The influence of mixed solvents volatility on charge state distribution of peptides during positive electrospray ionization mass spectrometry

Understanding the mechanisms that control and concentrate the observed electrospray ionisation (ESI) response from peptides is important. Controlling these mechanisms can improve signal-to-noise ratio in the mass spectrum, and enhances the generation of intact ions, and thus, improves the detection of peptides when analysing mixtures. The effects of different mixtures of aqueous: organic solvents (25, 50, 75%; v/v): formic acid solution (at pH 3.26) compositions on the ESI response and chargestate distribution (CSD) during mass spectrometry (MS) were determined in a group of biologically active peptides (molecular wt range 1.3 - 3.3 kDa). The ESI response is dependent on type of organic solvent in the mobile phase mixture and therefore, solvent choice affects optimal ion intensities. As expected, intact peptide ions gave a more intense ESI signal in polar protic solvent mixtures than in the low polarity solvent. However, for four out of the five analysed peptides, neither the ESI response nor the CSD were affected by the volatility of the solvent mixture. Therefore, in solvent mixtures, as the composition changes during the evaporation processes, the pKb of the amino acid composition is a better predictor of multiple charging of the peptides

High performance liquid chromatography coupled to electrospray ionisation mass spectrometry method for the detection of salivary human neutrophil alpha defensins HNP1, HNP2, HNP3 and HNP4

Human neutrophil alpha defensins are antimicrobial peptides involved in the first line of defence against invading pathogens. To develop a deeper understanding of the immune responses in relation to airway inflammation and exercise induced epithelial damage it is necessary to have a sensitive method that can detect these peptides in a saliva matrix. A selective and sensitive Liquid Chromatography Mass Spectrometry (LC-MS) method for the detection of four salivary HNP (HNP1, HNP2, HNP3 and HNP4) peptides has been developed and validated. The LC-MS responses of HNPs 1-3 were compared with the response obtained from the traditionally used enzyme-linked immunosorbent assay (ELISA) that measures the combined levels of these three defensins. The peptides were separated on a Phenomenex Kinetex® C8 column (50 x 3.0 mm, 2.6 µm) on an Agilent 1200 series HPLC system using a linear MeOH: H2O: acetic acid (0.1% v/v) gradient. The HPLC was coupled to a Waters Synapt G1 Electrospray Quadrupole Time of Flight mass spectrometer. A full scan range from 100-2000 m/z in the positive ion mode was used for the acquisition. The LC-MS method was linear for concentrations of HNP2 between 0.05 and 1 ng/µL with a LOD of 0.05 ng/µL and LOQ of 0.1 ng/µL. Inter- and intra- assay precisions (%CV) were 0.3 and 14.95%, respectively. HNPs were extracted from saliva by solid-phase extraction (SPE) with a recovery of 80-91%. The cross-validation data revealed no significance quantitative difference between LC-MS and ELISA (R2= 0.96) and confirms that the developed LC-MS method is a reliable method for the detection of these antimicrobial markers. However, superior selectivity in the developed LC-MS method provides a unique opportunity to assess individual alpha defensin levels in the same assay. HNP1, HNP2, HNP3 and HNP4 were evaluated in young athletes before, and up to, 2.5 h after an exercise intervention in order to assess if the developed LC-MS method was sensitive enough to detect rapid changes in their relative levels

The inhibition of anaerobic digestion by model phenolic compounds representative of those from Sargassum muticum

Practical yields of biogas from the anaerobic digestion of macroalgae, and Sargassum muticum in particular, are substantially below the theoretical maximum. There is considerable conjecture about the reasons for the relatively low practical methane yields from seaweed and polyphenols are suggested as one of the elements in the low yield of methane from brown seaweeds. However, there appears to be little information on the effect of specific phenolics on defined substrates. This paper examines the effect of some simple phenolic compounds, representative of those reported in Sargassum muticum, on methane production from a range of model substrates. Three simple phenolics were selected, gallic acid, epicatechin and phloroglucinol; at four addition levels, 0, 0.5, 3.5 and 7.5% w/w of substrate; for four substrates, a readily digested simple organic substance, glycerol, and three polymers found in seaweed, cellulose, alginic acid and the sodium salt of alginic acid. Alginic acid and its sodium salt were found to be recalcitrant with average methane yields equivalent to only 23% - 28% of their theoretical methane potential. Methane yield was further reduced by the presence of high concentrations (7% of substrate equivalent to 17.5 mg L-1) of phloroglucinol and epicatechin. None of the phenolic compounds studied appeared to inhibit the breakdown of the simple and readily digested compound, glycerol. Low methane yield in seaweed may be due to the recalcitrance of complex hydrocolloids and phenolic inhibition of the breakdown of more complex molecules in the initial hydrolysis stage of anaerobic digestion, but further research is required

