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Biomedical subjects

M Du

Publications and source records attributed to M Du.

At least 19 recordsLinked to original sources
PubMed2002

Off-odor volatiles and pink color development in precooked, irradiated turkey breast during frozen storage.

The effect of irradiation on color, lipid oxidation, and volatile production of precooked, irradiated turkey breast during frozen storage was studied. Turkey breast muscles were precooked, aerobically or vacuum-packaged, irradiated at 0, 2.5, or 5.0 kGy using a linear accelerator (electron beam), and then frozen-stored at -40 C. Lipid oxidation, volatiles, color values, gas production, and oxidation-reduction potential (ORP) of meat were determined during 3-mo storage periods. Ionizing radiation produced characteristic off-odor volatiles (dimethyldisulfide and methylthioethane) and lipid oxidation products in precooked, frozen turkey breast. The production of volatiles was accelerated by the confounding effect of high irradiation dose, aerobic packaging, and increased storage time. Volatile production and color changes in irradiated, precooked turkey breast were induced by different mechanisms. Irradiation increased pink color in precooked, vacuum-packaged turkey breast, and the pink color was stable during frozen storage. Decreased ORP and increased CO in irradiated meat indicated that denatured CO-heme pigments could be responsible for the pink color in precooked, irradiated turkey breast. Vacuum packaging was better than aerobic packaging in preventing lipid oxidation and oxidation-dependent volatile production, but pink color in precooked, irradiated turkey breast during frozen storage was maintained.

Animals↗
PubMed2002

Effect of dietary conjugated linoleic acid on the growth rate of live birds and on the abdominal fat content and quality of broiler meat.

Two experiments were conducted to investigate the influence of dietary conjugated linoleic acid (CLA) on the growth, body composition, abdominal fat accumulation, and meat quality in broilers. In Experiment 1, 50 broilers that were 3 wk old (total of 200 birds) were assigned to one of the four diets containing 0, 0.25, 0.5, or 1% CLA and were fed for 3 wk. In Experiment 2, 40 broilers that were 3 wk old (total of 120 birds) were assigned to one of the three diets containing 0, 2, or 3% CLA and fed for 5 wk. At the end of the 3-wk feeding trial, the average body weight of broilers for Experiment 1 was about 2.20 kg per bird for all treatments. For Experiment 2, after 5-wk feeding trial, the average body weights of birds were 4.04, 3.99, and 3.93 kg for the control, 2% CLA, and 3% CLA groups, respectively, with a non significant reduction in body weight as the levels of dietary CLA increased. There was no difference in abdominal fat weight, the total body fat, and protein content in broilers among the CLA treatments for Experiment 1. However, when the dietary CLA was increased to 2 or 3%, the total body fat content was reduced. The whole body fat content decreased from 14.2% in the control to 11.9 and 12.2% for 2 and 3% CLA, respectively. Dietary CLA at 2 and 3% levels influenced meat quality. After cooking, the breast meat from 2 or 3% dietary CLA treatment was harder and drier, and the color was a little darker than that of the control. These changes could be caused by the decreased unsaturated fatty acid content in meat after CLA feeding, which increased the melting point of the fat.

Adipose Tissue↗
PubMed2002

Effect of antioxidants on the quality of irradiated sausages prepared with turkey thigh meat.

