Characterization of antioxidants present in bitter tea (Ligustrum pedunculare)     

Chen ZY  Wong IY  Leung MW  He ZD  Huang Y 《Journal of agricultural and food chemistry》2002,50(26):7530-7535

The present study examined the antioxidants present in bitter tea (Ligustrum pedunculare). It was found that the crude glycoside fraction strongly protected human low-density lipoprotein (LDL) from oxidation. Further column chromatography led to purification of eight phenylethanoid or monoterpene glycosides: lipedoside A-I, lipedoside A-II, lipedoside B-I, lipedoside B-III, lipedoside B-V, lipedoside B-VI, osmanthuside B, and anatolioside. It was found that lipedoside A-I, lipedoside A-II, lipedoside B-V, and lipedoside B-VI were protective, whereas the other four compounds did not protect human LDL from Cu(2+)-medicated oxidation. Lipedoside A-I, lipedoside A-II, lipedoside B-V, and lipedoside B-VI also had a scavenging effect on 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH), comparable to that of alpha-tocopherol. The inhibitory effect of these four phenylethanoid or monoterpene glycosides on oxidation of human LDL and alpha-tocopherol was dose-dependent at concentrations of 5-40 microM. The present results demonstrate that bitter tea as a beverage contains effective antioxidants that may have benefits similar to those of green tea in terms of antioxidant activity.  相似文献   

Electron microscopical studies of the colonization of conidia of Cochliobolus sativus by soil microorganisms     

Joan N.F. Wong  K.M. Old 《Soil biology & biochemistry》1974,6(2):89-96

Conidia of Cochlioholus sativus were placed onto natural soil, incubated for periods up to 100 days, recovered and examined by scanning and transmission electron microscopy. Lysis of conidia and their colonization by soil microorganisms were studied.  相似文献   

Effects of mycorrhizal inoculation of upland rice on uptake kinetics of arsenate and arsenite          下载免费PDF全文

Fuyong Wu  Xueping Liu  Shengchun Wu  Ming Hung Wong 《植物养料与土壤学杂志》2015,178(2):333-338

We assessed the effect of mycorrhizal inoculation on short‐term uptake kinetics of arsenate and arsenite by excised roots of upland rice (Oryza sativa L. cv. Zhonghan 221). A concentration of 0.01–0.05 mM arsenic (As) differentially affected the influx rates of both arsenate and arsenite into rice roots non‐inoculated or inoculated with Glomus mosseae and G. versiforme. While V_max for arsenate uptake by non‐mycorrhizal roots was 1.02 µmol g^?1 fresh weight h^?1, it was reduced by a factor of 2.4 for mycorrhizal roots (about 0.42 µmol g^?1 fresh weight h^?1) in the high‐affinity uptake system. However, at high concentrations of 0.5–2.5 mM As only G. versiforme was able to reduce As influx. The results show that mycorrhizal effects on As uptake of upland rice are both concentration and species‐specific.  相似文献   

Effect of pH on in vitro ruminal conversion of L-tryptophan to 3-methylindole and indole   总被引：1，自引：0，他引：1  

A C Hammond  L L Slyter  J R Carlson  L P Wong  R G Breeze 《American journal of veterinary research》1984,45(11):2247-2250

Three in vitro experiments were conducted to determine the effects of pH on ruminal conversion of L-tryptophan (TRP) to 3-methylindole (3-MI) and indole (IND). Experiment 1 involved 2 closed-system incubations, each with triplicate replications of buffered ruminal fluid at initial pH of 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0. Highest molar conversions of TRP to 3-MI were 61.5 +/- 2.7% and 64.3 +/- 0.8% at initial pH treatments of 7.5 and 7.0 (final pH 7.3 and 6.9) for the 2 incubations, respectively. Experiment 2 used duplicate continuous cultures at each of 4 pH treatments. Following a common 5-day pretreatment period, effluent pH averaged 5.6, 6.1, 6.5, and 6.9 for the respective treatments. Data for 4 subsequent 5-day time periods showed production of 3-MI was affected by pH treatment (P less than 0.01), time (P greater than 0.01), and treatment X time (P less than 0.01); conversion of TRP to 3-MI reached 78% at pH 6.9 and decreased to less than 1% at pH 5.6. Production of IND was not related to pH treatment (P greater than 0.10). Total moles of volatile fatty acid (VFA) carbon produced showed a pH treatment X time interaction (P less than 0.01) which reflected a trend toward decreasing VFA production at lower pH and increasing VFA production at higher pH. Experiment 3 consisted of 2 pH treatments with additional continuous culture fermenters.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Cutaneous fungal flora in twenty horses free of skin or ocular disease     

P J Ihrke  A Wong  A A Stannard  S L Vivrette 《American journal of veterinary research》1988,49(6):770-772

The fungal flora of the hair and underlying skin from 2 sites was examined qualitatively in 20 horses free of skin or ocular disease. Fungi were isolated from both the hair and the underlying skin of all 20 horses. Twenty-two genera regarded commonly as saprophytes were identified and an additional 2 fungi resembled the perfect state of the cutaneous pathogenic genera Microsporum and Trichophyton. Cladosporium spp, Penicillium spp, and Rhizopus spp were the most frequently isolated saprophytes. In general, similar fungi were isolated from the hair and underlying skin, and differences were not noted in isolates from the saddle and rump regions.  相似文献   

National association of biology teachers (q8)     

Wong HK 《Science (New York, N.Y.)》1966,151(3712):887-889

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Evaluation of an antimicrobial resistance monitoring program for Campylobacter in poultry by simulation     

