bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcriptional Regulator LsrB of Sinorhizobium meliloti Positively Regulates the Expression of Genes Involved in Lipopolysaccharide Biosynthesis
Authors: Tang Guirong , Wang Ying , Luo Li 
Published: June 2014

ABSTRACT

Rhizobia induce nitrogen-fixing nodules on host legumes, which is important in agriculture and ecology. Lipopolysaccharide (LPS) produced by rhizobia is required for infection or bacteroid survival in host cells. Genes required for LPS biosynthesis have been identified in several
Rhizobium
species. However, the regulation of their expression is not well understood. Here,
Sinorhizobium meliloti
LsrB, a member of the LysR family of transcriptional regulators, was found to be involved in LPS biosynthesis by positively regulating the expression of the
lrp3-lpsCDE
operon. An
lsrB
in-frame deletion mutant displayed growth deficiency, sensitivity to the detergent sodium dodecyl sulfate, and acidic pH compared to the parent strain. This mutant produced slightly less LPS due to lower expression of the
lrp3
operon. Analysis of the transcriptional start sites of the
lrp3
and
lpsCDE
gene suggested that they constitute one operon. The expression of
lsrB
was positively autoregulated. The promoter region of
lrp3
was specifically precipitated by anti-LsrB antibodies
in vivo
. The promoter DNA fragment containing TN11A motifs was bound by the purified LsrB protein
in vitro
. These new findings suggest that
S. meliloti
LsrB is associated with LPS biosynthesis, which is required for symbiotic nitrogen fixation on some ecotypes of alfalfa plants.
F-Box Protein RcyA Controls Turnover of the Kinesin-7 Motor KipA in Aspergillus nidulans
Authors: Herrero Saturnino , Takeshita Norio , Fischer Reinhard 
Published: June 2014

ABSTRACT

Fungal filamentous growth depends on continuous membrane insertion at the tip, the delivery of membrane-bound positional markers, and the secretion of enzymes for cell wall biosynthesis. This is achieved through exocytosis. At the same time, polarized growth requires membrane and protein recycling through endocytosis. Endocytic vesicles are thought to enter the protein degradation pathway or recycle their content to the cell surface. In
Saccharomyces cerevisiae
, the Rcy1 F-box protein is involved in the recycling process of a v-SNARE protein. We identified a Rcy1 orthologue, RcyA, in the filamentous fungus
Aspergillus nidulans
as a protein interacting with the KipA kinesin-7 motor protein in a yeast two-hybrid screen. The interaction was confirmed through bimolecular fluorescence complementation. RcyA possesses an F-box domain at the N terminus and a prenylation (CaaX) motif at the C terminus. RcyA shows also similarity to Sec10, a component of the exocyst complex. The RcyA protein localized to the hyphal tip and forming septa, likely through transportation on secretory vesicles and partially on early endosomes, but independently of KipA. Deletion of
rcyA
did not cause severe morphological changes but caused partial defects in the recycling of the SynA v-SNARE protein and the positioning of the cell end markers TeaA and TeaR. In addition, deletion of
rcyA
led to increased concentrations of the KipA protein, whereas the transcript concentration was unaffected. These results suggest that RcyA probably labels KipA for degradation and thereby controls the protein amount of KipA.
Toxoplasma gondii Development of Its Replicative Niche: in Its Host Cell and Beyond
Authors: Blader Ira J. , Koshy Anita A. 
Published: June 2014

ABSTRACTIntracellular pathogens can replicate efficiently only after they manipulate and modify their host cells to create an environment conducive to replication. While diverse cellular pathways are targeted by different pathogens, metabolism, membrane and cytoskeletal architecture formation, and cell death are the three primary cellular processes that are modified by infections.Toxoplasma gondiiis an obligate intracellular protozoan that infects ∼30% of the world's population and causes severe and life-threatening disease in developing fetuses, in immune-comprised patients, and in certain otherwise healthy individuals who are primarily found in South America. The high prevalence ofToxoplasmain humans is in large part a result of its ability to modulate these three host cell processes. Here, we highlight recent work defining the mechanisms by whichToxoplasmainteracts with these processes. In addition, we hypothesize why some processes are modified not only in the infected host cell but also in neighboring uninfected cells.
How Does It Kill?: Understanding the Candidacidal Mechanism of Salivary Histatin 5
Authors: Puri Sumant , Edgerton Mira 
Published: June 2014

