Nucleosome-free region dominates histone acetylation in targeting SWR1 to promoters for H2A.Z replacement.

The histone variant H2A.Z is a genome-wide signature of nucleosomes proximal to eukaryotic regulatory DNA. Whereas the multisubunit chromatin remodeler SWR1 is known to catalyze ATP-dependent deposition of H2A.Z, the mechanism of SWR1 recruitment to S. cerevisiae promoters has been unclear. A sensitive assay for competitive binding of dinucleosome substrates revealed that SWR1 preferentially binds long nucleosome-free DNA and the adjoining nucleosome core particle, allowing discrimination of gene promoters over gene bodies. Analysis of mutants indicates that the conserved Swc2/YL1 subunit and the adenosine triphosphatase domain of Swr1 are mainly responsible for binding to substrate. SWR1 binding is enhanced on nucleosomes acetylated by the NuA4 histone acetyltransferase, but recognition of nucleosome-free and nucleosomal DNA is dominant over interaction with acetylated histones. Such hierarchical cooperation between DNA and histone signals expands the dynamic range of genetic switches, unifying classical gene regulation by DNA-binding factors with ATP-dependent nucleosome remodeling and posttranslational histone modifications.

Stepwise histone replacement by SWR1 requires dual activation with histone H2A.Z and canonical nucleosome.

Histone variant H2A.Z-containing nucleosomes are incorporated at most eukaryotic promoters. This incorporation is mediated by the conserved SWR1 complex, which replaces histone H2A in canonical nucleosomes with H2A.Z in an ATP-dependent manner. Here, we show that promoter-proximal nucleosomes are highly heterogeneous for H2A.Z in Saccharomyces cerevisiae, with substantial representation of nucleosomes containing one, two, or zero H2A.Z molecules. SWR1-catalyzed H2A.Z replacement in vitro occurs in a stepwise and unidirectional fashion, one H2A.Z-H2B dimer at a time, producing heterotypic nucleosomes as intermediates and homotypic H2A.Z nucleosomes as end products. The ATPase activity of SWR1 is specifically stimulated by H2A-containing nucleosomes without ensuing histone H2A eviction. Remarkably, further addition of free H2A.Z-H2B dimer leads to hyperstimulation of ATPase activity, eviction of nucleosomal H2A-H2B, and deposition of H2A.Z-H2B. These results suggest that the combination of H2A-containing nucleosome and free H2A.Z-H2B dimer acting as both effector and substrate for SWR1 governs the specificity and outcome of the replacement reaction.

Molecular basis of CENP-C association with the CENP-A nucleosome at yeast centromeres.

Histone CENP-A-containing nucleosomes play an important role in nucleating kinetochores at centromeres for chromosome segregation. However, the molecular mechanisms by which CENP-A nucleosomes engage with kinetochore proteins are not well understood. Here, we report the finding of a new function for the budding yeast Cse4/CENP-A histone-fold domain interacting with inner kinetochore protein Mif2/CENP-C. Strikingly, we also discovered that AT-rich centromere DNA has an important role for Mif2 recruitment. Mif2 contacts one side of the nucleosome dyad, engaging with both Cse4 residues and AT-rich nucleosomal DNA. Both interactions are directed by a contiguous DNA- and histone-binding domain (DHBD) harboring the conserved CENP-C motif, an AT hook, and RK clusters (clusters enriched for arginine-lysine residues). Human CENP-C has two related DHBDs that bind preferentially to DNA sequences of higher AT content. Our findings suggest that a DNA composition-based mechanism together with residues characteristic for the CENP-A histone variant contribute to the specification of centromere identity.

Identification of indications for albumin administration in septic patients with liver cirrhosis.

