Biomedical subjects

L Castle

Publications and source records attributed to L Castle.

At least 37 records · Page 2Linked to original sources

PubMed2002

Method development and analysis of retail foods for annatto food colouring material.

Analytical methods for the determination of the permitted food colouring annatto (E160b) have been developed or refined to encompass the wide range of food commodity types permitted to contain it. Specific solvent extraction regimens have been used depending upon the food commodity analysed and HPLC analysis techniques coupled with spectral confirmation have been used for the determination of the major colouring components. Qualitative and quantitative data on the annatto content of 165 composite and two single retail food samples covering a wide range of foods at levels above the limit of quantification (0.1 mg kg(-1)) is reported. Quantitative results are given for the major colour principals 9'-cis-bixin, 9'-cis-norbixin and trans-bixin. Semi-quantitative results are given for the minor bixin and norbixin isomers monocis- (not 9'-), di-cis- and trans-norbixin, for which authentic reference standards were not available. Repeat analyses (n = 4-9) of 12 different types of food commodity (covering the permitted range) spiked with annatto at levels between 1.7 and 27.7 mg kg(-1) gave mean recoveries between 61 and 96%. The corresponding relative SDs (RSD) were between 2.1 and 7.9%.

Animals↗

PubMed2002

Verification of the findings of acrylamide in heated foods.

We report here the first confirmation of the recent Swedish findings of acrylamide in heated foods. The verification exercise used an LC-MS/MS method developed for the purpose as well as an established GCMS method for acrylamide analysis. LC-MS/MS was suitable for the direct determination of acrylamide in aqueous extracts of foods by isotope dilution mass spectrometry (IDMS) using triply deuterated acrylamide. Some food matrices were not suited to the new method and mixed-mode solid-phase extraction (SPE) was used to clean these extracts. The foods tested included UK versions of some of the key food groups analysed in Sweden. Also tested were some foods heated under home-cooking conditions. There was good agreement between the LC-MS/MS results and the GC-MS results and the levels of acrylamide found here were similar to those reported for the corresponding foods analysed in the Swedish study. The analyses confirmed that acrylamide is absent from the raw or boiled foods but present at significant levels in fried, grilled, baked and toasted foods. The highest result was 12000 microg kg(-1) acrylamide in overcooked oil-fried chips.

Acrylamide↗

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↗

PubMed2001

A biomarker approach to measuring human dietary exposure to certain phthalate diesters.

Three groups of eight volunteers were administered stable isotope-labelled phthalate diesters in a single dose and the amount of the corresponding phthalate monoesters excreted in the urine was measured. Amongst the phthalates administered were the symmetrical dibutyl-, di-2-ethyl- and diisooctyl- phthalates along with the unsymmetrical benzylbutylphthalate. The control group received no dose, the low dose group received 168-255 microg of each phthalate and the high dose group received 336 to 510 microg of each phthalate. The excreted phthalate monoesters were measured by LC-MS following hydrolysis of conjugates. The bulk of phthalate monoester was excreted in the first 24 hour period following the dose. For dibutylphthalate, 64% and 73% on a mole basis of the low, and high dose respectively was excreted as monobutylphthalate. For dioctylphthalate (sum of the 2-ethylhexyl and the isooctyl species) the yield was 14 and 12% of the low and high dose excreted as monooctylphthalate. For benzylbutylphthalate, 67% and 78% was eliminated as monobenzylphthalate and only 6% (measured for the high dose only) was eliminated as monobutylphthalate. These conversion factors can be used in future studies to assess exposure to phthalate esters via measuring urinary levels of the monoester metabolites.

Biomarkers↗

PubMed2001

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact.

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (1H-NMR) and GC-MS. NMR detected the presence of cyanoisopropyl radical residues in the plastic at 470-3400 mg/kg whereas GC-MS detected TMSN at only 65-540 mg/kg in the samples. It is concluded that the bulk of cyanoisopropyl residues detected by NMR were either polymer-bound or were the products of side-reactions of the initiator radical. The migration of TMSN itself into the food simulants 3% aqueous acetic acid, 15% aqueous ethanol, and olive oil, at 40 degrees C for 10 days, was measured using GC-MS. Migration was very low with < 1 microg/kg released from a finished article (a drinking straw) and < 5 microg/kg from resin pellets. The overall conclusions from this work are that organic residues from aids to polymerization are generally found at reassuringly low levels in plastics intended for food contact and their potential for migration to foods is correspondingly low.

