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Biomedical subjects

A E Sherry

Publications and source records attributed to A E Sherry.

9 recordsLinked to original sources
PubMed2006

Evaluation of the use of conductimetry for the rapid and precise measurement of Salmonella spp. growth rates.

The growth rates of 14 Salmonella serovars in tryptone soy broth plus yeast extract (TSBYE) were estimated using conventional plating techniques and indirect conductimetry using a Don Whitley RABIT system. Both methods gave identical results for the maximum specific growth rate (mumax) P>0.05. However, using the conductimetric method, mumax for a single serovar was determined in less than 7 h, whereas the conventional method required an additional 24 h. In addition, the conductimetric method was considerably more precise, much less labour-intensive and required the use of considerably less consumables. Using conductimetry, a trained operator could accurately determine mumax for 24 serovars in 3 working days, but only one serovar using the conventional plate counting technique. Hence, the use of conductimetry can markedly increase the precision and accuracy of mumax determinations by allowing a very significant increase in the number of results obtained and in their precision. The data generated will allow the development of better mathematical growth models. The method can also be used to compare growth media and conditions and hence rapidly optimise detection protocols for this pathogen.

Bacteriological Techniques↗
PubMed2004

Comparison of 40 Salmonella enterica serovars injured by thermal, high-pressure and irradiation stress.

AIM: To investigate and compare the inherent resistance of 40 Salmonella serovars to heat, irradiation and high-pressure stress. METHODS AND RESULTS: D10 values for each of the three stresses were calculated for four serovars, chosen as representatives from a catalogue of 40. Based on these results, conditions for each stress were defined, which produced, on average, a three-log reduction in viability. Heat stress (57 degrees C for 13 min), high-pressure stress (350 MPa for 10 min at 20 degrees C) and irradiation stress (1.5 kGy at 20 degrees C) were applied to all 40 serovars in the collection. Injury and loss of viability for all serovars were determined. CONCLUSIONS: Cluster analysis identified five groupings of isolates in terms of resistance to the applied stresses. The independent response of each isolate to all three stresses suggests that there is no relationship between resistances. SIGNIFICANCE AND IMPACT OF THE STUDY: Each serovar is inherently different. For modelling of real-life food preservation processing the most resistant isolates for that process should be chosen. The results also emphasize the importance of including multiple stress resistant strains when food preservation systems apply multiple stresses.

Food Handling↗
PubMed1977

Column cation-exchange separation of melanin-related metabolites in urine from cases of melanoma.

We describe recent developments in the use of a stable free radical, diphenylpicrylhydrazyl, as a colorimetric detector of reducing metabolites in melanoma urines. A procedure for buffering aqueous/solvent reagent solutions is presented, and examples of the baseline stability achieved for reference chromatograms and urine samples are provided. Chromatograms of phaeomelanin precursors and of an extract of a highly pigmented hamster melanoma are also presented. Identities are tentatively assigned for some of the chromatographic peaks that have previously been correlated with disease, including isomers of cysteinyldopa, and observations of new pigment- and tumor-related metabolites in the chromatograms are noted.

Animals↗