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PubMedDate not supplied

Current research on food contact materials undertaken by the UK Ministry of Agriculture, Fisheries and Food.

Recent research funded by the UK Ministry of Agriculture, Fisheries and Food (MAFF) in the area of migration from food contact materials is reviewed and set within a framework of surveillance; evaluation of new technology; support of current regulations; and anticipation of future controls. Recent surveillance projects monitoring foods for migration of monomeric plasticizers (in particular di-(2-ethylhexyl)adipate), polymeric additives and mineral hydrocarbons are highlighted. Development of high temperature testing conditions for food contact materials has been carried out in support of regulations and proposals are made for the control of susceptors by analysis of release of volatiles. Migration of benzophenone from the printing ink of a paper board sleeve during microwave heating of a pre-cooked meal is described as a recent example of a migration situation that would not easily have been anticipated. Finally, the approach being adopted for investigating paper and board food contact materials for inorganic constituents, for volatile organic and for solvent-extractable organic components is outlined as an example of work being carried out in anticipation of future regulatory controls.

Chromatography, High Pressure Liquid↗
PubMed1999

Stability testing of selected plastics additives for food contact in EU aqueous, fatty and alternative simulants.

Within the framework of the AIR3-CT94-2360 EU-project, the stability of three plastics additives in three EU aqueous and fatty food simulants and in two alternative simulants was studied under various time-temperature conditions. The additives tested were bis(2-ethylhexyl) adipate (DEHA), bis(2-ethylhexyl) phthalate (DEHP) and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076). The various test conditions included exposures of 10 days at 40 degrees C, 1 h at reflux temperature for all aqueous simulants, 10 days at 40 degrees C and 1 h 175 degrees C for the olive oil and 2 days at 20 degrees C and 3 h at 60 degrees C for the isooctane simulant. Following the exposure, the additive samples were extracted from aqueous simulants with hexane. A sonication step was necessary to ensure maximum extraction of control samples. In the case of the isooctane simulant, the samples were analyzed directly from the simulant. The oil samples were extracted by acetonitrile. The extracts of samples exposed to various heat conditions as well as unexposed spiked controls and blanks were analysed by gas chromatography (GC) on a non-polar (5%--phenyl)-methylpolysiloxane capillary column with high temperature capabilities. The results showed that DEHA, DEHP and Irganox 1076 were stable at 40 degrees C and at reflux temperature in ethanolic or acidic aqueous simulants. The various additives were also stable in the organic isooctane simulant as well as in the fatty simulant olive oil. Studies on the stability of such additives used in food packaging are designed for regulatory purposes as an aid to decide whether the legislation should regulate limits for plasticizers based on a quantity in the food packaging itself or based on an ingested dose by the consumer.

Chromatography, Gas↗
PubMedDate not supplied

Salicylic acid and PEG-contained polyanhydrides: synthesis, characterization, and in vitro salicylic acid release.

Poly [bi(o-carboxyphenyl)adipate-polyethylene glycol] anhydrides--P(BOCA-PEG)--polymeric drugs were synthesized and characterized by Fourier transformed infrared spectroscopy, NMR, DSC, gel permeation chromatography, etc. Salicylic acid loading efficiency of these polymers ranged from 43.5% to 71.3%, which was much higher than that of other polymeric drugs with salicylic acid. The in vitro release of salicylic acid from the polymers was carried out in buffer conditions with different pH values and and rat gastrointestinal contents. The results showed the release rate of salicylic acid increased with the increase of PEG content in the polymers and the increase of pH value of degradation buffer solution. The rat cecal contents also greatly promoted the release of salicylic acid. In 0.1M phosphate buffer solution at pH8.0, 37 degrees C containing 5% rat cecal contents, P(BOCA-PEG200)(80:20) had 15% salicylic acid released in 21 hr, indicating its potential use in colon-specific salicylic acid delivery.

Animals↗
PubMed1999

Preparation of novel conjugates involving immunomodulating peptidoglycan monomer.

