borne Truncated
luxI
Homolog Controls Quorum-Sensing Systems and Extracellular Carbohydrate Production in
Methylobacterium extorquens
AM1
Authors: Penalver Carlos G. Nieto , Cantet Franck , Morin Danièle , Haras Dominique , Vorholt Julia A. 
Published: October 2006

ABSTRACT

A cryptic plasmid of
Methylobacterium extorquens
AM1 was found to encode
tslI
, a truncated
luxI
homolog.
tslI
was shown to be expressed and to control transcription of the acyl-homoserine lactone (HSL) synthase gene
msaI
and thus, indirectly, acyl-HSL production. In addition,
tslI
was found to positively regulate extracellular polysaccharide production.
Conformation of the AcrB Multidrug Efflux Pump in Mutants of the Putative Proton Relay Pathway
Authors: Su Chih-Chia , Li Ming , Gu Ruoyu , Takatsuka Yumiko , McDermott Gerry , Nikaido Hiroshi , Yu Edward W. 
Published: October 2006

ABSTRACTWe previously reported the X-ray structures of wild-typeEscherichia coliAcrB, a proton motive force-dependent multidrug efflux pump, and its N109A mutant. These structures presumably reflect the resting state of AcrB, which can bind drugs. After ligand binding, a proton may bind to an acidic residue(s) in the transmembrane domain, i.e., Asp407 or Asp408, within the putative network of electrostatically interacting residues, which also include Lys940 and Thr978, and this may initiate a series of conformational changes that result in drug expulsion. Herein we report the X-ray structures of four AcrB mutants, the D407A, D408A, K940A, and T978A mutants, in which the structure of this tight electrostatic network is expected to become disrupted. These mutant proteins revealed remarkably similar conformations, which show striking differences from the previously known conformations of the wild-type protein. For example, the loop containing Phe386 and Phe388, which play a major role in the initial binding of substrates in the central cavity, becomes prominently extended into the center of the cavity, such that binding of large substrate molecules may become difficult. We believe that this new conformation may mimic, at least partially, one of the transient conformations of the transporter during the transport cycle.
Bactericidal Activity of both Secreted and Nonsecreted Microcin E492 Requires the Mannose Permease
Authors: Bieler Sylvain , Silva Filo , Soto Claudio , Belin Dominique 
Published: October 2006

ABSTRACTMicrocin E492 (MccE492) is a bactericidal protein secreted byKlebsiella pneumoniaethat is active against various species ofEnterobacteriaceae. Interaction of MccE492 with target cells leads to the depolarization and permeabilization of their inner membranes. Several MccE492-specific proteins are required for the maturation and secretion of active MccE492. Surprisingly, the expression of only MceA, the polypeptide backbone of MccE492, is shown here to be toxic by itself. We refer to this phenomenon as endogenous MceA bactericidal activity to differentiate it from the action of extracellularly secreted MccE492. The toxicity of endogenous MceA is enhanced by an efficient targeting to the inner membrane. However, a periplasmic intermediate state is not required for MceA toxicity. Indeed, endogenous MceA remains fully active when it is fused to thioredoxin-1, a fast-folding protein that promotes retention of the C terminus of MceA in the cytoplasm. The C-terminal domain of MccE492 is required only for delivery from the extracellular environment to the periplasm, and it is not required for inner membrane damage. A common component is absolutely essential for the bactericidal activity of both endogenous MceA and extracellular MccE492. Indeed, toxicity is strictly dependent on the presence of ManYZ, an inner membrane protein complex involved in mannose uptake. Based on these findings, we propose a new model for cell entry, inner membrane insertion, and toxic activity of MccE492.
Survival and Growth in the Presence of Elevated Copper: Transcriptional Profiling of Copper-Stressed
Pseudomonas aeruginosa
Authors: Teitzel Gail M. , Geddie Ashley , De Long Susan K. , Kirisits Mary Jo , Whiteley Marvin , Parsek Matthew R. 
Published: October 2006