ABSTRACT

Histatins are salivary cationic peptides that provide the first line of defense against oral candidiasis caused by
Candida albicans
. This minireview presents a critical evaluation of our knowledge of the candidacidal mechanism of histatin 5 (Hst 5). Hst 5 is the most potent among all histatin family members with regard to its antifungal activity. The mode of action of Hst 5 has been a subject of intense debate. Unlike other classical host innate immune proteins, pore formation or membrane lysis by Hst 5 has largely been disproven, and it is now known that all targets of Hst 5 are intracellular. Hst 5 binds
C. albicans
cell wall proteins (Ssa1/2) and glycans and is taken up by the cells through fungal polyamine transporters in an energy-dependent manner. Once inside the fungal cells, Hst 5 may affect mitochondrial functions and cause oxidative stress; however, the ultimate cause of cell death is by volume dysregulation and ion imbalance triggered by osmotic stress. Besides these diverse targets, a novel mechanism based on the metal binding abilities of Hst 5 is discussed. Finally, translational approaches for Hst 5, based on peptide design and synergy with other known drugs, are considered a step forward for bench-to-bed application of Hst 5.
Membrane Fluidity and Temperature Sensing Are Coupled via Circuitry Comprised of Ole1, Rsp5, and Hsf1 in Candida albicans
Authors: Leach Michelle D. , Cowen Leah E. 
Published: June 2014

ABSTRACT

Temperature is a ubiquitous environmental variable which can profoundly influence the physiology of living cells as it changes over time and space. When yeast cells are exposed to a sublethal heat shock, normal metabolic functions become repressed and the heat shock transcription factor Hsf1 is activated, inducing heat shock proteins (HSPs).
Candida albicans
, the most prevalent human fungal pathogen, is an opportunistic pathogen that has evolved as a relatively harmless commensal of healthy individuals. Even though
C. albicans
occupies thermally buffered niches, it has retained the classic heat shock response, activating Hsf1 during slow thermal transitions such as the increases in temperature suffered by febrile patients. However, the mechanism of temperature sensing in fungal pathogens remains enigmatic. A few studies with
Saccharomyces cerevisiae
suggest that thermal stress is transduced into a cellular signal at the level of the membrane. In this study, we manipulated the fluidity of
C. albicans
membrane to dissect mechanisms of temperature sensing. We determined that in response to elevated temperature, levels of
OLE1
, encoding a fatty acid desaturase, decrease. Subsequently, loss of
OLE1
triggers expression of
FAS2
, encoding a fatty acid synthase. Furthermore, depletion of
OLE1
prevents full activation of Hsf1, thereby reducing
HSP
expression in response to heat shock. This reduction in Hsf1 activation is attributable to the E3 ubiquitin ligase Rsp5, which regulates
OLE1
expression. To our knowledge, this is the first study to define a molecular link between fatty acid synthesis and the heat shock response in the fungal kingdom.
Identification of Microorganisms by FilmArray and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Prior to Positivity in the Blood Culture System
Authors: Almuhayawi Mohammed , Altun Osman , Strålin Kristoffer , Özenci Volkan 
Published: June 2014

