Impact of atmospheric pressure variations on aerobic biodegradation test.

Biodegradation rate is an important index to evaluate the environmental risk of chemicals, which is usually determined by measuring oxygen consumption through respirometer in a biodegradation test. However, atmospheric pressure variations affect reactor oxygen concentration and oxygen volume recorded by respirometer in biodegradation test, and the parameters of reactor volume and test material amount amplify its effect. Atmospheric pressure variation >1 kPa could introduce >20% underestimation in biodegradation rate when a small amount of test material (0.04-0.2 g per 100 g of inoculum) and high reactor volume (2-4 L) were used according to the international standards. A 5 kPa drop in atmospheric pressure leads to a 6% decrease in headspace oxygen concentration in the reactor, which could subsequently inhibit biodegradation microbials and decrease the biodegradation rate by 30%. Moreover, the biodegradation process (oxygen consumption rate) could be accelerated/delayed several times by atmospheric pressure variations compared to the process without variations when the oxygen consumption rate was <5 mL h-1 in a 0.5 or 1 L reactor and <10 mL h-1 in a 2-L reactor. Mitigating the effects of atmospheric pressure variations on biodegradation test includes lowering the reactor volume, increasing the test material amount and recording atmospheric pressure for further modification.

Unusual 'feathery' cause of a parapharyngeal abscess in an infant.

A 7-month-old boy presented to the emergency department with reduced oral intake, neck swelling and fever. Clinical examination revealed a 3 cm left parotid and left level I neck swelling with left medialised tonsil but no trismus. Computed imaging confirmed the presence of an abscess in the peritonsillar area with extension into the parapharyngeal space and deep lobe of the parotid gland. The abscess was incised and drained transorally. Following drainage of the abscess, a small 3 mm suspicious foreign body was seen. After extraction, this was revealed to be a 60 mm feather. We would like to highlight this unusual case in an infant and to ensure that foreign body is considered as aetiology. There are only a handful of cases in the literature involving feathers causing neck abscesses and, to our knowledge, this is the first case where the patient presented with a pharyngeal abscess, which was drained transorally.

Evaluating the influences of mixing strategies on the Biochemical Methane Potential test.

Mixing plays an important role in the Biochemical Methane Potential (BMP) test, but only limited efforts have been put into it. In this study, various mixing strategies were applied to evaluate the influences on the BMP test, i.e., no mixing, shaking in water bath, shake manually once per day (SKM), automated unidirectional and bidirectional mixing. The results show that the effects of mixing are prominent for the most viscous substrate investigated, as both the highest methane production and highest maximal daily methane production were obtained at the highest mixing intensity. However, the organic removal efficiencies were not affected, which might offer evidence that mixing helps the release of gases trapped in digester liquid. Moreover, mixing is required for improved methane production when the digester content is viscous, conversely, mixing is unnecessary or SKM might be sufficient for the BMP test if the digester content is quite dilute or the substrate is easily degraded.

Towards a standardization of biomethane potential tests.

Production of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. Although several norms and guidelines for BMP tests exist, inter-laboratory tests regularly show high variability of BMPs for the same substrate. A workshop was held in June 2015, in Leysin, Switzerland, with over 40 attendees from 30 laboratories around the world, to agree on common solutions to the conundrum of inconsistent BMP test results. This paper presents the consensus of the intense roundtable discussions and cross-comparison of methodologies used in respective laboratories. Compulsory elements for the validation of BMP results were defined. They include the minimal number of replicates, the request to carry out blank and positive control assays, a criterion for the test duration, details on BMP calculation, and last but not least criteria for rejection of the BMP tests. Finally, recommendations on items that strongly influence the outcome of BMP tests such as inoculum characteristics, substrate preparation, test setup, and data analysis are presented to increase the probability of obtaining validated and reproducible results.

Impacts of inoculum pre-treatments on enzyme activity and biochemical methane potential.

