Development of an immunoassay for the residues of the herbicide bensulfuron-methyl   总被引：9，自引：0，他引：9  

Lee JK  Ahn KC  Park OS  Ko YK  Kim DW 《Journal of agricultural and food chemistry》2002,50(7):1791-1803

To develop a competitive indirect enzyme-linked immunosorbent assay based on polyclonal antibodies for the detection of the sulfonylurea herbicide bensulfuron-methyl, seven structurally related haptens were synthesized. Four of them mimicking the target analyte were conjugated to keyhole limpet hemocyanin by the N-hydroxysuccinimide activated ester method to use as immunogens, and all of them were conjugated to bovine serum albumin to use as plate-coating antigens. Polyclonal antibodies raised in rabbits and the coating antigens were screened and selected for the assay in simple homologous and heterologous ELISA formats. Three sensitive heterologous ELISAs were selected and optimized, showing the average IC(50) values of bensulfuron-methyl as low as 0.17, 0.09, and 0.09 ng/mL, the detection ranges of 0.04-0.60, 0.01-0.60, and 0.04-0.25 ng/mL, and the lowest detection limits of 0.03, 0.002, and 0.03 ng/mL, respectively. The cross-reactivities of other sulfonylurea herbicides and metabolites of bensulfuron-methyl to the antibodies were less than 15% in the two assays. Recoveries from the analyte-fortified water samples in assay I were in the range of 81-125% by simple dilution. The correlation between the ELISA and HPLC was 0.999 (n = 15) with a slope of 1.37 in the analysis of groundwater samples fortified with bensulfuron-methyl. The results obtained strongly indicate that the ELISA can be a highly sensitive and convenient tool for detecting bensulfuron-methyl residues in agricultural and environmental samples.  相似文献   

Effect of organic-phase solvents on physicochemical properties and cellular uptake of astaxanthin nanodispersions     

Anarjan N  Tan CP  Ling TC  Lye KL  Malmiri HJ  Nehdi IA  Cheah YK  Mirhosseini H  Baharin BS 《Journal of agricultural and food chemistry》2011,59(16):8733-8741

A simplex centroid mixture design was used to study the interactions between two chosen solvents, dichloromethane (DCM) and acetone (ACT), as organic-phase components in the formation and physicochemical characterization and cellular uptake of astaxanthin nanodispersions produced using precipitation and condensation processes. Full cubic or quadratic regression models with acceptable determination coefficients were obtained for all of the studied responses. Multiple-response optimization predicted that the organic phase with 38% (w/w) DCM and 62% (w/w) ACT yielded astaxanthin nanodispersions with the minimum particle size (106 nm), polydispersity index (0.191), and total astaxanthin loss (12.7%, w/w) and the maximum cellular uptake (2981 fmol/cell). Astaxanthin cellular uptake from the produced nanodispersions also showed a good correlation with their particle size distributions and astaxanthin trans/cis isomerization ratios. The absence of significant (p > 0.05) differences between the experimental and predicted values of the response variables confirmed the adequacy of the fitted models.  相似文献   

The effect of multi-walled carbon nanotubes on the molecular orientation of poly(vinyl alcohol) in drawn composite films     

Xiao Wang  Soo Young Park  Kwan Han Yoon  Won Seok Lyoo  Byung Gil Min 《Fibers and Polymers》2006,7(4):323-327

Poly(vinyl alcohol) (PVA)/multi-walled carbon nanotube (MWNT) composite films were prepared by casting a DMSO solution of PVA and MWNTs, whereby the MWNTs were dispersed by sonication. A significant improvement in the mechanical properties of the PVA drawn films was achieved by the addition of a small amount of MWNTs. The initial modulus and the tensile strength of the PVA drawn film increased by 30% and 45% respectively, with the addition of 1 wt% MWNTs, which are close to those calculated from the rule of mixtures, and were strongly dependent upon the orientation of the PVA matrix. The mechanical properties, however, were not improved with a further increase in the MWNT content. The orientation of MWNTs in the composite was not well developed compared to that of the PVA matrix. This result suggests that the improvement of the molecular orientation of the PVA matrix plays a major role in the increase of the mechanical properties of the drawn PVA/MWNT composite films.  相似文献   

Synchronization Using PGF2α and Estradiol With or Without GnRH for Timed Artificial Insemination in Dairy Cows     

