Intestinal dysbacteriosis mediates the reference memory deficit induced by anaesthesia/surgery in aged mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is associated with increased morbidity and mortality and has become a major concern for patients and caregivers. POCD is most common in older patients. Previous studies demonstrated that the gut microbiome affects cognitive function and behaviour, and perioperative factors, including the operation itself, antibiotics, opioids or acid-inducing drugs, affect the gut microbiome. Thus, we hypothesised that intestinal dysbacteriosis caused by anaesthesia/surgery induces POCD.

METHODS

Tibial fracture internal fixation was performed in 18-month-old C57BL/6 mice under isoflurane anaesthesia to establish the POCD model. The Morris water maze was used to measure reference memory after anaesthesia/surgery. High-throughput sequencing of 16S rRNA from faecal samples was used to investigate changes in the abundance of intestinal bacteria after anaesthesia/surgery. To confirm the role of the gut microbiome in POCD, we pretreated mice with compound antibiotics or mixed probiotics (VSL#3). Anaesthesia/surgery impaired reference memory and induced intestinal dysbacteriosis in aged mice.

RESULTS

The 16S rRNA sequencing data revealed 37 genera (18 families) of bacteria that changed in abundance after anaesthesia/surgery. Pretreating mice with compound antibiotics or mixed probiotics (VSL#3) prevented the learning and memory deficits induced by anaesthesia/surgery. We further conducted quantitative real-time polymerase chain reaction (qRT-PCR) of 22 common types of bacteria among the 37 total types to verify the results of bacterial flora changes after anaesthesia/surgery. Numbers of 8 types of bacteria changed after anaesthesia/surgery but returned to normal after treatment with a mix of probiotics.

CONCLUSIONS

Our data suggest that deficits in reference memory induced by anaesthesia/surgery are mediated by intestinal dysbacteriosis.

Supraglottic jet oxygenation and ventilation enhances oxygenation during upper gastrointestinal endoscopy in patients sedated with propofol: a randomized multicentre clinical trial

Background

Hypoventilation is the main reason for hypoxia during upper gastrointestinal endoscopy procedures with sedation. The key to preventing hypoxia is to maintain normal ventilation during the procedure. We introduced supraglottic jet oxygenation and ventilation (SJOV) through a new Wei nasal jet tube (WNJ) to reduce the incidence of hypoxia in patients sedated with propofol during upper gastrointestinal endoscopy procedures.

Methods

In a multicentre, prospective randomized single-blinded study, 1781 outpatients undergoing routine upper gastrointestinal endoscopy who were sedated with propofol by an anaesthetist were randomized into the following three groups: the supplementary oxygen via nasal cannula group [nasal cannula oxygen: O 2 (2 litres min -1 ) was administered via a nasal cannula]; the supplementary oxygen via WNJ group [WNJ oxygen: O 2 (2 litres min -1 ) was administered through a WNJ]; and the SJOV via WNJ group (WNJ SJOV: SJOV was administered via WNJ) at three centres from March 2015 to July 2016. The primary outcome of interest was the incidence of hypoxia (peripheral oxygen saturation of 75-89%). Other adverse events were also recorded.

Results

Supraglottic jet oxygenation and ventilation decreased the incidence of hypoxia from 9 to 3% ( P <0.0001). No severe hypoxia occurred in the WNJ SJOV group, one instance occurred in the WNJ oxygen group, and two instances were observed in the nasal cannula oxygen supply control group. Supraglottic jet oxygenation and ventilation-related minor adverse events increased significantly within 1 min after the procedure but decreased 30 min later.

Conclusions

The use of SJOV during upper gastrointestinal endoscopy for patients who are sedated with propofol reduces the incidence of hypoxia, with minor and tolerable adverse events. Supraglottic jet oxygenation and ventilation has a favourable risk-to-benefit ratio and may improve patient safety.

Clinical trial registration

NCT02436018.

Study of thermal stability of (3-aminopropyl)trimethoxy silane-grafted titanate nanotubes for application as nanofillers in polymers

Protonated titanate nanotubes (TiNT-H) were surface-modified with (3-aminopropyl)trimethoxy silane (APTMS) by a novel method suitable for the syntheses of large amounts of materials at a low cost. The usage of prepared nanotubes for polymer reinforcement was studied. Since the thermal stability of the nanofiller was important to preserve its functional properties, its stability was studied by in situ high-temperature measurements. The most thermally stable nanotubes were silanized for 20 min and used for the preparation of epoxy-based nanocomposites. The nanofiller formed smaller (a few hundred nm) and larger (a few μm) aggregates in the polymer matrix, and the amount of aggregates increased as the nanofiller content increased. The APTMS-modified titanate nanotubes bonded well with the epoxy matrix since amine groups on the TiNT's surface can react with an epoxy group to form covalent bonds between the matrix and the nanofiller. A very small addition (0.19-1.52 wt%) of the nanotubes significantly increased the glass transition temperature and the modulus in the rubbery state of the epoxy-based polymer. Smaller nanofiller content leads to a larger increase in these parameters and therefore better dynamic mechanical properties due to the smaller amount of large aggregates. APTMS-modified titanate nanotubes have proven to be a promising nanofiller in epoxy-based nanocomposites.

