Brillouin light scattering in niobium doped lead zirconate single crystal.

Brillouin light scattering experiments were performed for lead zirconate single crystals doped with niobium. Special attention was paid to the elastic mode softening near phase transition temperatures. The results are compared with data obtained by Raman light scattering experiments. We observed that the interaction between acoustic and optic modes is responsible for symmetry breaking far above TC, leading to polar regions' appearance. No changes in the acoustic mode frequency and its damping are observed at TC, where ε(T) exhibits a maximum value. The absence of these changes and the central peak observed in Raman experiments suggest that the phase transition at TC is mainly of the order-disorder type. The origin of other phase transitions is discussed as well.

Non-relaxor behaviour of low-frequency vibration spectra of relaxor ferroelectric PbCo1/3Nb2/3O3: evidences from Brillouin and Raman scattering measurements.

This paper presents the results of studies of a low-frequency vibration spectrum of PbCo1/3Nb2/3O3 (PCN) relaxor ferroelectric crystal using the Brillouin and Raman light scattering in the temperature range from 80 to 750 K. The analysis of the temperature behaviour of the longitudinal acoustic phonon in Brillouin scattering spectra showed no anomalies in the vicinity of 'diffuse phase transition' (T m = 250 K) in PCN. Polarized Raman light scattering spectra were obtained in PCN over the entire temperature range studied. Analysis of low-frequency optical mode behaviour in PCN during temperature change also revealed no correlations with dielectric permeability anomaly in the vicinity of T m: softening of optical phonon at 43 cm-1 frequency in VV polarization is observed at 170 K. In the same temperature range, there are anomalies (a 'narrow' and weak component) in quasi-elastic light scattering (QELS) obtained in temperature behaviour with VH polarization in Raman spectra in PCN. A 'wide' and intense QELS component, obtained in Raman spectra with VV polarization, shows anomalies in the vicinity of T m. We associate the anomalies of optical phonons and QELS with structure distortions in the formation of phase stratification and the dynamics of polar nano-regions.

Early cidofovir administration might be associated with a lower probability of respiratory failure in treating human adenovirus pneumonia: a retrospective cohort study.

OBJECTIVE: To compare outcomes of early and delayed treatment with cidofovir for human adenovirus (HAdV) pneumonia. METHODS: A retrospective cohort study in Korean military hospitals was conducted between January 2012 and December 2018. Patients with potentially severe HAdV pneumonia with risk factors for respiratory failure were included and divided into early (within 7 days from symptom onset) and delayed (after 7 days from symptom onset) treatment groups. The primary outcome was respiratory failure development within 21 days after symptom onset. RESULTS: A total of 89 patients with potentially severe HAdV pneumonia were enrolled in the cohort; they included 62 early and 27 delayed treatment patients. All patients were males in their early 20s. Significantly fewer patients in the early treatment group progressed to respiratory failure (8/62, 12.9%), compared to the delayed group (18/27, 66.7%, p < 0.001). Early treatment was associated with a lower 21-day probability of respiratory failure by the Kaplan-Meier method (p < 0.001). On multivariate analysis, monocyte count, hypoxaemia, confusion, whole lung involvement, and early cidofovir treatment within 7 days from symptom onset were included, and monocyte count (HR 0.995, 95%CI 0.991-1.000, p 0.042), confusion (HR 4.964, 95%CI 1.189-20.721, p = 0.028), and early cidofovir treatment (HR 0.319, 95%CI 0.115-0.883, p = 0.028) were significantly associated with respiratory failure. CONCLUSIONS: Early administration of cidofovir was associated with a lower hazard for respiratory failure development. It is suggested that cidofovir be administered within 7 days from symptom onset to prevent respiratory failure in patients with potentially severe HAdV pneumonia.

Fluoroquinolones versus trimethoprim-sulfamethoxazole for the treatment of Stenotrophomonas maltophilia infections: a systematic review and meta-analysis.

