Intensive care unit (ICU)-acquired bacteremia (IAB) is associated with high medical expenditure and mortality. Mechanically ventilated patients represent one third of all patients admitted to ICU, but the clinical features and outcomes in mechanically ventilated patients who develop IAB remain unknown. We conducted a 3-year retrospective observational cohort study, and 1,453 patients who received mechanical ventilation on ICU admission were enrolled. Among patients enrolled, 126 patients who had developed IAB ≧48 hours after ICU admission were identified. The study patients were divided into IAB and no IAB groups, and clinical characteristics of IAB based on specific bacterial species were further analyzed. The multivariate Cox regression analysis showed that ventilator support for chronic obstructive pulmonary disease and congestive heart failure, and patients admitted from nursing home were the independent risk factors for developing IAB. Patients with IAB were significantly associated with longer length of ICU stay, prolonged ventilator use, lower rate of successful weaning, and higher rate of ventilator dependence and ICU mortality as compared to those without IAB. IAB was the independent risk factor for ICU mortality (HR, 1.510, 95% CI 1.054–1.123; p = 0.010). The clinical characteristics of IAB related to specific bacterial species included IAB due to Pseudomonas aeruginosa being likely polymicrobial, lung source and prior antibiotic use; Escherichia coli developing earlier and from urinary tract source; methicillin-resistant Staphylococcus aureus related to central venous catheter and multiple sets of positive hemoculture; and Elizabethkingia meningoseptica significantly associated with delayed/inappropriate antibiotic treatment. In summary, IAB was significantly associated with poor patient outcomes in mechanically ventilated ICU patients. The clinical features related to IAB and clinical characteristics of IAB based on specific bacterial species identified in our study may be utilized to refine the management of IAB.
Management of acute respiratory failure is an important component of intensive care. In this review, we analyze 21 original research articles published last year in Critical Care in the field of respiratory and critical care medicine. The articles are summarized according to the following topic categories: acute respiratory distress syndrome, mechanical ventilation, adjunctive therapies, and pneumonia.
Ganglionated plexi (GP) ablation has been become an adjunct to pulmonary vein isolation (PVI). This study describes the long-term results of minimally invasive surgical PVI, ablation of GPs, and exclusion of the left atrial appendage for atrial fibrillation (AF).
Long-term follow-up of 55 months was performed in 139 consecutive patients (age 58.3±20.8 years) with symptomatic, drug-refractory lone AF who underwent minimally invasive surgical PVI, GPs ablation, and exclusion of the left atrial appendage. Success was defined as freedom from AF, atrial flutter, or atrial tachycardia off antiarrhythmic drugs.
AF was paroxysmal in 77.7%, persistent in 12.2% and long-standing persistent in 10.1%. Single-procedure success rate was 71.7%, 59.4% and 46.6% at 12, 24 and 60 months respectively. Single-procedure success rate was 72.9%, 62.6% and 51.8% for paroxysmal AF, 64.7%, 35.3%, and 28.2% for persistent AF, 71.4%, 64.3% and 28.6% for long-standing persistent AF at 12, 24 and 60 months respectively. Duration of AF>24 months (hazard ratio [HR]: 3.09, 95% confidence interval [CI]: 1.51 to 6.32; p = 0.002), left atrial diameter≥40 mm (HR: 4.03, 95% CI: 1.88 to 8.65; p<0.001), early recurrence of AF (HR: 4.66, 95% CI: 2.25 to 9.63; p<0.001) independently predicted long-term recurrence of AF. There was no procedure-related death. One patient converted to median sternotomy because of uncontrolled bleeding. Two patients underwent perioperative cerebrovascular events.
At nearly 5-year of clinical follow-up, single-procedure success rate of minimally invasive surgical PVI with GP ablation was 51.8% for paroxysmal AF, 28.2% for persistent AF, 28.6% for long-standing persistent AF after initial procedure. Patients with AF duration≤24 months, left atrial diameter<40 mm and no early recurrence of AF, had favorable outcomes.
