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81.
The properties of an Fe(3+)-peptide complex containing 5.6% Fe, obtained by the reaction of ferric chloride with an enzymatic hydrolysate of casein, are described. The major site of iron binding corresponds primarily to the carboxylate groups and to a lesser extent to the peptide bonds. The Fe(3+)-peptide complex is insoluble at acid pH and completely soluble at neutral to alkaline pH. When soluble, the Fe(3+) is tightly bound to the complex peptide mixture but can be displaced and complexed by a low molecular weight ligand such as cysteine. Its efficacy in relation to iron sulfate was compared in rats. Both iron sources were administrated in Milli-Q water by gastric gavage to male Wistar rats (180-200 g) after an 18 h fast with water ad libitum. Fe(3+) from the Fe(3+)-peptide complex was transferred to the blood in a dose-dependent manner (1-8 mg of Fe/kg), and the serum iron levels were significantly higher (p < 0.001) than in a similar group of rats treated with iron sulfate. In the comparative kinetics experiments, the rats received 4 mg of Fe/kg. Both iron sources presented maximum absorption, as indicated by the elevation of serum iron levels, 30 min after administration, and the AUC(0)(-->2h) of the Fe(3+)-peptide complex was significantly higher (p < 0.05) than that observed with iron sulfate. The simultaneous administration of free peptides (0-192 mg) with the Fe(3+)-peptide complex or iron sulfate did not modify the extent of absorption of iron from both sources, suggesting that the absorption is due to the complex formed and probably not to exchange reactions in the gastrointestinal tract. In the hemoglobin repletion experiments carried out on newly weaned rats with anemia induced by a low-iron diet, supplementation of the diet with the the Fe(3+)-peptide complex was as efficient as supplementation with iron sulfate in the conversion from diet to hemoglobin iron. These results, taken together, suggest that the Fe(3+)-peptide complex is a potential compound for use as an iron source in biological situations.  相似文献   
82.
The 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(*)(+)) assay was adapted to a flow injection (FI) system to obtain a sensitive and rapid technique for the monitoring of antioxidant activity of pure compounds and complex matrixes, such as beverages and food extracts. The FI system includes a HPLC pump that flows the mobile phase (a solution of ABTS(*)(+) in ethanol) through a 20 microL loop injector, a single bead string reactor filled with acid-washed silanized beads, a delay coil and a photodiode array UV-visible detector. The technique was very sensitive, with limits of detection and of quantification of 4.14 and 9.29 micromol of Trolox/L, respectively, and demonstrated high repeatability and reproducibility. The proposed technique was then applied to the evaluation of the antioxidant activity of some pure compounds, demonstrating good agreement with published data obtained by the original spectrophotometric ABTS(*)(+) assay. Finally, the total antioxidant activity of 10 beverages was determined by both the proposed and the original method. The values ranged from 0.09 mmol L(-)(1) for cola to 49.24 mmol L(-)(1) for espresso coffee and did not result significantly different from those obtained by the original spectrophotometric ABTS(*)(+) assay (Student's paired t-test: t = 1.4074, p = 0.1929). In conclusion, the proposed FI technique seems suitable for the direct, rapid and reliable monitoring of total antioxidant activity of pure compounds and beverages and, due to the ability to operate in continuous, it allows the analysis of about 30 samples h(-)(1) making the assay particularly suitable for large screening of total antioxidant activity in food samples.  相似文献   
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84.
Biospecific interaction analysis (BIA) was performed using surface plasmon resonance (SPR) and biosensor technologies to detect genetically modified Roundup Ready soybean gene sequences. We first immobilized, on SA sensor chips, single-stranded biotinylated oligonucleotides containing soybean lectin and Roundup Ready gene sequences, and the efficiency of hybridization to oligonucleotide probes differing in length was determined. Second, we immobilized biotinylated PCR products from nontransgenic soybeans (genomes carrying only the lectin gene), as well as from genetically modified Roundup Ready soybean, and we injected the oligonucleotide probes. Furthermore, we used the sensor chips carrying either lectin and Roundup Ready soybean PCR products or 21-mer oligonucleotide as probes, and we injected both nonpurified and purified asymmetric PCR products. The results obtained show that 13 and 15 mer oligonucleotides are suitable probes to detect genetically modified Roundup Ready soybean gene sequences (either target oligonucleotides or PCR products) under standard BIA experimental conditions. By contrast, when 11 mer DNA probes were employed, no efficient hybridization was obtained. All the SPR-based formats were found to be useful for detection of Roundup Ready gene sequences, suggesting that these procedures are useful for the real-time monitoring of hybridization between target single-stranded PCR products, obtained by using as substrates DNA isolated from normal or transgenic soybeans, and oligonucleotide or PCR-generated probes, therefore enabling a one-step, nonradioactive protocol to perform detection.  相似文献   
85.