BACKGROUND: Fluoroquinolones are a popular alternative to trimethoprim-sulfamethoxazole for Stenotrophomonas maltophilia infections. OBJECTIVES: To compare the effects of fluoroquinolones and trimethoprim-sulfamethoxazole on mortality of S. maltophilia infections. DATA SOURCES: PubMed and EMBASE. STUDY ELIGIBILITY CRITERIA: Clinical studies reporting mortality outcomes of S. maltophilia infections. PARTICIPANTS: Patients with clinical infections caused by S. maltophilia. INTERVENTIONS: Fluoroquinolone monotherapy in comparison with trimethoprim-sulfamethoxazole monotherapy. METHODS: Systematic review with meta-analysis technique. RESULTS: Seven retrospective cohort and seven case-control studies were included. Three cohort studies were designed to compare the two drugs, whereas others had other purposes. A total of 663 patients were identified, 332 of which were treated with trimethoprim-sulfamethoxazole (50.1%) and 331 with fluoroquinolones (49.9%). Three cohort studies were designed to compare the effect of the two drugs, whereas the others had other purposes. Levofloxacin was most frequently used among fluoroquinolones (187/331, 56.5%), followed by ciprofloxacin (114/331, 34.4%). The overall mortality rate was 29.6%. Using pooled ORs for the mortality of each study, fluoroquinolone treatment (OR 0.62, 95% CI 0.39-0.99) was associated with survival benefit over trimethoprim-sulfamethoxazole treatment, with low heterogeneity (I2 = 18%). Specific fluoroquinolones such as ciprofloxacin (OR 0.44, 95% CI 0.17-1.12) and levofloxacin (OR 0.78, 95% CI 0.48-1.26) did not show a significant difference in comparison with trimethoprim-sulfamethoxazole. In the sub-group analyses of adult and bacteraemic patients, significant differences in mortality were not observed between fluoroquinolones and trimethoprim-sulfamethoxazole. CONCLUSIONS: Based on a meta-analysis of non-randomized studies, fluoroquinolones demonstrated comparable effects on mortality of S. maltophilia infection to trimethoprim-sulfamethoxazole, supporting the use of fluoroquinolones in clinical S. maltophilia infections. Although the pooled analysis of overall studies favoured fluoroquinolones over trimethoprim-sulfamethoxazole, the studies included were observational, and sub-group analyses of certain fluoroquinolone agents did not show statistical differences with trimethoprim-sulfamethoxazole. Randomized clinical studies are needed to address these issues.

Post-exposure prophylaxis for Middle East respiratory syndrome in healthcare workers.

An effective post-exposure prophylaxis (PEP) strategy may limit the spread of infection. However, there is no consensus regarding PEP for Middle East respiratory syndrome coronavirus (MERS-CoV) infection. This study assessed the efficacy of ribavirin and lopinavir/ritonavir as PEP for healthcare workers (HCWs) exposed to patients with severe MERS-CoV pre-isolation pneumonia. The safety of the PEP regimen was assessed. HCWs with high-risk exposure to MERS-CoV pre-isolation pneumonia were retrospectively enrolled. HCWs who received PEP therapy were classified into the PEP group. PEP therapy was associated with a 40% decrease in the risk of infection. There were no severe adverse events during PEP therapy.

Relative risks of Internet-related addictions and mood disturbances among college students: a 7-country/region comparison.