Food Contamination↗

PubMed2000

The Cox-Maze procedure: the Cleveland Clinic experience.

The Cox-Maze procedure was designed to address the consequences of atrial fibrillation, tachycardia, hemodynamic impairment, and thromboembolism. From 1991 until June 1999, 100 patients underwent the Maze operation at the Cleveland Clinic Foundation. The group included 72 men with a mean age of 58 +/- 11 years (range, 23 to 78 years). Initially, the Maze-I procedure was performed primarily for patients with lone atrial fibrillation. However, since 1995, the Maze-III procedure has been performed exclusively, and it is typically combined with mitral valve repair. Twenty-three patients had only a Maze procedure, 60 patients had the Maze procedure/mitral valve repair, 10 patients had Maze procedure/coronary artery bypass, 6 had Maze procedure/mitral valve replacement, and 1 had Maze procedure/atrial septal defect repair. Chronic atrial fibrillation was present in 78% of patients for a mean of 8 +/- 9 years. There was a 1% perioperative mortality and 5% late mortality rate. Median hospital stay was 9 +/- 5 days. Six patients required new early permanent pacemaker insertion. With a mean follow-up of 3 years, 90.4% of patients are in sinus rhythm (or atrial pacing). Preoperative symptoms were reduced: 24% had preoperative syncope; none had syncope in follow-up; 14% of patients preoperatively had cerebral or systemic emboli; and there were no perioperative or late embolic events. The Maze procedure effectively addressed the major complications of atrial fibrillation and was associated with low perioperative and late morbidity rates.

Adult↗

PubMed2000

Analysis of annatto (Bixa orellana) food coloring formulations. 2. Determination of aromatic hydrocarbon thermal degradation products by gas chromatography.

Twenty samples of commercial annatto formulations have been analyzed for m-xylene and toluene using ambient alkaline hydrolysis, followed by solvent extraction and capillary gas chromatography. Fifteen of the samples contained <5 mg/kg toluene, four samples contained between 5 and 10 mg/kg toluene, and one sample contained 12 mg/kg toluene. The amounts found of m-xylene were 200 mg/kg (one sample), 160 mg/kg (one sample), between 30 and 88 mg/kg (four samples), between 7 and 25 mg/kg (seven samples), and <5 mg/kg (seven samples). Bixin-in-oil formulations contained the highest m-xylene concentrations and also gave the largest increase in headspace m-xylene concentration when heated in closed systems. The results are evidence for the thermal degradation of annatto during source extraction and processing, resulting in contamination by internal generation of both bixin and norbixin types with aromatic hydrocarbons. Two samples of norbixin of known production history (i. e., thermal versus nonthermal processes) were analyzed specifically to identify possible differences in their degradation component profiles. They were found to differ significantly in m-xylene content, which is consistent with their respective production histories.

Bixaceae↗

PubMed1999

Quality and safety aspects of reusable plastic food packaging materials: a European study to underpin future legislation.

The objective of this study was to develop a comprehensive package of quality assurance criteria for use by industry and regulatory authorities for ensuring the quality and safety-in-use (sensory, microbiological and chemical) of reused plastics for food packaging. The study included thermal degradation effects, flavour carry-over caused by flavour and off-flavour substances, the influence of washing processes on the materials, and the efficiency of washing processes in removing off-flavour substances and surrogate substances representing misuse chemicals as might be put in bottles by consumers. The microbial safety of the refillable plastic articles in relation to commercial washing processes and the industrial procedures applied has also been investigated. Lastly, the suitability of laboratory procedures using strips of bottle material for predicting the sorption and washing properties of refillable plastic bottles has been studied. In general it is concluded that reuse of the articles does not significantly influence any of the properties investigated. Neither the chemical, physical nor surface properties seem to be significantly influenced by repeated washing. It can be concluded, however, that it is very likely that most of the articles investigated will cause flavour carry-over to a new filling if they are contaminated with strongly flavoured products. Finally it can be concluded that the procedures evaluated can serve as a basis for future legislation on refillable articles, but for several procedures (like quick predictive testing with strips) more investigation is required to create a more solid basis.