Peptidoglycan monomer, the disaccharide pentapeptide beta-D-Glcp-N-Ac-(1-->4)-D-Murp-N-Ac-L-Ala-D-mesoA2pm- (epsilonN H2)-D-Ala-D-Ala (PGM) is an immunomodulator. PGM and/or its derivative N-tert-butyloxycarbonyl-L-tyrosyl peptidoglycan monomer (Boc-Tyr-PGM) were coupled to two polysaccharides: the glucuronoxylomannan (GXM) from Cryptococcus neoformans, type B, solubilized by ultrasonic irradiation (MW 12-400 kDa) and to the dextran FP 70 (MW 70 kDa). Both polysaccharides were activated by CNBr. Initially, unprotected PGM was coupled via its amino group to GXM. The reactions yielded 42%-52% of the conjugate, containing only 0.18%-0.31% of PGM. In another approach Boc-Tyr-PGM (having its amino group blocked) was reacted via its free carboxyl group. Both CNBr-activated polysaccharides were first coupled to adipic acid dihydrazide (ADH) and then subsequently coupled to Boc-Tyr-PGM. The dextran conjugate (approximately 80% yield ) contained 6.3% of Boc-Tyr-PGM. The isolation of GXM conjugate required several modifications and it was obtained in lower yield (approximately 30%) but contained 13.7% of Boc-Tyr-PGM. Both conjugates were water soluble and apyrogenic and suitable for further testing of biological activity.

Adjuvants, Immunologic↗
PubMed1983

Evaluation of emissions from simulated commercial meat wrapping operations using PVC wrap.

Meatwrapper's asthma is an elusive health problem with a suspected relationship to exposure to emissions from polyvinyl chloride (PVC) film cut with a hot wire. A study was conducted to determine how the type of wrap cutter (wire or rod) and its temperature affected the emissions from a simulated occupational wrapping process. The cutting temperatures covered the same range as was measured in Boston retail food stores. A commercial wrapping machine and samples of commercial PVC meat and produce wraps were used. Seventy five percent of the particulate from the hot wire was respirable, and the quantity of emissions was a strong function of the film tension and cutting technique. Particulate emissions did not increase steadily with increasing wire temperature, but plateaued or declined at high temperatures. Particulate emissions from the rod cutter were very low at low temperatures, but exceeded those of the wire at temperatures above 200 degrees C. The particulate was 100% dioctyl adipate (DOA, the plasticizer in the wrap) with wire temperatures below 200 degrees C, and was approximately 80% DOA for temperatures above this. Gaseous HCl was not detected in emissions from a hot wire operated below 150 degrees C, but HCl emissions increased rapidly to a plateau for temperatures above 200 degrees C. Approximately 20% of the HCl produced at temperatures above 200 degrees C was associated with the particulate, which appeared to act as a carrier and transport the HCl through water filled impingers. Field tests are needed to determine if particulate produced in the workplace may also behave as a carrier for HCl.

Aerosols↗
PubMed2001

Toxicity and biodegradation of products from polyester hydrolysis.

Toxicity of products from polyester hydrolysis such as succinic acid (SA), adipic acid (AA), mandelic acid (MA), terephthalic acid (TA), 1,4-butanediol (1,4-B), ethylene glycol (EG), styrene glycol (SG) and 1,4-cyclohexane dimethanol (1,4-C) was evaluated by phytotoxicity test on germination of young radish seeds and by cytotoxicity test on HeLa cells. The phytotoxicity test revealed SG > MA > 1,4-C > AA approximately SA > TA approximately EG > 1,4-B in order of decreasing toxicity taking into consideration the growth behavior after germination as well as the percentage of germination. Toxicity on HeLa cells decreased in slightly different order compared to that on young radish seeds, i.e. SG > 1,4-C > MA > TA > SA > AA > EG > 1,4-B. Tests for the phytotoxicity and for cytotoxicity indicated that the aromatic compounds were more harmful than the aliphatic ones. Each group of 4 strains which grew most rapidly on each agar plate containing SA, AA, MA, TA, 1,4-B, EG, SG and 1,4-C respectively as a sole carbon source was identified by the fatty acid methyl esters analysis. The modified Sturm test was carried out using the single isolated strain, an activated sludge or a mixed soil to measure the rate of mineralization of the compounds into carbon dioxide. The aliphatic compounds were mineralized more easily than the aromatic compounds. 1,4-C showed the most exceptionally slow degradation. A scrutiny of residual 1,4-C after degradation is required before polyesters containing 1,4-C could be classified into compostable because 1,4-C has detrimental effects on young radish seeds and HeLa cells and has a tendency to accumulate in the environment due to its slow degradability.