OBJECTIVES: This study aimed to determine the relative risks of addiction to the Internet, online gaming and online social networking of college students in six Asian countries/regions (Singapore, Hong Kong [HK]/Macau, China, South Korea, Taiwan and Japan) compared with students in the United States (US). It also explored the relative risks of depression and anxiety symptoms among students with Internet-related addictions from these countries/regions. STUDY DESIGN: This is a cross-sectional survey. METHODS: A convenience sample of 8067 college students aged between 18 and 30 years was recruited from seven countries/regions. Students completed a survey about their use of the Internet, online gaming and online social networking as well as the presence of depression and anxiety symptoms. RESULTS: For all students, the overall prevalence rates were 8.9% for Internet use addiction, 19.0% for online gaming addiction and 33.1% for online social networking addiction. Compared with the US students, Asian students showed higher risks of online social networking addiction but displayed lower risks of online gaming addiction (with the exception of students from HK/Macau). Chinese and Japanese students also showed higher risks of Internet addiction compared with the US students. In general, addicted Asian students were at higher risks of depression than the addicted US students, especially among Asian students who were addicted to online gaming. Addicted Asian students were at lower risks of anxiety than the addicted US students, especially among Asian students who were addicted to online social networking, and addicted students from HK/Macau and Japan were more likely to have higher relative risks of depression. CONCLUSIONS: There are country/regional differences in the risks of Internet-related addictions and psychiatric symptoms. It is suggested that country/region-specific health education programmes regarding Internet-related addictions are warranted to maximise the efficiency of prevention and intervention. These programmes should attempt to tackle not only problematic Internet-related behaviours but also mood disturbances among college students.

Appropriate non-carbapenems are not inferior to carbapenems as initial empirical therapy for bacteremia caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: a propensity score weighted multicenter cohort study.

The efficacy of empirical non-carbapenem antibiotics for extended-spectrum beta-lactamase-producing Enterobacteriaceae bacteremia (ESBL-B) is still inconclusive. We conducted a multicenter retrospective cohort study to evaluate the efficacy of empirical non-carbapenem antibiotics for treating ESBL-B. Electronic medical records of individuals who were diagnosed with ESBL-B were reviewed between January 2010 and December 2014 at four university hospitals in Korea. Patients were classified into non-carbapenem and carbapenem groups according to the empirical antibiotic regimen. Patients treated with appropriate empirical antibiotics and who subsequently received carbapenems as definitive therapy were included in the analysis. The inverse probability of treatment weights, a statistical method that adjusts baseline statistics by giving weights based on propensity score, was used. During the study period, 232 adequately treated patients with ESBL-B were included in the analysis: 49 patients in the non-carbapenem group and 183 in the carbapenem group. The baseline characteristics and severity of infection were similar after propensity score weighting. The 30-day mortality rates for the two groups were not statistically significantly different (non-carbapenems 6.3% and carbapenems 11.4%; P = 0.42). In a multivariate analysis, empirical treatment with non-carbapenem antibiotics was not associated with 30-day all-cause mortality (HR 1.02, 95% CI 0.99-1.06, P = 0.14). In a subgroup analysis, empirical treatment with piperacillin-tazobactam was also not associated with 30-day all-cause mortality (HR 1.21, 95% CI 0.37-4.00, P = 0.75). Appropriate non-carbapenems were not inferior to carbapenems as initial empirical therapy for ESBL-B.

Suggested new breakpoints of anti-MERS-CoV antibody ELISA titers: performance analysis of serologic tests.

To provide optimal cut-off values of anti-Middle East respiratory syndrome coronavirus (MERS-CoV) serologic tests, we evaluated performance of ELISA IgG, ELISA IgA, IFA IgM, and IFA IgG using 138 serum samples of 49 MERS-CoV-infected patients and 219 serum samples of 219 rRT-PCR-negative MERS-CoV-exposed healthcare personnel and patients. The performance analysis was conducted for two different purposes: (1) prediction of neutralization activity in MERS-CoV-infected patients, and (2) epidemiologic surveillance of MERS-CoV infections among MERS-CoV-exposed individuals. To evaluate performance according to serum collection time, we used 'days post onset of illness (dpoi)' and 'days post exposure (dpex)' assessing neutralization activity and infection diagnosis, respectively. Performance of serologic tests improved with delayed sampling time, being maximized after a seroconversion period. In predicting neutralization activity, ELISA IgG tests showed optimal performance using sera collected after 21 dpoi at cut-off values of OD ratio 0.4 (sensitivity 100% and specificity 100%), and ELISA IgA showed optimal performance using sera collected after 14 dpoi at cut-off value of OD ratio 0.2 (sensitivity 85.2% and specificity 100%). In diagnosis of MERS-CoV infection, ELISA IgG exhibited optimal performance using sera collected after 28 dpex, at a cut-off value of OD ratio 0.2 (sensitivity 97.3% and specificity 92.9%). These new breakpoints are markedly lower than previously suggested values (ELISA IgG OD ratio 1.1, sensitivity 34.8% and specificity 100% in the present data set), and the performance data help serologic tests to be practically used in the field of MERS management.