ABSTRACT

In this study, we investigated the performance of the FilmArray and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) in identifying microorganisms from blood culture (BC) bottles prior to positivity. First, we used simulated BacT/Alert FA Plus BC bottles with five each for
Escherichia coli
and
Staphylococcus aureus
isolates. The FilmArray identified all 10 isolates before BC positivity with 9/10 at 5 h and 1 at 7.5 h after incubation in the BC system. MALDI-TOF MS failed to identify the isolates prior to positivity. When the bottles were incubated for 2.5 h at room temperature (RT) before we put them into the BC system, the FilmArray identified 6/10 at 2.5 h and the remaining 4 at 5 h. Finally, we tested simulated BC bottles after incubation at RT. Interestingly, 9/10 isolates were identified with the FilmArray after 8 h of incubation at RT. Second, we studied clinical BC bottles in quadruplicate. When three-fourths of the parallel bottles signaled positive, the FilmArray was run on the fourth nonsignaled bottle and was found to be positive in 14/15 such cases. Third, we analyzed the performance of the FilmArray in the identification of microorganisms from clinical BC bottles before incubation in the system. Two milliliters of broth from 400 BC bottles was collected after arrival at the laboratory and stored at −70°C. Sixteen bottles later signaled positive in the system. When the frozen broth from these bottles was analyzed, the FilmArray identified all the microorganisms in 8/16 bottles prior to incubation in the BC system. This study shows that the FilmArray can identify microorganisms from BC bottles prior to positivity and in some cases even prior to incubation in the BC system.
Practical Agar-Based Disk Potentiation Test for Detection of Fosfomycin-Nonsusceptible Escherichia coli Clinical Isolates Producing Glutathione
S
-Transferases
Authors: Nakamura Genki , Wachino Jun-ichi , Sato Natsumi , Kimura Kouji , Yamada Keiko , Jin Wanchun , Shibayama Keigo , Yagi Tetsuya , Kawamura Kumiko , Arakawa Yoshichika 
Published: June 2014

ABSTRACT

The number of reports concerning
Escherichia coli
clinical isolates that produce glutathione
S
-transferases responsible for fosfomycin resistance (FR-GSTs) has been increasing. We have developed a disk-based potentiation test in which FR-GST producers expand the growth inhibition zone around a Kirby-Bauer disk containing fosfomycin in combination with sodium phosphonoformate (PPF). PPF, an analog of fosfomycin, is a transition-state inhibitor of FosA
PA
, a type of FR-GST from
Pseudomonas aeruginosa
. Considering its mechanism of action, PPF was expected to inhibit a variety of FR-GSTs. In the presence of PPF, zone enlargement around the disk containing fosfomycin was observed for FosA3-, FosA4-, and FosC2-producing
E. coli
clinical isolates. Moreover, the growth inhibition zone was remarkably enlarged when the Mueller-Hinton (MH) agar plate contained 25 μg/ml glucose-6-phosphate (G6P). When we retrospectively tested 12 fosfomycin-resistant (MIC, ≥256 μg/ml)
E. coli
clinical isolates from our hospital with the potentiation test, 6 FR-GST producers were positive phenotypically by potentiation disk and were positive for FR-GST genes: 5 harbored
fosA3
and 1 harbored
fosA4
. To identify the production of FR-GSTs, we set the provisional cutoff value, 5-mm enlargement, by adding PPF to a fosfomycin disk on the MH agar plates containing G6P. Our disk-based potentiation test reliably identifies FR-GST producers and can be performed easily; therefore, it will be advantageous in epidemiological surveys and infection control of fosfomycin-resistant bacteria in clinical settings.
Epidemic Klebsiella pneumoniae ST258 Is a Hybrid Strain
Authors: Chen Liang , Mathema Barun , Pitout Johann D. D. , DeLeo Frank R. , Kreiswirth Barry N. 
Published: June 2014

ABSTRACT

Carbapenem-resistant
Enterobacteriaceae
(CRE), especially
Klebsiella pneumoniae
carbapenemase (KPC)-producing
K. pneumoniae
, pose an urgent threat in health facilities in the United States and worldwide.
K. pneumoniae
isolates classified as sequence type 258 (ST258) by multilocus sequence typing are largely responsible for the global spread of KPC. A recent comparative genome study revealed that ST258
K. pneumoniae
strains are two distinct genetic clades; however, the molecular origin of ST258 largely remains unknown, and our understanding of the evolution of the two genetic clades is incomplete. Here we compared the genetic structures and single-nucleotide polymorphism (SNP) distributions in the core genomes of strains from two ST258 clades and other STs (ST11, ST442, and ST42). We identified an ~1.1-Mbp region on ST258 genomes that is homogeneous to that of ST442, while the rest of the ST258 genome resembles that of ST11. Our results suggest ST258 is a hybrid clone—80% of the genome originated from ST11-like strains and 20% from ST442-like strains. Meanwhile, we sequenced an ST42 strain that carries the same K-antigen-encoding capsule polysaccharide biosynthesis gene (
cps
) region as ST258 clade I strains. Comparison of the
cps
-harboring regions between the ST42 and ST258 strains (clades I and II) suggests the ST258 clade I strains evolved from a clade II strain as a result of
cps
region replacement. Our findings unravel the molecular evolution history of ST258 strains, an important first step toward the development of diagnostic, therapeutic, and vaccine strategies to combat infections caused by multidrug-resistant
K. pneumoniae
.

