348 research outputs found
Reactive oxygen species accelerate de novo acquisition of antibiotic resistance in E. coli
Reactive oxygen species (ROS) produced as a secondary effect of bactericidal antibiotics are hypothesized to play a role in killing bacteria. If correct, ROS may play a role in development of de novo resistance. Here we report that single-gene knockout strains with reduced ROS scavenging exhibited enhanced ROS accumulation and more rapid acquisition of resistance when exposed to sublethal levels of bactericidal antibiotics. Consistent with this observation, the ROS scavenger thiourea in the medium decelerated resistance development. Thiourea downregulated the transcriptional level of error-prone DNA polymerase and DNA glycosylase MutM, which counters the incorporation and accumulation of 8-hydroxy-2′-deoxyguanosine (8-HOdG) in the genome. The level of 8-HOdG significantly increased following incubation with bactericidal antibiotics but decreased after treatment with the ROS scavenger thiourea. These observations suggest that in E. coli sublethal levels of ROS stimulate de novo development of resistance, providing a mechanistic basis for hormetic responses induced by antibiotics.</p
Objective Acoustic-Phonetic Speech Analysis in Patients Treated for Oral or Oropharyngeal Cancer
Objective: Speech impairment often occurs in patients after treatment for head and neck cancer. New treatment modalities such as surgical reconstruction or (chemo) radiation techniques aim at sparing anatomical structures that are correlated with speech and swallowing. In randomized trials investigating efficacy of various treatment modalities or speech rehabilitation, objective speech analysis techniques may add to improve speech outcome assessment. The goal of the present study is to investigate the role of objective acoustic-phonetic analyses in a multidimensional speech assessment protocol. Patients and Methods: Speech recordings of 51 patients (6 months after reconstructive surgery and postoperative radiotherapy for oral or oropharyngeal cancer) and of 18 control speakers were subjectively evaluated regarding intelligibility, nasal resonance, articulation, and patient-reported speech outcome (speech subscale of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Head and Neck 35 module). Acoustic-phonetic analyses were performed to calculate formant values of the vowels /a, i, u/, vowel space, air pressure release of /k/ and spectral slope of /x/. Results: Intelligibility, articulation, and nasal resonance were best predicted by vowel space and /k/. Within patients, /k/ and /x/ differentiated tumor site and stage. Various objective speech parameters were related to speech problems as reported by patients. Conclusion: Objective acoustic-phonetic analysis of speech of patients is feasible and contributes to further development of a speech assessment protocol. Copyright (C) 2009 S. Karger AG, Base
Genome sequences of 10 new carnation mottle virus variants
Here, we report the genome sequences of 10 Carnation mottle virus variants. Six variants originated from a single proprietary carnation cultivar, and four were derived from four different proprietary cultivars. All variants showed nucleotide differences, but the last four did not show any variation at the amino acid level
Disentangling the effect of illness perceptions on health status in people with type 2 diabetes after an acute coronary event
Public Health and primary carePrevention, Population and Disease management (PrePoD
First Principles NMR Study of Fluorapatite under Pressure
NMR is the technique of election to probe the local properties of materials.
Herein we present the results of density functional theory (DFT) \textit{ab
initio} calculations of the NMR parameters for fluorapatite (FAp), a calcium
orthophosphate mineral belonging to the apatite family, by using the GIPAW
method [Pickard and Mauri, 2001]. Understanding the local effects of pressure
on apatites is particularly relevant because of their important role in many
solid state and biomedical applications. Apatites are open structures, which
can undergo complex anisotropic deformations, and the response of NMR can
elucidate the microscopic changes induced by an applied pressure. The computed
NMR parameters proved to be in good agreement with the available experimental
data. The structural evaluation of the material behavior under hydrostatic
pressure (from --5 to +100 kbar) indicated a shrinkage of the diameter of the
apatitic channel, and a strong correlation between NMR shielding and pressure,
proving the sensitivity of this technique to even small changes in the chemical
environment around the nuclei. This theoretical approach allows the exploration
of all the different nuclei composing the material, thus providing a very
useful guidance in the interpretation of experimental results, particularly
valuable for the more challenging nuclei such as Ca and O.Comment: 8 pages, 2 figures, 3 table
A molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids
We investigate in detail the initial susceptibility, magnetization curves,
and microstructure of ferrofluids in various concentration and particle dipole
moment ranges by means of molecular dynamics simulations. We use the Ewald
summation for the long-range dipolar interactions, take explicitly into account
the translational and rotational degrees of freedom, coupled to a Langevin
thermostat. When the dipolar interaction energy is comparable with the thermal
energy, the simulation results on the magnetization properties agree with the
theoretical predictions very well. For stronger dipolar couplings, however, we
find systematic deviations from the theoretical curves. We analyze in detail
the observed microstructure of the fluids under different conditions. The
formation of clusters is found to enhance the magnetization at weak fields and
thus leads to a larger initial susceptibility. The influence of the particle
aggregation is isolated by studying ferro-solids, which consist of magnetic
dipoles frozen in at random locations but which are free to rotate. Due to the
artificial suppression of clusters in ferro-solids the observed susceptibility
is considerably lowered when compared to ferrofluids.Comment: 33 pages including 12 figures, requires RevTex
Review of AdS/CFT Integrability, Chapter III.2: Exact world-sheet S-matrix
We review the derivation of the S-matrix for planar N=4 supersymmetric
Yang-Mills theory and type IIB superstring theory on an AdS5xS5 background.