BACKGROUND: Albumin infusion is the primary therapeutic strategy for septic patients with liver cirrhosis. Although recent studies have investigated the efficacy of albumin in the resuscitation stage of septic patients with liver cirrhosis, it remains unclear whether daily albumin administration can improve outcomes. Furthermore, the indications for initiating albumin therapy are not well defined. METHODS: Septic patients with liver cirrhosis were obtained from the Medical Information Mart for Intensive Care (MIMIC-IV 2.0) database. Marginal structural Cox models were employed to investigate the association between daily albumin infusion and 28-day mortality. We also aimed to explore under what circumstances enrolled patients could benefit most from albumin administration, based on the clinical parameters collected on the day of albumin infusion, including serum albumin concentration, serum lactate concentration, mean arterial pressure (MAP), and vasopressor dosage. RESULTS: A total of 2265 patients were included in the final analysis, of whom 1093 (48.3%) had received albumin treatment at least once. The overall 28-day mortality was 29.6%. After marginal structural modeling, daily albumin infusion was associated with a reduced risk of 28-day death (hazard ratio, 0.76; 95% CI 0.61-0.94). We found that patients benefit most from albumin infusion when initiated on the day of serum albumin concentration between 2.5 and 3.0 g/dL, serum lactate concentration greater than or equal to 2 mmol/L, MAP less than 60 mmHg, or vasopressor dosage between 0.2 and 0.3 mcg/kg/min (norepinephrine equivalent, NEE). CONCLUSIONS: Albumin infusion is associated with a reduction in mortality in septic patients with liver cirrhosis under specific circumstances. Serum albumin concentration, serum lactate, MAP, and vasopressor dosage were found to be modifiers of treatment effectiveness and should be considered when deciding to initial albumin infusion.

Prognostic Value of Neutrophil-to-Lymphocyte Ratio and Vaccination for Negative Conversion Time of Nucleic Acid in Nonsevere COVID-19 Patients Infected by SARS-CoV-2 Omicron Variant.

SARS-CoV-2 Omicron variant is significantly different from all the previous variants and has rapidly replaced other variants as the dominant variant across the globe. An easily obtained, inexpensive, and rapid marker is needed to predict the negative conversion time (NCT) of nucleic acid in nonsevere COVID-19 patients infected by the Omicron variant. This retrospective study enrolled 226 patients infected by the Omicron variant between April 23, 2022, and May 16, 2022. The median age of the patients was 61 (interquartile range (IQR), 48-70) years, and 56.2% were male. 84 patients (37.2%) had at least one comorbidity, and 49 patients (21.7%) were classified into the moderate illness group. 145 patients (64.2%) received at least one dose of vaccine, in which 67 patients (29.6%) received a booster dose of vaccine. The median duration of NCT was 8 (IQR, 7-11) days. Univariate Cox analyses found that high NLR (>2.22), aged ≥65 years, vaccination, and moderate illness were significantly related to the NCT of nucleic acid. Multivariate Cox regression analysis showed that high NLR (NLR > 2.22, hazard ratio (HR):0.718, 95% CI: 0.534-0.964, p = 0.028) and vaccination (vaccinated ≥1 dose, HR: 1.536, 95% CI: 1.147-2.058, p = 0.004) were independently associated with NCT of nucleic acid. NLR is a rapid, simple, and useful prognostic factor for predicting NCT of nucleic acid in nonsevere COVID-19 patients with the Omicron variant. In addition, vaccination may also play a valuable role in predicting the NCT of nucleic acid.

Structural insights into histone chaperone Chz1-mediated H2A.Z recognition and histone replacement.

Chz1 is a specific chaperone for the histone variant H2A.Z in budding yeast. The ternary complex formed by Chz1 and H2A.Z-H2B dimer is the major in vivo substrate of Swi2/snif2-related 1 (SWR1), the ATP-dependent chromatin remodeling enzyme that deposits H2A.Z into chromatin. However, the structural basis for the binding preference of Chz1 for H2A.Z over H2A and the mechanism by which Chz1 modulates the histone replacement remain elusive. Here, we show that Chz1 utilizes 2 distinct structural domains to engage the H2A.Z-H2B dimer for optimal and specific recognition of H2A.Z. The middle region of Chz1 (Chz1-M) directly interacts with 2 highly conserved H2A.Z-specific residues (Gly98 and Ala57) and dictates a modest preference for H2A.Z-H2B. In addition, structural and biochemical analysis show that the C-terminal region of Chz1 (Chz1-C) harbors a conserved DEF/Y motif, which reflects the consecutive D/E residues followed by a single aromatic residue, to engage an arginine finger and a hydrophobic pocket in H2A.Z-H2B, enhancing the binding preference for H2A.Z-H2B. Furthermore, Chz1 facilitates SWR1-mediated H2A.Z deposition by alleviating inhibition caused by aggregation of excess free histones, providing insights into how Chz1 controls the bioavailability of H2A.Z to assist SWR1 in promoter-specific installation of a histone mark. Our study elucidates a novel H2A.Z-recognition mechanism and uncovers a molecular rationale for binding of free histone by specialized histone chaperones in vivo.