During protein synthesis, the ribosome translates nucleotide triplets in single-stranded mRNA into polypeptide sequences. Strong downstream mRNA secondary (2°) structures, which must be unfolded for translation, can slow or even halt protein synthesis. Here we employ single molecule fluorescence resonance energy transfer to determine reaction rates for specific steps within the elongation cycle as the Escherichia coli ribosome encounters stem loop or pseudoknot mRNA 2° structures. Downstream stem-loops containing 100% G-C base pairs decrease the rates of both tRNA translocation within the ribosome and deacylated tRNA dissociation from the ribosomal exit (E) site. Downstream stem-loops or pseudoknots containing both G-C and A-U pairs also decrease the rate of tRNA dissociation, but they have little effect on tRNA translocation rate. Thus, somewhat surprisingly, unfolding of mRNA 2° structures is more closely coupled to E-site tRNA dissociation than to tRNA translocation.
Methylacetoin (3-hydroxy-3-methylbutan-2-one) and 2-methyl-2,3-butanediol are currently obtained exclusively via chemical synthesis. Here, we report, to the best of our knowledge, the first alternative route, using engineered Escherichia coli. The biological synthesis of methylacetoin was first accomplished by reversing its biodegradation, which involved modifying the enzyme complex involved, switching the reaction substrate, and coupling the process to an exothermic reaction. 2-Methyl-2,3-butanediol was then obtained by reducing methylacetoin by exploiting the substrate promiscuity of acetoin reductase. A complete biosynthetic pathway from renewable glucose and acetone was then established and optimized via in vivo enzyme screening and host metabolic engineering, which led to titers of 3.4 and 3.2 g l−1 for methylacetoin and 2-methyl-2,3-butanediol, respectively. This work presents a biodegradation-inspired approach to creating new biosynthetic pathways for small molecules with no available natural biosynthetic pathway.
The human 8-oxoguanine DNA glycosylase 1 (hOGG1), apurinic/apyrimidinic endonuclease 1 (APE1), and adenosine diphosphate ribosyl transferase (ADPRT) genes play an important role in the DNA base excision repair pathway. Single nucleotide polymorphisms (SNPs) in critical genes are suspected to be associated with the risk of lung cancer. This study aimed to identify the association between the polymorphisms of hOGG1 Ser326Cys, APE1 Asp148Glu, and ADPRT Val762Ala, and the risk of lung adenocarcinoma in the non-smoking female population, and investigated the interaction between genetic polymorphisms and environmental exposure in lung adenocarcinoma.
We performed a hospital-based case-control study, including 410 lung adenocarcinoma patients and 410 cancer-free hospital control subjects who were matched for age. Each case and control was interviewed to collect information by well-trained interviewers. A total of 10 ml of venous blood was collected for genotype testing. Three polymorphisms were analyzed by the polymerase chain reaction-restriction fragment length polymorphism technique.
We found that individuals who were homozygous for the variant hOGG1 326Cys/Cys showed a significantly increased risk of lung adenocarcinoma (OR = 1.54; 95% CI: 1.01–2.36; P = 0.045). When the combined effect of variant alleles was analyzed, we found an increased OR of 1.89 (95% CI: 1.24–2.88, P = 0.003) for lung adenocarcinoma individuals with more than one homozygous variant allele. In stratified analyses, we found that the OR for the gene-environment interaction between Ser/Cys and Cys/Cys genotypes of hOGG1 codon 326 and cooking oil fumes for the risk of lung adenocarcinoma was 1.37 (95% CI: 0.77–2.44; P = 0.279) and 2.79 (95% CI: 1.50–5.18; P = 0.001), respectively.
The hOGG1 Ser326Cys polymorphism might be associated with the risk of lung adenocarcinoma in Chinese non-smoking females. Furthermore, there is a significant gene-environment association between cooking oil fumes and hOGG1 326 Cys/Cys genotype in lung adenocarcinoma among female non-smokers.
Xylonate is a valuable chemical for versatile applications. Although the chemical synthesis route and microbial conversion pathway were established decades ago, no commercial production of xylonate has been obtained so far. In this study, the industrially important microorganism Escherichia coli was engineered to produce xylonate from xylose. Through the coexpression of a xylose dehydrogenase (xdh) and a xylonolactonase (xylC) from Caulobacter crescentus, the recombinant strain could convert 1 g/L xylose to 0.84 g/L xylonate and 0.10 g/L xylonolactone after being induced for 12 h. Furthermore, the competitive pathway for xylose catabolism in E. coli was blocked by disrupting two genes (xylA and xylB) encoding xylose isomerase and xylulose kinase. Under fed-batch conditions, the finally engineered strain produced up to 27.3 g/L xylonate and 1.7 g/L xylonolactone from 30 g/L xylose, about 88% of the theoretical yield. These results suggest that the engineered E. coli strain has a promising perspective for large-scale production of xylonate.