Animals↗
PubMed2004

Incorporation of different bridge length linkers in enzyme and its use in the preparation of enzyme conjugates for immunoassay.

An enzyme horseradish peroxidase (HRP), as a starting material, has been used to introduce different bridge length linkers, and its use in the preparation of enzyme conjugates for immunoassay is described. HRP was conjugated to adipic acid dihydrazide (ADH), gamma amino butyric acid (GABA), followed by ADH and 6-amino caproic acid (6ACA) followed by ADH. The different bridge length linkers-incorporated enzyme was coupled to a carboxylic derivative of cortisol. Four enzyme conjugates with different bridge length were prepared, such as cortisol-21-hemisuccinate-HRP (cortisol-21-HS-HRP), cortisol-21-HS-ADH-HRP, cortisol-21-HS-ADH-GABA-HRP, and cortisol-21-HS-ADH-6ACA-HRP. The influence of linker on sensitivity and specificity of the cortisol assay was studied. The study revealed that incorporation of a linker between hapten and enzyme increases the sensitivity and specificity of the assay.

Animals↗
PubMed1980

Preparation, characterization, and immunogenicity of Haemophilus influenzae type b polysaccharide-protein conjugates.

A method is presented for covalently bonding Haemophilus influenzae type b capsular polysaccharide (HIB Ps) to several proteins. The method is efficient and relies upon the use of adipic dihydrazide as a spacer between the capsular polysaccharide and the carrier protein. In contrast to the poor immunogenicity of the purified HIB Ps in mice and rabbits, the HIB Ps-protein conjugates induced serum anti-type b antibodies having bactericidal activity at levels shown to be protective in humans when low doses were injected subcutaneously in a saline solution. The antibody response in mice was related to the dose of the conjugates, increased with the number of injections, and could be primed by the previous injection of the carrier protein. The HIB Ps-protein conjugates were immunogenic in three different mouse strains. The importance of the carrier molecule for the enhanced immunogenicity of the HIB Ps-protein conjugates was shown by the failure of HIB Ps hybrids prepared with either the homologous polysaccharide or pneumococcus type 3 polysaccharide to induce antibodie in mice. Rabbits injected with the HIB Ps-protein conjugates emulsified in Freund's adjuvant produced high levels of serum anti-type b antibodies which induced a bactericidal effect upon H. influenzae type b organisms. It is proposed that the HIB Ps component of the polysaccharide protein conjugates has been converted to a thymic-dependent immunogen. This method may be used to prepare protein-polysaccharide conjugates with HIB Ps and other polysaccharides to be considered for human use.

Animals↗
PubMed1990

Urinary organic acid excretion during feeding of medium-chain or long-chain triglyceride diets in patients with non-insulin-dependent diabetes mellitus.

Medium-chain triglycerides (MCTs) are absorbed and metabolized differently from long-chain triglycerides (LCTs). Recent data indicate that MCTs may be useful as a dietary substitute in a variety of clinical disorders. The current studies were undertaken to characterize urinary organic acid excretion in patients with non-insulin-dependent diabetes mellitus during 4 d of an LCT or MCT diet. Urinary excretion of the dicarboxylic acids adipic, suberic, and 3-hydroxysebacic and the (omega-1) hydroxylation products 5-hydroxyhexanoic acid and 7-hydroxyoctanoic acid, was increased during MCT feeding as compared with LCT feeding. Urinary suberic and 7-hydroxyoctanoic acid excretions were increased 55- and 30-fold, respectively, during the MCT-substituted diet. Urinary organic acid profiles provide information on the fate of lipids during MCT feeding and may also be useful in assessing complicance during clinical trials employing MCT-substituted diets.