Jae Kwan JEONG  Hyun Gu KANG  Tai Young HUR  Ill Hwa KIM 《The Journal of reproduction and development》2013,59(1):97-101

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Cutaneous adverse food reactions in cats: retrospective evaluation of 17 cases in a dermatology referral population (2001–2011)     

LJ Vogelnest  KY Cheng 《Australian veterinary journal》2013,91(11):443-451

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Low levels of antibacterial drug resistance expressed by Gram-negative bacteria isolated from poultry carcasses in New Zealand     

EJ Pleydell  L Rogers  E Kwan  NP French 《New Zealand veterinary journal》2013,61(5):229-236

Abstract

AIM: To provide baseline data on the levels and patterns of antibacterial drug resistance expressed by Gram-negative bacteria isolated from poultry carcasses in New Zealand.

METHODS: Between July and December 2006, isolates of Escherichia coli (n=407) and Salmonella spp. (n=3) originating from carcass-rinse samples were submitted by testing laboratories affiliated to five major poultry processing plants. Isolates of Campylobacter jejuni (n=193) originating from retail poultry carcasses in 2005–2006 were retrieved from the Massey University archives. All isolates underwent disc diffusion susceptibility testing against panels of 12 (Enterobacteriaceae) and six (Campylobacter spp.) antibacterial drugs. Cephalothin-resistance in isolates of E. coli was confirmed using ETest strips, and confirmation of the resistance phenotypes for a subset of C. jejuni isolates used microbroth dilution assays. Patterns within the resistance phenotypes of the isolates were investigated using hierarchical clustering, and logistic regression modelling.

RESULTS: The majority of isolates (71.5% E. coli, 99% C. jejuni, and all three Salmonella spp. isolates) were fully susceptible to the drugs that were tested. Four (1%) E. coli isolates showed resistance to three or more drugs. The proportions of susceptible E. coli differed between the five processing plants. Resistances were detected in E. coli isolates, using disc diffusion to cephalothin (18.2%), ampicillin (4.4%), tetracycline (4.4%) and gentamicin (1.5%). There was an association between cephalothin-resistant isolates of E. coli and decreased susceptibility to gentamicin. Using ETests to ascertain the minimum inhibitory concentrations (MIC) of E. coli for cephalothin gave inconsistent results. One of 193 C. jejuni isolates was resistant to erythromycin, and microbroth dilution assays confirmed that this panel of C. jejuni was generally susceptible to antibacterial drugs.

CONCLUSIONS: The levels of resistance shown by Gram-negative bacteria isolated from chicken carcasses in New Zealand are among the lowest reported around the world. No resistance to extended-spectrum cephalosporin drugs was detected in E. coli, suggesting that CTX-M and AmpC beta-lactamases are rare or absent. Salmonella spp. are rarely isolated from poultry carcasses during routine testing in New Zealand, and the isolates identified during this study were fully susceptible to the drugs tested. A panel of C. jejuni isolates originating from retail poultry carcasses were susceptible to first-line and second-line antibacterial drugs. The use of cephalothin as a marker of resistance to first-generation cephalosporins may not be appropriate for non-type-specific E. coli of animal origin.  相似文献   

Flume tank and in situ trials for verification of static and dynamic methods for gear depth and underwater behavior of hairtail trolling lines     

Gebremeskel Eshetu Kebede  Chun Woo Lee  Subong Park  Mun Kwan Kim 《Fisheries Science》2018,84(6):939-952

We investigated the underwater shapes of trolling lines for the improvement of hairtail fishing efficiency. Two sets of experiments were carried out, one on a small scale, where flume tank tests of four models were scaled down by a ratio of 1:10 and trolled at different speeds, and another at full scale, comprising a survey on board a commercial fleet. In situ trials were conducted off the coast of Jeju Island, South Korea, at 33°27′57.528″N, 126°55′48.846″E, a potential fishing ground for hairtail fishing. The full-scale gear was set by altering sinker weights whilst changing the length of the warp line at different towing speeds. A dynamic method using a mass-spring technique and full-scale gear was developed. External and internal forces that govern the motion of the gear were considered. A non-linear differential equation of motion was developed, solved by a fourth-order Runge–Kutta method at a time step of 5?×?10^?4 s for each trial. A static method was also developed using full-scale gear to predict the equilibrium gear configuration under all fishing conditions. The dynamic method better predicts the actual underwater performance of trolling line gear in real time.  相似文献   

