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At least 1,405 records · Page 78Linked to original sources
PubMed2005

Temperature and treatment time influence high hydrostatic pressure inactivation of feline calicivirus, a norovirus surrogate.

Interest in high hydrostatic pressure processing as a nonthermal pasteurization process for foods continues to increase. Feline calicivirus (FCV), a propagable virus that is genetically related to the nonpropagable human noroviruses, was used for detailed evaluation of the high pressure processing parameters necessary for virus inactivation. Pressure inactivation curves of FCV strain KCD in Dulbecco's modified Eagle medium with 10% fetal bovine serum were obtained at 200 and 250 MPa as a function of time at room temperature. Pressure inactivation curves at 200 and 250 MPa also were determined as a function of temperature ranging from --10 to 50 degrees C at treatment times of 4 and 2 min, respectively. Tailing was observed for inactivation as a function of treatment time, indicating that the linear model was not adequate for describing these curves. The two nonlinear models, the log logistic and Weibull functions, consistently produced better fit to inactivation curves than did the linear model. The mean square errors were 0.381 for the log logistic model, 0.425 for the Weibull model, and 1.546 for the linear model. For inactivation as a function of temperature, FCV was most resistant to pressure at 20 degrees C. Temperatures above and below 20 degrees C significantly increased pressure inactivation of FCV. A 4-min treatment of 200 MPa at --10 and 50 degrees C reduced the titer of FCV by 5.0 and 4.0 log units, respectively; whereas at 20 degrees C the same treatment only reduced the titer by 0.3 log units. These novel results point to the potential for using temperatures above and particularly below room temperature to lower the pressure needed to cause the desired level of virus inactivation.

Animals↗
PubMed2002

Assessment of protein allergenicity: studies in brown norway rats.

For the safety evaluation of genetically engineered crops, the potential allergenicity of the newly introduced protein(s) has become an important issue. There is, however, no universal and reliable test system for the evaluation of the allergic sensitizing ability of food proteins. Therefore, there is a growing interest in the development of animal models. This paper summarizes the results of a promising food allergy model developed in Brown Norway (BN) rats. The results demonstrate that BN rats can be sensitized via the relevant oral route of exposure. Daily gavage dosing of the animals with several food proteins, without the use of adjuvants, resulted in significant antigen-specific IgE responses. In addition, the profile of allergens recognized by the immune system of the BN rat, appeared comparable to the profile of allergens recognized by allergic humans. Besides oral sensitization, local and systemic immune-mediated effects, such as increased gastrointestinal permeability, decreased breathing frequency, and decreased blood pressure, could also be observed in the sensitized animals after an oral challenge. All together, these observations suggest that this BN rat model might provide a suitable animal model to study the allergenicity of food proteins in humans.

Allergens↗
PubMed1985

Chemical modifications and genetic engineering of food proteins.

Relationships of structure to function of proteins can be studied using chemical modifications of amino-acid side chains and, more recently, recombinant deoxyribonucleic acid techniques to alter primary sequences. A wide array of chemical modifications are available to the food chemist for manipulating the functionality of food proteins. The esterification of side-chain carboxyl groups in proteins to yield polycationic polymers is emphasized in this review as an example of changing the functionality of a protein via chemical derivatization. However, chemical modifications of proteins generally suffer from a lack of control in the extent of derivatization attainable, oftentimes yielding polydisperse products. Recent advances in recombinant deoxyribonucleic acid technology offer the opportunity to relate systematically well-defined alterations in the primary sequence to changes in protein functionality. Using oligonucleotide-directed mutagenesis, one can now use synthetic oligodeoxynucleotides to prepare semisynthetic genes coding for specific changes in the primary sequence of proteins. Incorporation of the altered genes into an appropriate host can lead to the production of the modified protein for structure-function relationship studies. These recombinant deoxyribonucleic acid techniques may eventually provide the means to engineer proteins and enzymes.

Circular Dichroism↗
PubMed2002

Milk and dairy products in the 21st century. Prepared for the 50th anniversary of the journal of agricultural and food chemistry.