Gold catalyzed liquid phase oxidation of alcohol: the issue of selectivity

Commercial carbon nanotubes (CNTs) and carbon nanofibers (CNFs) modified in various ways at the surface have been used as supports for gold nanoparticles (AuNPs) in order to study their influence on the activity/selectivity of catalysts in the aqueous oxidation of alcohol. Particularly oxidative treatment was used to introduce carboxylic functionalities, whereas subsequent treatment with NH3 at different temperatures (473 K, 673 K and 873 K) produced N-containing groups leading to an enhancement of basic properties as the NH3 treatment temperature was increased. The nature of the N-containing groups changed as the temperature increased, leading to an increase in the hydrophobicity of the support surface. Similar Au particle size and similar textural properties of the supports allowed the role of chemical surface groups in both the activity and the selectivity of the reaction of glycerol oxidation to be highlighted. An increase of basic functionalities produced a consistent increase in the activity of the catalyst, which was correlated to the promoting effect of the basic support in the alcoholate formation and the subsequent C-H bond cleavage. The selectivity towards primary oxidation products (C3 compounds) was the highest for the catalysts treated with NH3 at 873 K, which presented the most hydrophobic surface. The same trend in the catalyst activity has been obtained in the aqueous benzyl alcohol base-free oxidation. As in the case of glycerol, the increasing of basicity and/or hydrophobicity increased the consecutive reactions.

A novel catalyst for synthesis of styrene: carbon nanofibers immobilized on activated carbon

Carbon NanoFibers (CNFs) with hierarchically structure have been immobilized onto Activated Carbon (AC) by impregnation with an aqueous solution of Fe(CH3COO)2, reduction and subsequent chemical vapor decomposition of ethylene. The morphology of the CNFs can be modulated by adjusting the pH of the Fe(CH3COO)2 solution used for impregnating the AC. A stable yield of 35% in the oxidative dehydrogenation of ethylbenzene to styrene was obtained at a temperature of 673 K, around 200 K lower than the current industrial process. The immobilized CNFs on AC catalysts combine the catalytic properties of the carbon nanofibers and the suprastructure of the AC host. The final material is an easy to handle active catalyst, with an open structure of immobilized CNFs avoiding the pressure drop problem, which is typically observed for fine powder forms of CNFs. The immobilized CNFs on AC are attractive for gas-phase fixed-bed industrial applications.

Bulk and surface structural investigations of diesel engine soot and carbon black

The microstructure and electronic structure of environmentally relevant carbons such as Euro IV heavy duty diesel engine soot, soot from a black smoking diesel engine, spark discharge soot as model aerosol, commercial furnace soot and lamp black are investigated by transmission electron microscopy, electron energy-loss spectroscopy and X-ray photoelectron spectroscopy. The materials exhibit differences in the predominant bonding, which influences microstructure as well as surface functionalization. These chemical and physical properties depend on the formation history of the investigated carbonaceous materials. In this work, a correlation of the microstructure of the samples to the predominant bonding and incorporation of oxygen into the carbons is obtained. It is shown that a high amount of defects and the deviation of the carbons from a perfect graphitic structure results in a increased incorporation of oxygen and hydrogen. A correlation between the length and curvature of graphene layers with the bonding state of carbon atoms and incorporation of oxygen and hydrogen is established.

Experimental and theoretical determination of low electron energy loss spectra of Ag and Ru

We show the experimental and calculated q-dependent low energy loss electron energy loss spectrum of Ru and Ag. The spectra were calculated within the time-dependent density-functional theory including local-field effects. For Ag, the momentum transfer was parallel to the (110) direction. For Ru the three main directions (010), (110) and (001) were investigated. The agreement between theory and experiment is very good for Ag and for momentum transfers parallel to the (001) direction of Ru. For momentum transfers parallel to the in-plane directions (110) and (010) the agreement for Ru is not satisfactory, which could be attributed to relativistic effects or to strong localization of the 4d states of Ru.

Characterization of nanostructured binary molybdenum oxide catalyst precursors for propene oxidation

High-resolution transmission electron microscopy characterization of molybdenum oxide catalyst precursors is carried out for a better understanding of the mechanisms leading to the active catalytic material. The precipitated material consists of both large-unit cell crystals and randomly orientated clusters on a 3-5 nm scale. The crystalline clusters are embedded in non-crystalline material, preventing the formation of large well-defined inactive orthorhombic MoO(3) crystals during activation of the catalyst material.

