bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Clinical Outcomes in Patients with Bloodstream Infections Due to Gram-Negative Bacteria According to Carbapenem MIC Stratification
Authors: Esterly John S. , Wagner Jamie , McLaughlin Milena M. , Postelnick Michael J. , Qi Chao , Scheetz Marc H. 
Published: July 2012

ABSTRACT

Predictive modeling suggests that actual carbapenem MIC results are more predictive of clinical patient outcomes than categorical classification of the MIC as susceptible, intermediate, or resistant. Some have speculated that current CLSI guidelines' suggested thresholds are too high and that clinical success is more likely if the MIC value is ≤1 mg/liter for certain organisms. Patients treated with carbapenems and with positive blood cultures for
Pseudomonas aeruginosa
,
Acinetobacter baumannii
, or extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria were considered for evaluation in this clinical retrospective cohort study. Relevant patient demographics and microbiologic variables were collected, including carbapenem MIC. The primary objective was to define a risk-adjusted all-cause hospital mortality breakpoint for carbapenem MICs. Secondarily, we sought to determine if a similar breakpoint existed for indirect outcomes (e.g., time to mortality and length of stay [LOS] postinfection for survivors). Seventy-one patients met the criteria for study inclusion. Overall, 52 patients survived, and 19 died. Classification and regression tree (CART) analysis determined a split of organism MIC between 2 and 4 mg/liter and predicted differences in mortality (16.1% versus 76.9%;
P
< 0.01). Logistic regression controlling for confounders identified each imipenem MIC doubling dilution as increasing the probability of death 2-fold (adjusted odds ratio [aOR] 2.0; 95% confidence interval [CI], 1.3 to 3.2). Secondary outcomes were similar between groups. This study revealed that patients with organisms that had a MIC of ≥4 mg/liter had worse outcomes than patients whose isolates had a MIC of ≤2 mg/liter, even after adjustment for confounding variables. We recommend additional clinical studies to better understand the susceptibility breakpoint for carbapenems.
Role of RelA and SpoT in Burkholderia pseudomallei Virulence and Immunity
Authors: Müller Claudia M. , Conejero Laura , Spink Natasha , Wand Matthew E. , Bancroft Gregory J. , Titball Richard W. 
Published: July 2012

ABSTRACT

Burkholderia pseudomallei
is a Gram-negative soil bacterium and the causative agent of melioidosis, a disease of humans and animals. It is also listed as a category B bioterrorism threat agent by the U.S. Centers for Disease Control and Prevention, and there is currently no melioidosis vaccine available. Small modified nucleotides such as the hyperphosphorylated guanosine molecules ppGpp and pppGpp play an important role as signaling molecules in prokaryotes. They mediate a global stress response under starvation conditions and have been implicated in the regulation of virulence and survival factors in many bacterial species. In this study, we created a
relA spoT
double mutant in
B. pseudomallei
strain K96243, which lacks (p)ppGpp-synthesizing enzymes, and investigated its phenotype
in vitro
and
in vivo
. The
B. pseudomallei
Δ
relA
Δ
spoT
mutant displayed a defect in stationary-phase survival and intracellular replication in murine macrophages. Moreover, the mutant was attenuated in the
Galleria mellonella
insect model and in both acute and chronic mouse models of melioidosis. Vaccination of mice with the Δ
relA
Δ
spoT
mutant resulted in partial protection against infection with wild-type
B. pseudomallei
. In summary, (p)ppGpp signaling appears to represent an essential component of the regulatory network governing virulence gene expression and stress adaptation in
B. pseudomallei
, and the Δ
relA
Δ
spoT
mutant may be a promising live-attenuated vaccine candidate.
Natural History of Inhalation Melioidosis in Rhesus Macaques (Macaca mulatta) and African Green Monkeys (Chlorocebus aethiops)
Authors: Yeager John J. , Facemire Paul , Dabisch Paul A. , Robinson Camenzind G. , Nyakiti David , Beck Katie , Baker Reese , Pitt M. Louise M. 
Published: July 2012