Equipment Reuse↗

PubMed1998

Establishment of a reference collection of additives and an analytical handbook of reference data to support enforcement of EU regulations on food contact plastics.

A collection has been made of additives that are required as analytical standards for enforcement of European Union legislation on food contact plastics. The 100 additives have been characterized by mass spectrometry, infra-red spectroscopy and proton nuclear magnetic resonance spectroscopy to provide reference spectra. Gas chromatographic retention times have been recorded to facilitate identification by retention index. This information has been further supplemented by physico-chemical data. Finally, chromatographic methods have been used to indicate the presence of any impurities in the commercial chemicals. Samples of the reference substances are available on request and the collection of spectra and other information will be made available in printed format and on-line through the Internet. This paper gives an overview of the work done to establish the reference collection and the spectral atlas, which together will assist enforcement laboratories in the characterization of plastics and the selection of analytical methods for additives that may migrate.

Chromatography, Gas↗

PubMed1997

Measurement of styrene oxide in polystyrenes, estimation of migration to foods, and reaction kinetics and products in food simulants.

The concentration of styrene-7,8-oxide has been measured in nine base resins and 16 samples of polystyrene articles intended for food contact. The epoxide was not detected in the resins (limit of detection 0.5 mg/kg) but was found in 11 of the 16 packaging samples at up to 2.9 mg/kg. Assuming that the propensity of styrene oxide to migrate is the same as styrene monomer, and using existing survey data for styrene monomer in packaging and foods, the migration levels expected for styrene oxide were calculated. Estimates were from 0.002 to 0.15 microgram/kg styrene oxide in foods. The stability of styrene oxide in the four standard EU food simulants was studied at 40, 100, 150 and 175 degrees C, to establish the transformation products to be expected following migration testing. The half-life at 40 degrees C in distilled water, 15% aqueous ethanol, 3% aqueous acetic acid and olive oil was 15, 23, < 1, > 2000 hr, respectively. The principal product was the diol from hydrolysis of the epoxide group. Ring opening in aqueous ethanol simulant gave the diol and also the glycol monoethyl ether. It is concluded that this instability of styrene oxide will reduce concentrations in foods, from an already low migration level to even lower levels with the formation of hydrolysis products that are less toxic than the parent epoxide.

Carcinogens↗

PubMed1997

Migration studies from paper and board food packaging materials. 1. Compositional analysis.

A survey of 32 paper and board materials intended for food contact has been undertaken. Sample composition was analysed to identify chemicals with a potential to migrate to foods. Representative materials covering a range of uses such as aqueous and fatty foods, and use at ambient and elevated temperatures, were obtained from industry. The samples were examined in their unfinished state, even where the final form would have included lamination to plastics, printing, or other treatments. A comprehensive and systematic analytical approach was applied which included determination of volatiles by headspace GC-MS, extraction using water, ethanol and chloroform with subsequent analysis by GC-MS and HPLC, and multi-element screening by ICP-MS. The solvent extracts were also weighed to determine the total amount of material available for migration. A large number of volatile substances were identified with alkyl and aryl aldehydes predominating in the majority of samples. Substances identified in solvent extracts included 2,6-di-tert-butyl-4-hydroxytoluene (BHT), di-tert-butylphenol, benzophenone, 4,4'-bis(dimethyl amino) benzophenone (Michler's ketone), triphenyl methane, bicyclohexylphenylphenanthrene carboxylic acid (and its methyl ester) and abietic acid. Levels of these substances were however generally below 1 mg/kg paper. Of the inorganic elements, arsenic and mercury were not detected above the limits of determination of 1.8 and 0.4 mg/kg respectively in any of the 10 samples examined. Cadmium was detected in teabag tissue and in unbleached Kraft paper at 0.3 mg/kg. Chromium was present in seven samples at 1.1-7.8 mg/kg, whilst lead was present in nine of the 10 samples at levels ranging from 0.3 to 5.9 mg/kg.

