Low molecular weight halocarbons in the Humber and Rhine estuaries determined using a new purge-and-trap gas chromatographic method

A number of chlorinated and brominated low molecular weight hydrocarbons (halocarbons) have been measured in and adjacent to the North Sea estuaries of the Humber and the Rhine. The measurements have been carried out using a newly constructed purge-and-trap sample work-up system coupled to megabore gas chromatography with electron capture detection. The results show that whereas the Humber is a pronounced source of the anthropogenic halocarbons carbon tetrachloride and perchloroethylene, the input from the Rhine into the North Sea of these compounds is more modest. Some halocarbons normally considered as mainly or even exclusively of natural origin are released from the two investigated estuaries into the North Sea. A distinct patch of high concentrations of the naturally produced compound bromoform was observed in the southwestern North Sea. The results have also been used to examine some of the halocarbons for common sources.

The Influence of Inert Packaging on the shelf Ageing of Gamma-Irradiation Sterilised ultra-high molecular weight polyethylene

Ultra-high molecular weight polyethylene (UHMWPE) is used for wear applications in total hip prostheses and total knee prostheses. Sterilisation of these prostheses is commonly by gamma-irradiation. This process creates reactive free radicals in the UHMWPE, greatly increasing its susceptibility to oxidative degradation. This study has investigated the influence of air and vacuum packaging on the properties of gamma-irradiated UHMWPE (GUR1050) following 3 years of shelf ageing. The findings indicate that vacuum packaging minimises oxidative degradation reactions that occur for UHMWPE during shelf ageing. However, gamma-irradiation of vacuum-packaged UHMWPE promotes a degree of cross-linking. It is proposed that this may enhance the wear performance of UHMWPE. Accelerated ageing studies indicate that 3 years of shelf ageing would also seem to reduce the susceptibility of gamma-irradiated UHMWPE to oxidative degradation upon removal from its vacuum packaging.

Studies on the immunoglobulin E responses to Teladorsagia circumcincta in sheep: purification of a major high molecular weight allergen.

Studies on the immunoglobulin (Ig)E immune responses to the gastric nematode, Teladorsagia circumcincta, have demonstrated a major high molecular weight allergen (HMWTc). Cross reactive allergens of similar MW were demonstrated for Trichostrongylus colubriformis and Cooperia curticei, but not for Haemonchus contortus. Purification of HMWTc was achieved by gel-filtration chromatography, and nonreducing SDS-PAGE and Western blot analysis revealed two closely associated bands with a molecular weight of approximately 140-150?kDa. Reduction showed four IgE reactive bands of 120, 50, 45 and 30?kDa, and deglycosylation abrogated the immunoreactivity of the 120 and 30?kDa bands. Ultrastructural immunolocalization by electron microscopy revealed that the IgE reactivity was confined to the cuticular surface of the infective (L3) larvae. ELISA studies to determine the IgE anti-HMWTc responses in lambs during their first grazing season, demonstrated significantly higher IgE antibody in lambs with low accumulative faecal egg count (FEC) compared to animals with high accumulative FEC. These studies provide evidence for a protective function of IgE antibody in Teladorsagia infections in lambs.

Determination of the molecular weight distribution of non-enzymatic browning products formed by roasting of glucose and glycine and studies on their effects on NADPH-cytochrome c-reductase and glutathione-S-transferase in Caco-2 cells

After thermal treatment of a mixture of glucose and glycine for 2 h at 125 degreesC, about 60% of the starting material was converted into nonsoluble, black pigments, whereas 40% of the mixture was still water-soluble. Dialysis of the latter fraction revealed 30.4% of low molecular weight compounds (LMWs; MW <10 000 De) and 10.0% high-molecular weight products [HMWs; MW greater than or equal to 10000 Dal. The water-soluble Maillard reaction products (MRPs) were separated by gel permeation chromatography and ultrafiltration, revealing that 60% of the water-soluble products of the total carbohydrate/amino acid mixture had MWs <1 000 Da and consisted mainly of non-coloured reaction products. MRPs with MWs between 1000 and 30000 Da were Found in comparatively low yields (about 1.3%). In contrast, about 31.1% of the MRPs exhibited MWs > 30000 Da, amongst which 14.5% showed MWs > 100000 Da, thus indicating an oligomerisation of LMWs to melanoidins under roasting conditions. To investigate the physiological effects of these MRPs, xenobiotic enzyme activities were analysed in intestinal Caco-2 cells. For Phase-I NADPH-cytochrome c-reductase, the activity in the presence of the LMW and HMW fraction was decreased by 13% and 22%: respectively. Phase-II glutathione-S-transferase activity decreased by 15% and 18%, respectively, after incubation with the LMW and the HMW fractions. Considering the different yields, 30% and 10%, respectively, of the LMW and the HMW fractions, the total amount of the LMW fraction present in the glucose-glycine mixture is more active in modulating three enzyme activities than that of the HMW fraction.

A low molecular weight hydro and organogelator derived from an isohexide and sol-gel transcription of the alcogel

Heating 2,5-di-O-methanesulfonyl-1,4:3,6-dianhydro-D-sorbitol (1) in a range of solvents led to the formation of a gel state at low concentrations. 1 was found to gel aromatics, alcohols and water. The structure of 1 in the solid state was solved by single crystal X-ray crystallography; no strong hydrogen bonds or associated solvents were found in the crystal. Electron micrographs revealed the morphology of the gels to be predominantly rod-like. The ethanol alcogel was used to template silica by sol-gel transcription.

Use of a novel micro-fluidic device to create arrays for multiplex analysis of large and small molecular weight compounds by surface plasmon resonance

There is an increasing demand to develop biosensor monitoring devices capable of biomarker profiling for predicting animal adulteration and detecting multiple chemical contaminants or toxins in food produce. Surface plasmon resonance (SPR) biosensors are label free detection systems that monitor the binding of specific biomolecular recognition elements with binding partners. Essential to this technology are the production of biochips where a selected binding partner, antibody, biomarker protein or low molecular weight contaminant, is immobilised. A micro-fluidic immobilisation device allowing the covalent attachment of up to 16 binding partners in a linear array on a single surface has been developed for compatibility with a prototype multiplex SPR analyser.

The immobilisation unit and multiplex SPR analyser were respectively evaluated in their ability to be fit-for-purpose for binding partner attachment and detection of high and low molecular weight molecules. The multiplexing capability of the dual technology was assessed using phycotoxin concentration analysis as a model system. The parent compounds of four toxin groups were immobilised within a single chip format and calibration curves were achieved. The chip design and SPR technology allowed the compartmentalisation of the binding interactions for each toxin group offering the added benefit of being able to distinguish between toxin families and perform concentration analysis. This model is particularly contemporary with the current drive to replace biological methods for phycotoxin screening.

Low molecular weight measles immunoglobulin M in subacute sclerosing panencephalitis and acute measles

Thirty eight patients with subacute sclerosing panencephalitis (SSPE) were investigated. Five patients who previously had measles immunoglobulin M (IgM) detected in unfractionated serum and cerebrospinal fluid (CSF) had measles IgM exclusively in the low molecular weight (LMW) fractions of serum and CSF. Measles IgM had previously not been found in unfractionated serum from 33 patients but was detected exclusively in the LMW fractions of serum from 30 patients. Seven children with acute measles had the expected high molecular weight (HMW) measles IgM in serum but 5 also had LMW measles IgM. Four young adults who had had measles in childhood had neither HMW nor LMW measles IgM in their sera.