ABSTRACTBurkholderia pseudomallei, the causative agent of melioidosis, is recognized as a serious health threat due to its involvement in septic and pulmonary infections in areas of endemicity and is recognized by the Centers for Disease Control and Prevention as a category B biothreat agent. An animal model is desirable to evaluate the pathogenesis of melioidosis and medical countermeasures. A model system that represents human melioidosis infections is essential in this process. A group of 10 rhesus macaques (RMs) and 10 African green monkeys (AGMs) was exposed to aerosolizedB. pseudomallei1026b. The first clinical signs were fever developing 24 to 40 h postexposure followed by leukocytosis resulting from a high percentage of neutrophils. Dyspnea manifested 2 to 4 days postexposure. In the AGMs, an increase in interleukin 1β (IL-1β), IL-6, IL-8, gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) was observed. In the RMs, IL-1β, IL-6, and TNF-α increased. All the RMs and AGMs had various degrees of bronchopneumonia, with inflammation consisting of numerous neutrophils and a moderate number of macrophages. Both the RMs and the AGMs appear to develop a melioidosis infection that closely resembles that seen in acute human melioidosis. However, for an evaluation of medical countermeasures, AGMs appear to be a more appropriate model.
Campylobacter jejuni Translocation across Intestinal Epithelial Cells Is Facilitated by Ganglioside-Like Lipooligosaccharide Structures
Authors: Louwen Rogier , Nieuwenhuis Edward E. S. , van Marrewijk Leonie , Horst-Kreft Deborah , de Ruiter Lilian , Heikema Astrid P. , van Wamel Willem J. B. , Wagenaar Jaap A. , Endtz Hubert P. , Samsom Janneke , van Baarlen Peter , Akhmanova Anna , van Belkum Alex 
Published: July 2012

ABSTRACT

Translocation across intestinal epithelial cells is an established pathogenic feature of the zoonotic bacterial species
Campylobacter jejuni
. The number of
C. jejuni
virulence factors known to be involved in translocation is limited. In the present study, we investigated whether sialylation of
C. jejuni
lipooligosaccharide (LOS) structures, generating human nerve ganglioside mimics, is important for intestinal epithelial translocation. We here show that
C. jejuni
isolates expressing ganglioside-like LOS bound in larger numbers to the Caco-2 intestinal epithelial cells than
C. jejuni
isolates lacking such structures. Next, we found that ganglioside-like LOS facilitated endocytosis of bacteria into Caco-2 cells, as visualized by quantitative microscopy using the early and late endosomal markers early endosome-associated protein 1 (EEA1), Rab5, and lysosome-associated membrane protein 1 (LAMP-1). This increased endocytosis was associated with larger numbers of surviving and translocating bacteria. Next, we found that two different intestinal epithelial cell lines (Caco-2 and T84) responded with an elevated secretion of the T-cell attractant CXCL10 to infection by ganglioside-like LOS-expressing
C. jejuni
isolates. We conclude that
C. jejuni
translocation across Caco-2 cells is facilitated by ganglioside-like LOS, which is of clinical relevance since
C. jejuni
ganglioside-like LOS-expressing isolates are linked with severe gastroenteritis and bloody stools in
C. jejuni
-infected patients.
Recent changes in climate and permafrost temperatures at forested and polar desert sites in northern Canada1This article is one of a series of papers published in this CJES Special Issue on the theme ofFundamental and applied research on permafrost in Canada.
Authors: Smith Sharon L. , Throop Jennifer , Lewkowicz Antoni G. 
Published: July 2012

Climate and ground temperature records up to 30 years in length from permafrost monitoring sites in a polar desert at Alert, Nunavut, and a boreal forest at Table Mountain, Northwest Territories, were analyzed by season and year to assess the ground thermal response to recent climate warming. Methods were developed to standardize incomplete ground temperature data sets and to hindcast air temperatures for comparative analysis. The timing and magnitude of climate warming varied, beginning in the 1960s in the Mackenzie Valley and the 1970s in the High Arctic. Ground temperature increases occurred in both regions but varied in magnitude and timing in relation to the external forcing and permafrost conditions. Significant increases in winter air temperatures in both regions appear to be largely responsible for recent increases in ground temperature, particularly at the polar desert sites where snow cover is minimal.
Nonperturbative time-dependent density functional theory (TDDFT) and time-dependent electron localization function (TDELF) study of the ionization of OCS and CS2 with ultrashort intense laser pulses — Orientational effects
Authors: Penka Emmanuel Fowe , Bandrauk André Dieter 
Published: July 2012