Impact of appropriateness of empiric therapy on outcomes in community-onset bacteremia by extended-spectrum-ß-lactamase producing Escherichia coli and Klebisella pneumoniae definitively treated with carbapenems.

Despite a significant increase of bloodstream infection caused by extended-spectrum-ß-lactamase (ESBL)-producing Enterobacteriaceae in the community-setting, information regarding clinical outcomes of inappropriate empiric therapy (IAT) in patients with those infections is limited. A multicenter-retrospective cohort study was conducted in four hospitals. A total of 249 adults were identified to have community-onset bacteremia caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae, and definitively treated with carbapenems. According to the appropriateness of empiric therapy, individuals were divided into an appropriate empiric therapy (AT) group (n = 106) and IAT group (n = 143). Patients who received AT showed more severe underlying conditions including underlying solid cancer, healthcare-association and intensive care unit (ICU) care, compared to the IAT group. Primary bacteremia was more commonly found in the AT group than in the IAT group, while urinary tract infection predominated more frequently in the IAT group than in the AT group. Multivariate analysis using propensity score analysis indicated that inappropriateness of empiric therapy was not an independent risk factor for 30-day death. ICU care, respiratory tract infection and underlying liver, renal and connective tissue diseases were significantly associated with mortality. In patients with bloodstream infections caused by ESBL-producing E. coli and K. pneumoniae in the community-setting, delay in appropriate therapy was not associated with an increased rate of death if the patients were definitively treated with carbapenems.

Empirical combination of a ß-lactam to vancomycin may not improve outcomes of methicillin-susceptible Staphylococcus aureus bacteremia, compared to vancomycin monotherapy.

To evaluate effect of empirical combination of a ß-lactam to vancomycin and vancomycin monotherapy in Staphylococcus aureus bacteremia (MSSA-B), we conducted a retrospective cohort study. Electronic medical records of individuals who were diagnosed with MSSA-B between January 2005 and February 2015 at a tertiary care center were reviewed. Patients were classified into three groups according to empirical antibiotic regimen (BL group, ß-lactam; VAN group, vancomycin; BV group, combination of ß-lactam and vancomycin), and 30-day all-cause mortality of each group was compared. During the study period, 561 patients with MSSA-B were identified. After exclusion of 198 patients (36 with poly-microbial infection, 114 expired within 2 days, and 48 already received parenteral antibiotics) and a matching process, 46 patients for each group were included. Baseline characteristics were similar except for severity and comorbidity scores. The 30-day mortality for all three groups were not significantly different (BL 4.3%, VAN 6.5%, BV 8.7%; P = 0.909). In a multivariate analysis, type of empirical antibiotic regimen was not statistically associated with 30-day all-cause mortality. In comparison with the VAN group, the BV group yielded a HR of 0.579 (95% CI = 0.086-3.890, P = 0.574). Pitt bacteremia score was the only significant factor for mortality. The empirical combination of a ß-lactam to vancomycin was not associated with lower mortality in treating MSSA-B, compared to vancomycin monotherapy.

Generic piperacillin/tazobactam is not associated with galactomannan false-positivity in adult patients with cancer: a case-control study.