The effects of antioxidants on the flavor and color of electron-beam-irradiated turkey sausages were studied. Sausages were prepared from turkey thigh meat, NaCl (2.0%), phosphate (0.5%), water (10%), and one of five antioxidant treatments (none, vitamin E, sesamol, rosemary extract, or gallic acid at 0.02%). Sausages were stuffed and cooked in an 85 C smokehouse to an internal temperature of 74 C, then chilled and sliced to 1.5-cm thickness, and vacuum-packaged. Packaged sausages were randomly divided into three groups and irradiated at 0, 1.5 or 3.0 kGy, using an electron beam. Volatiles, color, 2-TBA-reactive substances values, and sensory characteristics were analyzed. The antioxidant effect of sesamol was the highest, followed by vitamin E and gallic acid; rosemary extract had the weakest antioxidant effect. Irradiation induced red color in sausages, but addition of gallic acid, rosemary extract, or sesamol reduced it. Gallic acid was very effective in lowering the redness of irradiated and nonirradiated sausages. The redness (a*) values of sausages with added gallic acid that were irradiated at 0, 1.5, and 3.0 kGy were 1.49,2.03, and 2.29, respectively, whereas those of control sausages under the same irradiation conditions were 2.58, 2.81, and 3.25, respectively. The reduction of redness in irradiated sausages by antioxidants was not related to CO, because antioxidants had no effect on CO production by irradiation. The amount of total volatiles was decreased significantly by antioxidants, but antioxidants had minimal effect on the off-flavor of turkey sausages induced by irradiation.

Animals↗
PubMed2001

Novel boxlike dinuclear or chain polymeric silver(I) complexes with polypyridyl bridging ligands: syntheses, crystal structures, and spectroscopic and electrochemical properties.

The syntheses, characterization, crystal structures, and photophysical and electrochemical properties of two dinuclear and two polymeric Ag(I) complexes with three polypyridyl ligands, 2,3-di-2-pyridylquinoxaline (L(1)), 2,3-di-2-pyridyl-5,8-dimethoxyquinoxaline (L(2)), and 2,3,7,8-tetrakis(2-pyridyl)pyrazino[2,3-g] quinoxaline (L(3)), are described. The structures of the two boxlike dinuclear complexes with L(1) and L(2) and two chemically the same but differently crystallized one-dimensional zigzag chain coordination polymers also consisting of boxlike dinuclear subunits have been elucidated by X-ray analysis. [AgL(1)(CH(3)CN)](2)-(BF(4))(2).2CHCl(3) (1): monoclinic, C2/c; a = 28.631(2), b = 12.2259(11), c = 14.3058(12) A; beta = 99.180(2) degrees; Z = 4. [AgL(2)(CH(3)CN)(2)](2)(ClO(4))(2) (2): triclinic, P1; a = 12.3398(2), b = 13.750(2), c = 14.326(7) A; alpha = 83.494(3), beta = 74.631(3), gamma = 76.422(3) degrees; Z = 4. [[Ag(2)L(3)(NO(3))(2)].CH(3)CN](infinity) (3a): monoclinic, P2(1)/c; a = 9.5836(8), b = 13.4691(12), c = 14.0423(12) A; beta = 107.753(2) degrees; Z = 4. [Ag(2)L(3)()(NO(3))(2)](infinity) (3b): monoclinic, P2(1)/c; a = 8.4689(6), b = 16.0447(12), c = 11.7307(8) A; beta = 102.051(1) degrees; Z = 2. The structures of the dinuclear complexes 1 and 2 are similar to each other, with the two intramolecular Ag(I) centers of each complex being spanned by two ligands thus forming a unique boxlike cyclic dimer. In 1, each Ag(I) center is four-coordinated by three nitrogen atoms of two L(1) ligands and a CH(3)CN nitrogen donor, taking a distorted tetrahedral coordination geometry. The coordination environment of Ag(I) in 2 is similar to that in 1, except the formation of an additional weak coordination bond with the oxygen atom of the methoxy group of L(2). The structures of 3a,b are very similar to each other, except for the stacking patterns in the crystal lattices, and the cyclic boxlike dinuclear unit, which is similar to the structure of 1, constitutes the fundamental building block to form the one-dimensional zigzag chain structures due to the "end-on" nature of L(3). 1-3 exhibit metal-perturbed intraligand transitions in solution in 360-390 nm regions. Cyclic voltammetric studies of these complexes show the presence of reduction peak at approximately -0.5 V vs Fc(+/0). In the solid state at 77 K, they exhibit broad emission that may be assignable to originate from the metal-perturbed intraligand transitions.