The nonlinear nonperturbative response of OCS and CS2 to ultrashort (few cycles) intense laser pulses was studied numerically by time-dependent density functional theory (TDDFT) methods to understand molecular ionization as a function of laser–molecule orientation. A time-dependent electron localization function(TDELF) was used to visualize the nonlinear nonperturbative electron transfer occurring during the laser pulse. It was found that, for intensities I > 3.5 × 1014 W/cm2, the inner shell Kohn–Sham (KS) molecular orbitals contribute significantly to the ionization, whereas for the intensity I < 3.5 × 1014 W/cm2, the highest occupied molecular orbital (HOMO) shows the dominant response to the field. In general, the ionization rate maxima correspond to the alignment of maximum KS orbital densities with the laser pulse polarization instead of orbital ionization potentials (IP). These findings are corroborated through analysis of the TDELF images, where the ionization occurs from the lone pair or bond regions of the corresponding molecules.
The Performance of Hydrological Monthly Products Using SSM/I–SSMI/S Sensors
Authors: Vila Daniel , Hernandez Cecilia , Ferraro Ralph , Semunegus Hilawe 
Published: July 2012

Abstract
Global monthly rainfall estimates and other hydrological products have been produced from 1987 to the present using measurements from the Defense Meteorological Satellite Program (DMSP) series of the Special Sensor Microwave Imager (SSM/I). The aim of this paper is twofold: to present the recent efforts to improve the quality control (QC) of historical antenna temperature of the SSM/I sensor (1987–2008) and how this improvement impacts the different hydrological products that are generated at NOAA/National Environmental Satellite, Data, and Information Service (NESDIS). Beginning in 2005, the DMSP Special Sensor Microwave Imager/Sounder (SSMI/S) has been successfully operating on the F-16, F-17, and F-18 satellites. The second objective of this paper is focused on the application of SSMI/S channels to evaluate the performance of several hydrological products using the heritage of existing SSM/I algorithms and to develop an improved strategy to extend the SSM/I time series into the SSMI/S era, starting with data in 2009 for F-17. The continuity of hydrological products from SSM/I to SSMI/S has shown to be a valuable contribution for the precipitation and climate monitoring community but several sensor issues must be accounted for to meet this objective.
Least Squares Reconstruction of Doppler Radar Spectra for Irregular PRT
Authors: Kalogiros John 
Published: July 2012

Abstract
A least squares method for the reconstruction of Doppler spectra of weather radars with irregular pulse repetition time used to increase the range of unambiguous velocity is presented and evaluated. This method is a robust spectral method that is based on the least squares minimum norm principle and reconstructs both the magnitude and the phase of the discrete Fourier transform of the signal. The phase spectrum is useful in the estimation of the differential phase in dual-polarization radars with staggered sampling schemes, which is a case of irregular sampling. A computationally efficient iterative algorithm for estimating the mean frequency of the signal, which is required for the reconstruction of the spectrum, is described for possible real-time applications. A clutter filter method based on spectral interpolation, which can be applied to echoes with generally nonzero mean velocity, is also described and combined with the spectrum reconstruction method. Using simulated data it is shown that the least squares reconstruction method with or without the presence of clutter gives results with small bias and standard error and can be applied to wide spectra. The application of the method to real X-band radar data with a low signal-to-noise ratio and a high stagger ratio value of ⅚ showed that the least squares method has low sensitivity to the stagger ratio and satisfactorily gives spectral reconstruction for signal-to-noise ratio values as low as 10 dB.
Space–Time Scales of Northward Propagation of Convection during Boreal Summer
Authors: Chakraborty Arindam , Nanjundiah Ravi S. 
Published: July 2012