Effect of Partial Acid Hydrolysis and Heat‐Moisture Treatment on Formation of Resistant Tuber Starch     

SangIck Shin  Jaeeon Byun  Kwan Hwa Park  Tae Wha Moon 《Cereal Chemistry》2004,81(2):194-198

Structural characteristics of resistant starch (RS) were investigated. Tuber starches, hydrolyzed with 1N HCl at 35°C for 8 hr followed by autoclaving‐cooling treatment, were heated at 100°C for 16 hr after adjusting the moisture content to 20 or 30%. RS content of the tuber starches ranged from 5.4 to 22.7% depending on the source and type of treatment. Gelatinization parameters of RS isolated from partially acid‐hydrolyzed starch with autoclaving‐cooling followed by heat‐moisture treatment (HMT) showed higher enthalpy (ΔH) values and lower peak temperature (T_p) compared with non‐acid‐hydrolyzed RS. R values, the difference between completion and initial temperatures, and ΔH of RS increased by HMT. The X‐ray diffraction patterns of potato and sweet potato RS isolated from partially acid‐hydrolyzed starch with autoclaving‐cooling showed distinct sharp peaks at 15, 25, 27, and 28°, which decreased by HMT.  相似文献   

Marine microalgae as dietary supplements in the culture of juvenile Chinese horseshoe crabs,Tachypleus tridentatus (Xiphosura)          下载免费PDF全文

Billy K Y Kwan  Alice K Y Chan  Siu Gin Cheung  Paul K S Shin 《Aquaculture Research》2017,48(7):3910-3924

Five treatments (short‐neck clam Ruditapes philippinarum and four formulated diets with the green microalgae Dunaliella tertiolecta or the golden‐brown microalgae Isochrysis galbana in the ratio (dw/dw) of 5% or 10% to that of clam meat) were used to investigate the growth performance and haemolymph quality of juvenile Chinese horseshoe crabs Tachypleus tridentatus under laboratory culture. At the end of the 12‐week study, various growth and moulting indicators as well as haemolymph biochemical parameters did not show any significant differences among the treatments. Significantly higher percentages of haemolymph amoebocyte viability and granular‐spherical amoebocyte state were noted in both 5% and 10% I. galbana‐supplemented diets compared to that of clam meat. However, the percentages of these two haemolymph parameters in juveniles fed with D. tertiolecta decreased significantly at the end of the experiment. Such differences were attributed to the presence of polyunsaturated fatty acid (PUFA), notably eicosapentaenoic acid (EPA), in I. galbana that was absent in D. tertiolecta and clam meat. Like many marine invertebrates, juvenile horseshoe crabs do not naturally obtain sufficient PUFAs from their diets to meet developmental and physiological needs; hence, supplementing microalgae with high levels of EPA in a protein‐rich diet boosts immune competence and the health status of juvenile horseshoe crabs while under culture.  相似文献   

Moving beyond survivalism? Youth perspectives on non-Mandarin Chinese languages in the study of Chinese voluntary associations in Singapore and Vancouver     

Jean Michel Montsion  Junjia Ye  Justin P. Kwan 《Asia Pacific viewpoint》2023,64(3):317-328

The contributions of Chinese voluntary associations (CVAs) have often been viewed through a survivalist lens. As a process by which the activities of such organisations are interpreted through a rigid sense of what a Chinese community association is and should be, survivalist tendencies in academic scholarship must be re-thought to fully assess the functions of several types of CVAs, including amid the cultural rise of the People's Republic of China. In light of Sara Ahmed's notion of ‘orientation’, we offer a vantage point from which to rethink the roles of such associations. We do so by illuminating the contributions of key organisations involved in efforts to revitalise Chinese languages other than Mandarin in two locales outside of China, namely the Siong Leng Musical Association and Viriya Community Services in Singapore, and Wongs' Benevolent Association and Youth Collaborative for Chinatown in Vancouver. By focusing on these four voluntary associations in Singapore and Vancouver and, more specifically, on the perspectives of their youth members, we show the similar dialectical nature of their activities, which are caught in the dynamic interplays between local and global cultural forces and between intergenerational perspectives on language use.  相似文献