Journal Article↗
PubMed2001

Bis[mu-2-[(1,5-diaza-1-cyclooctyl)-methyl]phenolato-N,N',O:O]bis-[chlorozinc(II)]diacetone solvate: design of a square-pyramidal ZnN2O2Cl complex.

The title complex, [Zn(2)(C(13)H(19)N(2)O)(2)Cl(2)].2C(3)H(6)O, resides on a crystallographic inversion center. The two Zn(II) centers bridged by the phenoxo groups are in pentacoordinated distorted square-pyramidal coordination environments with an intramolecular Zn...Zn distance of 3.175 (3) A. The mesocyclic ligand takes a boat-chair conformation and an H atom from the 1,5-diazacyclooctane ring effectively blocks the axial coordination site opposite the Cl ligand to form the ZnN(2)O(2)Cl geometry. The crystal structure is stabilized by a N-H...O hydrogen bond between the amino group and an acetone molecule.

Crystallography, X-Ray↗
PubMed2001

On-line incorporation of cloud point extraction to flow injection analysis.

The on-line incorporation of cloud point extraction (CPE) to flow injection analysis (FIA) is demonstrated for the first time. The technical difficulties of inducing the cloud point phenomenon, separating the surfactant-rich phase from the aqueous phase, and detecting trace amounts of analyte(s) in the presence of the highly scattering surfactant medium in an on-line FIA system were resolved by the following: (1) mixing the sample solution containing the analyte(s) and CPE surfactant with an appropriate salting-out agent, (2) using a collection column to entrap the analyte-containing surfactant aggregates, and (3) employing the peroxyoxalate chemiluminescence reaction for the sensitive and selective determination of the analyte(s) in the presence of surfactant micelles. The figures of merit for the determination of coproporphyrin in pretreated urine samples were as follows: precision, 1.1-2.2% (RSD); limit of detection, 2.0 microg/L; and the calibration curve was linear from 46 to 2319 (micro/L (r = 0.9996).

Coproporphyrins↗
PubMed2001

Evaluation of the combination of nelarabine and fludarabine in leukemias: clinical response, pharmacokinetics, and pharmacodynamics in leukemia cells.

PURPOSE: A pilot protocol was designed to evaluate the efficacy of fludarabine with nelarabine (the prodrug of arabinosylguanine [ara-G]) in patients with hematologic malignancies. The cellular pharmacokinetics was investigated to seek a relationship between response and accumulation of ara-G triphosphate (ara-GTP) in circulating leukemia cells and to evaluate biochemical modulation of cellular ara-GTP metabolism by fludarabine triphosphate. PATIENTS AND METHODS: Nine of the 13 total patients had indolent leukemias, including six whose disease failed prior fludarabine therapy. Two patients had T-acute lymphoblastic leukemia, one had chronic myelogenous leukemia, and one had mycosis fungoides. Nelarabine (1.2 g/m(2)) was infused on days 1, 3, and 5. On days 3 and 5, fludarabine (30 mg/m(2)) was administered 4 hours before the nelarabine infusion. Plasma and cellular pharmacokinetic measurements were conducted during the first 5 days. RESULTS: Seven patients had a partial or complete response, six of whom had indolent leukemias. The disease in four responders had failed prior fludarabine therapy. The median peak intracellular concentrations of ara-GTP were significantly different (P =.001) in responders (890 micromol/L, n = 6) and nonresponders (30 micromol/L, n = 6). Also, there was a direct relationship between the peak fludarabine triphosphate and ara-GTP in each patient (r = 0.85). The cellular elimination of ara-GTP was slow (median, 35 hours; range, 18 to > 48 hours). The ratio of ara-GTP to its normal counterpart, deoxyguanosine triphosphate, was higher in each patient (median, 42; range, 14 to 1,092) than that of fludarabine triphosphate to its normal counterpart, deoxyadenosine triphosphate (median, 2.2; range, 0.2 to 27). CONCLUSION: Fludarabine plus nelarabine is an effective, well-tolerated regimen against leukemias. Clinical responses suggest the need for further exploration of nelarabine against fludarabine-refractory diseases. Determination of ara-GTP levels in the target tumor population may provide a prognostic test for the activity of nelarabine.