A review of seaweed pre-treatment methods for enhanced biofuel production by anaerobic digestion or fermentation

Macroalgae represent a potential biomass source for the production of bioethanol or biogas. Their use, however, is limited by several factors including, but not restricted to, their continuous supply for processing, and low biofuel yields. This review examines recent pre-treatment processes that have been used to improve the yields of either biogas or bioethanol from macroalgae. Factors that can influence hydrolysis efficiency and, consequently, biofuel yields, are highly affected by macroalgal composition, including content of salts, heavy metals, and polyphenols, structural make-up, as well as polysaccharide composition and relative content of carbohydrates. Other factors that can influence biofuel yield include the method of storage and preservation

A multi-ingredient containing, proteins, carbohydrate and creatine does not attenuate humoral immune response or performance decrease compared to carbohydrate during resistance training

Background: Nowadays, only carbohydrate has shown to be an effective countermeasure to exercise-induced immune dysfunction while the effect of protein remains controversial. The purpose of this study was to investigate the acute effects of a commercially available multi-nutrient supplement on performance and salivary markers of humoral immunity, following a bout of circuit resistance training in young athletes. Methods: Twelve recreationally resistance-trained males (age: 22 ± 1.4 years; body mass 79 ±9.78 kg; 1.81 ± 0.07 m height) volunteered to participate in the study completing 2 randomised controlled circuit resistance training sessions (CT). Participants ingested 2 doses of 500ml of water mixed 60g of a multi-ingredient (MTN) containing whey proteins, carbohydrate, creatine, HMB and sodium bicarbonate or maltodextrin (PL). Beverages were consumed (3 doses of ~166ml) during and after the workout (1 × 500ml). Both MTN and PL looks the same colour and flavour and provide a similar amount of calories (~230 per serving). CT involved three rounds of 7 resistance exercises (CMJs, Bench Press, Parallel-Squat, Upright row, Alternate Lunges, Dead Lift, Push-press, Abdominals) followed by 1 min rest. Participants performed 12 repetitions at 70% 1RM in each of the exercises with no rest in between (only the time to change from one exercise to the next). Measurements included pre and post (30 min and 60 min) salivary markers of humoral immune response: Antimicrobial Peptide, Alpha Defensins (HNP 1-3). The total kg lifted per exercise and in the overall workout was considered as indicator of performance. ANOVA design and Cohen d effect sizes (ES) were used to analyse potential differences between times and treatment conditions. Results: No significant differences were observed between the total weight (kg) lifted per exercise or for the entire session (p > 0.05). HNP 1-3 showed a strong trend (p = 0.06) with a moderate effect size (d = 0.53) at 30 min for the CHO condition [2.001 (1.95) vs 3.037 (2.49) ng/mL], nevertheless, no significant differences were observed at 60 min with respect to the values measured at both pre [3.825 (3.21) vs 2.001 (1.95) ng/mL] and 30 min [3.825 (3.21) vs 3.037 (2.49) ng/mL]. On the other side, HNP 1-3 did not increase at either 30 min [2.464 (3.31) vs 3.656 (3.22) ng/mL] or 60 min [2.464(3.31) vs 2.387 (2.46) ng/mL] post workout for the MTN treatment condition. No differences were observed between the two tested treatment conditions for the three analysed times points (pre, post 30 min and post 60 min). Conclusion: Ingesting both MTN and CHO supplements during and after a circuit resistance-training workout, resulted in no impact on performance. However, even when both nutritional interventions were effective to attenuate the increase of antimicrobial peptide alpha-defensins, MTN showed a stronger effect to blunt exercise-induced immune-dysfunction. These results did not support the notion that only carbohydrate with no added proteins is the only effective nutritional countermeasure against the transient post exercise immunosuppression

Poly(alkyl methacrylate) tooth coatings for dental care: evaluation of the demineralisation-protection benefit using a time-resolved in vitro method

