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COVIDTrach is a UK multidisciplinary collaborative project that aims to evaluate the outcomes of tracheostomy in COVID-19 patients. It also examines the implementation of national guidance in COVID-19 tracheostomies and the incidence of COVID-19 infections amongst those health care workers involved in the procedure. An invitation to participate in an online survey tool (REDCap) was disseminated to all UK NHS departments involved in tracheostomy in mechanically ventilated COVID-19 patients via the Federation of Surgical Specialty Associations, it’s subsidiary organisations and the Intensive Care Society. To date 78 hospitals have submitted 564 COVID-19 tracheostomy cases. Fifty-two percent (n=219/465) of patients who had undergone tracheostomy and were still alive had been successfully weaned from mechanical ventilation at the point of completing the survey. The all cause in-hospital mortality following tracheostomy was 12% (n=62/530), with 3% of these (n=2/62) due to tracheostomy related complications and the remaining deaths due to COVID-19 related complications. Amongst 400 cases submitting data two weeks after the tracheostomy, no instance of COVID-19 infection amongst operators was recorded. FFP3 masks or Powered Air Purifying Respirators were used by operators in 100% of tracheostomies and a face visor or hood with face shield was available in 99% of cases. This interim report highlights early outcomes following tracheostomy in mechanically ventilated COVID-19 patients. Future reporting from COVIDTrach will include more detailed analysis at later timepoints using comparator groups in order to provide a more comprehensive assessment of tracheostomy in COVID-19.

Aims: We have developed a technique to secure the LMA without obstructing the surgical field and have minimal interference with airway maintenance. Nasal endo-tracheal tube is the gold standard for airway maintenance; however, it can slow turnover time due to it requiring a longer recovery time compared with the laryngeal mask airway (LMA). The LMA position often obscures the surgical field in these cases often necessitating repositioning intra-operatively. This can adversely affect airway patency. Materials and methods: We audited two different techniques of securing LMAs (north-facing with our modification vs. south-facing conventional taped to the lower lip/chin) in a total of 223 patients undergoing bilateral extractions. A questionnaire for surgeons and anaesthetists was used to assess their suitability and complications occurred noting particularly obstructions caused to the LMA, cause for obstruction, management taken to correct obstruction. Results: We found the risk of partial or total obstruction of the airway during surgical extractions with a conventionally placed LMA to be around 36% compared with 19% with a retromolar positioned flexi-LMA during our study. Conclusion: The retro-molar positioned LMA not only increased operating space but showed a reduced number of obstructions caused to the LMA.

Trigallic acid was isolated by Counter Current Distribution from a partial acid hydrolysate of Chinese tannic acid. Trigallic acid in polar solvents solution occurs in four isomeric forms. This is revealed by the four peaks obtained with reversed phase high performance liquid chromatography. Their ratio is function of the solvent. The four isomeric trigallic acid forms are in equilibrium. They result from the meta-meta, meta-para, para-meta and para-para coupling of the three gallic acid building blocks in trigallic acid. This was proved by spectroscopic and chemical methods.

Branching has a strong influence on the processability and properties of polymers. However, the accurate characterization of branched polymers is genuinely difficult. Branched molecules of a certain molecular weight exhibit the same hydrodynamic volumes as linear molecules of substantially lower weights. Therefore, separation by size-exclusion chromatography (SEC), will result in the co-elution of molecules with different molecular weights and branching characteristics. Chromatographic separation of the polymer molecules in sub-microm channels, known as molecular-topology fractionation (MTF), may provide a better separation based on topological differences among sample molecules. MTF elution volumes depend on both the topology and molar mass. Therefore co-elution of branched molecules with linear molecules of lower molar mass may also occur in this separation. Because SEC and MTF exhibit significantly different selectivity, the best and clearest separations can be achieved by combining the two techniques in a comprehensive two-dimensional (MTFxSEC) separation system. In this work such a system has been used to demonstrate branching-selective separations of star branched polymers and of randomly long-chain-branched polymers. Star-shaped polymers were separated from linear polymers above a column-dependent molecular weight or size.