Caproates↗
PubMed1999

Effect of fruit juice intake on urinary quercetin excretion and biomarkers of antioxidative status.

BACKGROUND: Epidemiologic studies suggest that foods rich in flavonoids might reduce the risk of cardiovascular disease. OBJECTIVE: Our objective was to investigate the effect of intake of flavonoid-containing black currant and apple juice on urinary excretion of quercetin and on markers of oxidative status. DESIGN: This was a crossover study with 3 doses of juice (750, 1000, and 1500 mL) consumed for 1 wk by 4 women and 1 man corresponding to an intake of 4.8, 6.4, and 9.6 mg quercetin/d. RESULTS: Urinary excretion of quercetin increased significantly with dose and with time. The fraction excreted in urine was 0.29-0.47%. Plasma quercetin did not change with juice intervention. Plasma ascorbate increased during intervention because of the ascorbate in the juice. Total plasma malondialdehyde decreased with time during the 1500-mL juice intervention, indicating reduced lipid oxidation in plasma. Plasma 2-amino-adipic semialdehyde residues increased with time and dose, indicating a prooxidant effect of the juice, whereas erythrocyte 2-aminoadipic semialdehyde and gamma-glutamyl semialdehyde concentrations, Trolox-equivalent antioxidant capacity, and ferric reducing ability of plasma did not change. Glutathione peroxidase activity increased significantly with juice dose. CONCLUSIONS: Urinary excretion of quercetin seemed to be a small but constant function of quercetin intake. Short-term, high intake of black currant and apple juices had a prooxidant effect on plasma proteins and increased glutathione peroxidase activity, whereas lipid oxidation in plasma seemed to decrease. These effects might be related to several components of the juice and cannot be attributed solely to its quercetin content.

Adult↗
PubMed1986

Pseudomonas aeruginosa polysaccharide-tetanus toxoid conjugate vaccine: safety and immunogenicity in humans.

A Pseudomonas aeruginosa polysaccharide-tetanus toxoid (Ttxd) conjugate vaccine was produced. Polysaccharide was derived from lipopolysaccharide (LPS) and covalently linked to Ttxd by using carbodiimide with adipic acid dihydrazide as a spacer molecule. The conjugate possessed a relative molecular weight of greater than 350,000 and was nontoxic and nonpyrogenic. The vaccine bound serospecific monoclonal antibodies with an avidity similar to LPS and reacted with murine and human opsonic antibody. The vaccine was immunogenic in rabbits and mice and elicited IgG antibody to both LPS and Ttxd. The vaccine was safe when parenterally administered to humans and evoked only mild, transient reactions. Mean titers of IgG antibody to LPS rose 19-fold after immunization, with 82% of the volunteers responding with a fourfold or greater rise in titer. IgG antibody to LPS evoked after immunization was opsonic and highly effective at preventing fatal experimental burn wound sepsis due to P. aeruginosa.

Adolescent↗
PubMed1988

Comparison of spiramycin and erythromycin in the treatment of experimental guinea pig legionellosis.

Spiramycin was compared with erythromycin in a guinea pig model of severe Legionella pneumophila serogroup 1 infection. Male guinea pigs weighting 264-321 g were infected by the intraperitoneal route with 1.2 x 10(7) virulent L. pneumophila serogroup 1. Forty eight h after infection, animals that had lost greater than or equal to 9% of their body weight were randomly assigned to receive 48, 54 and 72 h after infection intraperitoneal injections of (1) distilled water (n = 20), (2) erythromycin lactobionate, 30 mg/kg per injection, (n = 22) or (3) the injectable form of spiramycin adipate, 30 mg/kg per injection (n = 22). Animals were observed daily for 15 days. All infected animals treated with distilled water died within four days of infection. Of the 22 animals treated with spiramycin, 10 (45.5%) died, and of the 22 animals treated with erythromycin, 11 (50.0%) died of disseminated L. pneumophila infection. In this animal model of very severe L. pneumophila infection, the injectable forms of erythromycin and of spiramycin gave similar results. Spiramycin should therefore be considered for the treatment of Legionnaires' disease in man.