Dairying into the 21st century will largely continue with the trends seen in the past few decades, although there is always the possibility of an unlikely but disruptive event. The politics of globalization will potentially be important in freeing up global trade in dairy products. Production on the farm will become increasingly efficient, resulting in continuing price benefits to the consumer. At the same time, increasing attention will be paid by the consumer, producer, and manufacturer to safety and quality issues. Environmental concerns will increase in importance, and the issue of methane production may be important for the industry over the next two decades. It is unlikely that genetically modified milk will be introduced soon, even if public acceptance ceases to be an issue; however, the use of genetic markers for accelerated genetic improvement of cows will have rapidly increasing importance. Despite increasing pressure from nonmilk alternatives, milk and dairy will still be the best sources of nutrition for the young and for traditional dairy products. Consumer concerns will be of overriding importance for the industry, and the safety of dairy foods must become absolute. Recent advances in the chemical, physical, and information sciences and technologies will be utilized to gain greater understanding of the increasingly complex food systems and to support the consumer objectives.

Agriculture↗
PubMed2000

[Natural history of atopy].

Atopy is defined by an individual propensity to develop IgE-dependent reactions against environmental allergens. It could be now defined by a propensity to develop a Th2 response against such allergens, which takes into account not only the IgE production but also the eosinophil activation and the pivotal role of T lymphocytes in this process. A number of factors are determinants of atopy: some of them precede birth, such as genetic factors and some peculiarities of the immune system during pregnancy, in relation to maternal atopy, to in utero allergen exposure or to pregnancy itself. After birth, car pollution could modify the response to allergens by enhancing the IgE production. Food habits, by favoring intake of omega-6 polyunsaturated fat acids contained in some vegetal fat instead of omega-3 polyunsaturated acids from fish, could facilitate IgE dependent sensitization. Viral infections could, depending on their nature and their circumstances of occurrence protect from atopy inversely induce some sensitizations. Finally the degree of exposure to allergens themselves is proportional to the probability of sensitization. Together, these determinants of atopy could account for the higher prevalence of atopy in developed countries. The clinical expression of atopy varies during life from atopic dermatitis to rhinitis and asthma. Infancy is the time for dermatitis and sensitization to food allergens. Sensitization to airborne allergens occurs thereafter. Asthma, sometimes introduced by one or several bronchiolitis episodes follows to dermatitis or can be associated to it. Rhinitis appears in children or young adults. Seasonal, it is due to pollens and is rarely associated with asthma. In contrast, perennial, it is due to indoor allergens and leads to bronchial hyperreactivity and asthma.

Adult↗
PubMed2000

Analysis of genetically modified oils.

Genetically modified oils with altered functional or nutritional characteristics are being introduced into the marketplace. A wide array of analytical techniques has been utilized to facilitate developing these oils. This article attempts to review the utilization of these analytical procedures for characterizing both the chemistry and some functionality of these oils. Although techniques to assess oxidative stability in frying and food applications are covered, measurement of nutritional characteristics are not.

Chromatography↗
PubMed2026

Boosting β-carotene in rice and wheat grains through seed-specific expression of a modified wheat or gene.

Vitamin A deficiency is a major public health problem affecting up to 50% of the world's population, as staple food crops like wheat and rice, which are often poor in many essential micronutrients such as vitamin A, are major staple food crops. Biofortification of cereal crops with β-carotene (provitamin A) through genetic engineering is a potential solution to overcome vitamin A deficiency. The Orange (Or) protein is involved in the regulation of carotenoid accumulation and previous studies demonstrated high carotenoid accumulation due to a single-nucleotide polymorphism (SNP) in the CDS leading to substitution of Arg to His in the OR protein results in carotenoid accumulation. In the present study, we showed that this substitution of a single amino acid at position 110 (Arg to His) of wild-type wheat TaOr (referred to as TaOrHis110) increased β-carotene accumulation in transgenic wheat and rice plants overexpressing TaOrHis110 under the control of the seed-specific promoter Glu1D1. HPLC analysis revealed increase in β-carotene content in rice grain up to eightfold in case of TP309 (japonica) cultivar, 13-fold in case of IET10364 (indica) cultivar and sevenfold in wheat cv. CPAN1676. Additionally, most of the carotenoid biosynthetic pathway genes were found to be upregulated in TaOrHis110 overexpressing seeds of TP309 and IET10364, which positively correlates with maximum increase in β-carotene content.

Oryza↗
PubMed2004

Expression of the catalase gene katA in starter culture Lactobacillus plantarum TISTR850 tolerates oxidative stress and reduces lipid oxidation in fermented meat product.