Longitudinal phenotypes in patients with acute respiratory distress syndrome: a multi-database study.

BACKGROUND: Previously identified phenotypes of acute respiratory distress syndrome (ARDS) have been limited by a disregard for temporal dynamics. We aimed to identify longitudinal phenotypes in ARDS to test the prognostic and predictive enrichment of longitudinal phenotypes, and to develop simplified models for phenotype identification. METHODS: We conducted a multi-database study based on the Chinese Database in Intensive Care (CDIC) and four ARDS randomized clinical trials (RCTs). We employed latent class analysis (LCA) to identify longitudinal phenotypes using 24-hourly data from the first four days of invasive ventilation. We used the Cox regression model to explore the association between time-varying respiratory parameters and 28-day mortality across phenotypes. Phenotypes were validated in four RCTs, and the heterogeneity of treatment effect (HTE) was investigated. We also constructed two multinomial logistical regression analyses to develop the probabilistic models. FINDINGS: A total of 605 ARDS patients in CDIC were enrolled. The three-class LCA model was identified and had the optimal fit, as follows: Class 1 (n = 400, 66.1% of the cohort) was the largest phenotype over all study days, and had fewer abnormal values, less organ dysfunction and the lowest 28-day mortality rate (30.5%). Class 2 (n = 102, 16.9% of the cohort) was characterized by pulmonary mechanical dysfunction and had the highest proportion of poorly aerated lung volume, the 28-day mortality rate was 47.1%. Class 3 (n = 103, 17% of the cohort) was correlated with extra-pulmonary dysfunction and had the highest 28-day mortality rate (56.3%). Time-varying mechanical power was more significantly associated with 28-day mortality in Class 2 patients compared to other phenotypes. Similar phenotypes were identified in four RCTs. A significant HTE between phenotypes and treatment strategies was observed in the ALVEOLI (high PEEP vs. low PEEP) and the FACTT trials (conservative vs. liberal fluid management). Two parsimonious probabilistic models were constructed to identify longitudinal phenotypes. INTERPRETATION: We identified and validated three novel longitudinal phenotypes for ARDS patients, with both prognostic and predictive enrichment. The phenotypes of ARDS can be accurately identified with simple classifier models, except for Class 3.

Addition of terlipressin to norepinephrine in septic shock and effect of renal perfusion: a pilot study.

PURPOSE: Terlipressin improves renal function in patients with septic shock. However, the mechanism remains unclear. Here, we aimed to evaluate the effects of terlipressin on renal perfusion in patients with septic shock. MATERIALS AND METHODS: This pilot study enrolled patients with septic shock in the intensive care unit of the tertiary hospital from September 2019 to May 2020. We randomly assigned patients to terlipressin and usual care groups using a 1:1 ratio. Terlipressin was intravenously pumped at a rate of 1.3 µg/kg/hour for 24 h. We monitored renal perfusion using renal contrast-enhanced ultrasound (CEUS). The primary outcome was peak sonographic signal intensity (a renal perfusion parameter monitored by CEUS) at 24 h after enrollment. RESULTS: 22 patients were enrolled in this study with 10 in the terlipressin group and 12 in the usual care group. The baseline characteristics of patients between the two groups were comparable. The peak sonographic signal intensity at 24 h after enrollment in the terlipressin group (60.5 ± 8.6 dB) was significantly higher than that in the usual care group (52.4 ± 7.0 dB; mean difference, 7.1 dB; 95% CI, 0.4-13.9; adjusted p = .04). Patients in the terlipressin group had a lower time to peak, heart rates, norepinephrine dose, and a higher stroke volume at 24 h after enrollment. No significant difference in the urine output within 24 h and incidence of acute kidney injury within 28 days was found between the two groups. CONCLUSIONS: Terlipressin improves renal perfusion, increases stroke volume, and decreases norepinephrine dose and heart rates in patients with septic shock.

Sudden coma at the onset of severe refractory thrombotic thrombocytopenic purpura with successful treatment.