Biochemical methane potential (BMP) tests were carried out to investigate the influence of inoculum pre-treatments (filtration and pre-incubation) on methane production from cellulose and wheat straw. First-order model and Monod model were used to evaluate the kinetic constants of the BMP assays. The results demonstrated that fresh inoculum was the best option to perform BMP tests. This was evidenced by highest enzyme activity (0.11 U/mL) and highest methane yields for cellulose (356 NmL CH4/gVS) as well as wheat straw (261 NmL CH4/gVS). Besides, high biodegradability (85.8% for cellulose and 61.3% for wheat straw) was also obtained when the fresh inoculum was used. Moreover, a kinetic evaluation showed that inoculum pre-incubation at 37°C or storage at 4°C introduced a lag-time whereas the effects on hydrolysis rate were less consequent. In summary, pre-treatments affected the enzyme activity of the inoculum, and further on, significantly influenced the methane production and the degradation kinetics of the investigated substrates. It is recommended that filtration of inoculum should be avoided unless in case too large particles therein.

Effects of substrate concentration on methane potential and degradation kinetics in batch anaerobic digestion.

In this study, two experiments were conducted to evaluate the impact of substrate concentrations on methane potential and degradation kinetics of substrate. The biochemical methane potential (BMP) tests in Experiment I were performed at a constant inoculum to substrate ratio (ISR), whereas, different ISRs were applied in Experiment II. Results obtained from Experiment I revealed that methane potential of substrate increased at a saturating trend with higher substrate concentrations, and could differ by up to 30% between the lowest and highest investigated concentrations. The results of Experiment II verified the results of Experiment I, and further showed that this trend also occurs when the substrate concentration is regulated with ISRs. In contrast, substrate concentration had no significant impact on the degradation kinetics. It was concluded that dilutions should be avoided when the substrate concentration is lower than 10 g VS/L in order to avoid underestimations of methane potential from BMP test.

Early prediction of Biochemical Methane Potential through statistical and kinetic modelling of initial gas production.

A major drawback of Biochemical Methane Potential (BMP) tests is their long test duration, which could be reduced substantially if the final gas production could be predicted at an earlier stage. For this purpose, this study evaluates 61 different algorithms for their capability to predict the final BMP and required degradation time based on data from 138 BMP tests of various substrate types. By combining the best algorithms it was possible to predict the BMP with a relative root mean squared error (rRMSE) of less than 10% just 6days after initiation of the experiment. The results from this study indicate that there is a possibility to shorten the test length substantially by combining laboratory tests and intelligent prediction algorithms. Shorter test duration may widen the possible applications for BMP tests in full-scale biogas plants, allowing for a better selection and proper pricing of biomass.

Towards eliminating systematic errors caused by the experimental conditions in Biochemical Methane Potential (BMP) tests.

The Biochemical Methane Potential (BMP) test is increasingly recognised as a tool for selecting and pricing biomass material for production of biogas. However, the results for the same substrate often differ between laboratories and much work to standardise such tests is still needed. In the current study, the effects from four environmental factors (i.e. ambient temperature and pressure, water vapour content and initial gas composition of the reactor headspace) on the degradation kinetics and the determined methane potential were evaluated with a 2(4) full factorial design. Four substrates, with different biodegradation profiles, were investigated and the ambient temperature was found to be the most significant contributor to errors in the methane potential. Concerning the kinetics of the process, the environmental factors' impact on the calculated rate constants was negligible. The impact of the environmental factors on the kinetic parameters and methane potential from performing a BMP test at different geographical locations around the world was simulated by adjusting the data according to the ambient temperature and pressure of some chosen model sites. The largest effect on the methane potential was registered from tests performed at high altitudes due to a low ambient pressure. The results from this study illustrate the importance of considering the environmental factors' influence on volumetric gas measurement in BMP tests. This is essential to achieve trustworthy and standardised results that can be used by researchers and end users from all over the world.

Determination of methane yield of cellulose using different experimental setups.

In this work, biochemical methane potential (BMP) tests with cellulose as a model substrate were performed with the aid of three manually operated or conventional experimental setups (based on manometer, water column and gas bag) and one automated apparatus specially designed for analysis of BMP. The methane yields were 340 ± 18, 354 ± 13, 345 ± 15 and 366 ± 5 ml CH4/g VS obtained from experimental setups with manometer, water column, gas bag, and automatic methane potential test system, which corresponded to a biodegradability of 82, 85, 83 and 88% respectively. The results demonstrated that the methane yields of cellulose obtained from conventional and automatic experimental setups were comparable; however, the methane yield obtained from the automated apparatus showed greater precision. Moreover, conventional setups for the BMP test were more time- and labour-intensive compared with the automated apparatus.