IMPORTANCE
Recombination events and replacement of chromosomal regions have been documented in various bacteria, and these events have given rise to successful pathogenic clones. Here we used comparative genomic analyses to discover that the ST258
K. pneumoniae
genome is a hybrid—80% of the chromosome is homologous to ST11 strains, while the remaining 20% is homologous to that of ST442. Meanwhile, a recent study indicated that ST258 strains can be segregated into two ST258 clades, with distinct capsule polysaccharide gene (
cps
) regions. Our analysis suggests ST258 clade I strains evolved from clade II through homologous recombination of
cps
region. Horizontal transfer of the
cps
region appears to be a key element driving the molecular diversification in
K. pneumoniae
strains. These findings not only extend our understanding of the molecular evolution of ST258 but are an important step toward the development of effective control and treatment strategies for multidrug-resistant
K. pneumoniae.
Understanding experiences of participating in a weight loss lifestyle intervention trial: a qualitative evaluation of South Asians at high risk of diabetes
Authors: Morrison Zoe , Douglas Anne , Bhopal Raj , Sheikh Aziz ,   on behalf of the trial investigators
Published: June 2014

ObjectiveTo explore the reasons for enrolling, experiences of participating and reasons for remaining in a family-based, cluster randomised controlled trial of a dietitian-delivered lifestyle modification intervention aiming to reduce obesity in South Asians at high risk of developing diabetes.DesignQualitative study using narrative interviews of a purposive sample of trial participants following completion of the intervention. Data were thematically analysed.SettingThe intervention was conducted in Scotland and resulted in a modest decrease in weight, but did not statistically reduce the incidence of diabetes.ParticipantsWe conducted 21 narrative interviews with 24 participants (20 trial participants and four family volunteers).ResultsMany participants were motivated to participate because of: known family history of diabetes and the desire to better understand diabetes-related risks to their own and their family's health; ways to mitigate these risks and to benefit from personalised monitoring. Home-based interventions, communication in the participant's chosen language(s) and continuity in dietitians supported their continuing engagement with the trial. Adaptations in food choices were initially accommodated by participants, although social and faith-based responsibilities were reported as important barriers to persevering with agreed dietary goals. Many participants reported that increasing their level of physical activity was difficult given their long working hours, physically demanding employment and domestic commitments; this being compounded by Scotland's challenging climate and a related reluctance to exercise in the outdoors.ConclusionsAlthough participants had strong personal interests in participation and found the information provided by dietitians useful, they nonetheless struggled to incorporate the dietary and exercise recommendations into their daily lives. In particular, increasing levels of physical exercise was described as an additional and in some cases unachievable burden. Consideration needs to be given to strengthening and supporting lifestyle interventions with community-based approaches in order to help overcome wider social and environmental factors.
Measures of vitamin K antagonist control reported in atrial fibrillation and venous thromboembolism studies: a systematic review
Authors: Mearns Elizabeth S , Hawthorne Jessica , Song Ju-Sung , Coleman Craig I 
Published: June 2014