ABSTRACT

Transcriptional profiles of
Pseudomonas aeruginosa
exposed to two separate copper stress conditions were determined. Actively growing bacteria subjected to a pulse of elevated copper for a short period of time was defined as a “copper-shocked” culture. Conversely, copper-adapted populations were defined as cells actively growing in the presence of elevated copper. Expression of 405 genes changed in the copper-shocked culture, compared to 331 genes for the copper-adapted cultures. Not surprisingly, there were genes identified in common to both conditions. For example, both stress conditions resulted in up-regulation of genes encoding several active transport functions. However, there were some interesting differences between the two types of stress. Only copper-adapted cells significantly altered expression of passive transport functions, down-regulating expression of several porins belonging to the OprD family. Copper shock produced expression profiles suggestive of an oxidative stress response, probably due to the participation of copper in Fenton-like chemistry. Copper-adapted populations did not show such a response. Transcriptional profiles also indicated that iron acquisition is fine-tuned in the presence of copper. Several genes induced under iron-limiting conditions, such as the siderophore pyoverdine, were up-regulated in copper-adapted populations. Interesting exceptions were the genes involved in the production of the siderophore pyochelin, which were down-regulated. Analysis of the copper sensitivity of select mutant strains confirmed the array data. These studies suggest that two resistance nodulation division efflux systems, a P-type ATPase, and a two-component regulator were particularly important for copper tolerance in
P. aeruginosa
.
A Conserved Inverted Repeat, the LipR Box, Mediates Transcriptional Activation of the
Streptomyces exfoliatus
Lipase Gene by LipR, a Member of the STAND Class of P-Loop Nucleoside Triphosphatases
Authors: Evangelista-Martínez Zahaed , González-Cerón Gabriela , Servín-González Luis 
Published: October 2006

ABSTRACT

Expression of the
Streptomyces exfoliatus lipA
gene, which encodes an extracellular lipase, depends on LipR, a transcriptional activator that belongs to the STAND class of P-loop nucleoside triphosphatases. LipR is closely related to activators present in some antibiotic biosynthesis clusters of actinomycetes, forming the LipR/TchG family of regulators. In this work we showed that purified LipR protein is essential for activation of
lipA
transcription in vitro and that this transcription depends on the presence of a conserved inverted repeat, the LipR box, located upstream of the
lipA
promoter. Mutagenesis of the
lipA
promoter region indicated that most transcription depends on LipR binding to the proximal half-site of the LipR box in close proximity to the −35 region of the promoter. Our experiments also indicated that LipR establishes contact with the RNA polymerase on both sides of the LipR box, since some activation was observed when only the distal half-site was present or when the entire LipR box was moved further upstream. We also showed that the LipR proteins of
S. exfoliatus
and
Streptomyces coelicolor
are functionally interchangeable both in vitro and in vivo, revealing the functional conservation of the regulatory elements in these two species.
Heterologous Expression, Purification, and Characterization of an
l
-Ornithine
N
5
-Hydroxylase Involved in Pyoverdine Siderophore Biosynthesis in
Pseudomonas aeruginosa
Authors: Ge Li , Seah Stephen Y. K. 
Published: October 2006

ABSTRACT

Pseudomonas aeruginosa
is an opportunistic pathogen that produces the siderophore pyoverdine, which enables it to acquire the essential nutrient iron from its host. Formation of the iron-chelating hydroxamate functional group in pyoverdine requires the enzyme PvdA, a flavin-dependent monooxygenase that catalyzes the
N
5
hydroxylation of
l
-ornithine.
pvdA
from
P. aeruginosa
was successfully overexpressed in
Escherichia coli
, and the enzyme was purified for the first time. The enzyme possessed its maximum activity at pH 8.0. In the absence of
l
-ornithine, PvdA has an NADPH oxidase activity of 0.24 ± 0.02 μmol min
−1
mg
−1
. The substrate
l
-ornithine stimulated this activity by a factor of 5, and the reaction was tightly coupled to the formation of hydroxylamine. The enzyme is specific for NADPH and flavin adenine dinucleotide (FAD
+
) as cofactors, as it cannot utilize NADH and flavin mononucleotide. By fluorescence titration, the dissociation constants for NADPH and FAD
+
were determined to be 105.6 ± 6.0 μM and 9.9 ± 0.3 μM, respectively. Steady-state kinetic analysis showed that the
l
-ornithine-dependent NADPH oxidation obeyed Michaelis-Menten kinetics with apparent

K
m

and
V
max
values of 0.58 mM and 1.34 μmol min
−1
mg
−1
.
l
-Lysine was a nonsubstrate effector that stimulated NADPH oxidation, but uncoupling occurred and hydrogen peroxide instead of hydroxylated
l
-lysine was produced.
l
-2,4-Diaminobutyrate,
l
-homoserine, and 5-aminopentanoic acid were not substrates or effectors, but they were competitive inhibitors of the
l
-ornithine-dependent NADPH oxidation reaction, with

K
ic

s of 3 to 8 mM. The results indicate that the chemical nature of effectors is important for simulation of the NADPH oxidation rate in PvdA.