Biomedical subjects

R Macarthur

Publications and source records attributed to R Macarthur.

7 recordsLinked to original sources

PubMed2004

Measurement uncertainty associated with overall migration testing.

The results from a single laboratory that took part in a series of check-sample exercises for overall migration were used to calculate the measurement uncertainty for the overall migration methodology. The results span 10 years of proficiency testing and cover a range of plastic materials tested using a variety of time and temperature test conditions. Twelve sets of results for overall migration into olive oil and 10 sets of results for overall migration into volatile simulants were used. The measurement uncertainty associated with the determination of overall migration from plastics into olive oil was estimated as +/- 2.6 mg dm-2 for results between 1.2 and 15.4 mg dm-2. The measurement uncertainty associated with the determination of overall migration into volatile simulants was estimated as +/- 1.4 mg dm-2 for results between 2.1 and 13 mg dm-2. These estimates are within the analytical tolerances set in European Union regulations, of 3 and 2 mg dm-2, respectively. The performance of all laboratories participating in these 22 check sample exercises was also evaluated. A very large majority (93%) of the participants used official test methods, sometimes with minor modifications as stated. For the simulant olive oil, an average of 81% of laboratories (13 rounds with an average of 21 participants in each) using official methods was within the tolerance specified in regulations. For the volatile food simulants, an average of 87% of laboratories (11 rounds with an average of 38 participants in each) using official methods was within the tolerance specified. It is concluded from this evaluation of within- and between-laboratory data that the official European Standard methods for overall migration testing are suitable for the analysis of routine samples.

Dietary Fats, Unsaturated↗

PubMed2002

Survey of 3-monochloropropane-1,2-diol (3-MCPD) in selected food groups, 1999-2000.

A survey of the levels of 3-monochloropropane-1,2-diol (3-MCPD) in a range of selected food products available in the UK is reported. The survey was carried out on behalf of the Food Standards Agency (FSA) to identify the food groups that might provide a significant contribution to 3-MCPD exposure from the diet. Three hundred samples comprising meat, dairy, cereal, soup and miscellaneous products were purchased from retail outlets and analysed using a GC-MS procedure, which had been formally validated by an earlier collaborative trial. 3-MCPD was detected in 89 (30%) of the samples. Three samples, all crackers, contained levels of 3-MCPD > 0.1 mg kg(-1), the highest level being 0.134 mg kg(-1). Levels of 3-MCPD were generally slightly higher in foods after cooking. In all cases where 3-MCPD was detected in cooked foods, it was also present in the uncooked sample.

Chemosterilants↗

PubMed2002

Survey of stable sulfur isotope ratios (34S/32S) of sulfite and sulfate in foods.

A study was conducted to determine the natural abundance sulfur isotope ratios in foods containing sulphite preservatives. This involved determining (1) the accuracy and repeatability of sulfur isotope ratios measured using an elemental analyser (EA) coupled to an isotope ratio mass spectrometer (IRMS); and (2) the isotope ratios of 21 samples of commercially available S(IV) oxo-anion compounds, nine samples of S(VI) sulfate salts and the isotope ratios of the sulfate obtained by modified Monier-Williams distillation of SO(2) from 33 retail foods containing sulfite preservatives. The sulfur isotope ratio data for SO(2) recovered from foodstuffs showed a large spread of results, which suggested that the SO(2) derived from sulfite preservatives does not have a distinctive sulfur signature ratio. The range of results (3.1-52.1) overlapped with that found for a range of commercially available sulfite and sulfate reagents commonly used to preserve food (sulfites 2.5-13.7, sulfates 10.0-16.9). Whilst the variability in isotope ratios originated from the food samples themselves, evidence from the analysis of SO(2) gas suggested that isotope fractionation during dissolution, reaction and recovery was also a confounding factor.

Barium Sulfate↗

PubMed2000

An improved method for the measurement of added vegetable fats in chocolate.