Adult↗
PubMed2001

Experiences from a school-based oral health promotion programme in Wuhan City, PR China.

OBJECTIVES: To evaluate the effect of a six-year oral health promotion programme for school children of Wuhan City, PR China. METHODS: The programme group (P-group) comprised 233 children who had just entered grade 1 (1989). The programme provided an oral health promotion programme, and 215 12-year-old children from three schools participated as a control group (C-group). After the 6-year period of the programme (1995), all of the children had a clinical examination according to the criteria of the WHO and responded to a structured questionnaire on dental health behaviour. RESULTS: The results showed that attitudes to dental care, regular tooth brushing habits, use of fluoridated toothpaste, gingival health and dental visits, frequencies of consuming sugary drinks/foods were improved in the p-group when compared with the C-group. CONCLUSION: The school-based oral health promotion programme should be expanded.

Attitude to Health↗
PubMed2001

Production of cloned goats from enucleated oocytes injected with cumulus cell nuclei or fused with cumulus cells.

This study was designed to produce cloned goats from cumulus cells. Cloning donor nuclei were from cumulus cells either freshly isolated or cultured in vitro. Enucleated oocytes were either injected with cumulus cell nuclei without piezo-driven manipulator (injection method) or fused with cumulus cells (fusion method). The survival rate of cloned embryos, obtained by injection, was higher than that derived from fusion (62.7 and 45.9%, respectively). Two cloned goats were derived by fusion with in vitro cultured cumulus cells without starvation, but died shortly after natural birth, from respiratory difficulties. Their birth weights (2.23 kg and 2.03 kg) were within the normal range (2.0-2.7 kg) and postmortem analysis revealed no morphological abnormalities. The third cloned goat, derived by injection of nuclei from freshly isolated cumulus cells, weighed 3.3 kg at birth, and was 37% overweight compared with the average weight of the same species. This goat is healthy and well as this paper is being prepared. Nested PCR-RFLP analysis confirmed that all the cloned goats were derived from the donor cells.

Animals↗
PubMed2001

Volatiles, color, and lipid oxidation of broiler breast fillets irradiated before and after cooking.

Chicken breast fillets were equally divided into three groups. One group was vacuum packaged, cooked in a water bath (cooked-in-bag) at 82 C for 25 min, and then irradiated at 0 or 3 kGy with a linear accelerator (V-C-I). The other two groups were irradiated at 0 or 3.0 kGy in vacuum packaging (V-I-C) or aerobic packaging (A-I-C). After 3 d of storage at 4 C, the irradiated meats were cooked in a water bath (cooked-in-bag) at 82 C for 25 min. After being cooked, meats were repackaged under vacuum and stored at 4 C. Breast fillets were analyzed at 0 and 21 d after cooking and analyzed for lipid oxidation, color, and volatiles. Irradiation accelerated lipid oxidation of breast fillets. Three days of storage of raw meat in aerobic conditions after irradiation had only minor influences on lipid oxidation after cooking. However, irradiation had a significant effect on the volatile production in meat. Dimethyl disulfide, related to irradiation odor, was significantly higher in irradiated fillets than in nonirradiated fillets for V-C-I and V-I-C, whereas it was only slightly higher for A-I-C. Other volatiles, such as 3-methyl butanal and 2-methyl butanal, were also produced in significant amounts after irradiation, especially in V-C-I and V-I-C. These results showed that irradiating cooked meat induced slightly more changes in volatiles than irradiating raw meat and then cooking. The amount of dimethyl disulfide between irradiated and nonirradiated samples for A-I-C was not different, because the dimethyl disulfide produced by irradiation disappeared during the 3 d in aerobic storage before cooking. Color a* value of irradiated fillets was higher than that of nonirradiated fillets. Irradiation also induced color L* and b* value changes. After 3 d of aerobic storage after irradiation of raw meat, the influence of irradiation on color after cooking was reduced. No significant lipid oxidation occurred during storage as shown by the low values for TBA-reactive substances.