Indirect, non-competitive amperometric immunoassay for accurate quantification of calpastatin, a meat tenderness marker, in bovine muscle.

A method is described for quantification of the beef tenderness marker, calpastatin, in meat samples by amperometric detection. Using a novel bovine recombinant partial calpastatin protein as standard antigen a low detection limit of 0.2 ng/mL was achieved. The influence of the complex matrix was minimised by heat pretreatment and dilution of the samples prior to detection of calpastatin. The relative error between the direct sample measurement and standard addition methods was 5.89%, confirming the accuracy of the developed amperometric immunoassay.

Design, development and application of a bioelectrochemical detection system for meat tenderness prediction.

The analytical method described, based on antibody-antigen bio-recognition and the measuring system for amperometric detection, was designed for accurate, easy to use and cost effective quantification of calpastatin, a meat tenderness biomarker. The novel assay for calpastatin quantification was integrated in a portable electrochemical device known as the Tendercheck system and was used to analyze meat samples collected from animals of different breeds and ages. The data obtained were correlated (R² = 0.62) with Warner Bratzler Shear Force (WBSF) measurements, a routinely used method for meat tenderness determination.

Plasma amyloid-ß as a function of age, level of intellectual disability, and presence of dementia in Down syndrome.

Adults with Down syndrome (DS) are at risk for developing Alzheimer's disease (AD). While plasma amyloid-ß (Aß) is known to be elevated in DS, its relationship to cognitive functioning is unknown. To assess this relationship, samples from two groups of subjects were used. In the first group, nondemented adults with DS were compared to: 1) a group of young and old individuals without DS and 2) to a group of patients with AD. Compared to these controls, there were significantly higher levels of plasma Aß in nondemented adults with DS while AD patients showed lower levels of plasma Aß. A larger second group included demented and nondemented adults with DS, in order to test the hypothesis that plasma Aß may vary as a function of dementia and Apolipoprotein E (ApoE) genotype. Plasma Aß levels alone did not dissociate DS adults with and without dementia. However, in demented adults with DS, ApoE4 was associated with higher Aß40 but not Aß42. After controlling for level of intellectual disability (mild, moderate, severe) and the presence or absence of dementia, there was an improved prediction of neuropsychological scores by plasma Aß. In summary, plasma Aß can help predict cognitive function in adults with DS independently of the presence or absence of dementia.

Label free capacitive immunosensor for detecting calpastatin--a meat tenderness biomarker.

An immunological capacitive biosensor for calpastatin was developed, optimized and applied for the analysis of meat extract samples. Anti-calpastatin antibody was immobilized on a gold electrode modified with a self-assembled monolayer of mercaptoundecanoic acid and Protein A from Staphylococcus aureus, and the obtained immunosensor was inserted as the working electrode in an electrochemical cell of a flow injection system. The dynamic range of the sensor was 20 to 160 ng/mL calpastatin. The electrode could be regenerated and re-used for more than 7 days with minimal reduction in sensitivity. For the analysis of real samples, the target analyte was extracted from the Longissimus dorsi muscle from beef carcasses directly after slaughtering. The extract was analyzed both with the developed immunosensor and microtiter plate ELISA, and a good correlation was obtained. However the immunosensor offers advantages of speed, simplicity, sensitivity and possibility for miniaturization over conventional assays for calpastatin quantification.

Monitoring of glucose and glutamate using enzyme microstructures and scanning electrochemical microscopy.