A normal-phase liquid chromatographic method is described for the determination of epoxides and particulary residual ethylene oxide and propylene oxide in polyether polyols. The residual epoxides are derivatized with diethylammonium N,N-diethyldithiocarbamate into the corresponding 1-(N,N-diethyldithiocarbamoyl)-2-hydroxy-ethane and -hydroxypropane. The dithiocarbamoyl esters are extracted into chloroform and separated by normal-phase liquid chromatography. Detection is done by ultraviolet at 278 nm. Total analysis time is about 45 min. Linearity (0.1–100 ppm), detection limits (0.5 ppm), recovery from spiked samples (> 95%) and interferences have been studied.

Elongation factor 1 (EF-1) regulates the specific interaction of aminoacyl-tRNA with the ribosome during the elongation phase of protein biosynthesis. Although individual functions of its separate chains have been well defined, to date there is hardly information about the structure and function of the whole complex. We describe here the complete subunit structure of elongation factor 1, and discuss its change during development of Artemia. Elongation factor 1 consists of a pentameric complex, composed of four different subunits alpha, beta, gamma, and delta in a molar ratio of 2:1:1:1. Although one molecule of EF-1 alpha dissociates easily from the complex EF-1 alpha 2 beta gamma delta under the influence of aminoacyl-tRNA and GTP, the second molecule of EF-1 alpha was found to remain firmly attached. Thus, in eukaryotic protein synthesis, movement of transfer RNAs to the ribosome seems under the influence of two distinct molecules of EF-1 alpha, a result possibly related to the presumed consumption of two molecules of GTP by EF-Tu during the elongation step of prokaryotic protein synthesis.

The structures and stereochemistry of the trimers, containing two acrylonitrile units and one styrene unit (An 2 S), produced during the spontaneous copolymerization of styrene (S) and acrylonitrile (An) were determined using 1 H NMR, 13 C NMR, and X-ray crystallography. HPLC conditions are described for the separation of the oligomers. The dresults indicate that the Mayo mechanism is not responsible for initiation of SAn copolymerization

Elongation factor (EF)-1 beta, a 26 kDa protein, is the eukaryotic equivalent of bacterial EF-Ts, the nucleotide exchange factor in protein synthesis. EF-1 beta catalyzes the exchange of guanine nucleotides bound to EF-1 alpha; the latter protein is the eukaryotic equivalent of bacterial EF-Tu. Limited proteolytic cleavage studies on EF-1 beta lead to the following picture: the protein is composed of two domains, an aminoterminal and a carboxyterminal domain, connected to each other by a stretch of hydrophilic, charged amino acids situated in the middle of the molecule. The carboxyterminal domain supplies the catalytic site for the nucleotide exchange reaction, whereas the aminoterminal domain interacts with EF-1 gamma, the third component of elongation factor 1. The regulatory, serine phosphate residue, Ser-89, localized in the hydrophilic stretch of EF-1 beta, does not appear to be necessary for the basic exchange reaction. The fourth component of the high molecular weight elongation factor complex (EF-1H), named EF-1 delta or 28 K protein, is homologous to EF-1 beta and contains regions very similar to the carboxyterminal part. EF-1 delta was found to be active in the nucleotide exchange reaction.

