Nano-Cu Derived from a Copper Nitride Precatalyst for Reductive Coupling of Nitroaromatics to Azo Compounds.

The study of structural reconstruction is vital for the understanding of the real active sites in heterogeneous catalysis and guiding the improved catalyst design. Herein, we applied a copper nitride precatalyst in the nitroarene reductive coupling reaction and made a systematic investigation on the dynamic structural evolution behaviors and catalytic performance. This Cu3N precatalyst undergoes a rapid phase transition to nanostructured Cu with rich defective sites, which act as the actual catalytic sites for the coupling process. The nitride-derived defective Cu is very active and selective for azo formation, with 99.6% conversion of nitrobenzene and 97.1% selectivity to azobenzene obtained under mild reaction conditions. Density functional theory calculations suggest that the defective Cu sites play a role for the preferential adsorption of nitrosobenzene intermediates and significantly lowered the activation energy of the key coupling step. This work not only proposes a highly efficient noble-metal-free catalyst for nitroarenes coupling to valuable azo products but also may inspire more scientific interest in the study of the dynamic evolution of metal nitrides in different catalytic reactions.

Phage-based technologies for highly sensitive luminescent detection of foodborne pathogens and microbial toxins: A review.

Foodborne pathogens and microbial toxins are the main causes of foodborne illness. However, trace pathogens and toxins in foods are difficult to detect. Thus, techniques for their rapid and sensitive identification and quantification are urgently needed. Phages can specifically recognize and adhere to certain species of microbes or toxins due to molecular complementation between capsid proteins of phages and receptors on the host cell wall or toxins, and thus they have been successfully developed into a detection platform for pathogens and toxins. This review presents an update on phage-based luminescent detection technologies as well as their working principles and characteristics. Based on phage display techniques of temperate phages, reporter gene detection assays have been designed to sensitively detect trace pathogens by luminous intensity. By the host-specific lytic effects of virulent phages, enzyme-catalyzed chemiluminescent detection technologies for pathogens have been exploited. Notably, these phage-based luminescent detection technologies can discriminate viable versus dead microbes. Further, highly selective and sensitive immune-based assays have been developed to detect trace toxins qualitatively and quantitatively via antibody analogs displayed by phages, such as phage-ELISA (enzyme-linked immunosorbent assay) and phage-IPCR (immuno-polymerase chain reaction). This literature research may lead to novel and innocuous phage-based rapid detection technologies to ensure food safety.

A new butenolide with antifungal activity from solid co-cultivation of Irpex lacteus and Nigrospora oryzae.

A new antifungal butenolide irperide (1) along with five known compounds were isolated from the co-culture of endophyte Irpex lacteus and pathogenic Nigrospora oryzae. The structure of 1, including the absolute configuration, was elucidated by analysis of NMR, HR-ESI-MS data and ECD spectra. Compounds 1, 4 and 6 exhibited significant antifungal activity against Aspergillus fumigatus, with MIC values of 1, 2 and 1 µg/mL, respectively.

Modeling Bacterial Flagellar Motor With New Structure Information: Rotational Dynamics of Two Interacting Protein Nano-Rings.

In this article, we develop a mathematical model for the rotary bacterial flagellar motor (BFM) based on the recently discovered structure of the stator complex (MotA5MotB2). The structure suggested that the stator also rotates. The BFM is modeled as two rotating nano-rings that interact with each other. Specifically, translocation of protons through the stator complex drives rotation of the MotA pentamer ring, which in turn drives rotation of the FliG ring in the rotor via interactions between the MotA ring of the stator and the FliG ring of the rotor. Preliminary results from the structure-informed model are consistent with the observed torque-speed relation. More importantly, the model predicts distinctive rotor and stator dynamics and their load dependence, which may be tested by future experiments. Possible approaches to verify and improve the model to further understand the molecular mechanism for torque generation in BFM are also discussed.

Effects of enteral nutrition supplemented with glutamine on intestinal mucosal immunity in burned mice.