Glucose oxidase and glutamate oxidase lines, with typical width of 100 microm, were patterned on gold surfaces using a micro-dispensing system, by shooting 100 pl droplets of the corresponding enzyme solutions. The probe of a scanning electrochemical microscope (SECM) was then carefully positioned in the close proximity of the enzyme microstructure and poised to +600 mV vs. Ag/AgCl, KCl 0.1 M. The H(2)O(2), generated by the enzyme lines at different concentrations of glucose and glutamate in the surrounding solution, was sequentially monitored. Reproducible calibration curves for glucose and glutamate were obtained in one single experiment, proving that the combination of enzyme microstructures with SECM can provide a new way of achieving multianalyte detection.

Immunization with fibrillar Abeta(1-42) in young and aged canines: Antibody generation and characteristics, and effects on CSF and brain Abeta.

We describe a study testing fibrillar beta-amyloid(1-42) (Abeta42) vaccination in dogs. Three young beagles (4.6 years) were immunized twice with Abeta42 and a Th1 adjuvant (TiterMax Gold). Animals generated primarily IgG2 and IgM antibody responses, which were specific for the Abeta(11-30) region of Abeta(1-42). Next, 3 aged beagles (8.9-13.8 years) were immunized 4 times with Abeta(42) and a Th2 adjuvant (Alum). We observed an acute increase in IgG2, a slower increase in IgG1 and Abeta antibodies of broader specificity (Abeta(1-15>) Abeta(11-30>) Abeta(6-20)). A nonsignificant increase in CSF Abeta(1-40) and decrease in Abeta(1-40/1-42) in cortex was detected. Canines may be a useful system for testing an Abeta vaccine.

Palm tree peroxidase-based biosensor with unique characteristics for hydrogen peroxide monitoring.

Three amperometric enzyme electrodes have been constructed by adsorbing anionic royal palm tree peroxidase (RPTP), anionic sweet potato peroxidase (SPP), or cationic horseradish peroxidase (HRP-C) on spectroscopic graphite electrodes. The resulting H(2)O(2)-sensitive biosensors were characterized both in a flow injection system and in batch mode to evaluate their main bioelectrochemical parameters, such as pH dependency, I(max), K(M)(app), detection limit, linear range, operational and storage stability. The obtained results showed a distinctly different behavior for the plant peroxidase electrodes, demonstrating uniquely superior characteristics of the RPTP-based sensors. The broader linear range observed for the RPTP-based biosensor is explained by a high stability of this enzyme in presence of H(2)O(2). The higher storage and operational stability of RPTP-based biosensor as well as its capability to measure hydrogen peroxide under acidic conditions connect with an extremely high thermal and pH-stability of RPTP.

Reduced neuronal expression of synaptic transmission modulator HNK-1/neural cell adhesion molecule as a potential consequence of amyloid beta-mediated oxidative stress: a proteomic approach.

Abstract Oxidative stress imparted by reactive oxygen species (ROS) is implicated in the pathogenesis of Alzheimer's disease (AD). Given that amyloid beta (Abeta) itself generates ROS that can directly damage proteins, elucidating the functional consequences of protein oxidation can enhance our understanding of the process of Abeta-mediated neurodegeneration. In this study, we employed a biocytin hydrazide/streptavidin affinity purification methodology followed by two-dimensional liquid chromatography tandem mass spectrometry coupled with SEQUEST bioinformatics technology, to identify the targets of Abeta-induced oxidative stress in cultured primary cortical mouse neurons. The Golgi-resident enzyme glucuronyltransferase (GlcAT-P) was a carbonylated target that we investigated further owing to its involvement in the biosynthesis of HNK-1, a carbohydrate epitope expressed on cell adhesion molecules and implicated in modulating the effectiveness of synaptic transmission in the brain. We found that increasing amounts of Abeta, added exogenously to the culture media of primary cortical neurons, significantly decreased HNK-1 expression. Moreover, in vivo, HNK-1 immunoreactivity was decreased in brain tissue of a transgenic mouse model of AD. We conclude that a potential consequence of Abeta-mediated oxidation of GlcAT-P is impairment of its enzymatic function, thereby disrupting HNK-1 biosynthesis and possibly adversely affecting synaptic plasticity. Considering that AD is partly characterized by progressive memory impairment and disordered cognitive function, the data from our in vitro studies can be reconciled with results from in vivo studies that have demonstrated that HNK-1 modulates synaptic plasticity and is critically involved in memory consolidation.