Since acute respiratory distress syndrome (ARDS) was first described in 1967 there has been large number of studies addressing its pathogenesis and therapies. Despite this intense research activity, there are very few effective therapies for ARDS other than the use of lung protection strategies. This lack of therapeutic modalities is not only related to the complex pathogenesis of this syndrome but also the insensitive and nonspecific diagnostic criteria to diagnose ARDS. This review article will summarize the key features of the new definition of ARDS, and provide a brief overview of innovative therapeutic options that are being assessed in the management of ARDS.
Acute respiratory distress syndrome (ARDS); pathogenesis; therapeutic options
Three new napyradiomycins (1–3) were isolated from the culture broth of a marine-derived actinomycete strain SCSIO 10428, together with six known related analogues napyradiomycin A1 (4), 18-oxonapyradiomycin A1 (5), napyradiomycin B1 (6), napyradiomycin B3 (7), naphthomevalin (8), and napyradiomycin SR (9). The strain SCSIO 10428 was identified as a Streptomyces species by the sequence analysis of its 16S rRNA gene. The structures of new compounds 1–3, designated 4-dehydro-4a-dechloronapyradiomycin A1 (1), 3-dechloro-3-bromonapyradiomycin A1 (2), and 3-chloro-6,8-dihydroxy-8-α-lapachone (3), respectively, were elucidated by comparing their 1D and 2D NMR spectroscopic data with known congeners. None of the napyradiomycins 1–9 showed antioxidative activities. Napyradiomycins 1–8 displayed antibacterial activities against three Gram-positive bacteria Staphylococcus and Bacillus strains with MIC values ranging from 0.25 to 32 μg mL−1, with the exception that compound 3 had a MIC value of above 128 μg mL−1 against Staphylococcus aureus ATCC 29213. Napyradiomycins 2, 4, 6, and 7 exhibited moderate cytotoxicities against four human cancer cell lines SF-268, MCF-7, NCI-H460, and HepG-2 with IC50 values below 20 μM, while the IC50 values for other five napyradiomycins 1, 3, 5, 8 and 9 were above 20 μM.
napyradiomycins; marine actinomycetes; natural products; antibacterial; cytotoxicity
α-Pinene is an important natural product that is widely used in flavorings, fragrances, medicines, fine chemicals and high-density renewable fuels. Currently, α-Pinene used in industry is mainly produced either by tapping trees (gum turpentine) or as a byproduct of paper pulping (crude sulfate turpentine, CST). However, the extraction of it from trees is tedious and inefficient and requires substantial expenditure of natural resources. Therefore, it is necessary to seek sustainable technologies for α-pinene production.
To construct the microbial synthetic pathway of α-pinene in E. coli, we co-expressed native geranyl diphosphate synthase (IspA) from E. coli and α-pinene synthase (Pt30) from Pinus taeda, and then to increase the geranyl diphosphate (GPP) content in the cells, a suitable geranyl diphosphate synthase (GPPS2) was selected from two different origins. Furthermore, to enhance α-pinene production, a novel biosynthetic pathway of α-pinene was assembled in E. coli BL21(DE3) with the heterologous hybrid mevalonate (MVA) pathway, GPPS2 and α-pinene synthase (Pt30). The final genetic strain, YJM28, harboring the above novel biosynthetic pathway of α-pinene, accumulated α-pinene up to 5.44 mg/L and 0.97 g/L under flask and fed-batch fermentation conditions, respectively. The conversion efficiency of glucose to α-pinene (gram to gram) in the metabolically engineered strain reached 2.61%.
In this paper, by using metabolic engineering techniques, the more efficient biosynthetic pathway of α-pinene was successfully assembled in E. coli BL21(DE3) with the heterologous hybrid MVA pathway, GPPS2 and α-pinene synthase (Pt30). In addition, this is the first report on α-pinene fed-batch fermentation, and our results represent improvements over previous reports.