We studied the intra- and interobserver variability of volume measurments of the hippocampus (HC) and the amygdala as applied to the detection of HC atrophy in patients with complex partial seizures (CPE), measuring the volumes of the HC and amygdala of 11 normal volunteers and 12 patients with presumed CPE, using the manual ray-tracing method. Two independent observers performed these measurements twice each using home-made software. The intra- and interobserver variability of the absolute volumes and of the normalised left-to-right volume differences (deltaV) between the HC (deltaV(HC)), the amygdala (deltaV(A)) and the sum of both (deltaV(HCA)) were assessed. In our mainly right-handed normals, the right HC and amygdala were on average 0.05 and 0.03 ml larger respectively than on the left. The interobserver variability for volume measurements in normal subjects was 1.80 ml for the HC and 0.82 ml for the amygdala, the intraobserver variability roughly one third of these values. The interobserver variability coefficient in normals was 3.6% for deltaV(HCA), 4.7% for deltaV(HC) and 7.3% for deltaV(A). The intraobserver variability coefficient was 3.4% for deltaV(HCA), 4.2% for deltaV(HC) amd 5.6% for deltaV(A). The variability in patients was the same for volume differences less than 5% either side of the interval for normality, but was higher when large volume differences were encountered, is probably due to the lack of thresholding and/or normalisation. Cutoff values for lateralisation with the deltaV were defined. No intra- or interobserver lateralisation differences were encountered with deltaV(HCA) and deltaV(HC). From these observations we conclude that the manual ray-tracing method is a robust method for lateralisation in patients with TLE. Due to its higher variability, this method is less suited to measure absolute volumes.

Preparation de cette phase de plus fort pouvoir de retention envers les composes polaires que les gels de silice

A new derivatized silica gel to which a polyol is bonded is investigated as a stationary phase for high-performance liquid chromatography. Efficient separations of polar compounds (carbohydrates, alkaloids, phenols, proteins) have been realized using straight-phase or normal adsorption chromatography and also with reversed-phase solvent systems. The polarity of the new phase is similar to or higher than that of silica gel itself, but the selectivity is different. A very high percentage of modifier can be used in straight-phase chromatography on Polyol-RSiL. This stabilizes the results and increases the potential interest for straight-phase techniques.

The complexation of several tannic acids (purified tannins) with soluble and insoluble proteins has been studied by high-performance liquid chromatography, Tannins are analysed in both the straight phase and the reversed-phase mode. Bovine serum albumin (BSA) and beer proteins were chromatographed in the size exclusion mode. Soluble proteins seem to complex preferentially with the higher molecular weight tannin polygalloyl glucose components, whereas insoluble standardized hide powder binds preferentially to lower molecular weight tannin components. The tanning capacity of different tannic acids can be expressed in milligrams of BSA bonded per milligram of tannin under standard conditions.

The selectivity, polarity and retentivity in normal-phase high-performance liquid chromatography of polyol- and polyphenol-derivatized silica gels were compared with those of non-derivatized silica gel and amino- and cyanopropyl-derivatized silica gels, using a polarity mixture containing anisole, nitrobenzene, diethyl phthalate, acetophenone, anthraquinone, benzhydrol, benzoic acid and benzanilide with a hexane-dioxane mobile phase. Both polyphenol-bonded silica gel and polyol-bonded silica gel were more polar than silica gel, as indicated by the higher retentivities and higher slopes of the graphs of the logarithm of k ′ against the logarithm of the molar fraction of the stronger solvent in a binary solvent system.

This contribution to the problems of carbohydrate (sugar) column liquid chromatography, evaluates several currently used systems (reversed phase octadecylated silica gel, amino modified silica gel, cation exchangers on polystyrene and on silica gel basis, polyol derivatised silica gel and anion exchange systems). The elution pattern, analysis time, column efficiency and column life time expectancy are considered to be the important points for this comparison. The application of silica gel-based cation exchanger and of polyol derivatised silica gel is new to this field. The comparison and/or evaluation tries to be critical and to come to a conclusion for the choice of a recommended system.

Conventional and microscale liquid chromatographic (micro-LC) systems were compared for the determination of piperine in pepper and pepper extracts. A polyphenol-derivatized silica gel was used in normal-phase adsorption chromatgoraphy and with anthraquinone as an internal standard. Differences in capacity ratios (k′) and in selectivities (α) were noted and are discussed. The standard deviation of the analysis is smaller for micro-LC, but the reasons are not obvious. Advantages claimed for micro-LC (better efficiency, permeability and quantitation) are illustrated.