The catalase gene katA of Lactobacillus sakei SR911 was cloned and expressed in Escherichia coli UM2 and Lactobacillus plantarum TISTR850 under strong lactococcal promoter P59 in E. coli-lactococcus expression vector pIL1020. The L. plantarum TISTR850 is a catalase-deficient strain isolated from local fermented meat product. The recombinant L. plantarum TISTR850 was shown to decompose hydrogen peroxide, and catalase activity approximately three times higher that of natural catalase-producing strain L. sakei SR911. The recombinant protein was also detected by in situ activity staining of the catalase enzyme. The recombinant L. plantarum TISTR850 did not accumulate hydrogen peroxide under glucose-limited aerobic conditions and remained viable after 60 h of incubation. The recombinant and host strain L. plantarum TISTR850 were used as starter cultures in the fermented meat product, and lipid oxidation was monitored over a 7-day storage at 20 degrees C determined as thiobarbituric acid-reactive substances (TBARS) value. The lipid oxidation level in the fermented meat product seeded with the catalase genetically modified starter culture L. plantarum TISTR850 was significantly lower than that of the natural catalase-deficient strain.

Catalase↗
PubMed2004

Enhancement of folates in plants through metabolic engineering.

Humans depend on plants as a major source of dietary folates. Inadequate dietary levels of the vitamin folate can lead to megaloblastic anemia, birth defects, impaired cognitive development, and increased risk of cardiovascular disease and cancer. The biofortification of folate levels in food crops is a target for metabolic engineering. Folates are synthesized de novo from pterins and para-amino benzoic acid, which are subsequently combined to form dihydropteroate, the direct precursor to dihydrofolate. We postulated that GTP cyclohydrolase-1, which catalyzes the first committed step in pterin biosynthesis, was a rate-limiting step in pterin synthesis in plants and, therefore, in folate synthesis. On this basis, we proposed that the expression of an unregulated bacterial GTP cyclohydrolase-1 in plants would increase pterin biosynthesis with a concomitant enhancement of folate levels. The folE gene encoding GTP cyclohydrolase-1 was cloned from Escherichia coli and introduced into Arabidopsis thaliana through plant transformation. The expression of bacterial GTP cyclohydrolase-1 in transgenic Arabidopsis resulted in a 1,250-fold and 2- to 4-fold enhancement of pterins and folates, respectively. These results helped to identify other potential factors regulating folate synthesis, suggesting ways to further enhance folate levels in food crops.

Arabidopsis↗
PubMed2004

Active delivery of trefoil factors by genetically modified Lactococcus lactis prevents and heals acute colitis in mice.

BACKGROUND & AIMS: Effective therapeutics for treating acute colitis, caused by disruption of the intestinal epithelial barrier, are scarce. Trefoil factors (TFF) are cytoprotective and promote epithelial wound healing and reconstitution of the gastrointestinal tract, which makes them good candidate therapeutics for acute colitis. However, orally administered TFF stick to the mucus of the small intestine and are absorbed at the cecum. METHODS: We have engineered the food-grade bacterium Lactococcus lactis to secrete bioactive murine TFF. The protective and therapeutic potentials of these TFF-secreting L. lactis were evaluated in parallel with purified TFF in the dextran sodium sulfate (DSS)-induced murine model for acute colitis and in established chronic colitis in interleukin (IL)-10(-/-) mice. Disease was evaluated by blinded macroscopic and microscopic inflammatory scores and by myeloperoxidase activity. RESULTS: Intragastric administration of TFF-secreting L. lactis led to active delivery of TFF at the mucosa of the colon and, in contrast to administration of purified TFF, proved to be very effective in prevention and healing of acute DSS-induced colitis. The in situ secreted murine TFF significantly decreased morbidity and mortality and stimulated prostaglandin-endoperoxide synthase 2 expression, which represents a major therapeutic pathway. In addition, this approach was successful in improving established chronic colitis in IL-10(-/-) mice. CONCLUSIONS: We have positively evaluated a new therapeutic approach for acute and chronic colitis that involves in situ secretion of murine TFF by orally administered L. lactis. This novel approach may lead to effective management of acute and chronic colitis and epithelial damage in humans.

Acute Disease↗
PubMed1995

Effects of the dopamine D1 receptor antagonist SCH 39166 on the ingestive behaviour of alcohol-preferring rats.