After deriving the S-matrix for the su(2) and su(3) sectors at the one-loop
level based on coordinate Bethe ansatz, we show how su(2|2) symmetry leads to
the exact asymptotic S-matrix up to an overall scalar function. We then briefly
review the spectrum of bound states by relating these states to simple poles of
the S-matrix. Finally, we review the derivation of the asymptotic Bethe
equations, which can be used to determine the asymptotic multiparticle
spectrum.Comment: 20 pages, see also overview article arXiv:1012.3982, v2: references
to other chapters updated, v3: references added and minor change
Paraneoplastic cerebellar degeneration associated with antineuronal antibodies: analysis of 50 patients
Paraneoplastic cerebellar degeneration (PCD) is a heterogeneous group of
disorders characterized by subacute cerebellar ataxia, specific tumour
types and (often) associated antineuronal antibodies. Nine specific
antineuronal antibodies are associated with PCD. We examined the relative
frequency of the antineuronal antibodies associated with PCD and compared
the neurological symptoms and signs, associated tumours, disability and
survival between groups of PCD with different antibodies. Also, we
attempted to identify patient-, tumour- and treatment-related
characteristics associated with functional outcome and survival. In a
12-year period, we examined >5000 samples for the presence of antineuronal
antibodies. A total of 137 patients were identified with a paraneoplastic
neurological syndrome and high titre (> or =400) antineuronal antibodies.
Fifty (36%) of these patients had antibody-associated PCD, including 19
anti-Yo, 16 anti-Hu, seven anti-Tr, six anti-Ri and two anti-mGluR1.
Because of the low number, the anti-mGluR1 patients were excluded from the
statistical analysis. While 100% of patients with anti-Yo, anti-Tr and
anti-mGluR1 antibodies suffered PCD, 86% of anti-Ri and only 18% of
anti-Hu patients had PCD. All patients presented with subacute cerebellar
ataxia progressive over weeks to months and stabilized within 6 months.
The majority of patients in all antibody groups had both truncal and
appendicular ataxia. The frequency of nystagmus and dysarthria was lower
in anti-Ri patients (33 and 0%). Later in the course of the disease,
involvement of non-cerebellar structures occurred most frequently in
anti-Hu patients (94%). In 42 patients (84%), a tumour was detected. The
most commonly associated tumours were gynaecological and breast cancer
(anti-Yo and anti-Ri), lung cancer (anti-Hu) and Hodgkin's lymphoma
(anti-Tr and anti-mGluR1). In one anti-Hu patient, a suspect lung lesion
on CT scan disappeared while the PCD evolved. Seven patients improved by
at least 1 point on the Rankin scale, while 16 remained stable and 27
deteriorated. All seven patients that improved received antitumour
treatment for their underlying cancer, resulting in complete remission.
The functional outcome was best in the anti-Ri patients, with three out of
six improving neurologically and five were able to walk at the time of
last follow-up or death. Only four out of 19 anti-Yo and four out of 16
anti-Hu patients remained ambulatory. Also, survival from time of
diagnosis was significantly worse in the anti-Yo (median 13 months) and
anti-Hu (median 7 months) patients compared with anti-Tr (median >113
months) and anti-Ri (median >69 months). Patients receiving antitumour
treatment (with or without immunosuppressive therapy) lived significantly
longer [hazard ratio (HR) 0.3; 95% confidence interval (CI) 0.1-0.6; P =
0.004]. Patients > or =60 years old lived somewhat shorter from time of
diagnosis, although statistically not significant (HR 2.9; CI 1.0-8.5; P =
0.06)
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