Benzophenones↗

PubMed1997

Migration studies from paper and board food packaging materials. Part 2. Survey for residues of dialkylamino benzophenone UV-cure ink photoinitiators.

A survey of retail samples was conducted in two phases with 50 general paper and board food contact materials and articles analysed in 1992, and 121 samples, specifically of printed cartonboard, analysed in 1995. Packaging samples were extracted with ethanol containing 0.4% triethylamine. The extracts were analysed using high performance liquid chromatography (HPLC) and the presence of 4,4'-bis (dimethylamino) benzophenone (Michler's ketone, MK) and 4,4'-bis (diethylamino)-benzophenone (DEAB) confirmed using gas chromatography coupled to mass spectroscopy (GC-MS). The limits of detection for MK and DEAB in packaging were 0.05 mg/kg and 0.1-0.2 mg/kg respectively. In the first phase, MK was detected in 24% of the 50 samples at concentrations of 0.06-3.9 mg/kg paper. DEAB was detected in 12% of samples (0.1-0.2 mg/kg). In the second phase, 26% of the 121 cartonboard samples contained detectable MK (0.1-1.6 mg/kg) and 4% contained DEAB (0.2-0.7 mg/kg). Residues of the monoamine 4-(dimethylamino)benzophenone (DMAB) were found in 10% of the 1992 samples (0.1-0.6 mg/ kg). DMAB was not surveyed in 1995. These levels are too low to indicate the use of these cure agents for printing the packages. Rather, the most likely origin is from the use of recycled fibres. For three samples where the highest concentration of MK was detected, the food was analysed by GC-MS after extraction and clean-up. There was no measurable migration of MK at a detection limit of 2 micrograms/kg food. It is concluded, therefore, that the concentrations of MK present in the packaging samples analysed are unlikely to pose a risk to human health.

Benzophenones↗

PubMed1997

Reactions of epoxide monomers in food simulants used to test plastics for migration.

The reactions of four epoxides used as monomers for food contact plastics were studied in the food simulants distilled water, 15% aqueous ethanol, 3% aqueous acetic acid and olive oil. Loss of the parent substance and formation of products was monitored to establish the transformation products to be expected in each simulant following migration testing of plastics. Each epoxide was stable in olive oil but suffered extensive loss in the three aqueous simulants. Reaction half-lives were from < 1 to 10 h in aqueous acetic acid, 25-63 h in distilled water, and 33-87 h in aqueous ethanol simulant. Hydrolysis to the diol was the main reaction pathway. Epoxide ring opening in aqueous ethanol simulant gave the diol and also the diol monoethyl ether. It is concluded that, for aqueous simulants and by implication for most foods, testing plastics against specific migration limits for epoxides is not likely to give reliable results due to their reactivity. The present EC mode of control for these reactive monomers, via compositional limits in food contact plastics, is more practical since the hydrolysis products are less toxic than the parent epoxide.

Benzhydryl Compounds↗

PubMed1997

Supercritical fluid extraction of sulphamethazine and its metabolites from meat tissues.

An investigation is reported of factors affecting the supercritical fluid extraction of sulphamethazine and five of its metabolites from spiked meat (swine liver and kidney). The addition of the polar modifier methanol to the carbon dioxide extracting fluid was found to generally enhance recoveries under subcritical and supercritical conditions. Recoveries of the ionic metabolites were increased by up to 72% when employing tetramethylammonium hydroxide for ion pairing in situ with the supercritical fluid extraction. Extraction efficiency is demonstrated to be dependent on the matrix. Extractions of the less polar compounds from the kidney are more successful than from the liver, which corresponds to their partitioning into the supercritical fluid and/or the greater fraction of highly extractable fatty materials. The kidney was more retentive than liver for the relatively more polar compounds, which suggests that the liver offers a less polar environment under the same extraction conditions.

Animals↗

PubMed1997

EMF genes regulate Arabidopsis inflorescence development.