α-Pinene; Geranyl diphosphate synthase; α-Pinene Synthase; E. coli
The isopentenols, including isoprenol and prenol, are excellent alternative fuels. However, they are not compounds largely accumulated in natural organism. The need for the next generation of biofuels with better physical and chemical properties impels us to develop biosynthetic routes for the production of isoprenol and prenol from renewable sugar. In this study, we use the heterogenous mevalonate-dependent (MVA) isoprenoid pathway for the synthesis of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) intermediates, and then convert IPP and DMAPP to isoprenol and prenol, respectively.
A mevalonate titer of 1.7 g/L was obtained by constructing an efficient MVA upper pathway in engineered E. coli. Different phosphatases and pyrophosphatases were investigated for their abilities in hydrolyzing the IPP and DMAPP. Consequently, ADP-ribose pyrophosphatase was found to be an efficient IPP and DMAPP hydrolase. Moreover, ADP-ribose pyrophosphatase from Bacillus subtilis (BsNudF) exhibited a equivalent substrate specificity towards IPP and DMAPP, while ADP-ribose pyrophosphatase from E. coli (EcNudF) presented a high substrate preference for DMAPP. Without the expression of any phosphatases or pyrophosphatases, a background level of isopentenols was synthesized. When the endogenous pyrophosphatase genes (EcNudF and yggV) that were capable of enhancing the hydrolyzation of the IPP and DMAPP were knocked out, the background level of isopentenols was still obtained. Maybe the synthesized IPP and DMAPP were hydrolyzed by some unknown hydrolases of E. coli. Finally, 1.3 g/L single isoprenol was obtained by blocking the conversion of IPP to DMAPP and employing the BsNudF, and 0.2 g/L ~80% prenol was produced by employing the EcNudF. A maximal yield of 12% was achieved in both isoprenol and prenol producing strains.
To the best of our knowledge, this is the first successful report on high-specificity production of isoprenol and prenol by microbial fermentation. Over 1.3 g/L isoprenol achieved in shake-flask experiments represents a quite encouraging titer of higher alcohols. In addition, the substrate specificities of ADP-ribose pyrophosphatases were determined and successfully applied for the high-specificity synthesis of isoprenol and prenol. Altogether, this work presents a promising strategy for high-specificity production of two excellent biofuels, isoprenol and prenol.
Isoprenol; Prenol; Metabolic engineering; Escherichia coli; Biofuel
Aberrant expression of C-X-C motif chemokine 5 (CXCL5) contributes to the progression of various cancers. This study analyzed the clinical significance of serum CXCL5 (sCXCL5) levels of nasopharyngeal carcinoma (NPC) patients, with the goal of building a novel prognostic score model.
Serum samples were collected prior to treatment from 290 NPC patients for the detection of sCXCL5 with ELISA. Half of the patients (n = 145) were randomly assigned to the training set to generate the sCXCL5 cutoff point using receiver operator characteristic (ROC) analysis, while the other half (n = 145) were assigned to the testing set for validation. Associations between sCXCL5 levels and clinical characteristics were analyzed. A prognostic score model was built using independent predictors derived from multivariate analysis. A concordance index (C-Index) was used to evaluate prognostic ability.
The sCXCL5 cutoff point was 0.805 ng/ml. Sex, age, histology, T classification, clinical classification and local recurrence were not associated with sCXCL5 levels. However, sCXCL5 levels were positively associated with N classification, distant metastasis and disease progression (P<0.05). A high sCXCL5 level predicted poor 6-year overall survival (OS), poor 6-year distant metastasis-free survival (DMFS), and poor 6-year progression-free survival (PFS). A prognostic score model was subsequently constructed based on sCXCL5 levels and clinical classification (C-C model), which are independent predictors of OS, DMFS, and PFS, as confirmed by the multivariate analysis. Furthermore, this novel model successfully divided the patients into four risk subgroups in the training set, the testing set and the entire set of patients. The C-Indices were 0.751 and 0.762 for the training set and the testing set, respectively.
sCXCL5 level was determined to be an independent prognostic factor for NPC patients. The novel statistical C-C model, which includes sCXCL5 levels and clinical classification, could be helpful in predicting the prognosis of NPC patients.
