Gene/Protein Disease Symptom Drug Enzyme Compound
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Sanitation standard operating procedures (SSOPs) are an integral component of process control and are often the first step in the implementation of food safety regulations. The objective of this study was to assess and compare the efficacies of sanitation programs used in a variety of shell egg processing facilities. In-line, off-line, and mixed operations were evaluated. Sixteen direct or indirect egg contact surfaces were sampled in various shell egg processing facilities in the southeast United States. Samples were collected at the end of a processing day (POST) and again the next morning before operations began (PRE). Total aerobic plate counts (APCs) were obtained and Enterobacteriacae were enumerated. No significant differences (P > 0.05) between POST and PRE bacterial counts were found for the 16 sampling sites. In general, high APCs were found on the wall of the recirculating water tank both POST and PRE. The APCs for the rewash belt were considerably high for all plants sampled. APCs were also high for the vacuum loaders. APCs for washers and washer brushes were relatively low for most plants sampled. PRE and POST levels of plant sanitation, as determined by direct microbial plating, did not differ significantly. At this point, it is difficult to draw definitive conclusions about how rigid SSOPs should be for the shell egg processing industry.
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PMID:Survey of shell egg processing plant sanitation programs: effects on egg contact surfaces. 1292 43

Few studies describe immune responses to exercise in children, compared with adults, and none have investigated the influence of carbohydrate (CHO) intake. We hypothesized less perturbation and a faster recovery of the immune system with exercise in children, regardless of supplemental energy. Twelve boys (9.8 +/- 0.1 y) and 10 men (22.1 +/- 0.5 y) cycled for 60 min at 70% o(2max) while drinking 6% CHO (CHO-T) or flavored water (FW-T). Blood samples were collected before (PRE), immediately after (POST), and 60 min after (REC) exercise. Boys, compared with men, had smaller (p < 0.05) increases in total leukocytes (28% versus 38%), natural killer (NK) cells (78% versus 236%), and NK T cells (42% versus 128%) at POST, averaged across beverage trials. Exercise did not increase tumor necrosis factor-alpha (TNF-alpha), but significantly (p < 0.05) increased IL-6 in men (189%), but not in boys (11%). In both trials, lymphocytes and T cells at REC were suppressed (p < 0.05), relative to PRE, in men (-21%), but not in boys (4%). IL-6 remained elevated ( p< 0.001) in men at REC, with no change from POST in boys. In boys, but not in men, CHO significantly (p < 0.05) attenuated increases in neutrophil, lymphocyte, and NK cell counts at POST. Neutrophils at REC in CHO-T were lower (p < 0.05) than in FW-T in men ( approximately 25%) and in boys ( approximately 17%). CHO had no effect on TNF-alpha or IL-6 in either group. Our results indicate a distinct pattern of the immune response to exercise and CHO intake in boys, compared with men.
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PMID:Immune responses to strenuous exercise and carbohydrate intake in boys and men. 1531 65

Two new artificial photolyase models that recognize pyrimidine dimers in protic and aprotic organic solvents as well as in water through a combination of charge and hydrogen-bonding interactions and use a mimic of the flavine to achieve repair through reductive photoinduced electron transfer are presented. Fluorescence and NMR titration studies show that it forms a 1:1 complex with pyrimidine dimers with binding constants of approximately 10(3) M(-1) in acetonitrile or methanol, while binding constants in water at pH 7.2 are slightly lower. Excitation of the complex with visible light leads to clean and rapid cycloreversion of the pyrimidine dimer through photoinduced electron transfer catalysis. The reaction in water is significantly faster than in organic solvents. The reaction slows down at higher conversions due to product inhibition.
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PMID:Design, synthesis, and evaluation of a biomimetic artificial photolyase model. 1554 85

Ultraviolet (UV) light is being considered as a disinfectant by the water industry because it appears to be very effective for controlling potential waterborne pathogens, including Cryptosporidium parvum. However, many organisms have mechanisms such as nucleotide excision repair and photolyase enzymes for repairing UV-induced DNA damage and regaining preirradiation levels of infectivity or population density. Genes encoding UV repair proteins exist in C. parvum, so the parasite should be able to regain infectivity following exposure to UV. Nevertheless, there is an increasing body of evidence that the organism is unable to reactivate following UV irradiation. This paper describes the effective inactivation of C. parvum by UV light, identifies nucleotide excision repair genes in the C. parvum and Cryptosporidium hominis genomes and discusses the inability of UV-exposed oocysts to regain infectivity.
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PMID:The response of Cryptosporidium parvum to UV light. 1566 31