A method for identifying refined vegetable fats added to chocolate (cocoa butter equivalents, CBEs) was combined with established quantitative methods for determining the level of vegetable fat added to cocoa butter with the aim of providing improved precision. The identification of fats was based on the analysis of sterol and triterpene alcohol degradation products formed during the processing of the fat. The procedure was able to successfully discriminate between 95% of pairs of fats from a set (33) of CBE-type vegetable fats. Subsequent analysis of 80 mixtures of four CBEs with chocolate successfully identified, on cross-validation, 94% of the samples. Combining the qualitative procedure with established quantitative methodology, based on the analysis of triacylglycerols, improved the method precision from +/- 2.1% to +/- 0.3% (5% addition of CBE at 95% confidence). Identifying the fat analytically permits the use of quantitative methods for determining the level of added fat in chocolate that have improved precision in comparison with the measurement of an unidentified fat. This may obviate the need to use factory inspection as a means to identify the ingredients of a product and monitor compliance with proposed legislation.

Cacao↗

PubMed2000

3-monochloropropane-1,2-diol (3-MCPD) in soy sauces and similar products available from retail outlets in the UK.

A survey of the level of 3-monochloropropane-1,2-diol (3-MCPD) in soy sauces and similar products available in the UK is reported. The survey was carried out by the Joint Ministry of Agriculture, Fisheries and Food/Department of Health Food Safety and Standards Group (JFSSG) to check for compliance with the Food Advisory Committee's (FAC) recommended limit for 3-MCPD of 0.01 mg/kg following reports that soy sauces in several European countries had been found to contain high levels (up to 124 mg/kg) of 3-MCPD. Forty samples of soy sauce and similar products purchased from retail outlets were analysed using a GC-MS procedure which had been formally validated by an earlier collaborative trial. 3-MCPD was undetectable in 21 (52%) of samples analysed in the survey, with a further five samples containing very low levels of between 0.01 and 0.02 mg/kg. Five samples (13%) contained 3-MCPD at levels in the range 0.020-1 mg/kg while nine samples (23%) were found to contain 3-MCPD at levels greater than 1 mg/kg, with the highest level being 30.5 mg/kg.

Carcinogens↗

PubMed1999

Phase I/II studies of docetaxel (Taxotere) combined with estramustine in men with hormone-refractory prostate cancer.

Evaluation of the combined regimen of estramustine and docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA) in men with hormone-refractory prostate cancer is in its early stages. While this combination is promising in terms of efficacy, adverse events associated with estramustine are a concern. Estramustine has been associated with side effects such as nausea, vomiting, edema, and serious vascular events. Reported here are the results of phase I and phase II trials in which 280 mg estramustine was given three times daily on days I to 5 in 21-day treatment cycles with docetaxel at varying doses. Data from patients evaluable thus far support the efficacy of this combination, both in chemotherapeutically naive patients and in those who have had prior therapy. A survival benefit from this combination appears achievable from these early studies. As significant antitumor activity can be achieved with docetaxel alone, future studies need to define the minimal dose of estramustine for this combination.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1982

Thresholds for seeing visual phantoms and moving gratings.

Moving visual phantoms look like real gratings and generate movement aftereffects as do real gratings. Three experiments have been carried out to test whether phantoms resemble real gratings in other ways. Changes in the spatiotemporal frequency of an inducing grating effect the minimum contrast at which it will induce phantoms, but only insofar as the changes affect the visibility of the inducing gratings. Changes in the areal extent of the inducing grating and in the extent of the gap across which phantoms must be induced alter the visibility of the phantoms but, again, only to the extent that the changes affect the visibility of the inducing gratings themselves. Phantoms induced by high-contrast gratings may be cancelled by gratings of near-threshold contrast when the latter are presented 180 degrees out of phase with the inducing gratings. It is concluded that the appearance of phantoms is governed solely by the detectability of their inducing gratings, but that the effects of phantoms on pattern-sensitive channels are not the same as are the effects of real gratings. The pattern characteristics of phantoms thus do not represent a spread of energy from inducing to phantom regions of visual space or their neural representations.

Figural Aftereffect↗