Complex III Qo site semiquinone has been assigned pivotal roles in productive energy-conversion and destructive superoxide generation. After a 30 year search, a genetic heme bH knockout arrests this transient semiquinone EPR radical, revealing the natural engineering balance pitting energy-conserving, short-circuit minimizing, split electron transfer and catalytic speed against damaging oxygen reduction.
Complex III; Cytochrome bc1; Semiquinone; Qo; Superoxide; Electron transfer
Adenocarcinoma (AC) and squamous cell carcinoma (SqCC) are two major histological subtypes of lung cancer. Genome-wide association studies (GWAS) have made considerable advances in the understanding of lung cancer susceptibility. Obvious heterogeneity has been observed between different histological subtypes of lung cancer, but genetic determinants in specific to lung SqCC have not been systematically investigated. Here, we performed the GWAS analysis specifically for lung SqCC in 833 SqCC cases and 3,094 controls followed by a two-stage replication in additional 2,223 lung SqCC cases and 6,409 controls from Chinese populations. We found that rs12296850 in SLC17A8-NR1H4 gene region at12q23.1 was significantly associated with risk of lung SqCC at genome-wide significance level [additive model: odds ratio (OR) = 0.78, 95% confidence interval (CI) = 0.72–0.84, P = 1.19×10−10]. Subjects carrying AG or GG genotype had a 26% (OR = 0.74, 95% CI = 0.67–0.81) or 32% (OR = 0.68, 95% CI = 0.56–0.83) decreased risk of lung SqCC, respectively, as compared with AA genotype. However, we did not observe significant association between rs12296850 and risk of lung AC in a total of 4,368 cases with lung AC and 9,486 controls (OR = 0.96, 95% CI = 0.90–1.02, P = 0.173). These results indicate that genetic variations on chromosome 12q23.1 may specifically contribute to lung SqCC susceptibility in Chinese population.
Previous genome-wide association studies (GWAS) strongly suggested the importance of genetic susceptibility for lung cancer. However, the studies specific to different histological subtypes of lung cancer were limited. We performed the GWAS analysis specifically for lung squamous cell carcinoma (SqCC) with 570,009 autosomal SNPs in 833 SqCC cases and 3,094 controls and replicated in additional 2,223 lung SqCC cases and 6,409 controls from Chinese populations (822 SqCC cases and 2,243 controls for the first replication stage and 1,401 SqCC cases and 4,166 controls for the second replication stage). We found a novel association at rs12296850 (SLC17A8-NR1H4) on12q23.1. However, rs12296850 didn't show significant association with risk of lung adenocacinoma (AC) in 4,368 lung AC cases and 9,486 controls. These results indicate that genetic variations on chromosome 12q23.1 may specifically contribute to lung SqCC susceptibility in Chinese population.
The objective of this study was to investigate the safety and pharmacokinetics of edaravone administered by single or successive intravenous infusions in healthy Chinese volunteers.
A total of 30 subjects (15 males and 15 females) were recruited and randomly assigned to three groups receiving edaravone doses of 20, 30, and 60 mg. All subjects received a single dose of edaravone during a 30-minute period, and only the 30 mg dose group continued to receive the same dose successively by intravenous infusion twice daily for the next 5 days. Plasma concentrations of edaravone were monitored by high-performance liquid chromatography at the following times: 15, 30, 45, 60, 75, 105, 165, 225, 300, 390, 480, 600, and 720 minutes after edaravone administration.
The area under the plasma concentration-time curve during a dosage interval (AUCτ) values of the single dose in the 20, 30, and 60 mg dose groups were 3.64±1.37, 5.17 ± 0.93, and 11.25 ± 3.42 mg · h/L, respectively, while in the group receiving repeated dosing of 30 mg, the mean AUCτ value was 5.06 ± 0.89mg · h/L. The corresponding maximum plasma drug concentration (Cmax) values were 1599.0 ± 382.6, 2378.7 ± 316.7, and 4540.1 ± 901.1 ng/mL, respectively, in the single-dose groups, and 2479.1 ± 477.9 ng/mL in the 30 mg repeated-dose group. The mean AUCτ and Cmax ratios between the repeated-dose group and the single-dose groups were 0.98 and 1.04. All laboratory test abnormalities (including increased alanine transaminase and triacylglycerol levels, and decreased white blood cell counts and creatinine levels) were mild and tolerable. All abnormal blood biochemical indices returned to normal levels after 7 days.