OBJECTIVE: The aim of this study was to investigate the effects of enteral nutrition (EN) supplemented with glutamine (GLN) on Peyer's patches and intestinal immunoglobulin A (IgA) response in burned mice. METHODS: Thirty-four mice were randomly assigned to a normal control group (n = 10), an EN group (n = 12), and an EN supplemented with GLN (EN + GLN) group (n = 12) and mice in the EN and EN + GLN groups received a 20% total body surface area, full-thickness scald burn on the back. Then the burned mice were fed with conventional EN or EN + GLN for 7 d. There was isonitrogenous and isocaloric intake in the EN and EN + GLN groups. On day 7 after injury, entire intestines were collected and intestinal IgA levels, total lymphocyte yield, lymphocyte subpopulations, and total apoptotic ratio in Peyer's patches were analyzed. RESULTS: Total lymphocyte yield, numbers of lymphocyte subpopulations, and intestinal IgA levels in the EN + GLN group were significantly higher than those in the EN group (P < 0.05). The total apoptotic ratio in Peyer's patches was markedly decreased in the EN + GLN group compared with that in the EN group (P < 0.05). CONCLUSION: The results indicated that EN supplemented with GLN is superior to conventional EN with respect to improvement of intestinal immunity in burned mice.

Effects of early enteral nutrition supplemented with arginine on intestinal mucosal immunity in severely burned mice.

BACKGROUND: To investigate the effects of early enteral nutrition (EN) supplemented with Arginine (Arg) on intestinal mucosal immunity in severely burned mice. METHODS: Forty-four mice were randomly assigned into four groups: a sham injury+EN group (n=10), a sham injury+EN+Arg group (n=10), a burn+EN group (n=12), and a burn+EN+Arg group (n=12) and the mice in two experimental groups received a 20% total body surface area (TBSA), full-thickness scald burn on the back. Then, the burned mice were given a 175 kcal/kg body wt/day of conventional enteral nutrition or an isonitrogenous and isocaloric enteral nutrition supplemented with Arg by gastric gavage for 7 days. There was isonitrogenous and isocaloric intake in two experimental groups. The mice in two control groups received the same procedures as above, except for burn injury. On day 7 after injury, all mice among four groups were euthanized and the entire intestine was harvested. Intestinal immunoglobulin A (IgA) levels, total lymphocyte yield, and lymphocyte subpopulations in Peyer's patches were analyzed. Levels of IFN-gamma, IL-2, IL-4 and IL-10 in gut homogenates were also measured by ELISA. RESULTS: Total lymphocyte yield, numbers of lymphocyte subpopulations, and intestinal IgA levels in the EN+ARG group were higher than those in the EN group (p<0.05). Levels of gut tissue cytokines were significantly altered with enteral Arg supplementation: levels of IL-4 and IL-10 were increased, and levels of IFN-gamma and IL-2 declined, when compared with the EN-fed mice (p<0.05). CONCLUSIONS: The results of this study suggested that enteral nutrition supplemented with Arg has changed the cytokine concentrations in intestinal homogenates from a pro- to an anti-inflammatory profile, increased sIgA levels and changed lymphocytes in severely burned mice.

Effects of glutamine added to enteral nutrition on Peyer's patch apoptosis in severely burned mice.

BACKGROUND AND AIMS: This study aimed to investigate the influence of enteral glutamine (GLN) supplementation on Peyer's patch apoptosis in severely burned mice. METHODS: Thirty-four mice were randomly assigned to a normal group (n=10), an EN group (n=12) and an EN supplemented with GLN (EN+GLN) group (n=12) and the mice in the EN and EN+GLN groups received a full-thickness scald burn over 20% total body surface area (TBSA) on the back. The burned mice then were fed orally with a common EN or an isonitrogenous and isocaloric EN supplemented with GLN for 7 days. On day 7 after injury, all surviving mice were euthanised and the entire intestine was collected. The percentage of apoptotic cells and cell percentage of phenotype in Peyer's patches were determined by flow cytometry (FCM). The FasL expression in Peyer's patches was analysed by reverse transcription polymer chain reaction (RT-PCR) and FCM. Both TNF-alpha levels and caspase-3 activity in Peyer's patches were also assessed. RESULTS: The results revealed that the percentage of lymphocyte subsets in Peyer's patches after burn injury significantly altered: the percentage of CD4 and CD19 cells declined and the percentage of CD8 cells correspondingly increased, when compared with the normal control mice (p<0.05). On the other hand, the total apoptotic ratio and all lymphocytes subset apoptosis in Peyer's patches were markedly increased (p<0.05), which were consistent with up-regulation in the FasL expression at the levels of both mRNA and protein, TNF-alpha levels and caspase-3 activity in Peyer's patches. Enteral GLN supplementation partially reversed these changes: the total apoptotic ratio and all lymphocytes subpopulation apoptosis in Peyer's patches were markedly decreased when compared with the EN group (p<0.05). The percentage of lymphocyte subsets within Peyer's patches also restored the condition prior to injury. However, no significant differences in the FasL expression, including mRNA and protein, were observed between the EN and EN+GLN groups. Although, both TNF-alpha levels and caspase-3 activity in Peyer's patches were lower in the EN+GLN group than in the EN group (p<0.05). CONCLUSIONS: This study suggests that enteral GLN supplementation is superior to a common enteral nutrition with respect to attenuating apoptosis in Peyer's patches, which might be more effective in decreasing TNF-alpha levels and down-regulating caspase-3 activity in Peyer's patches.