Mutations in EMBRYONIC FLOWER (EMF) genes EMF1 and EMF2 abolish rosette development, and the mutants produce either a much reduced inflorescence or a transformed flower. These mutant characteristics suggest a repressive effect of EMF activities on reproductive development. To investigate the role of EMF genes in regulating reproductive development, we studied the relationship between EMF genes and the genes regulating inflorescence and flower development. We found that APETALA1 and AGAMOUS promoters were activated in germinating emf seedlings, suggesting that these genes may normally be suppressed in wild-type seedlings in which EMF activities are high. The phenotype of double mutants combining emf1-2 and apetala1, apetala2, leafy1, apetala1 cauliflower, and terminal flower1 showed that emf1-2 is epistatic in all cases, suggesting that EMF genes act downstream from these genes in mediating the inflorescence-to-flower transition. Constitutive expression of LEAFY in weak emf1, but not emf2, mutants increased the severity of the emf phenotype, indicating an inhibition of EMF activity by LEAFY, as was deduced from double mutant analysis. These results suggest that a mechanism involving a reciprocal negative regulation between the EMF genes and the floral genes regulates Arabidopsis inflorescence development.

Alleles↗

PubMed1996

A UK retail survey of aflatoxins in herbs and spices and their fate during cooking.

A survey of aflatoxins in herbs and spices has been carried out and cooking experiments conducted to assess the stability of aflatoxin in spice sauces. Of 157 retail samples which included curry powders, pepper, cayenne pepper, chilli, paprika, ginger, cinnamon and coriander, nearly 95% of samples contained below 10 micrograms/kg total aflatoxins and only nine samples had higher levels. The highest concentration in a retail sample was 48 micrograms/kg in a chilli powder. In addition to retail sampling, 14 consignments of whole chilli and chilli powder were sampled at the port of entry. Only two samples, both chilli powder, were above 10 micrograms/kg; containing 35 and 51 micrograms/kg total aflatoxins. Cooking experiments showed that aflatoxin levels in spiced sauces are not reduced by domestic cooking with either microwave or conventional gas oven heating.

Aflatoxins↗

PubMed1996

Oligomers in plastics packaging. Part 1: Migration tests for vinyl chloride tetramer.

Vinyl chloride (VC) tetramer has been studied as a representative oligomer that has the potential for migration from plastics packaging. Poly(vinyl chloride) (PVC) bottles for retail beverages were analysed by a process of dissolution followed by gas chromatography. Tetramer levels ranged from 70 to 190 mg/kg in the plastic. When these bottles were tested for migration into the simulants distilled water, 3% acetic acid, 15% ethanol and olive oil, no tetramer migration was detected at a limit of 5-10 micrograms/kg. Since, of the low molecular weight oligomers, the tetramer had the highest concentration in the PVC plastics, it is concluded that the other VC oligomers of higher molecular weight, would not migrate above this limit of detection either.

Acetates↗

PubMed1995

Cloning and characterization of a novel cDNA that is IFN-gamma-induced in mouse peritoneal macrophages and encodes a putative GTP-binding protein.

Macrophage activation by IFN-gamma results in a cascade of gene expression. To identify genes activated in mouse peritoneal macrophages by IFN-gamma, we created a cDNA subtraction library of IFN-gamma-induced genes. We have isolated from this subtraction library a novel cDNA clone, called Mg21, whose mRNA is absent in unstimulated mouse peritoneal macrophages and is induced to high levels within 4 h following the addition of IFN-gamma. Induction of Mg21 mRNA by IFN-gamma occurred in the presence of cycloheximide, indicating that expression of Mg21 mRNA does not require protein synthesis. A small amount of Mg21 mRNA was also induced by LPS, but not by IL-2, IL-4, IL-10, or TNF-alpha. The DNA sequence of Mg21 is 1617 nucleotides and contains an open reading frame that codes for a protein of 415 amino acids with a predicted molecular weight of 47,106 Da. The predicted amino acid sequence lacks a signal sequence or transmembrane segments, indicating that the protein is an intracellular protein. Computer search of the GenBank and EMBL databases indicates that this cDNA clone is unique but has 57% sequence identity with IRG-47, which is a mouse gene induced by IFN-gamma in pre-B and B lymphocyte cell lines. IRG-47 encodes an intracellular protein that contains three conserved protein motifs present in GTP-binding proteins. Analysis of the protein sequence of Mg21 showed that these three conserved protein motifs are also present in Mg21.

Amino Acid Sequence↗