Abstract
This study uses precipitation estimates from the Tropical Rainfall Measuring Mission to quantify the spatial and temporal scales of northward propagation of convection over the Indian monsoon region during boreal summer. Propagating modes of convective systems in the intraseasonal time scales such as the Madden–Julian oscillation can interact with the intertropical convergence zone and bring active and break spells of the Indian summer monsoon. Wavelet analysis was used to quantify the spatial extent (scale) and center of these propagating convective bands, as well as the time period associated with different spatial scales. Results presented here suggest that during a good monsoon year the spatial scale of this oscillation is about 30° centered around 10°N. During weak monsoon years, the scale of propagation decreases and the center shifts farther south closer to the equator. A strong linear relationship is obtained between the center/scale of convective wave bands and intensity of monsoon precipitation over Indian land on the interannual time scale. Moreover, the spatial scale and its center during the break monsoon were found to be similar to an overall weak monsoon year. Based on this analysis, a new index is proposed to quantify the spatial scales associated with propagating convective bands. This automated wavelet-based technique developed here can be used to study meridional propagation of convection in a large volume of datasets from observations and model simulations. The information so obtained can be related to the interannual and intraseasonal variation of Indian monsoon precipitation.
The Role of Ice Cover in Heavy Lake-Effect Snowstorms over the Great Lakes Basin as Simulated by RegCM4
Authors: Vavrus Steve , Notaro Michael , Zarrin Azar 
Published: July 2012

Abstract
A 20-km regional climate model, the Abdus Salam International Centre for Theoretical Physics Regional Climate Model version 4 (ICTP RegCM4), is employed to investigate heavy lake-effect snowfall (HLES) over the Great Lakes Basin and the role of ice cover in regulating these events. When coupled to a lake model and driven with atmospheric reanalysis data between 1976 and 2002, RegCM4 reproduces the major characteristics of HLES. The influence of lake ice cover on HLES is investigated through 10 case studies (2 per Great Lake), in which a simulated heavy lake-effect event is compared with a companion simulation having 100% ice cover imposed on one or all of the Great Lakes. These experiments quantify the impact of ice cover on downstream snowfall and demonstrate that Lake Superior has the strongest, most widespread influence on heavy snowfall and Lake Ontario the least. Ice cover strongly affects a wide range of atmospheric variables above and downstream of lakes during HLES, including snowfall, surface energy fluxes, wind speed, temperature, moisture, clouds, and air pressure. Averaged among the 10 events, complete ice coverage causes major reductions in lake-effect snowfall (&gt;80%) and turbulent heat fluxes over the lakes (&gt;90%), less low cloudiness, lower temperatures, and higher air pressure. Another important consequence is a consistent weakening (30%–40%) of lower-tropospheric winds over the lakes when completely frozen. This momentum reduction further decreases over-lake evaporation and weakens downstream wind convergence, thus mitigating lake-effect snowfall. This finding suggests a secondary, dynamical mechanism by which ice cover affects downstream snowfall during HLES events, in addition to the more widely recognized thermodynamic influence.
Regional Comparison of GOES Cloud-Top Properties and Radar Characteristics in Advance of First-Flash Lightning Initiation
Authors: Mecikalski John R. , Li Xuanli , Carey Lawrence D. , McCaul Eugene W. , Coleman Timothy A. 
Published: July 2012

Abstract
Lightning initiation (LI) events over Florida and Oklahoma are examined and statistically compared to understand the behavior of observed radar and infrared satellite interest fields (IFs) in the 75-min time frame surrounding LI. Lightning initiation is defined as the time of the first lightning, of any kind, generated in a cumulonimbus cloud. Geostationary Operational Environmental Satellite (GOES) infrared IFs, contoured frequency by altitude diagrams (CFADs) of radar reflectivity, and model sounding data, analyzed in concert, show the mean characteristics over time for 36 and 23 LI events over Florida and Oklahoma, respectively. CFADs indicate that radar echoes formed 60 min before Florida LI, yet Oklahoma storms exhibited a ~30-min delayed development. Large ice volumes in Florida developed from the freezing of lofted liquid hydrometeors formed by long-lived (~45 min) warm rain processes, which are mostly absent in Oklahoma. However, ice volumes developed abruptly in Oklahoma storms despite missing a significant warm rain component. GOES fields were significantly different before 30 min prior to LI between the two locations. Compared to Florida storms, lower precipitable water (PW), higher convective available potential energy, and higher 3.9-μm reflectance in Oklahoma, suggest stronger and drier updrafts producing a greater abundance of small ice particles. Somewhat larger 15-min 10.7-μm cooling rates in Oklahoma confirm stronger updrafts, while clouds in the 60–30-min pre-LI period show more IF variability (e.g., in the 6.5–10.7-μm difference). Florida storms (high PW, slower growth) offer more lead time for LI predictability, compared to Oklahoma storms (low PW, explosive growth), with defined anvils being obvious at the time of LI.
The relationship between sugar-containing methadone and dental caries: A systematic review
Authors: Tripathee Sheela , Akbar Tahira , Richards Derek , Themessl-Huber Markus , Freeman Ruth 
Published: July 2012