Recent products of piperacillin/tazobactam (PTZ) from the original manufacturer, previously considered a major cause of galactomannan (GM) false-positivity, are reported not to be related to it. However, data regarding generic PTZ are limited and controversial. To evaluate the effect of generic PTZ on GM false-positivity in Korea, we performed a case-control study in adult patients with cancer. A case-control study was designed. Electronic medical records of cancer patients who were admitted and tested for serum GM between March and June 2014 at a tertiary care university hospital were reviewed. During the study period, a single generic PTZ (C manufacturer, Korea) was used. Patients who received PTZ within 24 h prior to serum GM testing were enrolled. Age- and GM test date-matched non-PTZ patients were selected as controls. A total of 110 patients received PTZ within 24 h prior to serum GM testing during the study period. The GM optical density index (ODI) of the PTZ group did not vary significantly from that of the control group (p = 0.251). The percentage of false-positive patients in the PTZ group was also similar to that of the control group (p = 0.538). There was no statistical relationship between GM ODI titer and time interval from PTZ administration (p = 0.095) or cumulative PTZ dose (p = 0.416). In a case-control study that evaluated 220 patients, a generic PTZ in Korea was not related to GM false-positivity.

The MYB46/MYB83-mediated transcriptional regulatory programme is a gatekeeper of secondary wall biosynthesis.

BACKGROUND: The secondary cell wall is a defining feature of xylem cells and allows them to resist both gravitational forces and the tension forces associated with the transpirational pull on their internal columns of water. Secondary walls also constitute the majority of plant biomass. Formation of secondary walls requires co-ordinated transcriptional regulation of the genes involved in the biosynthesis of cellulose, hemicellulose and lignin. This co-ordinated control appears to involve a multifaceted and multilayered transcriptional regulatory programme. SCOPE: Transcription factor MYB46 (At5g12870) has been shown to function as a master regulator in secondary wall formation in Arabidopsis thaliana. Recent studies show that MYB46 not only regulates the transcription factors but also the biosynthesis genes for all of the three major components (i.e. cellulose, hemicellulose and lignin) of secondary walls. This review considers our current understanding of the MYB46-mediated transcriptional regulatory network, including upstream regulators, downstream targets and negative regulators of MYB46. CONCLUSIONS AND OUTLOOK: MYB46 is a unique transcription factor in that it directly regulates the biosynthesis genes for all of the three major components of the secondary wall as well as the transcription factors in the biosynthesis pathway. As such, MYB46 may offer a useful means for pathway-specific manipulation of secondary wall biosynthesis. However, realization of this potential requires additional information on the 'MYB46-mediated transcriptional regulatory programme', such as downstream direct targets, upstream regulators and interacting partners of MYB46.

Risk factors for cytomegalovirus gastrointestinal diseases in adult patients with cancer.

Cytomegalovirus (CMV) gastrointestinal (GI) disease has been noticed frequently in cancer patients, causing abdominal pain, diarrhea, and GI bleeding. However, little is known about its actual incidence, clinical presentation, and the risk factors for its development among cancer patients. To answer these questions, we analyzed all cases that occurred during an 18-year period at our center. A case-control study was performed to identify risk factors for CMV GI disease. Electronic medical records were reviewed from individuals who were admitted and diagnosed with CMV GI disease during the period of January 1995 through March 2013 at a tertiary care center. Two CMV disease-free cancer patients were matched as controls. A total of 98 episodes of CMV GI disease were included in this study, and the overall incidence rate was 52.5 per 100,000 cancer patients, with an increasing trend throughout the study period. According to multivariate analysis, male sex, low body mass index, lymphopenia, hematological malignancy, and steroid use and red blood cell transfusion within 1 month prior to the CMV disease were identified to be independent risk factors. Among these factors, RBC transfusion showed the highest odds ratio (OR = 5.09). Male sex, low body mass index, lymphopenia, hematological malignancy, steroid use, and red blood cell transfusion within 1 month prior to the CMV disease diagnosis were independent risk factors for the development of CMV GI disease in adult patients with cancer.