Biomedical subjects

Pearse McCarron

Publications and source records attributed to Pearse McCarron.

5 recordsLinked to original sources

PubMed2007

Feasibility of gamma irradiation as a stabilisation technique in the preparation of tissue reference materials for a range of shellfish toxins.

The effect of gamma-irradiation on concentrations of hydrophilic and lipophilic phycotoxins has been investigated by use of HPLC-UV and LC-MS. Pure toxins in organic solvents and toxins in mussel (Mytilus edulis) tissues were irradiated at three different doses. In solution all toxin concentrations were reduced to some extent. Most severe decreases were observed for domoic acid and yessotoxin, for which the smallest dose of irradiation led to almost complete destruction. For pectenotoxin-2 the decrease in concentration was less severe but still continuous with increasing dose. Azaspiracid-1 and okadaic acid were the least affected in solution. In shellfish tissue the decrease in toxin concentrations was much reduced compared with the effect in solution. After irradiation at the highest dose reductions in concentrations were between ca. 5 and 20% for the lipophilic toxins and there was no statistical difference between control and irradiated samples for azaspiracids in tissue. Irradiation of shellfish tissues contaminated with domoic acid led to a more continuous decrease in the amount of the toxin with increasing dose. The effect of irradiation on the viability of microbial activity in shellfish tissues was assessed by using total viable counting techniques. Microbial activity depended on the type of shellfish and on the pretreatment of the shellfish tissues (with or without heat treatment). As far as we are aware this is the first investigation of the effectiveness of irradiation as a technique for stabilising tissue reference materials for determination of phycotoxins. Our results suggest that this technique is not effective for materials containing domoic acid. It does, however, merit further investigation as a stabilisation procedure for preparation of shellfish tissue materials for some lipophilic toxins, in particular azaspiracids. Chemical structures of the toxins investigated in the study.

Animals↗

PubMed2006

Effect of addition of antibiotics and an antioxidant on the stability of tissue reference materials for domoic acid, the amnesic shellfish poison.

Five separate reference materials (RMs) were prepared from a mussel (Mytilus edulis) tissue containing domoic acid (DA) from scallop hepatopancreas (Pecten maximus). Homogenates were separately spiked with antibiotics, an antioxidant, or a combination of both. Control materials did not contain any additives and were prepared from lightly cooked and autoclaved mussel tissues. Stability studies were run over a 148-day period at three different temperature conditions: -20 degrees C, +4 degrees C and +40 degrees C. DA contents in all materials were characterised by HPLC-UV. Homogeneities were demonstrated at the beginning of the study, with coefficients of variance of less than 4% (n = 9). DA was stable at -20 degrees C in all materials. The control materials showed significant degradation after two days at +40 degrees C, and after eight days at +4 degrees C. Each of the materials containing additives demonstrated better stability during the initial period of the study. In addition there was no significant degradation in any of the materials with additives stored at +4 degrees C over the duration of the study. The material containing a combination of the antibiotics and the antioxidant displayed the best stability of all the materials. There was no significant reduction in DA concentration at all temperature conditions after eight days, and after 32 days the decrease at +40 degrees C was still <20 %. Following this, a DA laboratory reference material (LRM) was prepared and, based on previous results, spiked with both the antioxidant and antibiotics. A short-term stability study on this material gave similar results to the corresponding material in the additives study. This study shows that combined use of the additives investigated in the preparation of a mussel tissue reference material for DA ensures analyte stability for a period of up to eight days at temperatures of up to +40 degrees C, a condition that is particularly important when shipping test materials globally. Aliquots of individual feasibility materials used in the study.

Animals↗

PubMed2006

Fit-for-purpose shellfish reference materials for internal and external quality control in the analysis of phycotoxins.