ObjectiveTo aid trialists, systematic reviewers and others, we evaluated the degree of standardisation of control measure reporting that has occurred in atrial fibrillation (AF) and venous thromboembolism (VTE) studies since 2000; and attempted to determine whether the prior recommendation of reporting ≥2 measures per study has been employed.DesignSystematic review.Search strategyWe searched bibliographic databases (2000 to June 2013) to identify AF and VTE studies evaluating dose-adjusted vitamin K antagonists (VKAs) and reporting ≥1 control measure. The types of measures reported, proportion of studies reporting ≥2 measures and mean (±SD) number of measures per study were determined for all studies and compared between subgroups.Data extractionThrough the use of a standardised data extraction tool, we independently extracted all data, with disagreements resolved by a separate investigator.Results148 studies were included, 57% of which reported ≥2 control measures (mean/study=2.13±1.36). The proportion of time spent in the target international normalised ratio range (TTR) was most commonly reported (79%), and was frequently accompanied by time above/below range (52%). AF studies more frequently reported ≥2 control measures compared with VTE studies (63% vs 37%; p=0.004), and reported a greater number of measures per study (mean=2.36 vs 1.53; p<0.001). Observational studies were more likely to provide ≥2 measures compared with randomised trials (76% vs 33%; p<0.001) and report a greater number of measures (mean=2.58 vs 1.63; p<0.001). More recent studies (2004–2013) reported ≥2 measures more often than older (2000–2003) studies (59% vs 35%; p=0.05) and reported more measures per study (mean=2.23 vs 1.48; p=0.02).ConclusionsWhile TTR was often utilised, studies reported ≥2 measures of VKA control only about half of the time and lacked consistency in the types of measures reported. A trend towards studies reporting greater numbers of VKA control measures over time was observed over our review time horizon, particularly, with AF and observational studies.
Solitary plasmacytoma of the index finger
Authors: Daneshbod Yahya , Nowshadi Pooria Ali , Negahban Shahrzad , Aledavood Azita , Ramzi Mani , Fanaie Sara , Bedayat Gholamreza , Medeiros L Jeffrey 
Published: June 2014

IntroductionSolitary osseous plasmacytoma rarely involves the distal extremities. We report a case and provide a brief review of the relevant literature.Case presentationWe report a 64-year-old man who presented with swelling, mild pain and a deformed right index finger. The workup led to the diagnosis of solitary osseous plasmacytoma and the patient eventually required amputation of his finger. With clinical follow-up, the disease spread to regional lymph nodes and subsequently the patient developed systemic involvement and received chemotherapy.ConclusionsSolitary osseous plasmacytoma should be considered in the differential diagnosis of distal extremity neoplasms.
M1 is not M1 in ischemic stroke: the disability-free survival after mechanical thrombectomy differs significantly between proximal and distal occlusions of the middle cerebral artery M1 segment
Authors: Behme D , Kowoll A , Weber W , Mpotsaris A 
Published: June 2014

AimsRecent recommendations on the designation of target artery lesions in acute ischemic stroke include the anatomical differentiation between a proximal and a distal occlusion site of the M1 segment of the middle cerebral artery (MCA). The aim of this study was to evaluate whether these occlusion types differ in terms of a disability-free (modified Rankin Scale (mRS) 0 or 1) clinical outcome at 90 days.MethodsA retrospective analysis was performed of all patients with MCA M1 occlusions who had a successful revascularization result after mechanical thrombectomy between October 2009 and September 2013 and for whom follow-up at 90 days was available. Imaging data were regraded and re-evaluated according to the modified Thrombolysis In Cerebral Infarction (mTICI) scale and the respective vessel occlusion site definitions. Outcome measures included National Institutes of Health Stroke Scale (NIHSS), mRS, Alberta Stroke Program Early CT Score (ASPECTS) scoring and procedural timings.Results62 patients were successfully recanalized; follow-up at 90 days was available for 42/62 patients (68%). There were proximal MCA occlusions in 24/42 patients (57%) and distal occlusions in 18/42 (43%). Baseline NIHSS, ASPECTS, procedural timings and final mTICI scores did not differ significantly between proximal and distal M1 occlusions. There was a statistically significant difference between proximal and distal M1 occlusions regarding a disability-free early outcome (mRS 0 or 1) at discharge (p=0.03) and at 90 days (p=0.04).ConclusionsProximal occlusions of the M1 segment of the MCA incorporating the lenticulostriate perforators are associated with a poorer clinical outcome than distal M1 occlusions that spare these perforators. Involvement of these perforators might become an additional predictor of clinical outcome after mechanical thrombectomy in ischemic stroke.