Regula G  Lo Fo Wong DM  Ledergerber U  Stephan R  Danuser J  Bissig-Choisat B  Stärk KD 《Preventive veterinary medicine》2005,70(1-2):29-43

An ideal national resistance monitoring program should deliver a precise estimate of the resistance situation for a given combination of bacteria and antimicrobial at a low cost. To achieve this, decisions need to be made on the number of samples to be collected at each of different possible sampling points. Existing methods of sample size calculation can not be used to solve this problem, because sampling decisions do not only depend on the prevalence of resistance and sensitivity and specificity of resistance testing, but also on the prevalence of the bacteria, and test characteristics of isolation of these bacteria. Our aim was to develop a stochastic simulation model that optimized a national resistance monitoring program, taking multi-stage sampling, imperfect sensitivity and specificity of diagnostic tests, and cost-effectiveness considerations into account. The process of resistance testing of Campylobacter spp. isolated from cloacal swab samples from poultry was modeled using a Markov Chain Monte Carlo model. Different sampling scenarios on the number of flocks to be tested, the number of birds from each flock, and the number of campylobacter colonies submitted to susceptibility testing were evaluated regarding the precision of the resulting prevalence estimate. Precision of the prevalence estimate was defined as the absolute difference between apparent and true prevalence of resistance. A partial budget approach was utilized to find the most cost-effective combination of samples to obtain a defined precision of the prevalence estimate. For a sampling scenario testing 100 flocks, five birds per flock, and one campylobacter colony per sample, the median error of the prevalence estimate was 2.5%, and 95% of the simulations resulted in an error of 7% or less. When the total number of samples was kept constant, maximizing the number of flocks tested, and only testing one bird per flock resulted in the most precise prevalence estimate. Submitting more than one campylobacter colony to resistance testing did not improve the prevalence estimate. Partial budget analysis indicated that the most cost-effective strategy was testing of two birds per flock, and submitting one colony per sample to resistance testing.  相似文献   

Long-term effects of early life L-arginine supplementation on growth performance, lymphoid organs and immune responses in Leghorn-type chickens     

Deng K  Wong CW  Nolan JV 《British poultry science》2005,46(3):318-324

The effects of a short-term dietary arginine supplementation after hatching on subsequent growth and the immune system were assessed in growing male Leghorn-type chickens. An arginine-deficient basal diet (67 g/kg) supplemented with 0 (control), 2.7 (LA) or 5.4 (HA) g L-arginine/kg, was offered ad libitum to 1-d-old male ISA Brown chicks for 4 weeks, then all birds were offered ad libitum a commercial pullet grower feed (8.9 g arginine/kg) for another 8 weeks. Supplemented birds had higher growth rates and feed intake than control birds during the 4-week supplementation period, but these effects did not persist into the subsequent periods. When the supplementation ceased at week 4, no differences in lymphoid organ weights relative to body weight (BW), primary serum antibody levels against sheep red blood cells (SRBC) or cutaneous reactivity of toe webs to phytohaemagglutinin (PHA) were detected. LA-fed birds had lower immunoglobulin (Ig) G levels against bovine serum albumin (BSA) than the control at week 4, but this effect did not persist at weeks 8 and 12. No difference in anti-BSA IgM levels was detected among birds at week 4; at week 12, however, the LA-fed birds had a significantly higher anti-BSA IgM level than the control. An increased anti-SRBC antibody level and a reduced relative bursa weight in HA-fed birds were evident at week 8, without any prior effects. It is concluded that short-term supplementary L-arginine had minimal effects on immunity, but some enhancement of SRBC antibody responses in later stages of growth was observed with previous L-arginine administration.  相似文献   

Herd-level risk factors for subclinical Salmonella infection in European finishing-pig herds   总被引：3，自引：0，他引：3  

Lo Fo Wong DM  Dahl J  Stege H  van der Wolf PJ  Leontides L  von Altrock A  Thorberg BM 《Preventive veterinary medicine》2004,62(4):253-266

Our objective was to find herd factors associated with pigs testing seropositive for Salmonella. Data were collected from 359 finishing-pig herds in Germany, Denmark, Greece, The Netherlands and Sweden, between 1996 and 1998. Pigs fed non-pelleted feed (dry or wet) had 2- and 2.5-times lower odds of seropositivity, compared to pigs fed pelleted feed. The protective effect of non-pelleted feed over pelleted feed may be ascribed to the structure and composition. Also, pigs that were given whey (to drink or as the liquid part of the diet) had 2.6-times lower odds to test seropositive than pigs not getting whey. Pigs produced in batches in herds with hygienic-lock facilities had >3-times lower odds for testing seropositive compared to pigs in herds where only one or neither factor was present. In herds where the caretaker(s) washed hands consistently before tending to the animals, pigs had 1.5-times lower odds of seropositivity than pigs in herds where the caretaker did not. Pigs which were able to have snout contact with pigs in neighbouring pens (because pen separations were either open or too low) had 1.7-times higher odds to test seropositive compared to pigs for which such contact was prevented. Pigs in herds recruiting from more than three supplier herds had three-times higher odds to test seropositive than pigs in herds which breed their own replacement stock or recruit from a maximum of three supplier herds.  相似文献   

The need for a cross-species approach to the study of pain in animals     

Paul-Murphy J  Ludders JW  Robertson SA  Gaynor JS  Hellyer PW  Wong PL 《Journal of the American Veterinary Medical Association》2004,224(5):692-697

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