The present study evaluated the effect of the selective and long-acting dopamine D1 receptor antagonist SCH 39166 on several aspects of the ingestive behaviour of genetically selected alcohol-preferring rats, bred from Sardinian alcohol-preferring rats. The effect of subchronic (8 days) subcutaneous drug administration was evaluated on the simultaneous daily intake of 10% ethanol, food and water. SCH 39166, 0.1 mg/kg, did not significantly modify the intake of the three ingesta. The dose of 1 mg/kg differentially modified rat ingestive behaviour, inhibiting intake of 10% ethanol, without modifying total fluid and food intake. The higher dose of 5 mg/kg produced a non-selective suppression of ingestive behaviour, which was accompanied by behavioural impairment. Acute drug injection was tested on 2-h intake of 10% sucrose, 0.1% saccharin, water or food. The doses of 0.1 and 1 mg/kg markedly inhibited the 2-h intake of 10% sucrose and 0.1% saccharin, but they did not modify either the 2-h water intake in water deprived and water sated rats or the 2-h food intake in food deprived rats. These findings suggest an important role of mechanisms mediated by D1 receptors in the control of alcohol and sweet solution intake, but not in water and food intake. Moreover, they indicate that SCH 39166, in relation to its selectivity and long-lasting activity, is an interesting pharmacological tool to investigate further the role of D1 receptor mechanisms in the control of ingestive behaviour.

Alcohol Drinking↗
PubMed2006

Spatial learning in Long-Evans Hooded rats and C57BL/6J mice: different strategies for different performance.

Spatial learning abilities of rodents have been extensively used to explore the management of a wide range of cognitive and emotional processes such as learning, memory, attention and anxiety. Knowledge about the organization and processing of spatial learning has mainly been obtained in rats. Due to increasing generation of genetically modified mice, cognitive abilities of mice are now extensively tested. The present paper aimed at comparing spatial representation, learning and strategies in C57BL/6J mice and Long-Evans Hooded rats when subjected to the same spatial learning paradigm, i.e. learning a food location in a crossmaze. We also analyzed the influence of environmental richness on learning modalities in both species. Our results showed that rats and mice could exhibit similar spatial learning abilities in some circumstances. However, Long-Evans rats and C57BL/6J mice may set up different strategies depending on the availability of visual information within the environment. Rats' learning strategies mainly relied on distant visual cues and seemed more efficient than those used by mice as they needed less time than mice to solve the task. We emphasize that the strategies of mice are less robust and flexible than the ones set up by rats. Finally, the richness of the environment was shown to affect speed and quality of spatial learning in both species.

Analysis of Variance↗
PubMed2006

Enterohemorrhagic Escherichia coli O157:H7 gal mutants are sensitive to bacteriophage P1 and defective in intestinal colonization.

Enterohemorrhagic Escherichia coli (EHEC), especially E. coli O157:H7, is an emerging cause of food-borne illness. Unfortunately, E. coli O157 cannot be genetically manipulated using the generalized transducing phage P1, presumably because its extensive O antigen obscures the P1 receptor, the lipopolysaccharide (LPS) core subunit. The GalE, GalT, GalK, and GalU proteins are necessary for modifying galactose before it can be assembled into the repeating subunit of the O antigen. Here, we constructed E. coli O157:H7 gal mutants which presumably have little or no O antigen. These strains were able to adsorb P1. P1 lysates grown on the gal mutant strains could be used to move chromosomal markers between EHEC strains, thereby facilitating genetic manipulation of E. coli O157:H7. The gal mutants could easily be reverted to a wild-type Gal(+) strain using P1 transduction. We found that the O157:H7 galETKM::aad-7 deletion strain was 500-fold less able to colonize the infant rabbit intestine than the isogenic Gal(+) parent, although it displayed no growth defect in vitro. Furthermore, in vivo a Gal(+) revertant of this mutant outcompeted the galETKM deletion strain to an extent similar to that of the wild type. This suggests that the O157 O antigen is an important intestinal colonization factor. Compared to the wild type, EHEC gal mutants were 100-fold more sensitive to a peptide derived from bactericidal permeability-increasing protein, a bactericidal protein found on the surface of intestinal epithelial cells. Thus, one way in which the O157 O antigen may contribute to EHEC intestinal colonization is to promote resistance to host-derived antimicrobial polypeptides.

Animals↗
PubMed2000

Predictions of biodiversity response to genetically modified herbicide-tolerant crops.