The influence of Peyer's patch apoptosis on intestinal mucosal immunity in burned mice.

The aim of this study was to investigate the influence of apoptosis on Peyer's patches and the intestinal immunoglobulin A (IgA) response in burned mice. Sixty male Balb/c mice were randomly assigned into the sham-burn (control) group (n=30) and the burn group (n=30). The mice in the burn group received a full-thickness scald burn over 20% of the total body surface area (TBSA), on the back. At 12, 24 and 72 h, respectively, after injury, the burned mice (n=10, at every time point) were anaesthetised and their entire intestines were collected. The mice in the sham-burn group were treated with the same procedure as above, except for the burn injury. The number of Peyer's patches on every entire intestine and the total Peyer's patches cell yield were counted. The changes of lymphocyte subpopulations in Peyer's patches were measured by flow cytometry (FCM). And the levels of intestinal IgA were examined by enzyme-linked immunosorbent assay (ELISA). Fluoresceinisothiocyanate (FITC)-conjugated Annexin-tau and propidium iodide (PI) double-staining cells were analysed by FCM for apoptotic ratio in Peyer's patches. The results showed that the total Peyer's patch cell yield and the numbers of CD3, CD4, CD8 and CD19 cells were significantly decreased at 12, 24 and 72 h after injury (P<0.05), and that the intestinal IgA levels were markedly reduced at 24 and 72 h (P<0.05). On the other hand, total apoptotic ratio and all cell subpopulation apoptosis in Peyer's patches were dramatically increased at 12, 24 and 72 h after injury (P<0.05). These results indicated that severe burns led to a significant decrease in the number of Peyer's patch cells and in intestinal IgA levels, which was closely associated with strongly increased apoptosis in Peyer's patches.

[Effect of early enteral immune nutrition on immune function of intestine in mice with severe burn].

OBJECTIVE: To investigate the effects of early enteral nutrition supplemented with immune nutrient on intestine immune function in mice with severe burn. METHODS: Twenty-four BALB/c mice were inflicted with 20% TBSA full-thickness scald, then they were randomly divided into EN(with oral administration of common enteral nutrition after 2 hours) and EIN (with oral administration of common enteral nutrition and glutamine, arginine after 2 hours) groups. Another 10 mice were used as the normal control (NC) group. The supplied energy ratio( carbohydrate: fat: protein)in former 2 groups was 82:3:15, and the ratio of energy to nitrogen was 150: 1. The energy requirement of each mouse was calculated according to 732.2 kJ x kg(-1) x d(-1), one third of the requirement was administrated on 1st day, and one half of it on 2nd day, and full energy requirement was started on the 3rd day,and the requirement was divided into 4-6 portions every day. The feed was isocaloric, isonitrogenous, and isovolumic for the 2 experimental groups. All mice were sacrificed and entire small intestine was harvested for determination of intestinal IgA level by ELISA, total Peyer's patches (PP) lymphocytes and their apoptosis ratio, and changes in PP lymphocytes (CD3+, CD4+, CD19+) on 7th day of the experiment. RESULTS: Compared with those in NC group [(4.5 +/- 0.6) x 10(6), (42 +/- 7) microg/cm, respectively], total PP lymphocytes and intestinal IgA levels in EN and EIN groups obviously decreased [(2.3 +/- 0.4) x 10(6), (35 +/- 6) microg/cm, (3.8 +/- 0. 5) x 10(6), (38 +/- 6), microg/cm, respectively, P < 0.05] , among which the values in EIN group were higher than EN group (P < 0.05). The changes in PP lymphocytes were similar to that of total PP lymphocytes. Compared with that in NC group [(4.8 +/- 2.1)%], the apoptosis ratio of PP lymphocytes in EN and EIN groups significantly increased [(12.7 +/- 2.4)%, (8.0 +/- 1.7)%, respectively, P < 0.05], however the ratio in EIN group was lower than that of EN group (P < 0.05). CONCLUSIONS: Early enteral nutrition supplemented with immune nutrient can improve intestinal immune function in mice with severe burn.