Diesel engine exhaust emission: oxidative behavior and microstructure of black smoke soot particulate

Soot particulate collected from a Euro III heavy duty diesel engine run under black smoke conditions was investigated using thermogravimetry, transmission electron microscopy, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy. The characterization results are compared with those of commercial carbon black. The onset temperature toward oxidation of the diesel engine soot in 5% O2 is 150 degrees C lower than that for carbon black. The burn out temperature for the diesel engine soot is 60 degrees C lower than that of the carbon black. The soot primary particles exhibit a core-shell structure. The shell of the soot particles consists of homogeneously stacked basic structure units. The commercial carbon lamp black is more graphitized than the diesel engine soot, whereas the diesel engine soot contains more carbon in aromatic nature than the carbon black and is highly surface-functionalized. Our findings reveal that technical carbon black is not a suitable model for the chemistry of the diesel engine soot.

Retrograde cerebral perfusion of oxygenated, compacted red blood cells attenuates brain damage after hypothermia circulation arrest of rat

BACKGROUND

It was proved that higher haematocrit (Hct) might improve the function of brain after hypothermia circulation arrest (HCA). In the present study we established a new rat HCA model and investigated whether retrograde cerebral perfusion of oxygenated, compacted red blood cells (RBC) could attenuate brain injury after HCA.

METHODS

A new rat HCA model was developed and rats were randomly distributed into three groups: HCA group, HCA combined with retrograde cerebral perfusion of oxygenated, compacted red blood cell group (HCArcp group), and sham operation group (sham op. group). Animals both in the HCA group and in the HCArcp group underwent HCA 90 min at 18 degrees C. Brain damage after HCA was evaluated with light microscopy and electron microscopy. Immunohistochemistry and RT-PCR techniques were used to measured the different expressions of the C-Fos, Bcl-2, Bax mRNA and protein among the groups. Additionally we measured the wet/dry ratio of the brain in order to evaluate the oedema degree after HCA.

RESULTS

The new HCA model of rat we developed was comparable to the clinical setting not only in terms of the intubation, anaesthesia method and materials employed but also in terms of the priming volume in relation to body weight. The number of injured neurones in the hippocampus CA1 and parietal cortex, but not in the thalamus of the HCA group, was significantly greater than that of the HCArcp group (P<0.05). The mean score of mitochondrion of the hippocampus CA1 in the HCA group was significantly higher than in the HCArcp group (P<0.05). The expression of C-Fos, Bax mRNA and protein in the hippocampus CA1 and/or parietal cortex area was higher in the HCA group than in the HCArcp group (P<0.05). Expression of the mRNA and protein of Bcl-2 was higher in the HCArcp group than in the HCA group (P<0.05). The degree of oedema after HCA between the HCA group and HCArcp group had no significant difference (P>0.05).

CONCLUSIONS

We established a new rat model of HCA comparable to the clinical setting. Retrograde cerebral perfusion of oxygenated, compacted RBC is a simple, effective, and safe method to protect the brain during HCA. Adjusting the gene expression in relation to apoptosis might contribute to the neuroprotective effects of a retrograde cerebral infusion of oxygenated, compacted RBC.

Anisotropy and collection angle dependence of the oxygen K ELNES in V2O5: a band-structure calculation study

We present a theoretical study of the anisotropy and collection angle dependence of the oxygen K ELNES in V2O5. Ab initio band-structure calculations were performed with WIEN97, a program package based on the full potential linearised augmented plane waves (FP-LAPW) method. An analysis of the site and angular momentum projected DOS allowed the identification of differently coordinated oxygens and the separation of the oxygen K-edge into contributions from terminal (vanadyl) oxygens, bridging oxygens and chain oxygens. The major contribution to the anisotropy of the O K-edge ELNES could be assigned to transitions at the vanadyl oxygen. Theoretical calculations predict that the extent of changes in the ELNES would be large enough for detection in collection angle dependent O K-edge measurements. A variation in the fine structure of the O K-edge with decreasing collection angle was confirmed by experiments.

High resolution EELS using monochromator and high performance spectrometer: comparison of V2O5 ELNES with NEXAFS and band structure calculations

Using single crystal V2O5 as a sample, we tested the performance of the new aberration corrected GATAN spectrometer on a monochromatised 200 kV FEG FEI (S)TEM. The obtained V L and O K ELNES were compared with that obtained in a common GATAN GIF and that in the new spectrometer, without monochromatised beam. The performance of the new instrumentation is impressive: recorded with an energy-resolution of 0.22 eV, the V L(3) edge reveals all the features due to the bulk electronic structure, that are also revealed in near-edge X-ray absorption fine structure (NEXAFS) with a much higher energy-resolution (0.08 eV). All features of the ELNES and NEXAFS are in line with a theoretical spectrum derived from band-structure calculations.