We simulated the effects of the introduction of genetically modified herbicide-tolerant (GMHT) crops on weed populations and the consequences for seed-eating birds. We predict that weed populations might be reduced to low levels or practically eradicated, depending on the exact form of management. Consequent effects on the local use of fields by birds might be severe, because such reductions represent a major loss of food resources. The regional impacts of GMHT crops are shown to depend on whether the adoption of GMHT crops by farmers covaries with current weed levels.

Agriculture↗
PubMed1995

Biotechnology and potential nutritional implications for children.

The tools of biotechnology have enormous potential to develop new, safe, and nutritious foods and food products that could benefit the immediate and long-term nutritional and health needs of the pediatric population. This is especially true as more emphasis is placed on the prevention, rather than the treatment, of chronic degenerative and metabolic diseases. But the promise of biotechnology for nutritional and health benefits of children's diets must be accepted with cautious optimism. Many advances in food technology and nutritional composition of food animals and plants have already been made through biotechnology, but they represent only the beginning of the necessary research. These advances have been based on relatively little knowledge of basic human nutritional needs, particularly during the dynamic pediatric period of growth and development. More importantly, these advances have been predicated with no understanding of dietary nutrient interactions. Changing nutrient composition of foods through biotechnology may alter nutrient interactions, nutrient-gene interactions, nutrient bioavailability, nutrient potency, and nutrient metabolism. Biotechnology has the potential to produce changes in our foods and in our diet at a pace far greater than our ability to predict the significance of those changes on pediatric nutrition. The Human Genome Project, which relies on biotechnology, will revolutionize science and medicine. Pediatrics will be one of the first medical specialties to benefit from the outcome of this project as recombinant DNA manipulations will replace diet therapies for treating metabolic diseases. Somatic gene therapy eventually may be the ideal means for diagnosis, treatment, and cure of inherited diseases and metabolic disorders; however, many problems exist, especially in situations in which nutrients are involved in the complex regulation of gene expression. DNA and genes themselves do not determine the fate of an individual. The genetic material provides the potential for the individual, but this potential can be modified by environmental factors. The interaction of nutrients with genes is a major determinant in the final outcome of the individual. Biotechnology promises children a more productive and better quality of life, but achieving the full potential of this promise demands a continued diligent search for knowledge of nutrition and nutrient-gene interactions.

Biotechnology↗
PubMed1996

Modification of biochemical pathways in industrial yeasts.

Yeasts have many applications in industrial food and beverage production. While these uses are often of ancient origin, modern demands for control of the amounts of process-derived compounds and for cost-effective processing can make it desirable to modify metabolic pathways of production yeasts. While the genetics of standard laboratory strains of Saccharomyces cerevisiae are well described, industrial strains and species are less characterized, and many of them have a complicated genetic constitution. Nevertheless, their biochemical pathways can be modified, and the knowledge becoming available on the physiology of genetic reference strains of S. cerevisiae is a great help in directing the modifications of the industrial yeasts towards practical goals.

Amino Acids↗
PubMed2004

The influence of dietary flaxseed and other grains, fruits and vegetables on the frequency of spontaneous chromosomal damage in mice.

Spontaneous genetic damage, whether mutations or chromosomal aberrations, undoubtedly arise from a variety of sources including replication errors, oxidative damage, background radiation, and chemical exposure. Given the numerous correlations between diet and cancer, it seemed possible that diet could influence the spontaneous rate of DNA damage and its genetic consequences. Since diets high in vegetables, fruits, and grains are associated with lower rates of cancer, we supplemented the diets of mice and measured the frequency of micronuclei in the peripheral blood. Micronuclei arise from broken chromosomes or chromosome loss in the erythroblast. They are first seen in the short reticulocyte stage of the red blood cell but persist for the entire 30-day lifespan of the cell in mice. C57Bl mice were placed on a defined diet (AIN-93G) supplemented to 20% final dry weight with grains or freeze-dried fruits or vegetables. The micronucleus frequency was measured in a pre-exposure blood sample and every 2 weeks thereafter for 6 weeks. This was possible in spite of the low spontaneous frequency of 1/1000-2/1000 cells by the use of a novel flow cytometric method, which permitted the analysis of both the mature red blood cells and reticulocytes. Of the foods tested, flaxseed proved to be the most protective by reducing the incidence of micronuclei in both the reticulocyte and normochromatic erythrocyte cell populations by 30 and 11%, respectively. The results show that at least one class of spontaneous genetic damage can be modified by diet and suggests that short-term experiments with small numbers of animals can be used to identify dietary anticarcinogens that may influence human cancer rates.

Animals↗