Most patients develop coma several days after the onset of thrombotic thrombocytopenic purpura (TTP) caused by microvascular occlusion. However, aggravated coma as the first symptom of TTP has rarely been reported. Although plasma exchange (PEX) and steroids have reduced mortality, the prognosis of patients with TTP is still poor. We reported a patient with refractory TTP presenting with aggravated coma on admission. After days of successful PEX, rituximab, and glucocorticoid therapy for clinical remission, the patient regained consciousness and returned to his normal life with a good outcome. Our case highlights that TTP should be considered when coma occurs as the first symptom.

Association Between Pathophysiology and Volume of Distribution Among Patients With Sepsis or Septic Shock Treated With Imipenem: A Prospective Cohort Study.

BACKGROUND: This study was performed to explore the apparent volume of distribution (Vd) of imipenem in patients with sepsis or septic shock. METHODS: A prospective, observational, single-center study was conducted in patients with sepsis or septic shock. The patients were treated with 1 g of imipenem mixed with 200 mL of normal saline infused intravenously over a 3-hour period at 8-hour intervals. The concentration of imipenem was 5 mg/mL, and the rate of infusion was 5.5 mg/min. Blood samples for measuring imipenem serum concentrations with high-performance liquid chromatography were obtained before and at 0, 1, 2, 3, and 5 hours after drug infusion on study days 1 and 3. Pharmacokinetic parameters were calculated according to a noncompartment model. RESULTS: A total of 25 adult patients were enrolled in this study, of whom 15 were diagnosed with sepsis and 10 with septic shock. The initial Vd (Vc) of imipenem was significantly lower in the sepsis than that in the septic shock group (mean [standard deviation], 26.5 [7.1] vs 40.7 [11.0] L; P = .001). The Vc of imipenem was significantly related to serum albumin levels (r = -0.517; P = .008) as well as Acute Physiology and Chronic Health Evaluation II (APACHE II) scores (r = 0.606; P = .001). Multivariate linear regression identified serum albumin levels and APACHE II scores on day 1 as independent factors influencing the Vc of imipenem (P < .05). The difference in Vd between the imipenem steady state and the initial state was significantly higher in nonsurvivors than in survivors (mean [standard deviation], 1.7 [21.5] vs -13.1 [11.4] L; P = .046). CONCLUSIONS: APACHE II scores and serum albumin levels were found in this study to be independent factors that may affect the Vc of imipenem in patients with sepsis or septic shock. CLINICAL TRIALS REGISTRATION: clinicaltrials.gov, NCT03308214.

Early- and Late-Onset Bloodstream Infections in the Intensive Care Unit: A Retrospective 5-Year Study of Patients at a University Hospital in China.

BACKGROUND: Limited data are available regarding the current microbiological characteristics of bloodstream infections (BSIs) in intensive care units (ICUs) in China. This retrospective study aimed to determine the epidemiology of early- and late-onset BSIs in our ICU. METHODS: We retrospectively collected data about ICU patients with BSI from 2013 to 2017. The patients were divided into the early- and late-onset BSI groups according to if BSI occurred within or beyond 48 hours after ICU admission. Univariate and multivariate logistic regression analyses were used to assess the risk factors for infection with multidrug resistant organisms (MDROs). RESULTS: Of 5474 ICU admissions, 486 (8.9%) patients with BSIs and with 500 microorganisms were included in this study, 246 (50.6%) of whom had early-onset BSIs. Two hundred and seventy patients were infected with MDROs. The proportion of MDRO infections was significantly higher among patients with late-onset BSIs than among those with early-onset BSIs (57.9% vs. 41.5%, P = .017). The ICU mortality rate was significantly higher in the late-onset BSI group (44.6% vs. 33.8%, P = .014) and early and appropriate antimicrobial treatment significantly improved the survival rate among patients with BSI (P < .001). CONCLUSIONS: MDROs affected more than half of patients with BSI in the ICU. Early appropriate empirical antimicrobial therapy could improve clinical outcome of patients with BSIs.

A Ventilator-associated Pneumonia Prediction Model in Patients With Acute Respiratory Distress Syndrome.