Surface plasmon resonance (SPR) based biosensors have been described for the identification of genetically modified organisms (GMO) by biospecific interaction analysis (BIA). This paper describes the design and testing of an SPR-based BIA protocol for quantitative determinations of GMOs. Biotinylated multiplex Polymerase Chain Reaction (PCR) products from nontransgenic maize as well as maize powders containing 0.5 and 2% genetically modified Bt-176 sequences were immobilized on different flow cells of a sensor chip. After immobilization, different oligonucleotide probes recognizing maize zein and Bt-176 sequences were injected. The results obtained were compared with Southern blot analysis and with quantitative real-time PCR assays. It was demonstrated that sequential injections of Bt-176 and zein probes to sensor chip flow cells containing multiplex PCR products allow discrimination between PCR performed using maize genomic DNA containing 0.5% Bt-176 sequences and that performed using maize genomic DNA containing 2% Bt-176 sequences. The efficiency of SPR-based BIA in discriminating material containing different amounts of Bt-176 maize is comparable to real-time quantitative PCR and much more reliable than Southern blotting, which in the past has been used for semiquantitative purposes. Furthermore, the approach allows the BIA assay to be repeated several times on the same multiplex PCR product immobilized on the sensor chip, after washing and regeneration of the flow cell. Finally, it is emphasized that the presented strategy to quantify GMOs could be proposed for all of the SPR-based, commercially available biosensors. Some of these optical SPR-based biosensors use, instead of flow-based sensor chips, stirred microcuvettes, reducing the costs of the experimentation.  相似文献   
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87.
The karité (Vitellaria paradoxa Gaertner) is an economically important African tree with significant but little studied variation across its broad distribution range. Differences in economically important fat characteristics were determined for 42 karité populations in 11 countries. The results showed very high variability in all measured parameters both within and between populations. Kernel fat content range is generally 20–50%. Fatty acid composition is dominated by stearic (25–50%) and oleic (37–62%) acids. The variable relative proportions of these two fatty acids produces major differences in karité butter consistency across the species distribution range. The principal triglycerides are stearic-oleic-stearic (13–46%) and stearic-oleic-oleic (16–31%). Ugandan karité fat is liquid and requires fractionation to obtain a butter. West African karité butter is more variable, with soft and hard consistencies produced within the same local populations. The hardest butters are produced on the Mossi Plateau in Burkina Faso and northern Ghana. The implications of distinctive population characteristics as germplasm resources for the chocolate and cosmetic industries are discussed.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   
88.
Based on cluster groups from the first-round analyses of the Third International Swine CD Workshop, 38 monoclonal antibodies (MAbs) including eight internal controls were analysed by flow cytometry (FCM) and immunohistochemistry (IH) in the second-round analysis of the B-cell section of this workshop. Targets in this section included peripheral blood lymphocytes and cells isolated from ileal Peyer's patches (PP), mesenteric lymph nodes (MLN) of adult animals, bone marrow cells from newborn piglets and thymus cells isolated from foetuses at day 105 of gestation.Immunohistochemistry of these 38 MAbs identified four sets, whose ligands were co-expressed with CD21, which showed a tissue distribution compatible with specificity for cells including those of the B-cell lineage. Another group of miscellaneous antibodies appeared to identify other cells, several antibodies were negative. Two-colour flow cytometry (2C-FCM) was carried out by pairing each antibody of interest with antibodies to SWC7, CD21, sIgM and a polyclonal rabbit anti-swine immunoglobulin antiserum (RaSwIg).The anti-CD21 MAb BB6-11C9 (no. 20) and IAH-CC51 (no. 19), established in previous workshops, as well as the cross-reactive anti-human CD21 B-1y4 (no. 146), clustered together in FCM analyses of the first round and showed similar cellular distribution in IH. A further cluster was formed by the standard CC55 (no. 55) and 2A10/8 (no. 102) submitted as SWC7 specific. The second SWC7 standard 2F6/8 (no. 100) clustered separately, but IH showed an identical pattern of reactivity to the other SWC7 MAb.Unfortunately, this work could not identify any other novel clusters with specificity for B-cells, as the statistical clustering of other MAbs could not be substantiated by IH or subsequent two-colour-FCM work. However, we could identify MAb with similar cellular distribution. The ligands for the cross-reactive anti-human CD40 G28.5 (no. 25) and STH224 (no. 153) were expressed on very similar targets, similarly the ligands for the MAb pair JM1H1 (no. 139) with BB6-10A10 (no. 142) and the MAb pair 3F7/11 (no. 115) with 1C2F10 (no. 187).  相似文献   
89.
The aim of this study was to assess extenders for cooling equine semen at 5°C and to be used in assisted reproductive technologies (ARTs). Four ejaculates were obtained from each of four stallions. Gel-free semen was diluted in three different extenders: (1) SMK, an opaque skim milk–based extender; (2) SMT, a skim milk (65%) and Tyrode medium (35%); and (3) BSAG, a clear extender containing 1% bovine serum albumin. Samples were packaged (10 mL; 50 × 106 sperm/mL) and stored in a cooling device at 5°C for 12 hours. Analyses were done at 0, 4, 8, and 12 hours after cooling. Semen was analyzed for sperm motility characteristics using a computer-assisted sperm analysis, for plasma membrane and acrosome integrity and mitochondrial membrane potential, using fluorescent probes (propidium iodide, Hoechst 33342, fluorescein isothiocyanate–conjugated Pisum sativum agglutinin, and 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolyl carbocyanine iodide [JC-1]). Morphology was evaluated with differential interference contrast microscopy and sperm chromatin integrity by the toluidine blue technique. Data were analyzed by analysis of variance and by Tukey test, with time as a repeated measure (SAS, 1998), when P < .05 was significant. In general, milk-based extenders (SMT and SMK) showed improved maintenance of semen quality compared with BSAG. Finally, the addition of skim milk to equine semen extender for cooling at 5°C for 12 hours seems to play a crucial role in sperm preservation. Although, optically clearer extenders are desired for use in ARTs, such as sperm sexing, the milk-free extender (BSAG) is less efficient for cooled-stored equine semen.  相似文献   
90.
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