Edaravone was safe and well tolerated in the volunteers and displayed linear increases in the Cmax and AUCτ values.
In this review, 21 original papers published last year in the respirology and critical care sections of Critical Care are classified and analyzed in the following categories: mechanical ventilation, lung recruitment maneuvers, and weaning; the role of positive end-expiratory pressure in acute lung injury models; animal models of ventilator-induced lung injury; diaphragmatic dysfunction; the role of mechanical ventilation in heart-lung interaction; and miscellanea.
Amicetin, an antibacterial and antiviral agent, belongs to a group of disaccharide nucleoside antibiotics featuring an α-(1→4)-glycoside bond in the disaccharide moiety. In this study, the amicetin biosynthesis gene cluster was cloned from Streptomyces vinaceusdrappus NRRL 2363 and localized on a 37-kb contiguous DNA region. Heterologous expression of the amicetin biosynthesis gene cluster in Streptomyces lividans TK64 resulted in the production of amicetin and its analogues, thereby confirming the identity of the ami gene cluster. In silico sequence analysis revealed that 21 genes were putatively involved in amicetin biosynthesis, including 3 for regulation and transportation, 10 for disaccharide biosynthesis, and 8 for the formation of the amicetin skeleton by the linkage of cytosine, p-aminobenzoic acid (PABA), and the terminal (+)-α-methylserine moieties. The inactivation of the benzoate coenzyme A (benzoate-CoA) ligase gene amiL and the N-acetyltransferase gene amiF led to two mutants that accumulated the same two compounds, cytosamine and 4-acetamido-3-hydroxybenzoic acid. These data indicated that AmiF functioned as an amide synthethase to link cytosine and PABA. The inactivation of amiR, encoding an acyl-CoA-acyl carrier protein transacylase, resulted in the production of plicacetin and norplicacetin, indicating AmiR to be responsible for attachment of the terminal methylserine moiety to form another amide bond. These findings implicated two alternative strategies for amide bond formation in amicetin biosynthesis.
We present proof-of-concept in vitro results demonstrating the feasibility of using single molecule fluorescence resonance energy transfer (smFRET) measurements to distinguish, in real time, between individual ribosomes programmed with several different, short mRNAs. For these measurements we use either the FRET signal generated between two tRNAs labeled with different fluorophores bound simultaneously in adjacent sites to the ribosome (tRNA-tRNA FRET) or the FRET signal generated between a labeled tRNA bound to the ribosome and a fluorescent derivative of ribosomal protein L1 (L1-tRNA FRET). With either technique, criteria were developed to identify the mRNAs, taking into account the relative activity of the mRNAs. These criteria enabled identification of the mRNA being translated by a given ribosome to within 95% confidence intervals based on the number of identified FRET traces. To upgrade the approach for natural mRNAs or more complex mixtures, the stoichiometry of labeling should be enhanced and photobleaching reduced. The potential for porting these methods into living cells is discussed.
We employ single-molecule fluorescence resonance energy transfer (smFRET) to study structural dynamics over the first two elongation cycles of protein synthesis, using ribosomes containing either Cy3-labeled ribosomal protein L11 and A- or P-site Cy5-labeled tRNA or Cy3 and Cy5 labeled tRNAs. Pre-translocation (PRE) complexes demonstrate fluctuations between classical and hybrid forms, with concerted motions of tRNAs away from L11 and from each other when classical complex converts to hybrid complex. EF-G·GTP binding to both hybrid and classical PRE complexes halts these fluctuations prior to catalyzing translocation to form the post-translocation (POST) complex. EF-G dependent translocation from the classical PRE complex proceeds via transient formation of a short-lived hybrid intermediate. A-site binding of either EF-G to the PRE complex or of aminoacyl-tRNA·EF-Tu ternary complex to the POST complex markedly suppresses ribosome conformational lability.