Aldehydes↗
PubMed2001

Volatile profiles and lipid oxidation of irradiated cooked chicken meat from laying hens fed diets containing conjugated linoleic acid.

The objective of this study was to determine the influence of dietary conjugated linoleic acid (CLA) on lipid oxidation, volatile profiles, and sensory characteristics of irradiated cooked chicken meat. Forty-eight 27-wk-old White Leghorn hens were fed a diet containing 0, 1.25, 2.5, or 5.0% CLA. After 12 wk of feeding trial, hens were slaughtered, and boneless, skinless breast and thigh muscles were separated. Meats of three birds from a dietary treatment were pooled and ground together through a 9-mm and a 3-mm plate, and patties were prepared. Patties were individually packaged and cooked in a water bath at 85 C for 15 min. After cooling to room temperature, patties were repackaged in oxygen-permeable or oxygen-impermeable bags, irradiated at 0 or 3 kiloGray (kGy) with an electron beam irradiator, and analyzed for lipid oxidation, volatile profiles, and sensory characteristics at 0 and 5 d of storage at 4 C. Cooked meat patties from hens fed CLA diets had lower TBA-reactive substances values and produced less hexanal and pentanal than the control. The irradiated and nonirradiated cooked chicken meat with aerobic packaging developed severe lipid oxidation during the 5-d storage at 4 C. Irradiation accelerated lipid oxidation in aerobic-packaged cooked chicken meat, but its effect was not as significant as that of the packaging. No odor differences were found among the cooked chicken meats from the different dietary CLA treatments. The increased storage stability of cooked meat from hens fed CLA diets was caused by the increased saturated fatty acids and CLA content in meat lipids. Tissue CLA was stable from oxidative changes and had minimal effect on volatile production in irradiated and nonirradiated cooked chicken meat during storage.

Animal Feed↗
PubMed2001

Aspirin and salicylate bind to immunoglobulin heavy chain binding protein (BiP) and inhibit its ATPase activity in human fibroblasts.

Salicylic acid (SA), an endogenous signaling molecule of plants, possesses anti-inflammatory and anti-neoplastic actions in human. Its derivative, aspirin, is the most commonly used anti-inflammatory and analgesic drug. Aspirin and sodium salicylate (salicylates) have been reported to have multiple pharmacological actions. However, it is unclear whether they bind to a cellular protein. Here, we report for the first time the purification from human fibroblasts of a approximately 78 kDa salicylate binding protein with sequence identity to immunoglobulin heavy chain binding protein (BiP). The Kd values of SA binding to crude extract and to recombinant BiP were 45.2 and 54.6 microM, respectively. BiP is a chaperone protein containing a polypeptide binding site recognizing specific heptapeptide sequence and an ATP binding site. A heptapeptide with the specific sequence displaced SA binding in a concentration-dependent manner whereas a control heptapeptide did not. Salicylates inhibited ATPase activity stimulated by this specific heptapeptide but did not block ATP binding or induce BiP expression. These results indicate that salicylates bind specifically to the polypeptide binding site of BiP in human cells that may interfere with folding and transport of proteins important in inflammation.

Adenosine Triphosphatases↗
PubMed2001

[Fast SEP measurement applied to intraoperative spinal cord monitoring].

Spinal cord monitoring techniques based on measuring somatosensory evoked potential (SEP) are presented. The principles and the experimental system for spinal cord monitoring are described in detail in the paper. The fast SEP measurement algorithm using pseudo-random sequence technique is also given. Experimental results show that our techniques can greatly improve the monitoring as compared to the traditional method, and further research in this connection is worth doing.

Algorithms↗