The need for reference materials for quality control of analysis of foodstuffs has been stressed frequently. This has been particularly true in the phycotoxins field, where there is a great shortage of both pure calibration standards and reference materials. Worldwide there are very few independent bodies that produce certified reference materials for phycotoxins, the main producers currently being the National Research Council Canada and the Japanese Food Research Laboratory. Limited availability of contaminated shellfish and algae, as well as the time and knowledge necessary for the production of adequate reference materials, continuously lead to limited editions of certified reference materials and even more limited production of in-house reference materials. The restricted availability of in-house quality control materials promotes the rapid use of the limited certified reference materials, which in turn hampers the production of the suite of materials required globally for complete protection of public health. This paper outlines the various options that analysts can pursue in the use of reference materials for internal and external quality control, with a view to optimising the efforts of both reference materials users and reference materials producers. For this purpose, the logical sequence is reviewed from the discovery of a new bioactive compound in shellfish, through initial method development up to regulation for food safety purposes including accepted reference methods. Subsequently, the requirements for and efforts typically spent in the production and characterisation of laboratory reference materials, certified reference materials and other test materials used in inter-laboratory studies or proficiency testing, in the area of marine biotoxins are evaluated. Particular emphasis is put on practical advice for the preparation of in-house reference materials. The intricate link between reference material characterisation and method performance is outlined to give guidance on the appropriate in-house method validation in the rapidly developing field of phycotoxins.

Animals↗

PubMed2006

Tissue distribution and effects of heat treatments on the content of domoic acid in blue mussels, Mytilus edulis.

The effect of heat treatment on domoic acid (DA) content in soft tissues of mussels Mytilus edulis was investigated using high performance liquid chromatography. DA concentrations in whole flesh, hepatopancreas and tissue remainder were measured in fresh, steamed and autoclaved mussel flesh. Relative decreases in DA and tissue fluid following heat treatments of whole flesh were similar resulting in approximately equal concentrations of DA pre- and post-treatment. DA concentration decreased in the hepatopancreas and increased in tissue remainder suggesting some organ disruption of mussels during heat treatment. These findings suggest that heat treatments using either conventional steaming or autoclaving at 121 degrees C are not appropriate techniques to reduce DA in mussels during commercial processing. We also conclude that sample pre-treatment has a minimal effect on the result of a DA analysis on whole mussel tissues. The stability of DA at different temperatures within a shellfish matrix was separately tested. Reductions in DA concentration (ca. 3-7%) compensate for some of the discrepancies between what was found in the cooking fluids in the initial study and what was expected based on the whole flesh concentration of the uncooked material.

Animals↗

PubMed2005

Tissue distribution, effects of cooking and parameters affecting the extraction of azaspiracids from mussels, Mytilus edulis, prior to analysis by liquid chromatography coupled to mass spectrometry.

This study used liquid chromatography coupled to mass spectrometry to identify some parameters important in the analysis of azaspiracids. The first aspect was the distribution of azaspiracids within mussels, in particular the content in the digestive gland as compared to the remaining tissues. In our study, azaspiracids accumulated in the digestive gland, similar to other lipophilic toxins. The ratio of toxin in the digestive gland compared to the whole mussel was on average circa 5, both for a bulk sample collected in Norway in 2004 and for 28 samples from Ireland collected over 3 years (2001-2003). These results may justify the practise to only analyse the digestive gland, a step considered necessary to achieve adequate detection limits for azaspiracids both in the mouse bioassay and other analytical techniques. Steaming of mussels as a sample pre-treatment was found to be another parameter affecting the result. Azaspiracids concentrated indirectly, i.e. through the loss of water or juice from the matrix. The cooked shellfish tissues had a concentration of azaspiracids 2-fold higher than the uncooked shellfish, both for whole flesh and for digestive gland tissue. This finding is of particular importance since it may affect the maximum guidance level at which shellfish may be allowed for human consumption. Finally, parameters affecting the extraction efficiency were studied, including the nature of the extraction solvent, the sample-to-solvent ratio and replicate extraction. The largest differences were observed between different solvents and between different sample-to-solvent ratios, while the effect of replicate extraction was minimal if large sample-to-solvent ratios were used. Duplicate extraction using 100% methanol was found to be the best combination of parameters.

Animals↗