BACKGROUND: Mechanical ventilation is crucial for acute respiratory distress syndrome (ARDS) patients and diagnosis of ventilator-associated pneumonia (VAP) in ARDS patients is challenging. Hence, an effective model to predict VAP in ARDS is urgently needed. METHODS: We performed a secondary analysis of patient-level data from the Early versus Delayed Enteral Nutrition (EDEN) of ARDSNet randomized controlled trials. Multivariate binary logistic regression analysis established a predictive model, incorporating characteristics selected by systematic review and univariate analyses. The model's discrimination, calibration, and clinical usefulness were assessed using the C-index, calibration plot, and decision curve analysis (DCA). RESULTS: Of the 1000 unique patients enrolled in the EDEN trials, 70 (7%) had ARDS complicated with VAP. Mechanical ventilation duration and intensive care unit (ICU) stay were significantly longer in the VAP group than non-VAP group (P < .001 for both) but the 60-day mortality was comparable. Use of neuromuscular blocking agents, severe ARDS, admission for unscheduled surgery, and trauma as primary ARDS causes were independent risk factors for VAP. The area under the curve of the model was .744, and model fit was acceptable (Hosmer-Lemeshow P = .185). The calibration curve indicated that the model had proper discrimination and good calibration. DCA showed that the VAP prediction nomogram was clinically useful when an intervention was decided at a VAP probability threshold between 1% and 61%. CONCLUSIONS: The prediction nomogram for VAP development in ARDS patients can be applied after ICU admission, using available variables. Potential clinical benefits of using this model deserve further assessment.

Physiological effects of different recruitment maneuvers in a pig model of ARDS.

BACKGROUND: In acute respiratory distress syndrome (ARDS), lung recruitment maneuvers can recruit collapsed alveoli in gravity-dependent lung regions, improving the homogeneity of ventilation distribution. This study used electrical impedance tomography to investigate the physiological effects of different recruitment maneuvers for alveolar recruitment in a pig model of ARDS. METHODS: ARDS was induced in ten healthy male pigs with repeated bronchoalveolar lavage until the ratio of arterial partial pressure of oxygen (PaO2) of fraction of inspired oxygen (P/F) was < 100 mmHg and remained stable for 30 min (TARDS). ARDS pigs underwent three sequential recruitment maneuvers, including sustained inflation, increments of positive end-expiratory pressure (PEEP), and pressure-controlled ventilation (PCV) applied in random order, with 30 mins at a PEEP of 5 cmH2O between maneuvers. Respiratory mechanics, hemodynamics, arterial blood gas, and electrical impedance tomography were recorded at baseline, TARDS, and before and after each recruitment maneuver. RESULTS: In all ten pigs, ARDS was successfully induced with a mean 2.8 ± 1.03 L bronchoalveolar lavages. PaO2, P/F, and compliance were significantly improved after recruitment with sustained inflation, increments of PEEP or PCV (all p < 0.05), and there were no significant differences between maneuvers. Global inhomogeneity index significantly decreased after recruitment with sustained inflation, increments of PEEP, or PCV. There were no significant differences in global inhomogeneity before or after recruitment with the different maneuvers. The decrease in global inhomogeneity index (ΔGI) was significantly greater after recruitment with increments of PEEP compared to sustained inflation (p = 0.023), but there was no significant difference in ΔGI between increments of PEEP and PCV or between sustained inflation and PCV. CONCLUSION: Sustained inflation, increments of PEEP, and PCV increased oxygenation, and regional and global compliance of the respiratory system, and decreased inhomogeneous gas distribution in ARDS pigs. Increments of PEEP significantly improved inhomogeneity of the lung compared to sustained inflation, while there was no difference between increments of PEEP and PCV or between sustained inflation and PCV.

Circulating Th1 and Th2 Subset Accumulation Kinetics in Septic Patients with Distinct Infection Sites: Pulmonary versus Nonpulmonary.