The metalloporphyrins, Me-TSPP [Me=Cr(III), Mn(III), Mn(II), Fe(III), and TSPP=meso-(tetra-p-sulfonatophenyl)porphyrin], which possess electron spins S=3/2, 2, 5/2, and 5/2, respectively, comprise an important series of model systems for mechanistic studies of NMR paramagnetic relaxation enhancement (NMR-PRE). For these S>1/2 spin systems, the NMR-PRE depends critically on the detailed form of the zero-field splitting (zfs) tensor. We report the results of experimental and theoretical studies of the NMR relaxation mechanism associated with Fe(III)-TSPP, a spin 5/2 complex for which the overall zfs is relatively large (D approximately = 10 cm(-1)). A comparison of experimental data with spin dynamics simulations shows that the primary determinant of the shape of the magnetic relaxation dispersion profile of the water proton R1 is the tetragonal fourth-order component of the zfs tensor. The relaxation mechanism, which has not previously been described, is a consequence of zfs-induced mixing of the spin eigenfunctions of adjacent Kramers doublets. We have also investigated the magnetic-field dependence of electron-spin relaxation for S=5/2 in the presence of a large zfs, such as occurs in Fe(III)-TSPP. Calculations show that field dependence of this kind is suppressed in the vicinity of the zfs limit, in agreement with observation.
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PMID:NMR paramagnetic relaxation due to the S=5/2 complex, Fe(III)-(tetra-p-sulfonatophenyl)porphyrin: central role of the tetragonal fourth-order zero-field splitting interaction. 1591 23

The growing use of global freshwater supplies is increasing the need for improved modeling of the linkage between groundwater and riparian vegetation. Traditional groundwater models such as MODFLOW have been used to predict changes in regional groundwater levels, and thus riparian vegetation potential attributable to anthropogenic water use. This article describes an approach that improves on these modeling techniques through several innovations. First, evapotranspiration from riparian/wetland systems is modeled in a manner that more realistically reflects plant ecophysiology and vegetation complexity. In the authors' model programs (RIP-ET and PRE-RIP-ET), the single, monotonically increasing evapotranspiration flux curve in traditional groundwater models is replaced with a set of ecophysiologically based curves, one for each plant functional group present. For each group, the curve simulates transpiration declines that occur both as water levels decline below rooting depths and as waters rise to levels that produce anoxic soil conditions. Accuracy is further improved by more effective spatial handling of vegetation distribution, which allows modeling of surface elevation and depth to water for multiple vegetation types within each large model cell. The use of RIP-ET in groundwater models can improve the accuracy of basin scale estimates of riparian evapotranspiration rates, riparian vegetation water requirements, and water budgets. Two case studies are used to demonstrate that RIP-ET produces significantly different evapotranspiration estimates than the traditional method. When combined with vegetation mapping and a supporting program (RIP-GIS), RIP-ET also enables predictions of riparian vegetation response to water use and development scenarios. The RIP-GIS program links the head distribution from MODFLOW with surface digital elevation models, producing moderate- to high-resolution depth-to-groundwater maps. Together with information on plant rooting depths, these can be used to predict vegetation response to water allocation decisions. The different evapotranspiration outcomes produced by traditional and RIP-ET approaches affect resulting interpretations of hydro-vegetation dynamics, including the effects of groundwater pumping stress on existing habitats, and thus affect subsequent policy decisions.
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PMID:Linking riparian dynamics and groundwater: an ecohydrologic approach to modeling groundwater and riparian vegetation. 1622 61

Three covalently linked tryptophan-thymine oxetane compounds used as a model of the (6-4) photolyase-substrate complex have been prepared. Under 290 nm light, efficient splitting of the thymine oxetane with aromatic carbonyl compounds gives the thymine monomer and the corresponding carbonyl compounds by the covalently linked tryptophan via an intramolecular electron transfer, and exhibits a strong solvent dependence: the quantum yield (Phi) is ca. 0.1 in dioxane, and near 0.3 in water. Electron transfer from the excited tryptophan residue to the oxetane unit is the origin of fluorescence quenching of the tryptophan residue, and is more efficient in strong polar solvents. The splitting efficiency of the oxetane radical anion within the tryptophan.+-oxetane.- species is also solvent-dependent, ranging from ca. 0.2 in dioxane to near 0.35 in water. Thus, the back electron transfer reaction in the charge-separated species would be suppressed in water, but is still a main factor causing low splitting efficiencies in the tryptophan-oxetane systems. In contrast to the tryptophan-oxetane system, fast nonradiation processes are the main causes of low efficiency in the flavin-oxetane system. Hence, nonradiative processes of the excited FADH-, rather than electron transfer to oxetane, may be an important factor for the low repair efficiency of (6-4) photolyase.
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PMID:Model studies of the (6-4) photoproduct photoreactivation: efficient photosensitized splitting of thymine oxetane units by covalently linked tryptophan in high polarity solvents. 1639 71