Animals↗
PubMed1985

Digestibility of native and modified starches: in vitro studies with human and rabbit pancreatic amylases and in vivo studies in rabbits.

The effects of cooking and chemical modification of purified starches on the relative rates and extent of their hydrolysis were studied in vitro by using purified human and rabbit pancreatic amylases. Comparison was made with an in vivo study of postprandial glucose and insulin response in adult rabbits. Uncooked starches showed negligible hydrolysis in vitro, whereas cooking (10 min, 100 degrees C) increased both the rate and extent of hydrolysis of all starches. Soluble potato starch was the most and potato amylose the least hydrolyzed. Unmodified tapioca and waxy corn starch were hydrolyzed at the same rate and to the same extent as soluble potato starches. In most cases chemical modification did not change the rate and extent of hydrolysis of the starches. Minor differences between human and rabbit pancreatic amylase exist, but there is a general resemblance between the two amylases in their starch-hydrolyzing properties (correlation coefficient = 0.90; P less than 0.001). The in vivo study showed that uncooked starches elicited no detectable glucose and insulin responses, whereas all the cooked starches except amylose caused glucose and insulin responses comparable to the response seen when feeding glucose. Chemically modified starches (especially waxy corn acetylated distarch adipate) seemed to promote a faster rate of absorption, but the total glucose response (i.e., for the entire 180-min duration) was similar for modified starches and their unmodified counter-parts. The in vivo results showed an overall qualitative similarity to the in vitro results but presented a quantitative difference in the magnitude of the responses for various starch preparations. A good correlation exists between the in vitro and in vivo results (correlation coefficient = 0.84; P less than 0.01). This indicates that the action of pancreatic amylases is an important determinant in the digestion and absorption of these carbohydrates.

Amylases↗
PubMed2000

Glutamate: an amino acid of particular distinction.

In this introductory paper to the symposium, we consider why L-glutamate (GLU) is such an abundant biomolecule. We begin with a brief discussion of the prebiotic dawn of events and some evolutionary features of GLU in the biological and metabolic world. The properties of GLU are then examined with reference to its overall structural motif and to the reactivity of the molecule at the tautomeric 2 carbon and at the 4- and 5-C positions. This chemical viewpoint reveals that the GLU molecule offers a number of features/properties not shared by its homologs (amino adipic and aspartic acids). These properties make GLU a favorable choice for facilitating its involvement in multiple metabolic processes that play major roles in the nitrogen economy of the host, as well as serving as a nutrient, an energy-yielding substrate, a structural determinant and an excitatory molecule.

Evolution, Molecular↗
PubMed1986

Purification and characterization of yeast L-kynurenine aminotransferase with broad substrate specificity.

L-Kynurenine aminotransferase [L-kynurenine:2-oxoglutarate aminotransferase (cyclizing), EC 2.6.1.7] has been purified to homogeneity and crystallized from cell-free extracts of a yeast, Hansenula schneggii, grown in a medium containing L-tryptophan as an inducer. The enzyme has a molecular weight of about 100,000 and consists of two subunits identical in molecular weight (52,000). The enzyme exhibits absorption maxima at 280, 335, and 430 nm, and contains 2 mol of pyridoxal 5'-phosphate per mol of enzyme. The enzyme-bound pyridoxal 5'-phosphate shows negative circular dichroic extrema, in contrast with other pyridoxal 5'-phosphate acting on L-amino acids. In addition to L-kynurenine and alpha-ketoglutarate, which are the most preferred substrates, a large number of L-amino acids and alpha-keto acids can serve as substrates; the extremely broad substrate specificity is the most characteristic feature of this yeast enzyme. The enzyme activity is significantly affected by both carbonyl and sulfhydryl reagents. Certain dicarboxylic acids such as adipate and pimelate act as competitive inhibitors. Addition of various substrate amino acids to the culture medium results in the inductive formation of aminotransferases which are immunochemically indistinguishable from L-kynurenine aminotransferase.