BACKGROUND: Persistent peripheral CD4+T cell differentiation towards T helper (Th)2 rather than Th1 has been proved to be related to immunosuppression and poor prognosis in sepsis. However, it is unclear whether these circulating Th1 and Th2 subtype accumulations differed in septic populations of distinct infection sites and presented different associations with outcomes among patients with pulmonary versus nonpulmonary sepsis. METHODS: From a secondary analysis of a prospective observational study, seventy-four previously immunocompetent patients with community-acquired severe sepsis within 24 hours upon onset were enrolled. Whole blood was collected on the admission day (D0), 3rd day (D3), and 7th day (D7). The patients were classified as pulmonary (n = 52) and nonpulmonary sepsis (n = 22). Circulating Th1 and Th2 populations were evaluated by flow cytometry, and clinical data related to disease severity and inflammatory response were collected. The associations of circulating Th1 and Th2 subset accumulations with distinct infection sites or outcomes within subgroups were explored. RESULTS: Patients with pulmonary sepsis held similar disease severity and 28-day mortality with those of nonpulmonary sepsis. Of note is the finding that circulating Th2 levels on D7 (P = 0.04) as well as Th2/Th1 on D3 (P = 0.01) and D7 (P = 0.04) were higher in the pulmonary sepsis compared with nonpulmonary sepsis while Th1 levels were lower on D0, D3, and D7 (P = 0.01, <0.01, and =0.05, respectively). Compared to 28-day survivors, higher Th2/Th1 driven by increased Th2 were observed among 28-day nonsurvivors on D3 and D7 in both groups. The association between circulatory Th2 populations or Th2/Th1 and 28-day death was detected in pulmonary sepsis (P < 0.05, HR > 1), rather than nonpulmonary sepsis. CONCLUSIONS: Circulating Th2 accumulation was more apparent among pulmonary sepsis while nonpulmonary sepsis was characterized with the hyperactive circulating Th1 subset among previously immunocompetent patients. This finding suggested that circulating Th1 and Th2 subset accumulations vary in septic subgroups with different infection sites.

Early and dynamic alterations of Th2/Th1 in previously immunocompetent patients with community-acquired severe sepsis: a prospective observational study.

BACKGROUND: T helper (Th) cells regulate sepsis processes, including primary pathogen clear and secondary pathogen defence. The objectives of this study were to determine the early and dynamic alterations of Th1 and Th2 populations to community-acquired severe sepsis upon onset among previously immunocompetent patients and whether it was related to clinical outcomes. METHODS: This prospective observational cohort study was conducted at a general intensive care unit (ICU) of a tertiary teaching hospital in China. Immunocompetent patients with community-acquired severe sepsis within 24 h upon onset were included as septic group. Healthy volunteers and critically ill patients without severe sepsis were recruited as controls. Whole blood was collected on D0, 3rd day (D3) and 7th day (D7) for septic group and once upon enrollment for controls. Th1 and Th2 populations were measured by flow cytometry and assessed for associations with 28-day mortality using cox proportional hazard models. Associations of dynamic alterations of Th cell subpopulations with clinical outcomes were investigated. RESULTS: This study demonstrated that community-acquired severe sepsis patients (n = 71) had increased Th2/Th1 and Th2 populations, compared to healthy controls (n = 7) and critically ill patients without severe sepsis (n = 7) at admission. Among the septic cohort, values of Th2/Th1 were significantly higher in non-survivors than survivors on D0 (p = 0.04), D3 (p < 0.001) and D7 (p < 0.001). Patients with persistently increasing Th2/Th1 demonstrated the highest mortality (47.1%) and incidence of ICU-acquired infections (64.7%). CONCLUSIONS: Th2/Th1 was markedly up-regulated with Th2 dominance upon community-acquired severe sepsis onset among previously immunocompetent patients and its persistently dynamic increase was associated with ICU-acquired infections and 28-day death. Trial registration Institutional Ethics Committee of Zhongda Hospital, 2014ZDSYLL086, registered in June 2014-prospectively registered; ClinicalTrials.gov, NCT02883218, registered on 25 Aug 2016-retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT02883218?cond=NCT02883218&rank=1.

A prospective observation on nutrition support in adult patients with severe burns.