An in vitro method for the time-resolved quantification of acid-mediated tooth demineralisation has been developed and evaluated against putative non-permanent protective formulations based on a series of poly(alkyl methacrylate)s. Using a thermostatted carousel, dentally relevant substrates consisting of hydroxyapatite discs or sections of bovine teeth have been exposed to aqueous citric acid under controlled conditions, before and after being treated with the polymeric coatings. The dissolution of phosphate was monitored by the determination of 31P by Inductively Coupled Plasma—Mass Spectrometry and by the spectrophotometric phosphovanadomolybdate method. Dose-response plots constructed for both groups of treated substrates have revealed that the coatings significantly reduce erosion rates but are less effective at inhibiting tooth demineralisation than the standard fluoride treatment. The approach has enabled an evaluation of the erosion-protection efficiency of each coating

Women's experiences of their osteoporosis diagnosis at the time of diagnosis and 6 months later: A phenomenological hermeneutic study

This paper describes a phenomenological hermeneutic study of experiences of women who were recently diagnosed with osteoporosis. The research objective was to investigate women's experiences of living with osteoporosis during the first 6 months after diagnosis when treatment was first prescribed. Fifteen women were included in the study. The inclusion criteria were a DXA scan at one of the two hospitals showing a T-score below −2.5 (lower back or hip), age 65 years or older; no previous known osteoporotic fracture; at least one of the known risk factors for osteoporosis; and prescription of anti-osteoporotic treatment. Exclusion criteria were previous diagnosis of osteoporosis or previous treatment with anti-osteoporotic medication. Data were collected through in-depth interviews shortly after diagnosis and 6 months later. The performed analyses were inspired by Paul Ricoeur's theory of interpretation of texts comprising three levels: naïve reading, structural analysis, and critical interpretation and discussion. Three key themes emerged: 1) being diagnosed, 2) being prescribed medical treatment, and 3) being on the path of learning to live with osteoporosis. The findings suggest a need for improved support for the patients to gain understanding of their diagnosis and the risk of osteoporotic fracture as well as to learn to live with osteoporosis. The study highlights new health promotion areas for targeting interventions at newly diagnosed patients, helping them accept and interpret the diagnosis, and the medical treatment

The Effects of Halogenated Compounds on the Anaerobic Digestion of Macroalgae

The urgent need to replace fossil fuels has seen macroalgae advancing as a potential feedstock for anaerobic digestion. The natural methane productivity (dry weight per hectare) of seaweeds is greater than in many terrestrial plant systems. As part of their defence systems, seaweeds, unlike terrestrial plants, produce a range of halogenated secondary metabolites, especially chlorinated and brominated compounds. Some orders of brown seaweeds also accumulate iodine, up to 1.2% of their dry weight. Fluorine remains rather unusual within the chemical structure. Halogenated hydrocarbons have moderate to high toxicities. In addition, halogenated organic compounds constitute a large group of environmental chemicals due to their extensive use in industry and agriculture. In recent years, concerns over the environmental fate and release of these halogenated organic compounds have resulted in research into their biodegradation and the evidence emerging shows that many of these compounds are more easily degraded under strictly anaerobic conditions compared to aerobic biodegradation. Biosorption via seaweed has become an alternative to the existing technologies in removing these pollutants. Halogenated compounds are known inhibitors of methane production from ruminants and humanmade anaerobic digesters. The focus of this paper is reviewing the available information on the effects of halogenated organic compounds on anaerobic digestion

Influence of electrolytes and a supercharging reagent on charge state distribution and response of neuropeptide ions generated during positive electrospray ionisation mass spectrometry

To aid in the detection of trace quantities of neuropeptides in a biological matrix (as saliva), the influence of different electrolytes and a supercharging reagent on the positive electrospray ionisation mass spectrometry (ESI-MS) response was investigated. Ammonium acetate, sodium chloride and sodium bicarbonate (10–7 M to 10–3 M) and the supercharging reagent m-nitrobenzyl alcohol (m-NBA) was added to the mobile phase and the effect on the ESI response and charge-states distribution (CSD) was studied in a group of peptides (molecular weight range 2.2 kDa to 3.5 kDa; CGRP, VIP, GLP1, CRF and PrRP). As expected, the result indicates that the ESI response is affected by the presence of additives: ammonium acetate shifted the observed charge states ratio whereas the addition of m-NBA resulted in the appearance of higher maximum charge state ions. This increase in higher charge state for all the peptide ions, [M + nH]n+ to [M + (n +?1)H]n + 1, was atttributed to protonation of the C-terminal. However, when the composition of MeCN in a mobile phase �containing m-NBA was increased, an enhancement of the total ion signal was observed for non-polar peptide samples. This is a very interesting observation as this is not observed in samples without m-NBA and could be a result of how these peptide ions are solubilised and �positioned relative to the droplet surface/air interface