We report here our femtosecond studies of the photoreduction dynamics of the neutral radical flavin (FADH) cofactor in E. coli photolyase, a process converting the inactive form to the biologically active one, a fully reduced deprotonated flavin FADH(-). The observed temporal absorption evolution revealed two initial electron-transfer reactions, occurring in 11 and 42 ps with the neighboring aromatic residues of W382 and F366, respectively. The new transient absorption, observed at 550 nm previously in photolyase, was found from the excited-state neutral radical and is probably caused by strong interactions with the adenine moiety through the flavin U-shaped configuration and the highly polar/charged surrounding residues. The solvation dynamics from the locally ordered water molecules in the active site was observed to occur in approximately 2 ps. These ultrafast ordered-water motions are critical to stabilizing the photoreduction product FADH(-) instantaneously to prevent fast charge recombination. The back electron-transfer reaction was found to occur in approximately 3 ns. This slow process, consistent with ultrafast stabilization of the catalytic cofactor, favors photoreduction in photolyase.
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PMID:Femtosecond dynamics of flavin cofactor in DNA photolyase: radical reduction, local solvation, and charge recombination. 1685 Oct 98

Escherichia coli photolyase catalyzes the repair of cyclobutane pyrimidine dimers (CPD) in DNA under near UV/blue-light irradiation. The enzyme contains flavin adenine dinucleotide (FAD) and methenyltetrahydrofolate (MTHF) as noncovalently bound light sensing cofactors. To study the apoprotein-chromophore interactions we developed a new procedure to prepare apo-photolyase. MTHF-free photolyase was obtained by binding the C-terminal His-tagged holoenzyme to a metal-affinity column at neutral pH and washing the column with deionized water. Under these conditions the flavin remains bound and the defolated enzyme can be released from the column with 0.5 M imidazole pH 7.2. The MTHF-free protein was still capable of DNA repair, showing 70% activity of native enzyme. Fluorescence polarization experiments confirmed that MTHF binding is weakened at low ionic strength. Apo-photolyase was obtained by treating the His-tagged holoenzyme with 0.5 M imidazole pH 10.0. The apo-photolyase thus obtained was highly reconstitutable and bound nearly stoichiometric amounts of FAD(ox). Photolyase reconstituted with FAD(ox) had about 34% activity of native enzyme, which increased to 83% when FAD(ox) was reduced to FADH(-). Reconstitution kinetics performed at 20 degrees C showed that apo-photolyase associates with FADH(-) much faster (k(obs) approximately 3,000 M(-1) s(-1)) than with FAD(ox) (k(obs)=16 [corrected] M(-1) s(-1)). The dissociation constant of the photolyase-FAD(ox) complex is about 2.3 microM and that of E-FADH(-) is not higher than 20 nM (pH 7.2).
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PMID:Reversible resolution of flavin and pterin cofactors of His-tagged Escherichia coli DNA photolyase. 1693 96

The aim of this study was to investigate in a placebo-controlled field study the effect of a (n-3)-vitamin supplementation on erythrocyte membrane fluidity (EMF), oxidant/antioxidant markers and plasmatic omega3/omega6 fatty acid ratio (FAR) in 12 eventing horses. Venous blood was sampled at rest before (PRE) and after (POST) a three week treatment period with either the supplement (group S, n=6) or a placebo (group P, n=6) as well as after 15min (POST E15') and 24h (POST E24h) after a standardised exercise test. The following markers were analysed: EMF, plasma antioxidant capacity of water and lipid soluble components, ascorbic acid, uric acid (UA), glutathione (reduced: GSH, oxidised: GSSG), vitamin E (Vit E), beta-carotene, glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity, selenium, copper (Cu), zinc (Zn), oxidised proteins (Protox), lipid peroxides (Pool) and FAR. EMF did not differ between group S and P after treatment, but GPx remained unchanged in group S whereas it decreased in group P and plasma Cu/Zn ratio remained unchanged whereas it increased in group P. FAR were significantly increased in group S. Exercise induced a significant decrease of EMF (POST vs. E24h) in both groups, but which was significantly lower at E15' in group S than in group P. Exercise induced a significant increase of UA and ACW (POST vs. E15') and Protox (POST vs. E24h) in both groups. An exercise-related decrease in GSH and Pool (POST vs. E15') was found in group P, whereas Vit E and FAR (POST vs. E24h) significantly decreased in both groups. The study showed that exercise induced a decrease in EMF in horses associated with changes of blood oxidative balance. The (omega-3)-vitamin supplementation tested improved the oxidative balance poorly but delayed the exercise-induced decrease of EMF and increased the FAR.
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PMID:Effects of exercise and oral antioxidant supplementation enriched in (n-3) fatty acids on blood oxidant markers and erythrocyte membrane fluidity in horses. 1711 Jan 41


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