Nutrition therapy is considered an important treatment of burn patients. The aim of the study was to delineate the nutritional support in severe burn patients and to investigate association between nutritional practice and clinical outcomes. Severe burn patients were enrolled (n 100). In 90 % of the cases, the burn injury covered above 70 % of the total body surface area. Mean interval from injury to nutrition start was 2·4 (sd 1·1) d. Sixty-seven patients were initiated with enteral nutrition (EN) with a median time of 1 d from injury to first feed. Twenty-two patients began with parenteral nutrition (PN). During the study, thirty-two patients developed EN intolerance. Patients received an average of about 70 % of prescribed energy and protein. Patients with EN providing <30 % energy had significantly higher 28- d and in-hospital mortality than patients with EN providing more than 30 % of energy. Mortality at 28 d was 11 % and in-hospital mortality was 45 %. Multiple regression analysis demonstrated that EN providing <30 % energy and septic shock were independent risk factors for 28- d prognosis. EN could be initiated early in severe burn patients. Majority patients needed PN supplementation for energy requirement and EN feeding intolerance. Post-pyloric feeding is more efficient than gastric feeding in EN tolerance and energy supplement. It is difficult for severe burn patients to obtain enough feeding, especially in the early stage of the disease. More than 2 weeks of underfeeding is harmful to recovery.

Nonhistone Scm3 binds to AT-rich DNA to organize atypical centromeric nucleosome of budding yeast.

The molecular architecture of centromere-specific nucleosomes containing histone variant CenH3 is controversial. We have biochemically reconstituted two distinct populations of nucleosomes containing Saccharomyces cerevisiae CenH3 (Cse4). Reconstitution of octameric nucleosomes containing histones Cse4/H4/H2A/H2B is robust on noncentromere DNA, but inefficient on AT-rich centromere DNA. However, nonhistone Scm3, which is required for Cse4 deposition in vivo, facilitates in vitro reconstitution of Cse4/H4/Scm3 complexes on AT-rich centromere sequences. Scm3 has a nonspecific DNA binding domain that shows preference for AT-rich DNA and a histone chaperone domain that promotes specific loading of Cse4/H4. In live cells, Scm3-GFP is enriched at centromeres in all cell cycle phases. Chromatin immunoprecipitation confirms that Scm3 occupies centromere DNA throughout the cell cycle, even when Cse4 and H4 are temporarily dislodged in S phase. These findings suggest a model in which centromere-bound Scm3 aids recruitment of Cse4/H4 to assemble and maintain an H2A/H2B-deficient centromeric nucleosome.

The Current Epidemiological Landscape of Ventilator-associated Pneumonia in the Intensive Care Unit: A Multicenter Prospective Observational Study in China.

Background: Ventilator-associated pneumonia (VAP) is among the most important hospital-acquired infections in the intensive-care unit setting. However, clinical data regarding the epidemiology of VAP in China are limited. Methods: A multicenter, longitudinal, observational study was performed from March 2013 to December 2015 to prospectively collect data on patients diagnosed with VAP. Specifically, patients supported by invasive mechanical ventilation for longer than 48 hours were included. Clinical data were recorded for each VAP patient. The exact pathogen distribution and the incidence of VAP were calculated. Risk factors associated with mortality were analyzed using univariate and multivariate regression analyses. Results: A total of 2492 patients received mechanical ventilation for longer than 48 hours and were enrolled in the study. A total of 129 (5.0%) patients fulfilled the VAP criteria, and 38 (29.5%) patients were diagnosed with early-onset VAP. The incidence of VAP was 4.5 per 1000 ventilation days, with a 28-day mortality rate of 45%. Individual pathogens, including 115 bacteria and 2 fungi, were identified in 117 (90.7%) enrollees, and 87 (75.7%) bacteria were multidrug-resistant organisms. Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa were the most commonly detected pathogens causing VAP. No difference in the distribution of pathogens was observed between early- and late-onset VAP or between surviving and non-surviving patients. Multivariate regression revealed that older ages and Sequential Organ Failure Assessment Scores were correlated with increased 28-day mortality rates. Conclusions: High pathogen resistance and mortality were found in both early- and late-onset VAP. Clinical Trials Registration: NCT01943331.

Radical Cascade-Triggered Controlled Ring-Opening Polymerization of Macrocyclic Monomers.

A strategy for the controlled radical ring-opening polymerization of macrocyclic monomers is reported. Key to this approach is an allyl alkylsulfone-based ring-opening trigger that can undergo a radical cascade reaction to extrude sulfur dioxide and generate an alkyl radical for controlled chain propagation. A systematic study correlating reaction conditions with polymer molecular weight and molecular weight distribution allowed excellent control over polymerization. The versatility of this radical cascade-triggered ring-opening polymerization approach was further demonstrated through the first radical block copolymerization of macrocyclic monomers, and the incorporation of degradable functionality into the polymer backbone.