Objectives: To review the evidence of a relationship between sugar-containing methadone and dental caries. Data sources: A systematic search of Cochrane Library, PubMed, PsychINFO, EMBASE, MEDLINE, Current Controlled Trials, WHO, OHRN, SIGLE and ERIC databases was conducted from January 1978 up to June 2010. Study selection: Articles were assessed and data abstracted independently by two reviewers. Papers that provided information about methadone and dental caries and were written in English were included, regardless of type of publication, authors, source of financial support and outcomes. Nineteen articles were identified; of these only three contained quantitative evidence, one of which was a survey. Conclusions: Many people on oral methadone maintenance programmes have been reported to have high levels of dental caries. However, there is no strong evidence to support a direct link between sugar-containing methadone and an increase in dental caries. High quality studies are required to assess the potential adverse effects of methadone on oral health.
Histomorphological and ultrastructural changes of the placenta in mice exposed to formaldehyde
Authors: Monfared Ali Louei 
Published: July 2012

Formaldehyde (FA) is widely used in industrial and medical settings. It has long been suspected of causing adverse reproductive and developmental effects. However, the effects of exposure to FA on the reproduction are still a matter of scientific controversy. In this study, we evaluate the hypothesis that adverse developmental outcomes of the exposure to FA might be due to its effects on the placental structure. So, histological changes of the placenta in the mice exposed to FA gas were assessed at light and electron microscopy levels. A total of 40 pregnant Balb/C mice were randomly allotted to four groups in which the animals were exposed to FA at the doses of 0 (control), 7, 14 and 28 ppm, respectively, by inhalation, consecutively, for 8 h/d during the organogenesis period. On day 17 of gestation, the animals were killed and the histological specimens of the placentas were taken for light and electron microscopy studies. Also, morphological parameters of the placentas were measured manually. The results showed that the effects of FA on the placenta are not dose dependent. In the FA-exposed mice, an increase in the number and size of trophoblastic giant cells and an enlargement of spongiotrophoblastic cells in the basal zone of placenta were seen. Also, a significant increase in placental weight as well as the ratio of placental to fetal weight but a decrease in the fetal weight were found in the treated groups when compared with those in the control mice ( p < 0.05). Moreover, ultrastructural results demonstrated that the diameter of labyrinth interhemal membrane as well as the thickness of trophoblastic basement membranes were significantly increased in the FA-exposed mice. In addition, in the FA-treated animals, a severe accumulation of cytoplasmic droplets in the II and III trophoblastic layers of the placenta were seen. In conclusion, this study may suggest that the exposure to FA during the organogenesis period at doses of 7–28 ppm induces toxic changes in the placental structure. These changes disrupt placental functions and leads to a decrease in the fetal weight.
Hepatoprotective potential of astaxanthin against 2,3,7,8-tetrachlorodibenzo-p-dioxin in cultured rat hepatocytes
Authors: Turkez Hasan , Geyikoglu Fatime , Yousef Mokhtar I , Togar Basak , Gürbüz Hasan , Celik Kubra , Akbaba Giray B , Polat Zuhal 
Published: July 2012

The purpose of this study was to evaluate the effect of carotenoid astaxanthin (ASTA) on cultured primary rat hepatocytes treated with 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) on the cell viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT), lactate dehydrogenase (LDH) activity, 8-oxo-2-deoxyguanosine (8-OH-dG), total antioxidant capacity (TAC), and total oxidative stress (TOS) levels, and liver micronucleus rates. ASTA (2.5, 5, and 10 µM) was added to cultures alone or simultaneously with TCDD (5 and 10 µM) for 48 h. The results of MTT and LDH assays showed that both doses of TCDD caused significant decrease in cell viability. Also, TCDD significantly increased TOS and decreased TAC level in rat hepatocytes. On the basis of increasing doses, the dioxin caused significant increase in micronucleated hepatocytes) and 8-OH-dG level as compared to control culture. The presence of ASTA with TCDD minimized its effects on primary hepatocytes cultures and DNA damages.