Electron beam induced changes in transition metal oxides

Electron beam induced changes in maximal valence transition metal oxides V(2)O(5), M(o)O(3) and TiO(2) (anatase) were studied by means of electron energy-loss spectroscopy and electron diffraction in transmission electron microscopy. For V(2)O(5), the observed chemical shifts of the L-edge reveal the reduction of V(5+) to V(2+). The structure changes from orthorhombic V(2)O(5) to cubic VO. MoO(3) can be reduced to a phase with an oxidation state less than that in MoO(2). No notable structural or electronic change in TiO(2) (anatase) is observed. The different behaviours of the studied oxides under an electron beam are discussed with respect to bonding energy and lattice structure.

Desoxyepothilone B: an efficacious microtubule-targeted antitumor agent with a promising in vivo profile relative to epothilone B

A new class of 16-membered macrolides, the epothilones (Epos), has been synthesized and evaluated for antitumor potential in vitro and in vivo. Recent studies in these and other laboratories showed that epothilones and paclitaxel (paclitaxel) share similar mechanisms of action in stabilizing microtubule arrays as indicated by binding-displacement studies, substitution for paclitaxel in paclitaxel-dependent cell growth, and electron microscopic examinations. The present study examined cell growth-inhibitory effects in two rodent and three human tumor cell lines and their drug-resistant sublines. Although paclitaxel showed as much as 1, 970-fold cross-resistance to the sublines resistant to paclitaxel, adriamycin, vinblastine, or actinomycin D, most epothilones exhibit little or no cross-resistance. In multidrug-resistant CCRF-CEM/VBL100 cells, IC50 values for EpoA (1), EpoB (2), desoxyEpoA (3) (dEpoA), desoxyEpoB (4) (dEpoB), and paclitaxel were 0.02, 0.002, 0.012, 0.017, and 4.14 microM, respectively. In vivo studies, using i.p. administration, indicated that the parent, EpoB, was highly toxic to mice and showed little therapeutic effect when compared with a lead compound, dEpoB. More significantly, dEpoB (25-40 mg/kg, Q2Dx5, i.p.) showed far superior therapeutic effects and lower toxicity than paclitaxel, doxorubicin, camptothecin, or vinblastine (at maximal tolerated doses) in parallel experiments. For mammary adenocarcinoma xenografts resistant to adriamycin, MCF-7/Adr, superior therapeutic effects were obtained with dEpoB compared with paclitaxel when i.p. regimens were used. For ovarian adenocarcinoma xenografts, SK-OV-3, dEpoB (i.p.), and paclitaxel (i. v.) gave similar therapeutic effects. In nude mice bearing a human mammary carcinoma xenograft (MX-1), marked tumor regression and cures were obtained with dEpoB.

Farnesyl transferase inhibitors cause enhanced mitotic sensitivity to taxol and epothilones

An important class of cellular proteins, which includes members of the p21ras family, undergoes posttranslational farnesylation, a modification required for their partition to membranes. Specific farnesyl transferase inhibitors (FTIs) have been developed that selectively inhibit the processing of these proteins. FTIs have been shown to be potent inhibitors of tumor cell growth in cell culture and in murine models and at doses that cause little toxicity to the animal. These data suggest that these drugs might be useful therapeutic agents. We now report that, when FTI is combined with some cytotoxic antineoplastic drugs, the effects on tumor cells are additive. No interference is noted. Furthermore, FTI and agents that prevent microtubule depolymerization, such as taxol or epothilones, act synergistically to inhibit cell growth. FTI causes increased sensitivity to induction of metaphase block by these agents, suggesting that a farnesylated protein may regulate the mitotic check point. The findings imply that FTI may be a useful agent for the treatment of tumors with wild-type ras that are sensitive to taxanes.

[Extraction-spectrophotometric determination of copper in tablets and injections of Chinese medicine]

Cu reacts with neo-cuproin and eosin Y to form a coloured associated complex. In chloroform its apparent E value is 6.83 X 10(4) 1 mol-1 cm-1 at lambda = 544 nm. We used this system to determine the contents of trace copper in some tablets and injections of Chinese medicine. This method is simple, highly sensitive and selective.

[Studies on the stability and some other important physical properties of polysaccharides polyphase liposome (PPL)]

The stability and some other important physical properties of PPL were investigated by means of electron microscopy and MPV-TAS experiments. The results are rated as follows: Good integrity of liposome homogeneity of its particle size were reached, and at 100 degrees C PPL was found to undergo sterilization without causing changes of its shape and encapsulation efficiency for 1 h. Also, the distribution of PPL particle size and the regularity of the change of PPL particle in size were determined by Coulter counter. Using this method, the kinetic equation of coalescence of polyphase liposome and the activation energy for coalescence were obtained, and through these results the stability of PPL is elucidated.