Amino Acids↗
PubMed1986

Preparation of high capacity affinity adsorbents using new hydrazino-carriers and their use for low and high performance affinity chromatography of lectins.

Two kinds of carriers with high concentrations of hydrazino groups were prepared by simple and convenient procedures. Hydrazino-carriers (I) and (II) were obtained on incubation of epoxy-activated carriers with hydrazine hydrate and adipic acid dihydrazide, respectively. Disaccharides were coupled to the hydrazino carriers through reductive amination in the presence of sodium cyanoborohydride. The reaction time was much shorter (24 h) than that in the case of the method involving amino-Sepharose 6B (800 h) [Matsumoto, I., Kitagaki, H., Akai, Y., Ito, Y., & Seno, N. (1981) Anal. Biochem. 116, 103-110]. The glycamyl-Sepharose thus obtained showed high adsorption capacities for lectins. Glycamyl-TSKgel G3000 PW obtained by the same method with TSKgel G3000 PW, which is a hydrophobic vinyl polymer matrix for high performance gel permeation liquid chromatography, could be successfully used for the high performance liquid affinity chromatography of lectins. N-Acetylglutamic acid was coupled to hydrazino-Sepharose 4B (I) in the presence of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline. The adsorbent obtained was used for the affinity chromatography of Japanese horseshoe crab lectin.

Animals↗
PubMed2001

Generation of a broad esterolytic subtilisin using combined molecular evolution and periplasmic expression.

Concomitant activity improvement of an evolved enzyme toward two very different ester substrates was achieved when a unique combination of functional periplasmic enzyme expression in Escherichia coli, random mutagenesis, DNA shuffling and cell-based kinetic screenings was applied. Specifically, we focused on the conversion of subtilisin E into an enzyme with broader esterase activity as opposed to its native amidase activity. Cell-based microtiter assays were performed on N-acetyl-D,L-phenylalanine p-nitrophenyl ester (Phe-NPE) and sucrose 1'-adipate (S1'A), as well as on the tetrapeptide amide substrate N-succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroanilide. After a single modified cycle of directed molecular evolution, we isolated a number of clones exhibiting increased activity toward Phe-NPE. In the following rounds of screenings, mutants with improved activity on Phe-NPE were also tested on S1'A. Three mutants were identified with increased esterolytic activity on Phe-NPE and S1'A, while having similar amidase activity to that of the parental enzymes. Because the two ester substrates are structurally distinct, we have evolved a more general esterolytic subtilisin and this may have important applications in synthesis.

Amidohydrolases↗
PubMed2000

Propionic and L-methylmalonic acids induce oxidative stress in brain of young rats.

The in vitro effects of propionic and L-methylmalonic acids on some parameters of oxidative stress were investigated in the cerebral cortex of 21-day-old rats. Chemiluminescence, thiobarbituric acid-reactive substances (TBA-RS) and total radical-trapping antioxidant capacity (TRAP) were measured in brain tissue homogenates in the presence of propionic or L-methylmalonic acids at concentrations ranging from 1 to 10mM. Both acids significantly increased chemiluminescence and TBA-RS and decreased TRAP, indicating a simulation of lipid peroxidation and a reduction of tissue antioxidant potential. Other organic acids tested which accumulate in some organic acidemias (suberic, sebacic, adipic, 3-methylglutaric and 4-hydroxybutyric acids) did not affect these parameters. This study provides evidence that free radical generation may participate in the neurological dysfunction of propionic and methylmalonic acidemias.

Animals↗